NAS-NS-3058.txt

Nationdal

 

Academy
of
Sciences

National Research Council

The Radiochemistry
of Plutonium

U

R 1,111 3%
7 Commission

 
COMMITTEE ON NUCLEAR SCIENGCE

D. A. Bromley, Chairman
Yale University

R. D. Evans, Vice Chairman
Massachusetts Institute of Technology

Lewis Slack, Secrelary
Naticnal Research Council

E. C. Anderson
Los Alamos Scientific Laboratory

N. E. Ballou
U. 8. Naval Radiological Defense
Laboratory

Martin J. Barger
National Bureau of Standards

C. J. Borkowski
Oak Ridge National Laboratory

Herbert Goldstein
Columbia Universgity

Bernd Kahn
Taft Sanitary Engineering Center

LIAISON MEMBERS

Harold Glager
Office of Naval Research

George A, Kolstad

Jerry B. Marion
University of Maryland

R. L. Platman
Argonne National Laboratory

Ernest C. Pollard
Pennsylvania State University

Katharine Way
Oak Ridge National Laboratory

George W. Wetherill

‘University of California

Marvin E. Wyman
University of Illinois

William §. Rodney
National Science Foundation

Atomic Energy Commission

SUBCOMMITTEE ON RADIOCHEMISTRY

Nathan E, Ballou, Chairman
1J. 8. Naval Radiological Defense
Laboratory

G. R. Choppin
Florida State University

Herbert M. Clark
Rensselaer Polytechnic Institute

Richard M. Diamond
Lawrence Radiation Laboratory

Jerome Hudls
Brookhaven National Laboratory

Jere D. Knight
Los Alamos Scientific Laboratory

W. E. Nervik
Lawrence Radiation Laboratory

Julian M. Nielsen
Battelle Pacific Northwest

G. D. O'Kelley
Oak Ridge National Laboratory

E. P. Steinberg
Argonne National Laboratory

D. N. Sunderman
Battelle Memorial Institute

John W. Winchester
Massachusetie Institute of Technology

R. P. Schuman, Consultant
Sri Venkateswara University
Tirupati, Andhra Pradesh, India
The Radiochemistry of Plutonium
George H, Coleman

September 1, 1965

UNIVERSITY OF CALIFORNIA
Lawrence Radiation Laboratory

Livermore, California

AEC Contract No, W-7405-eng-48

Subcommittee on Radiochemistry
Nationel Academy of Sciences— Nationzl Research Council

 

Printed in USA, Price $2.00. Available from the Clearinghouse for Federal
Scientific and Technical Informaton, National Bureau of Standards, U. S.
Department of Commerce, Springfield, Virginia.
FOREWORD

The Subcommittee on Radiochemistry is one of a number of
subcommittees working under the Commlittee on Nuclear Scilence
wlthln the Natlonsal Acedemy of Sciences - Nationael Research
Council. TIte members represent government, industrial, and
university laboratories in the areas of radiochemiptry and
nuclear chemipgtry. Support for the activities of this and
other subcormittees of the Committee on RNuclear Sclence is
provided by a grent from the Natiomal Scilence Foundation.

The Subcommittee has concerned 1tself with preparation of
publications, encouraging and supporting activitles in nuclear
education, spomsoring sympoeiz on selected current topics 1n
radiochemistry and nuclear chemlstry, and investigating special
problems as they ariese. A series of moncgraphs on the radio-
chemistry of essentielly all the elemente and on radiochemical
technlques is being published. Initiation end encouragement
of publicatlon of erticles on nuclear education in various
subjJect areas of chemistry bave occurred, and development and
improvement of certain educetional mctivities (e.g., laboratory
and demonstration experiments with radiocasctivity) have been
encouraeged and asgisted. Radloactive contaminatlon of reagents
end materinls has been lnvestigeted and epeclfic recommendatlons
made.

This serlies of monographs bas resulted from the need for
comprehensive compllations of radiochemical and nuclear chemical
information. Each monograph collects in one volume the pertinent
information required for radlochemical work with an individual
element or with a specialized technique, The U, S, Atomlc Energy
Commission hes sponsored the printing of the series.

Comments and suggestions for further publicatione and

activitles of value to persons working with radlcasctivity are
welcomed by the Subcommittee.

N. E. Ballou, Chalrman
Subcommittee on Radiochemistry

iil
PREFACE

This report has been prepared as one of a series of monographs on the radio-
chemistry of the elements for the Subcommitte on Radiochemistry of the Committee
on Nuclear Science within the National Academy of Sciences. There is included a
review of the nuclear and chemical features of plutonium of particular interest to
the radiochemist, a discussion of sample dissolution and counting techniques, and
finally, a collection of radiochemical procedures for plutonium .

The literature search was completed epproximately through September 1964.
It is hoped that the bibliography is sufficiently extensive to serve the needs of the
radiochemipt, but it is to be expected that important references were omitted.
The author would appreciate being made aware of such omissions, that they might
be included in possible future editions of this monograph.

The author wishee to express thanks to Dr. Earl Hyde, for the loan of his
extensive card file on the radiochemistry of plutonium, to Carl Wenarich and the
staff of the LRL Library who greatly assisted in the literature search, to Mrs.
Shauna Ness who typed the first draft, and to Mrse. Vivian R. Mendenhall who
competently edited the final draft and prepared the bibliography.

Finally the author thanks his colleagues at the Lawrence Radiation Laboratory,
especially Dr. R. W. Hoff, for reading and criticizing the manuscript, and Dr.

P. C. Stevenson for his continued interest and support during the writing of this
monogreaph,

George H. Coleman
Lawrence Radiation Laboratory

University of California
Livermore, California

iv
II.
IT1.

vL

VIIL

VIIL,

CONTENTS

General Reviews of the Inorganic and Analytical Chemistry
of Plutonium . '
General Reviews of the Radiochemistry of Plutonium .
Table of Isotopes of Plutonium . . . .
Chemistry of Plutonium of Special Interest to the Radiochemist
A. Metallic Plutonium
A.1 Preparation
A_.2 Physical Properties
A.3 Chemical Properties
B. Compounds of Pu
C. Plutonium Ions in Solution
.1 Oxidation States
2 Oxidation Reduction Reactions
3 Disproportionation Reactions
.4 Radiolytic Reduction of Pu Solutions
5 Hydrolytic Reactions of Plutonium
6 Pu(IV) Polymer
.7 Complex [on Formation .

coppaao0

D. Separation Methods
D.1 Co-precipitation and Precipitation
D.2 Solvent Extraction Methods |
D.3 Ion Exchange .
Dissolution of Plutonium Samples for Analysis
A. DMetallic Plutonium
B. Other Compounds
C. Biological and Environmental Samples
Source Preparation and Counting Methods
A. Source Preparation
A.1 Direct Evaporation
A.2 Electrodeposition
A.3 Other Methods
B. Counting
Safety Considerations
A. Radioactive Safety -
B. Criticality Safety
Collection of Procedures
A. Introduction
B, Listing of Contents

Procedure 1. Determination of Pu in solutions containing large
amounts of Fe and Cr . .

Procedure 2. Separation and determination of Pu by TTA
extraction

Page No.

© O @M B bR W N R

W © O W W O © W O W =~I N N N = =2 ==
© O 3 1 60 O 0 6 o0 o U Bk b J o0 g,

102
102
103
105

105
105

108

112
Procedure

Procedure
Procedure

Procedure

Procedure
Procedure

Procedure

Procedure

‘Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Procedure

Glossary . .

References .

3.

4.
9.
6.

9a.

9b.
10.

11.

12.

13.

14.

15.

16.

17.

18.

19.
20.

21.
22,

23.

24.

25.

CONTENTS (Continued)

"Procedures (Continued)

Separation and determination of Pu in
U - fission product mixtures

Plutonium
Plutonium

Separation of Plutonium from Uranium and
Fisgion Products in Irradiated Reactor
Targets

Determination of Pu
Uranium and Plutonium Analysis

Separation of Plutonium from Irradiated
Uranium

Separation of Plutonium from Urahium Metal

Purification of Plutonium from Uranium and
Fission Products

Uranium and Plutonium from Environmental
Samples of Soi1l, Vegetation and Water

Plutonium from Environmental Water
Samples

Plutonium from Environniental Water
Samples

Separation of Plutonium in Uranium-Plutonium
Figssion Element Alloys by TBP Extraction
from Chloride Sclutions . .

Separation of Pu before Spectrographic Analysis
of Impurities Anion Exchange Method .

Separation of Plutonium Before Spectrographic
Analysis of Impurities. Extraction
Chromatography Method Using TBP

Separation of Np and Pu by Anion Exchange

Separation of Np and Pu by Cation Excha.nge
Chromatography .

Determination of Plutonium in Urine

Determination of Pu239 in Urine (Small Area
Electrodeposition Procedure)

Determination of Plutonium in Urine

Determination of Americium in Urine in the
Presence of Plutonium . .

Determination of Plutonium in Urine by Anion
Exchange

Determination of Plutonium in Urine by Co-~
crystallization with Potassium Rhodizonate

Determination of Plutonium in Urine and Bone
Ash by Extraction with Primary Amines

Page No.

114
116
118

122
124
126

129
130

131
132
134

1317

140
142
144
148

149
150

153
155

158
161
164

166
167
169
1.

10.

11.

12,

13.

14.

15.

The Radiochemistry of Plufonifim

GEORGE H. COLEMAN
Lawrence Radiation Laboratory, Universii:y of California

Livermore, California

I. GENERAL REVIEWS OF THE INORGANIC AND ANALYTICAL
CHEMISTRY OF PLUTONIUM '

J. J. Katz and G. T. Seaborg,. '"The Chemistry of the Actinide Elements," Chap.
VIO, (John Wiley and Sons Inc., New York, 1957), pp. 239-325. _
"Plutonium," in Nouveau Traite de Chimie Minerale, Paul Pascal, Genl. Ed. Vol.

XV, "Uranium et Transuraniens' (Masson et Cie, Paris, 1962) pp 324-864.

 

"The Complex Compounds of the Transuranium Elements,'" A. D. Gel'man,

A. I. Moskvin, L. M. Zaitsev, and M. P. Mefod'eva (Consultants Bureau, New
York, 1962 transl. by C. N. and T. I. Turton). '

M. Taube, . Plutonium, (Macmillan Co., New York, 1964; transl. by E.

Lepa and-Z. Nanowski) Chap. 2, pp 39-84.

R. E. Connick, "Oxidation States, Potentials, Equilibria, and Oxidation-Reduction
Reactions of Plutonium,''in The Actinide Elements, Natl. Nucl. Energy Series, Div.
IV, Plutonium Project Record Vol. 14A; Chap. 8, G. T. Seaborg and J. J. Katz,
Eds. (McGraw-Hill Book Co., Inc., New York, 1954) pp 221-300.

J. C. Hindman, "Ionic and Molecular Species of Plutonium in Solution," in The
Actinide Elements, Vol. 14A, Chap. 10, pp 371~-434.

B. B. Cunningham,l'"Preparation and Properties of the Compounds of Plutonium,"
in The Actinide Elerments, Vol. 14A, Chap. 10, pp 371-434. -

C. F. Metz, "The Analytical Chemistry of Plutonium," Anal. Chem. 29, 1748 (1957).
D. Nebel, "The Analytical Chemistry of Plutonium,'" Joint Publications Research
Service NYC, AEC Report JPRS-11689. transl. from Chem. Tech. Leipzig, 13
522 (1961).

P. N. Palei, "Analytical Chemistry of the Actinides,"' transl. by S. Botcharsky,
AERE-LIB/TRANS-787. (See also J. Anal. Chem. USSR 12, 663 (1957).)

A. J. Moses, ""The Analytical Chemigtry of the Actinide Elemenis' (Macmillian
Co., New York, 1963).

A. Schiffers, "Plutonium, seine chemischen und physillilischen Eigenschaften,"
Chemiker Zeit. 86, 656 (1962).

K. W. Bagnall, "The Transuranium Elements," Sci. Progr. (London) 52, 66-83
{(1964).

V. I Kuznetsov, S. B. Savvin, and V. A. Mikhailov, "Progress in the Analytical

 

 

 

 

 

Chemistry of Uranium, Thorium and Plutonium,' Russ. Chem. Rev. 29, 243 (1960).
R. Kraft, C. J. Wensrich and A. L. Langhorst, '""Chemical Analysis of Plutonium
and Plutonium Alloys: Methods and Techniques,' Lawrence Radiation Laboratory,
University of California, Livermore, Calif. UCRL-6873, 1262.

1
186.

17.

1a.

19,

I0I. GENERAL REVIEWS OF THE RADIOCHEMISTRY
OF PLUTONIUM"

E. K. Hyde, "Radiochemical Separations of the Actinide Elements!' in The
Actinide Elements, National Nuclear Energy Series, Div. IV, Plutonium
Project Record Vol. 14A, G. T. Seaborg end J. J. Katz, Eds. (McGraw-Hill
Book Co., New York, 1854) Chap. 15.

E. K. Hyde, "Radiochemical Separations Methods for the Actinide Elements,"
in Proc. of the International Conference on the Peaceful Uses of Atomic Energy,
Geneva, 1955, A/CONF. 8/7, (United Nations, New York, 1956) pp 281-303,
Paper T28.

M. P. Faugeras, ''Separation et Purification des Isotopes, (of Plutonium),! in
Nouveau Traite de Chemie Minerale, Paul Pascal, Gen. Ed., Vol. IV,
"Uranium et Transuraniens," ( Masson et Cie, Paris, 1962) pp 339-385.

M. Taube, Plutonium (Macmillan Co., New York, 1884; transl. by E. Lepa and
Z. Nanowski). "Radiochemical Methods of Analysis,' pp 78-84.
Il — TABLE OF ISOTOPES OF PLUTONIUM "

 

 

Specific a Particle
Activity Type of Energy
Isotope Half Life (d/m/ug) Decay (MeV) Method of Preparation
Pu232 36 min -- @2%, 6.58 U232 4 100 MeV a
EC 98% particles
Pu?? 20 min -- @0.1%, 6.30 U233 4 40 MeV o
EC 99 + % particles
Pu23% 9.0 hr -- @6%, 6.19 233,235 40 MeV o
EC 94% particles Daughter of
Pu>3® 26 min -- 03 X 10799, 5.85 u233:235 | 50-30 Mev
EC 99 + % a particles
Pu?3® 285 yr 1.18x10° & 5.763 (69%) TUZ°° + 40 MeV o particles
5.716 (31%) Daughter Np236
Daughter Cm?240
237 235 , .
Pu 45.6 days -- a 0.003%, 5.36 (79%) U + 40 MeV agparticles
EC99+ % 5.65 (21%)
Pu?*®® g4yr  3.88x107 & 5.495 (12%) U228 4 deuterons
- 5.452 (28%) Daughter Cm?242
Pu239 1 high energy
neutrons
Np237 + neutrons
Pu??? 24360 yr 1.36 x10° @ 5.147 (13%) UZS® 4 neutrons
5.134 (17%)
5.096 (10%)
pu®4? g580yr 5.00x10° 4 5.162 (16%) U235 4 neutrons
5.118 (24%) Pu239 + neutrons
Daughter of Cm?244
Pu??l  13.0yr  257x108  sax1073%, 4.89 %38 | neutrons
B- 99 + % Daughter of Cm245
U236 + o particles
Pu?®? 379 x10° se5x10° o 4.898 (76%) U= 4 neutrons
yr 4.858 (24%) Am241 4 neutrons
Pu?¥d 498 hr -- B~ --- Pu42 | neutrons
Pu244 7.6 X 107 42.8 a -—- Am243 + neutrons
yr Pu242 + neutrons
Pu?%®  10.6 hr -- B~ --- Pu?4% 4 neutrons
Pu246 10.85 days ~-- B~ - U23B + neutrons (ther-

monuclear explosion)

 

The data for this table were taken from the recent review of Hyde, 192 This work
should be consulted for further details and references to the literature.
IV. CHEMISTRY OF PLUTONIUM OF SPECIAL INTEREST TO THE RADIOCHEMIST
A, Metallic Plutonium

A.1 Preparation

Plutonium metal is most commonly prepared by the reduction of a halide by a more
electropositive metal such as calcium. Connor ~ has compared various combinations
of halide and reducing metal and found that the only satisfactory reactions were PuFB,
PuF , and PuCl3 reduced with Ca metal. Harmon and Reaslfi4 and 01:'1:h-3o6 have
discussed the conversion of Pu salts to metal on an industrial scale, while Anselin,

et 31.30 describe a method for the conversion on a gram scale.

A.2 Physical Properties

Pu is a typically silver-white appearing metal which has a number of peculiar
physical properties. The metal undergoes a total of five allotropic modifications
below the melting point, two of which have negative coefficients of thermal expansion.

Table IV-1 summarizes the more important physical properties.

A.3 Chemical Properties

Pu is a very reactive metal. The potential for the couple Pu = Pu Tt + e is
2.03 volts, which places it between acandium (Sc) and thorium (Th) in the EMF series
of elements. Pu oxidizes more readily than does U, and resembles cerium (Ce) in its
reactions in air. Superficial oxidation of a freshly prepared surface occurs in a few
hours in normal air. The oxide is more or less adherent, and in several days the
oxidation reaction accelerates until finally the oxidation to Pqu is complete. However,
the oxide coating protects the underlying metal in dry air, and the oxidation proceeds
more slowly. Pu metal is attacked at elevated temperatures by most gases; Hz, N2'
halogens, SOZ’ etc. Pumetal dissolves easily and rapidly in modérately concentrated
HCI1 and other halogen acids.

Pu forms intermetallic compounds with intermediate solid solutions with most

metallic elements. However, simple eutectic mixtures are usually made with the group '_

Va and VIa ‘metals, and very little solubility in either the liquid or solid state is ex-
hibited by alkali and alkaline earth metals. '
The behavior of Pu toward various solutions is given in Table IV-~2.
TABLE IV-1. Physical Properties of Plutonium Metal”

 

 

copp

Appearance

- Melting point 639.5°C
Boiling point 3508 +£ 19°C
Properties of the various @ B
allotropic modifications
Transition temperature
to next higher phase (°C) 125 210
Density (g/cm?’) 19.82 17.82
(at T°C)~ (25) (133)
Crystal structure Monoclinic Body -
centered
monoclinic
Coelficient of linear 67X 107°  41x 107"
expansion (°C-1)
(in temp range °C) (80-120) (160~200)
Liatent heat of trans-
formation to next higher 958 140
phase (cal/g-atom)
Electrical resistivity 68.5u0- cm

(at 25°C)
Self heating coefficient {1,923 £ 0.019) X 10™° W/g

Ionization potential 5.1+ 0,5 eV

 

"Data compiled from various secondary sources, including 'E‘rancis,137

Silvery white; quickly oxidizes in air

315

17,14
(235)

Orthorhombic

35 x 1070

(220-280)

156

460

15.92
(320)

Face-
centered cubic

8.6 x 1070

(340-440)

17

Colfinberry and Waldron,

475

16,00
(465)

Body-or face-
céentered
tetragonal

94

~ and Jette, 2

1
L

4
1

640

16.48
(510)

Body-
centered
cubic

15
490G-550

940
TABLE IV-2. -Behavior of Pu Metal in Various Solutions

 

 

Solution Behavior
H20 Very slowly attacked _
Salt water .Rapidly attacked after induction period
HCl, HI, HBr Rapid dissoclution

Acetic acid

HC1O
HNO

4

3

H3PO4

H2804
Sulfamic acid

No visibie reaction in concentrated acid; slow dissolution in
dilute acid '

Rapid dissolution in concentrated acid

Very slow attack, limited principelly to the oxide coating. The
surface is passivated

Rapid dissolution in concentrated acid
Very slow attack with similar behavior to I-INO3

 

Rapid dissolution

B. Compounds of Pu

Pu forms compounds with a large number of elements. Compounds of Pu in the

II through VI oxidation states are known, Cu.n.ningham,7 and Faugeras and Heuberger

128

describe the preparation and properties of those compounds which have been prepared.

Gel'man, et al.

emphasize the data on complex compounds and attempt to systematize

the data by relating the structures and coordination numbers of the complex compounds

to other actinide elements, as well as to other regions of the periodic table.

The compounds of the III, IV and VI oxidation states are the ones with which the

radiochemist deals, and the insoluble compounds are of primary interest. Of these

the insoluble hydroxides, fluorides, and oxalates, phosphates and peroxides of the

ITT and IV states are of major interest in precipitation and co-precipitation reactions

and are described in more detail in that section.

Omne of the great complicating

factors in Pu chemistry is the formation of a polymeric form by hydrolysis in dilute

acigd or neutral solutions. The polymeric form can be quite intractable in many reactions

2

and may be difficult to destroy. The section on hydrolytic reactions of Pu gives

details,

Table IV-3 lists solubility information for the more stable Pu compounds which

have been prepared.

TABLE IV-3. Solubility of Plutonium Compounds”

 

 

.Reference

Pul, -PuH, s. ™ Hcl, H,S0,, i. HNO,, decomp. in HyO
'Pu]:"-‘a—PuF4 decompoeses influoride complexing agents; e. g. H3BO3

i. H20, mineral acids
Pu02F2 i. H20 27
Na.PuF5 sl. s, dilute H-‘NOBHF, i. NaF-HF s. HSBOS'
Pul-'*‘6 decomposes violently in H20
PuCl3 8. H20, acid
CszPuCI6 8. acid, HEO
PuBr3 s, HZO
TABLE IV-3 (Cont.)

 

Reference

PuI3 5. H20
Pu(IO3)'.3 s. HNOB, i. H2504-KIO3, excess

HIO3
Pu(IO3)4 = HNOS, decomposed in stC)3
PuO2 s. slowly in boiling mineral acids;

reaction speeded by fusion with

NaHSO4 or HF added to HNOg;

solubility is more difficult if ignited

" above 500°
Pu(OH)3 8. mineral acid
Pu(OH) 8. mineral acid
4 -23 264
Pu02(OH)2 g. mineral acid, Kgp = 1.8 X.10
Pu peroxide g, conc. HNO3, HZSO4
MPu(SO4)2, M=Na, K, Rb, Cs, NH4 i. MZSO4-H2$O4, 8. H20 alcohol
Pu(SO4)2 8. HZO’ i. alcohol
M4Pu(804)4, M=K, Rb, NH4 B. H20, i. elcohol
Pu{NO,) s. H.,O, colloidal Pu forms in
3’4 %us

MZPU(Noa)G, M=K, Rb, Cs, Tl

PuPO 4

PU(HPO4)Z- XHZO
Pu,H(PO,),: YH,O0

PucC, szC3

1_31.10(303

KG[Pu(Cos)S]- mH,0

K12 [ Pu(CO3)g] - mHO
M,[PuO,(CO4)4], M=K, NH,

HPuFe(CN)g- xHg0
PUFe(CN)B

PuB[Fe(CN)G] 4 X0
(PuO,) ,[Fe(CN)g] o+ xH,0

PU(C,0,), *6H,0

Pu02(0204) -3 HZO

NaPqu(Czl-IBOz)z

aque soln. s. HNOS, ether, acetone
i. conc.HNO3, 8. H20, dil acid
s. hot conc. mineral acid; sl. s.

H3P04, NaOH; i. HC2H302

i. rnineral acid — H3PO4

s. HCl, HpSO4, i. cold conc HNO,
8. hot conc. I-l'l\TO3—1\TaLF2

i. H20, gl. s. cold mineral acids
i, alcohol

s. NagCOs, LiHCOa, sl. s.
s. mineral acid

i. HCI1

i, HCl

i. HC1

i, HC1

i. H30, s. mineral acid; sl. s. K,C,0,,
(NH).C.O 27274
: 4'27274

i. Hy0, 8. HySO4, HNO3, HCIOg4 sl. s.
acid~-K9Cg0O4, NH2C504 minimum s.
in 1.5 M HNOg - 0.025 M H,C50,

H20,

264

s. mineral acid; sl. s, acid -

H2C204
gl. s. hot H

O, s. acid

2
*Compiled primarily from the reviews of Cun.ningharn7 and Faugeras and Heuberger128

Unless otherwise specified, the data are taken from these reviews.
**The following abbreviations are usead:
s. soluble
i, insaluble
sl, s. slightly soluble
- conc. concentrated
dil. dilute .
C. Plutonium Ions in Solution
C.l Ogxidation States
Plutonium in aqueous solution exists in the +3, +4, +5, or +6 oxidation states,
resembling both uranium (U), neptunium (Np) and americinm (Am) in this respect.
The formal oxidation potential diagrams for Pu in acid and basic solution are

teken from Latimer, 220

ACID SOLUTION

2.03 Pu

+++ -0.97 Pu+4 -1.15 PuO+ -0.93 Pu02++

Pu 9

l -1.04

 

BASIC SOLUTION

2

pu 2:42 Pu(OH), 9.95

-0.76 Pu020H -0.26

 

 

 

Pu(OH)4 PuO2 (OH)2

-0.51

 

Formal oxidation potentials for Pu couples in various 1 M sclutions are shown in
Table IV-4. The displacements of the potentials are due to the complex-forming
tendencies of the anions with Pu,

TABLE IV-4, Formal Potentials for Pu Couples in Various 1 M Solutions

 

 

Pu(lI)-Pu(IV}) Pu(IV)-Pu(VI) Pu(HI)-Pu(VI) Pu(V)-Pu(VI)
HCIO, -0.982 ~1.043 -1.023 -0.92
HCl -0.970 -1.052 -1.024 -0.912
HNO, -0.92 -1,05 -1.04  —-----
H,S0, -0.74 -1.2-1.4 e-e-e- —eeees

 

The lower oxidation states become more stable in the actinide series from U to
Am, and correspondingly the higher oxidation states become more difficult to attain. -
- This effect is illustrated in Table IV-5, which shows the free energies of formation

of various actinide ions,
TABLE IV-5. Free Energy of Formation of Actinide Ions (kcal/mole)

 

 

Mt vt Mo; MO';'
U ~124.4 . -138.4 -237.6 -236.4
Np _128.4 ~124.9 ~221.0 -194.5
Pu ~140.5 ~118.2 -204.9 -18B3.5
Am -160.5 -110.2 (-194.5) -156.7

 

Thus the most stable +3 ion in this series is Am , While the most stable +6 ion is

+_|.
uo, .

enough in agueous solution to be useful in separation chemistry.

Pu is the first member of this series in which the tripositive state is stable

This fact is of supreme importance in the radiochemistiry of Pu, since Pu can be
selectively maintained in either the +3 or +4 oxidation states in separation schemes.
Advantage is taken of this ability in many of the collected procedures in section VI. -

The oxidation-reduction behavior of Pu is complicated by several factors:

(1) P&lOt disproportionates into Pu-l-4 and Puo-;'- and under certain conditions Pu+3,
put . Puo;' and Puo-;_ can all exist in equilibrium; Put? ig a small, highly

charged ion and therefore undergoes extensive hydrolysis at low acidity and forms
many stable complex ions. This tendency is a dominant feature of Pu(IV) chemistry.
Pu(IV) forms a long-chain compound or polymer by hydrolytic reactions, Pu(IV)
polymer is one of the more unpleasant aspects of Pu chemistry from the standpoint of
the radiochemist.

C.2 Oxidation-Reduction Reactions

 

Table IV-6 lists reagents and conditions to effect changes in oxidation state for
Pu ions. It must be emphasized that a relatively small change in conditions may -
produce a large change in the equilibrium, and that some of the oxidation-reduction
reactions may proceed beyond those listed. Therefore, the listed reactions should
be taken as a guide only.

In general, the change in oxidation state between +3 and +4 is rapid, since only
one electron is invalved in this change. Similarly PuO+ and Pu0++ changes are rapid.

2 2
Changes in the oxidation state of Pu which involve the making or breaking of a Pu-O
bond are usually slower. However, Hj.ndmam,184 in a general review of the kinetics of

actinide oxidation-reduction reactions, gives examples of reactions involving M-O
bonds which proceed as rapidly as some involving only electron transfer, Newton and

R:a,bideamu302 have also reviewed the kinetics of actinide oxidation-reduction reactions.
C.3 Disproporticnation Reactions

 

The potentials of the various Pu couples are such that appreciable quantities of
several oxidation states may exist in equilibrium, Pu(IV) and Pu{V) are both unstable
with respect to disproportionation into higher and lower oxidation states in weakly
acid, uncomplexed media. There are several important equilibria which must be

considered for an understanding of Pu oxidation-reduction chemistry,
TABLE TV-6. Oxidation-Reduction Reactions of Plutonium Ions*
' A. Pu(Im)—» Pu(IV)

 

 

Reagents Selution Temp. Rate Reference
- - i K .
BrQjg Dilute acid R.T. Very rapid
Cett 1.5 MHCI R.T. Very rapid
6§ M HCI, R.T. Very rapid 235
dilute H2504 R.T. Very rapid 235
(312 0.5 MHClL R.T. Slow (tl/2 > 9 hr)
H202 R-6 M HCl R.T. Equilibrium at 90%
Pu(IV) in several hours 145
4-8 M HCIO, - R.T. Equilibrium at 80-90%
Pu(IV) in several hours 145
Crzo; Dilute acid R.T. Extremely rapid
HIO, Dilute acid R.T. Extremely rapid
MnO, Dilute acid R.T. Extremely rapid 79
O, 0.5 M HCI R.T. No oxidation in 42 hr-
97° C 2.5% oxidized in 4 hr,
more rapid in higher
NOé HNO, R.T Very rapid 63
0.4 — 2 M HNOg, )
Fe(ll) Sulfamate, R.T. Complete in few minutes 63

0.1 M HNO,

 

b
This table is an enlarged version of the one given by Katz and Seaborgl which was

compiled from data given by Connick.

tained from this source.

Aok
R.T. =

room temperature.

10

Unless otherwise specified, the data were ob-
B. Pu(IV)—» Pu(I)

 

 

Reagents Sclution Temp. "Rate Reference
Hydroquinone Dilute HNO, R.T. Rapid
Ha, Pt 0.5M — 4.0 M HCI R.T. > 99% reduced in 40 min
1 0.1 M KI+ 0.4 M HCI R.T. ty)p = 2 min
I-]ZSO3 8.05 M NH4HSO3, R.T. t1/2 = ~2 min 65
.3 M HNOj3
NH,OH" 0.5 M HNO, + 0.1 M R.T. ;)5 ~40 min
NH3OHt
NHoOH- HCL, HCI mm== | e e em e me -
Zn . 0.5 M HC1 R.T. Rapid
502 1 M HNOj R.T. t1/2 < 1 min
Tit+H 6 M HCI, R.T. Very rapid 235
dilute H9504 R.T. Very rapid 235
1 NHNO3 + 1 NHpSO4R.T. Rapid 103
crit Dilute HC1 or H980O4 R.T. Rapid 235, 449
Ascorbic HNO3 Rapid 418, 402
Acid 0.5 M HNO3, 0.01 M R.T. Rapid 65
Ascorbic acid
6 M HNO3 0.1 M
Ascorbic acid, Fe(II)
Sulfarmate R.T. Rapid 65
H902 7.5 M HCI1 R.T. Complete in several hr 145

 

11
C. Pu{IvV)—> Pu(VI)

 

 

Reagents Solution Temp. Rate Reference
NaBiQOg 5 M HNOg3 + 0.84 R.T. Complete in less than
g/liter 5 min
BrO, 0.1 M BrO3, 85° C 99% oxidized in 4 hr
1 M HNOg
ce™ 0.1 M cet?, 0.5 M R.T. Complete in 15 min
HNO3
HOC1 pH 4.5, -8.2, 8o° C Complete in 15 min
0.1 M HOC1
45% K2CO3 40° C Complete in 5-10 min
H5IOg 0.02 M H5IOg, R.T. t1/2 = 100 min
_ 0.22 M HNOj
Mno; 1 M HNOj3, 0,001 M 25°C t1/2 = 50 min
MnOJZ
O3 Ce'i_3 or Ag+ catalyst 0°C Complete in 30 min
0.25 M HgS0,, no 19°C Complete in 15 hr 150
catalyst
0.25 M H9S04, no o —
catalyst 65°C Complete in 1-1/2 hr 150
2 NHCI, no catalyst R.T. 2-8 hr depending on 275, 276
concentration of Pu
Ag™ AgT +890g, 1.1 M  25°C Complete in 1 min
HNOj3
0.5 N HgSQOy4, Solid 0 361, 39
Ag(I)
Cr,Oq 0.05 M HClOy, 25°C t1/2 = 15 min
dilute H3504 R.T. Complete in 9 hr 129
HNO, 0.55 M HNOg3, 98 + 1° 80% complete in 2 hr 301
1x1073 M Pu
Cl 0.03 M H,S504 + B0°C t = 35 min
2 Saturated2C12 1/2,
0.1 M HCIOy4, 0.025 22°C t1/2 =2 hr
M Cly 0.056 M C1”
Electrolysis 0.5 M HC104 R. T. Complete in 30 min 454

 

12
D. Pu(VI)— Pu(IV)

 

 

Reagents Solution Temp, Rate Reference
HCOOH HNOq R.T. Slow
Cg0g 0.02 M HCy04 75° C tj/p = 60 min
1 23MHI, 3.1 M ? Rapid
HNOj3
++ i
Fe HCl R.T. Rapid
2-6 M HNO3, 1 M R.T. Rapid 75
Ferrous Sulfamate _
2-4 N Ho504 R.T. Fairly fast 361, 39
NO,, HNO, ? ? 96
H202 HNOg R.T. Fast, reduction 295

continues to PU(IOI)

 

E. PuV) —>Pu(lV)

 

Reagents Solution Temp. Rate Reference

 

HNOy = =m=mwmmes----—- R.T. Slow
NH3OH" 0,5 M HCI, 0.015 M R.T. Slow
NH3OH?

 

F. Pul(VI)— Pu(V)

 

 

Reagents Scolution Temp. Rate Reference
I pH 2 R.T. Instantaneous
NHoNH3 0.5 M HCL, 0,06 M 25°C ty/g = 180 min
NHgNH:
SO39 pH -2 25°C Complete in 5 min
Fett 0.052— 2 M HClO4, 0-25°C  ======-=m=mmmomo oo 301
L=

 

The first of these is the disproportionation of Pu(IV) according to the reaction

sput? + 2H,0 = opu®3 + Puos* + 4H"

for which the concentration equilibrium constant may be written
_ Pud? (puo} ™y (h*

+4.3
u )

KC

 

(P

Table IV-7 lists K, for this reaction under similar conditions of acidity and ionic
strength for different acids.

13
TABLE IV-7. Concentration Equilibrium Congtant for the Disproportionation
of Pu*® in Various Acids at 25°C*

 

+ o

 

Acid H £1.0M;u=1.0
HClOy4 9x 1073
HC1 2x 1073
HNO3 4x 107

A
sto4 Very low

 

 

H
5 Taken from Gel'man et a1.3
Appreciable quantities of Pu{Ill), Pu(IV),
and Pu(VI) cannot exist together in H2504
solutions.
These data show that strong influence of the anionic medium on the equilibrium.
The equilibrium is shified markedly to the left even at these low ionic strengths by the
strong complexes formed by Pu(IV). Conversely, the equilibrium is shifted to the right by
lowering the concentration of the acid and complex forming anion, atleast until the onset of
hydrolysis at pH 1-1.5. The hydrolytic reactions again stabilize Pu(IV).

The disproportionation reaction probably occurs as a series of bimolecular reactions.

According to Connick and McVey,lOO the reaction path may be
2Pu** = pu™ + Puo,’ (Slow)
Puog + Pu+4 = Pu02++ + Pu+3 (Fast)

The firet reaction is slow because Pu-0O bond formation is involved, while the second
reaction only requires electron transfer, The rate of the first reaction is second-
order in Pu(IV) concentration and inverse third-order in H+ concentration, The

fallowing reaction sequence is consistent with these discrepancies

Pu** + H,0 = PuoH™ + H
PuOH" + H,0 = Pu(OH), " + H'
PuOH" + Pu(om), " = Pu™® 4 Puoy + H0 + H
C1"ocker'106 determined the relative armount of c_eacfi oxidation state present over a

wide range of temperature and HNOg concentration, He found that the minimum
concentration of HNOg to prevent formation of Pu(VI) in a 4 X 1073 M Pu(IV) solution
is 1.5 M, while at 98°C the required concentration of acid is 8 M.

The gecond impartant equilibrium is the disproportionation of Pu(V), which is
unstable in moderately acid solution with respect to the reaction

2 Pu(V) = Pu(IV) + Pu(VI)

29

Connick™" describes this overall reaction as proceeding by either of the two slow

reactions
(a) 2 Puol + 4t = putt

++
9 + PuO2 + 2H20

(B) Puo, + Pu*® + 48" = 2Pu™ + 2H,0

2

14
followed by the fast reaction

(C) Puo;r + putd - Puo;‘* + put3

Reactions A and B involve the breaking of Pu-O bonds, while C does not., HReaction A
is probably only important until sufficient Pu*3 is formed for reaction B to occur,
since B is kinetically more probable than A.

These disproportionation reactions may be involved in oxidation-reduction
reactions by other reagents. Instead of direct oxidation or reduction, the
disproportionation reaction can occur first, followed by direct oxidation or reduction

of the appropriate product.

C.4 Radiolytic Reduction of Pu Solutions

 

The alpha particles emitted in the decay of Pu239

um to decompose solutions of Pu239 by radiolysis. The radiolysis products then oxidize

supply enough energy to the medi-

or reduce the Pu, depending on the nature of the solution and the oxidation state of -
the Pu, This effect was first described by Kasha and Shelin(-.-215 who noticed 0.6%
reduction of Pu(VI) to Pu(IV) per day in perchloric acid salution which was independent
of acidity over a range 0.1 to 2 M. The rate of reduction in HCl was considerably
less. In both cases the reaction is slow enough to allow the equilibrium quantities
of the various oxidation states to be present. The reduction of Pu(VI) probably
proceeds first to Pu(V), and the lower states obtained by disproportionation of this
ion.
Rabideau
rates of HC1O4 and HCl reduction and found that the situation is complicated by the

21_3 26

confirmed the above qualitative results concerning the relative

production of Cl~ in HClO4 solutions and Clg in HC1 solutions, Also, if Br is added
to HC1O4 solutions, a net oxidation instead of reduction occurs if the mean oxidation
number is initially approximately 4,

~ 308

Pages 309

and PageE and Haissinsky found that the rate of reduction depended
very strongly on the nature of the anion in a study of external gamma-radiation
induced reduction of Pu(VI). The rates of reduction decreased in the order

ClOZl= ¥ SOZ >Cl > NOS—. These results presumably also apply to auto-reduction
by alpha particles,

Popov et 53.1.320

on the other hand found only oxidation by irradiation of HNOg
. solutions of Pu with external x-radiation, . The rate of oxidation decreased with an
increase of NO3_ and total acidity.

The lesson to the radiochemist is clear: The stated oxidation states of old Pu
salutions, particularly low acidity HClO,4 and H,50, solutions, should be viewed

with suspicion.

C.5 Hydrolytic Reactions of Plutonium

Pu in all of its oxidation states exists in aqueous solutions as highly charged ions

 

and therefore undergoes hydrolysis reactions in dilute acid solutions. The tendencies
for these ions to undergo hydrolysis is dependent on the charge and ionic radius. The
tendency thus increases with increasing atomic number for all the oxidation states

of the actinide series and in the case of Pu increases in the order PuOéH- < Pu+++<Pu+4.

15
Pu+4 has approximately the same tendency to hydrolyze as Ce-Hjr but legs than that of
Hf+4 and Zr+4.

The constant for the first displacement of a proton from the hydration sphere,
along with the solubility product for the hydroxide of the various Pu ions, is given in

Table IV-8. In the case of Pu_"-3 and Pu+4, the hydrolysis reaction may be writiten

n+ _ (n-1)+ + .
Pu (,0)1" + H,0 = PuOH (H,0),*7""" + H,0" ;

or in the case of PuO-;-

+

2+ _ +
PuO, (H,0); +H,0 = PuO,OH (H,0)_ , + H,O .

2 3

PuO§+ hydrolyzes to a greater extent than a simple dipositive ion of the same
radius, showing the effect of the highly charged central Pu ion.

TABLE IV-8. First Hydrolysis Constants and Solubility Products for Plutonium Ions,

 

 

P .

Ton Hydroxide Ky Kgp of Hydroxide  p.p

putl Pu(OH), 7.22 (u = 0.069, HCIO,) 2 x 10~20 *
7.37 (u = 0.034, HCI) 7 x 1078 *

pu?t Pu(OH), 1.27 @ = 2.0)

PuO,’  PuO,(OH),  3.33 (1.86 X 10”% M HNO,) (3 +1)x10°%° (244)

 

*As quoted in Gel' man et al, _3

C.6 Pu(IV) Polymer

By far the most important hydrolytic reaction from a radiochemical standpoint
is the formation of colloidal aggregates in Pu(IV) solutions by succesgive hydrolysis
reactions. The polymer presumably forms with oxygen or hydroxyl bridges and the
reaction is apparently irreversibie, Pu(OH)4 forms when the reaction proceeds to
completion. In intermediate stages, however, the colloid remains in solution and has
properties markedly different from those of the free ion. In macro concentrations the
color of a 0.3 M HNO,4 solution changes from brown to bright green when the solution
is heated. The adsorption spectra of polymer has an entirely differerit character than
monomeric Pu(lV) solutions.

The polymer can be formed from many solutions. The formation of Pu(IV)
polymer is favored by an increase in the Pu concentration and temperature or by 'a
decrease in the acidity, As the total nitrate concentration increases the polymer

- 104

precipitates, up {0 a maximum at 2-3 M NO3 . The presence of strong complexing

-anions inhibit the formation of polymer. Nevertheless, the presence of polymeric Pu

should be suspected whenever the acid concentration is below 0,5 M.SZ'?

Polymer is
formed when solutions are diluted with water because of the existence of transient
regions of high pH, even though the final acidity may be high enough to prevent formation

327, 64

of the polymer. The polymer is also formed by adding less than a stoichio-

metric quantity of acid in the dissolution of Pu(OH) 4 precipitate. Fortunately, Pu{OH) 4

16
can be precipitated from originally monomeric golutions and redissolved without

appreciable formation of polymer by using excess reagents. 239

Pu(IV) polymer may
be completely precipitated from solution by much less than stoichiometric amounts
(approximately 0.15 equivalents of anion) of oxalate, iodate, and phosphate, for
example. This phenomenon indicates that the complex contains few charges. This

305 10 remove ionic Pu from the colloidal

fact was utilized by Ockenden and Welch
form by means of cation exchange.

Depolymerization is very slow at room temperature in moderate acid concentra-
tions. The rate is Increased by heating, stronger acid concentration, and addition of
strong complexing agents such as fluoride and sulfate.

Care must be taken to prevent the formation of Pu(IV) polymer in radiochemical
separations because of the very different chemical properties of the polymer. The
example of non-adsorption on cation exchange resin has already been given, The
Pu(IV) polymer does not extract into tri- n-butyl phosphate, (TBP), for example, but
does extract into di-n-butyl phosphoric acid, (DBP).{"l The formation of polymer in

solutions of diethylene glycol dibutyl ether (butex) has been observed.qzo7

104

Costanzo and Biggers have determined the rate of polymerization and de-

polymerization as a function of acidity, temperature, Pu concentration, and salt con-
centration. Miner278 has summarized information concerning the formation of
polymer in nitrate solutions. Both the above references give suggestions for the
avoidance of polymer formation in handling and shipping macro amounts of Pu,
Polymeric Pu(lV) adsorbs strongly onto glass, paper, etc., indicating that it is
positively charged, 78 Saturation on glass occurs at approximately 1 ug/ cmg.

Samartseva345 found that the adsorption is greater on silica than on glass, that 5 to 8

hours was necessary te reach equilibrium with 10_8 to B X 10—10 M Pu(lV) solutions,
and that adsorbtion on glass was reversgible at pH < 4,
The adsorption of Pu(IV)399 and (VI)BqE6

agqueous solution. It was found that from 1% to 4% of the Pu(IV) can adsorb on a Pt
399

on platinum (Pt) has been studied from

surface from organic extractants such as TBP, tri-n-octylamine, {TOA), etc.
Increasing the concentration of the extractant or the aqueous nitric acid phase in

edquilibrium with the organic phase decreased the adsorption.

C.7T Complex lon Formation

 

The formation of complex ionsg in aqueous solutions with anionic ligands is an
important feature of the aqueous chemistry of Pu. Complex formation and hydrolysis
are competing reactions and may be looked upon as the displacement of the HZO
molecules in the hydration sphere by the anionic ligand or by OH , respectively. The
ability of an ion to form complexes is dependent on the magnitude of the ionic potential

which may be defined by the equation
d=z/r.

z is the charge on the ion and r is the lonic radius. The values of the ionic potentialg

of Pu in different oxidation states are given in Table IV-8,

17
TABLE IV-9. Jonic Potential of Plutonium in Various Oxidation States

 

 

Cation Ionic radius (A) Charpge Ionic potential
put? | . 0.90 a+ 4.44
PuS 1.03 3+ 2.91

+2
PuO, 0.81 2+ 9.47
Pu02+ 0. 87 1+ 1.15

 

*After Gel'man et al. 3

The relative tendency of Pu ions to form complexes then is
Pu(IV) > Pu(l) > Pu(VI) > Pu(V)

Gel' man et al, 3 show that the anionic ligand has some effect on this series.
For example, the positions of Pu(IIl) and Pu(VI) are interchanged in the case of oxalate
complexes.

Singly charged anions form weaker complexes with actinides generally than do
multiply charged anions, The order of complex forming ability with some anions is

3>C1 >C104.

CO,; > C,0, > 5O, > F~ > NO
Tables IV-10, IV-11, and IV-12 list available gtability constants for complexes of
Pu(OI), Pu(fv), Pu(V), and Pu(VI), respectively, which are based on the review of
Gel' man et al. 3 The chemigtry of complex compounds and ions of the actinides was
also reviewed by Comyns.97 Table IV-13 lists stability constants for some complexes
of several actinides for comparison.

18
TABLE IV-10. Stability Constants of Pu(IIl) Iona*

 

 

IJonic
Complex-formation reaction ~_strength K Ref,
Putd+ NO, = PuNO;2 . ' 5.8 + 0.5
Putd + 2NO, = Pu(NOa); 14.3 + 0.8
Putd + 3NO; = Pu(No3);’ ' 14.4 + 0.8
Putd + c1” = Pucit? 0.5 0.58
1.0 1,1
putd s 504'2 = PusO, 10
Putd + 25072 = Pu(sO,)." 50
4 4’2 *3
3.6 x 1011
+3 -2 _ - B
Pu'” +2C,0, % = Pu(C,0,), 2.0 X 10
. 1.4 x 109
+ - -
Pu " + 3C,0O 2=Pu(CO) 3 2.4 % 109
294 294)3 10
4.5 X 10
+3 -2 -5 11
Pu*? + 4,02 = Pu(C,0,), 4.2 X 10
8.3 X 10°
Pu™ + 4HC,0, = Pu(HC,0,),; 6.3 x 1012
- 1.0 9.1 x 1010
Putd + 4% = pyy~4 1.0 x 1021
1.0 2.3 x 1017
0.1 (1.3-3.9) x 1018
pu'd + Hy 2 = Pupy? 7.7 x 101173
g 1.0 1.6 X 10°
+ 1 -2 -1 +2 +
Pu  + -2-1-12-7 = -2-P1.12-y + H -~
+3 -3 _ -9 11
Pu + 4CGH507 = Pu(C6H507)4 1x 10
+3 -2 -9 15
Pu ~ +6C,H,0. = Pu(C,H,0,), 5% 10
+ - -
Pu'? + 5C,H,0, = Pu(C,H,0,). 2 - 5 x 1016 511

 

=|=Basel:l on the review of Gel' man et al. 3 The data are taken from this source

unless otherwise specified.
ke - . )
*'y 4 is the anion of ethylenediaminetetraacetic acid.
=|‘3Va|.1ue|a| at zero ionic strengih.

19
TABLE IV-11, Stability Constants of Pu(IV) Complexes”

 

 

Ionic
Complex-formation reaction strength K Ref,
Putt+ c1m = puc1t® 1 1.38
putt + 201" = PuCl, 2 0.87
putd + NO; = Pu(N03)+3 . 2.0 2.9 + 0.6
8.0 4.7
1.0 3.48 + 0.06
+3 - _ +2
Pu(NO,)™ + NO; = Pu(NO,), 6.0 0,96
+2 - _ +
Pu(NO,), “ + NO; = Pu(NOy)] 6.0 0.33
+ - 0
0 - -
Pu(NO,) + NO; = Pu(NO,) ] ]
= T = '2 - -
Pu(NO); + NO; = Pu(NO,);
putt + BF = Pur 3+ BT 1 1.7x 10%
2 1.1x 10%
Putd + 2HF = PuF2+2+ ai”" - -
putt+ 3mF - PuF, + 85" - -
Pu+4+4H.F=PuF4+4H+ - -
Putd + so4'2 = Pu(SO4)+2 1.0 4.8 X 10°
+4 _2 0
Pu""+ 250, = Pu(s0,), - -
+4 _2 -3
Pu'® + 350, = Pu(SO,), - ]

Pu™ + 0052 = Pu(CO3)+2 10.0 9.1 x 1046
putt + 0204’2 = Pu(C,0,)* 1,3 X 1011%*
. , 1.0 3.6 X 108

+ - *
Pu -~ +2C.0.% = Pu(C.0,)0 3.2 X 1020%*
204 20475 L6
- 1.0 8.3x 108
put +3C.072 = Pu(C,0,) 2 1.0 X 1027
294 204)3 ”
: 1.0 2.5 X 1023
Put?t + 4,072 = Pu(Cc,0,) 4 8.0 X 1029%*
204 2044 o
1.0 3.0x 10
: 3.1 X 1027
Pu(HPO,), + (n+ 4 - 3m)H T
_ ntH4-Im
= Pu(PO,)_H" + (2 - m)E4PO,, - -
wherem =1,2,..5andn=0,1,2,..3m
2P + H,0, + H,0 = Pu(00)(OH)Pu*> 0.5 8.8 X 10°
+ 3HT {brown complex)
oput? + 2H,0, = Pu(00), Pu*? + 4u* 0.5 6.3 x 108

(re'd complex)

20
TABLE IV-11.

(Continued)

 

 

 

Ionic

Complex-formation reaction strength K Ref,

putd 4+ TP 2 pyy 0 0.1 1.58x 1024
1.4 x 1028

put? 4 S Hypy =3 Pugy +H' -
Pu'? + 4c H, 0.7 = PulcH,0), " 1.7 x 1027
pu** + 6C,H,072 = Pulc,H,0,);" 2.0 x 1031
Pu+4 + A(".Ac—:a=3 = Pu(AcAc)-"3 0.1 3.16 X 1010
Pu (AcAc)™S + AcAc™ = Pu(AcAc)2+2 0.1 1.58x 10°
Pu(AcAc),;t2+ AcAc™ = Pu(AcAc)y 0.1 2.51X 10°
Pu(AcAc); + AcAc” = Pu(AcAc), 0.1 1.0 x 108
Putt + C,H,0, = Pu(C,H,0,)*3 - 2.0 x 10° 359
Putt + 2C,H,05 = Pu(C,H40,)52 , 1 x 10° 359
Pu™ + 3C,H,05 = PulC,H,0,)}1 - 8 x 1013 359
Put®+ 4C,H,0, = Pu(CyH,0,), - 2 x 10%8 359
pa? + 5C,H,0, = Pu(C,H,0,)7" - 4 X 102 359
NOTES:

%
Based on the review of Gel' man et al. 3 The data

less otherwise specified,

Kok .
Values at zero ionic strength,

%
3J.f&b]:)revia‘c:lons are:

1, 474

4 ~ is the anion of ethylenediaminetetraacetic acid.

2. AcAc” = [CH,COCHCOCH,] .

21

are taken from this source un-
TABLE IV-12, Stability Constants of Pu(V) and Pu(VI) complexes*

 

 

Ionic
Complex-formation reaction strength K
PuO, + Cl™ = Pu02010 0.67
+ -9 - 4
PuO, + C,0, 2= Pu0,C,0; 3 0.05 3.3 X 107
+ 2 _ -
Puo.;’ +y % - puoz.,,""** 7.9 x 1010™3
0.05 1.6 x 1010
puo.? + NO. = PuO.NOT 72
9 3 oNOg
+ - 0
PuO,NO, + NO; = PuO,(NOg)% 36 + 0.3
PuO, 2 + C1” = PuO,C1" 1.0 1.25
0.73 % 0.07
Pu0, 2 + 2C1” = Pquclg 0.35
PuO;z +y~4 = Pqu'y-z 1.75X 101;’=3
6.9 X 107
Puol? + .02 = Puo,c.0” 1.0 4.3 x 10°
2 204 2C20, »3
5.0 X 1012
+2 ] ! 11
PuOL2 +2C,0, = PuO,(C,0,), - 1.0 3.0 X 10
PuO, 2 + CH,CO0™ = PuO, (CH,CO0)" 1.9 X 10°
PuO, 2 + 2CHCOO™ = PuO,(CH4COO), 2.0 x 108
Pu02+2 + 3CH,CO0" = PuO,(CH4COO),” 2.9 X 107
+2 -2_ -2 15%3
Pu0, + 2C0, %= Pu0,(CO,), 1 X10

 

*Taken from the review of Gel'man et a1’

* - - - o -
* ¥ 4 is the anion of ethylenediaminetetraacetic acid.

*3Va.1ues at zero ionic strength.
TABLE IV-13. Stability Constants of Complexes of Several Act:i.nides*

 

 

Complex-formation reaction U - Np Pu Am
M3+ 2C,0,72 = Me(C,0,),- - - 11.55™3 11.46™3
MeT34 4% = Mey 4** - - 21,0™3 20.6"3
Me* + C,0,% = Me(c,0, 12 8.61 8.54 8.74 -
Me*t + 20,02 = Me(C,0,), 16.9 17.54 16.9 -
Me*® +3¢,0,72 = Me(C,0,), 2 22.7 24.0 23.4 -
Me** + 4c,0,7% = Me(C,0,),7* 27.7 27.4 27.5 -
MeO," + C,0, % = MeD,(C,0,) - 5,04 4,52 -
MeO," + 2C,0,% = Me0,(C,0,),? - 7.36 7.38 -
MeO," % + CH,CO0™ = MeO,(CH,CO0) 2.7 3.31 3.27 -
MeO,"? + 2CH,CO0™ = Me02(0H3c00)2° 5.10 5.83 6.29 -
MeO, 2 + 3CH,CO0™ = MeO,(CH,CO0);”  6.41 7.90 7.36 -
MeO,+2 + €,0,72 = Me0,C,0,” 6.77 - 6.64 -
MeO, "2+ 2C,0,7% = Me0,(C,0,);2 12.0 - 11.5 -
MeO32 +2C0;2 = MeO,(CO,), 2 14,0 - 15,0 -

 

*Taken from the review by Gel'man et a.l.3

% _
Y 4 ig the anion of ethylenediaminetetraacetic acid.

e
3Therrnod:,rn.':unic values calculated by A. 1. Moskvin,

23
D. Separation Methods

D.1 Co-precipitation and Precipitation

 

Co-precipitation and precipitation present different problemes to the radiocchemist
because, in general, the insoluble compounds of Pu which have degirabie properties
in precipitation reactions are not those formed in co-precipitation reactions. Of the
and PuF, and co-precipitation of Pu(Il)

3 4
and Pu(IV) by LaF3 are analogous. Since the radiochemist is likely to have small or

common reactions, only precipitation of PuF

trace quantities of Pu in a relatively large volume, co-precipitation reactions are more

important to him, and will be considered first.

Co-precipitation
Co-precipitation reactions are extremely important in the radiochemistry
of Pu. Indeed, the first separation and isolation of the element was accomplished by
co-precipitation with LaF,. This method has become the "classic' radiochemical
method for Pu and is still widely used.

The co-precipitation behavior of Np and Pu toward a number of precipitants is
shown in Table IV-14, taken from the review of Hyde.16 The behavior of these elements
is represgentative -of the actinides in a given oxidation state, The posgsibility of separa-
tion arises when the elements can be maintained in separate oxidation states, and a
selective precipifant is used. The review of Bonner and Kahn49 gives a thorough
discussion of the mechanism of co-precipitation and a good review of co-precipitation
data for all the elements through 1949. The co-precipitation behavior of Pu has been
discussed by Leader.253

The separation of Pu by co-precipitation usually takes advantage of the afore-
mentioned oxidation and reduction cycles to effect purification. The procedure may be
illustrated with the carrying of Pu(III) and Pu(IV) and the non-carrying of Pu(VI) on
LaF

very similar to that of Pu interfere. The oxidation-reduction cycle may be repeated

3 Only those elements with co-precipitation and oxidation-reduction behavior

as many times as needed to get any desired degree of purity. The use of L‘En.F:3 pre-
cipitation ig also a valuable group gseparation and volume reduction step, since not
very many elements have acid-insoluble fluorides.

In many radiochemical procedures, LaF3 is mounted for alpha counting to

191, 83, 82, 446 Chenley et 21,83 report a 2.6 % negative bias by this

determine the Pu.
method because of absorption of the alpha particles in the LaF3. This bias is a
function of the thickness of the counting sample and must be determined for each pro-
cedure.

Calcium is one of the elements which interferes with LaF3 co-precipitation,
since the fluoride is moderately insoluble. One method of solving the problem of high
Ca concentrations (>200 mg/1) is reported by Scheidhauer and Messainguiral.351 The
Pu is oxidized to Pu(VI) and Can is precipitated away from the Pu. Following re-

duction, the Pu can either be co-precipitated or separated by other means.

24
TABLE IV-14. Co-precipitation Behavior of Trace Amounts of Plutonium and
Neptunium in Principal Valence States.16

 

 

Carrier compound Pu(III) Pu(lv) Pu(VI) Np(IV) Np(V) Np(VI)
Hydroxides c* C C C C c
Lanthanum fluoride C C NC**  C C NC
Phosphates:

Zirconium phosphate NC C NC C NC

Thorium pyrophesphate NC C NC

Thorium hypophosphate C NC

U(IV) hypophosphate C NC
Oxalates:

Thorium oxalate C C NC C

U(IV) oxalate C C NC

Bismuth oxalate C C NC

Lanthanum oxalate C C NC NC
Iodates:

Zirconium iodate C NC

Thorium iodate- C NC C NC

Ceric iodate : C NC
Sodium uranyl acetate NC NC C NC Poor*B C
Zirconium phenylarsonate NC C NC C Poor NC
Thorium peroxide C C
Bismuth arsonate C NC

 

i
The letter ""C" indicates that the co-precipitation has been observed to be nearly

quantitative under proper conditions. .

e
The letters ""NC'" mean that co-precipitation may be made less than 1 to 2 percent
under proper conditions. :

"Poor'" indicates an intermediate percentage of carrying.

Co-precipitation of Pu with LaF43 is a common step in the analysis of biological
360, 349, 257, 125, 208, 53

material for Pu’

Bismuth phosphate. The carrying of Pu on BiPO4 is another of the early,
widely used methods of separating Pu from U and fission products. The development
401 Like LaFj, BiPO4 carries

both Pu(III) and Pu(IV) when precipitated from moderately concentrated nitric acid. A

of the process is reported by Thompson and Seaborg.

peculiarity is the fact that Pu(IV) is more efficiently carried than Pu(IIl}. The optimum
conditions for the co-precipitation of Pu have been reported by Ada.mgon.z0 These are:
1) co-precipitation at the minimum BiPO4 solubility, 2)the absence of strong com-
plexing agents, 3) slow precipitation, and 4) minimum digestion after precipitation is
éomplete.

In addition to being very successful in the large scale processing Pu, BiPO4 pre-
341, 415

126

cipitations have been used in general radiochemical procedures to concentrate

237

Pu from large volumes of water and to determine Pu in urine. The procedure of

Rydberg341 uses the familiar oxidation-reduction cycle to effect purification. Plutonium

25
is first oxidized to Pu(VI) with sodium bismuthate, BiPO4 precipitated from 0.1 N
HNOS, then reduced with ferrous ion, and finally precipitated with BiPO4.

Zirconium phosphate. Zirconium phosphate is a specific co-precipitant for

Pu(IV), in contrast to BiPO, and LaFg, which carry both Pu(IIl) and Pu(IV). Hyde16

describes a Np-Pu separation based on the reduction to Pu(IIl) before precipitating

 

zirconium phosphate.

18

Other inorganic co-precipitants. Dupetit and Aten1 described the co-

 

precipitation of actinides with thorium peroxide and uranium peroxide. All the elements
were In the tetravalent oxidation state. They found, that in general, the crystal type
made little difference in the co-precipitation of these elements. For example, Pu carried
equally well with thorium peroxide, which has a similar crystal structure to plutonium
peroxide, and with uranium peroxide which has a different structure.

A mixture of Pu(Ill) and Pu(IV) has been carried on lanthanum iodate from dilute
HC1 solution.293

Plutonium can be separated directly from a urine sample by co-precipitation with
calciurn ammoniumm phosphate. 102,74 .

Pu(IV) and Am(IIT) have been quantitatively co-precipitated with K5La(SO4)4_,15
and Pu(IV) and Np(IV) have been separated by precipitation of the Pu from solutions

1

which are unsaturated in KZSO4. The minimumn Pu solubility in this system occurs at

0.7 m.1°2

 

Organic co-precipitants. Zirconium phenylarsonate is a specific carrier
for Pu(IV) and has been used in analytical procedures to determine the oxidation

193, 414, 227 and to separate Np and Pu after reduction with NH20H.392 King227
4

state,
used 2 X 10~

the same time not oxidizing the Pu(III). Voigt et al.

N NHZOH to prevent the reduction of Pu{IV) during the analysis, while at
414 found that the precipitation of
Pu is nearly quantitative from a formate buffer of pH approximately 2, and slightly less
g0 from HCI solutions. Ice 22
HC1 solutions.

Merz273 used mandelic acid and p-bromomandelic acid with Y(TII) to carry |

got quantitative recovery in precipitations from 1 M

Pu(Ill) quantitatively at pH 2-4 and above. Zirconium was used for Pu(IV) at higher
acidities. The precipitation was about 85% complete at 1 M HCl and HNO‘.3 for p-
bromomandelic acid, and somewhat lower than this for mandelic acid.

422

Weiss and Shipman quantitatively recovered Fe, Pu, Ce, and Pr from solution

by the formation of oxine homogeneously in solution by the hydrolysis of 8-acetoxy-

quinoline. _
These workers determined Pu in urine by co-crystailization with potassium
rhodizonate.421‘ 374 Kuznetsov and Akimov3247 co-precipitated Pu(IV) from 3 M

HNQ3 golutions with butyl rhodamine. The method is quantitative and separates from
all elements except Th(IV) and U(VI). Repeated precipitations effect the separation.
Other dyes were succegsfully used to separate Pu by the same procedure.

26
Precipitation
Precipitation of macro quantities of Pu is necessary in many analytical
and radiochemical procedures. The precipitation reactions which have been found
useful in practice will be reviewed in this section. The use of various precipitates as
purification steps for Pu is illustrated by Table IV-15, which gives decontamination

431

factors for Pu from Fe, Co, Zr, Mo, Ru, and Ce. As usual, Zr and Ru give the

mogt trouble.

 

 

TABLE IV-15. Decontamination Factors for Plutonium by Precipitation Me’chods.431
Plutonium Plutonium (II1) Plutonium (IV) Plutonium (TIT)

Element peroxide oxalate oxalate fluoride

Fe 50 33 10 1.4

Co 30 47 > 95 8.6

Zr 1 3.5 > 44 1.1

Mo > 140 > 13 > 15 1.1

Ru >14 > 38 | 33 36

Ce 6 1 1 1.1

 

Hydroxide. Both Pu(Ill) and Pu(IV) may be precipitated from mineral acid
solution by sodium, potassium or ammonium hydroxide as hydrated hydroxides or
hydrous oxides. Care must be taken in redissolving Pu(IV) hydroxide in acid to pre-
vent formation of Pu.(].'V) polymer, by maintaining a high acid concentration during the
dissolution. Once formed, the polymer dissolves very slowly in acid solutions. This

subject is treated more fully in the section on polymeric Pu(IV).

Fluoride. PuF, and PuFs may be precipitated from acid solution by
addition of excess HF. Prevot et al.329 found that PuF3 forms a more tractable,
crystalline precipitate than does PuF4. The compound is stable to oxidation if the

323 The freshly precipitated

precipitate is kept slurried in the supernatant solution.
compounds dissolve readily in reagents which complex fluoride ion, such as H3BO3,
but if heated to 500° dissolve only with difficulty. Metathesis to the hydroxide with
éodium or potassium hydroxide is another method of solution. .Tones214 found that
Pu]Ei"3 was suitable for use as a gravimetric standard for Pu, at least for a period of
several months. This method has not been widely used, however. It is interesting to
note that PuO2 prepared by ignition of this Pu.'E‘3 at 500°C in oxygen was readily soluble
in nitric acid, in contrast to the findings of other workers. This solubility is attrib-

uted to the extremely fine particle size of PuO2 prepared in this work.

Peroxides. Pu(IV) peroxide is formed when hydrogen peroxide is added to
acid solutions of Pu(III), Pu(IV), Pu(V), and Pu(VI), because H202 can act as both an
oxidant and a reductant. Pu(IV) peroxide always incorporates some of the anion pres-
ent into the crystalline precipitate. It has been suggested7 that the presence of the

anion is due to a more or less random placement between sheets of Pu and peroxide

27
oxygen in the ratio 1:3. If an excess of peroxide is used in the precipitation, the
ratio may be lower. The extra peroxide also serves to hold the sheets together.

Precipifation of plutonium peroxide has been used as a purification step for Pu
72,158, 329,425

329

from mosgt other cations and as a step in the preparation of high purity

Pu compounds and solutions. This precipitation has been used to separate Pu from

Am, the Am remaining in the supernatant solu‘cion,?2 and to separate Pu and U_277 In
the latter procedure the Pu was oxidized to Pu{VI) by potassium bromate which served
as a holding oxidant, and uranyl peroxide precipitated. Separation factors of 2-4

were cobhtained.

Oxalates. Precipitation of plutoniumm oxalate from dilute acidic solution
265
The

separation factors from other elements are-not so great in some cases as in the
431, 141

has been used as a concentration step before conversion to oxide or metal.
peroxide precipitation procedure (Table IV-14), but the precipitate is easy to
filter and work with. These compounds undergo decomposition by the action of their

134, 389, 216

own alpha radioactivity. The oxalate is decompoesed into carbonate and CO,

and the CO may reduce either Pu(VI) or Pu(lV).

Other compounds. The precipitation of plutonium (IV) sulfate tetrahydrate
has been used to prepare a high purity Pu compound for use as a gravimetric standard
424

for Pu.

obtained after five successive recrystallizations. This compound is suitably stable as -

Starting with a grossly impure solution, a product of 99.98% purity was

a gravimetric standard at least for 1!3--months.448
Dicesium plutonium (IV) hexachoride has also been proposed as a primary

279

gravimetric standard. The compound can be prepared by precipitation from an 8

M HCI solution of Pu(IV) by addition of CsCl in HCI.

D.2 Solvent Extraction Methods

 

The large-scale processing of reactor targets is largely done by liquid-liquid
exiraction. This is so because of a combination of desirable properties of this
method; for example, great specificity for U and Pu, easy adaptability to remote
handling facilities, etc. These advantages are easily carried over to laboratory
separations where specificity and ease of handling are equally important.

A very great deal of research on liquid-liquid extraction systems for Pu has
been carried out in the development of large-scale processes, and a large portion of
the solvent extraction data reported in this section was taken under the spur of the
seemingly never-ending quest for more specific extractants, better radiation stability,
and the like. The basic data on the extractive properties of a given solvent are, of
course, equally applicable in the laboratory or indfistrial situation.

The general principles of solvent extraction have been put forth in the book by
Morrison and Freiser,292 and in a comprehensive review by Mza.rcus.zs'ir The solvent

388 ' has

extraction data for Pu have been thoroughly reviewed by Smith. Carleson

written a good general survey of the processing chemistry of nuclear fuel for Pu, while
.. 4580 . - . .

a recent symposium contained much of interest concerning the newer extraction

systems.

28
In this section the data will most often be given in terms of the distribution
coefficient D, which is defined by the equation

_ concentration of the solute in the organic phase
concentration of the solute in the aqueous phase

 

To save gpace, the notation "Dx” for "the distribution coefficient of species x'' will

be used in the text.

QOrgano Phogphorous Compounds

 

This large and important class of extractants includes the neutral and
acidic esters of ortho phosphoric acid and related compounds, the phosphonates,
phosphinates and phosphine oxides. The class divides naturally into neutral and
acidic compounds by the differences in extraction mechanism. The neutral compounds
extract by solvation of a neutral complex in the organic phase by the phosphoryl
oxygen, while the acidic compounds, in general, operate by an ion-exchange reaction
to form an extractable species. Further solvation may occur in the organic phase in

some extiraction systems of this type.

Neutral Compounds

Tri-n-butylphosphate (TBP), (C4H90)3PO, will serve as the typical
compound of thig type. A complete survey of the literature on TBP extraction of Pu
ig beyond the scope of this review. The more recent papers will be emphasized,
although earlier project work will necessarily be included. A summary of early work

on TBP has been given by Geary.m3

The physical and chemical properties of TBP

2
as an extracting agent have been summarized by McKay and Healy. 59 The TBP-nitrate
system will be discussed first, followed by other aqueous systems, and finally other

neutral organo-phosphorous compounds.

TBP-nitrate systems. Hesford and McK.':l.},.r”B have formulated the ex-

 

traction reaction of metal nitrates into TBP as

MP +p NO,

+q TBP,) = M (NOy) - q TBP,, (1)

where p is the charge on the metal ion and gq is the number of TBP molecules solvating
the nitrate molecule in the organic phagse. The subscript (o) refers to species in the
organic phase, and species withoit subscripts are in the agueous phase. The equilib-

rium constant, neglecting activity coefficients, is then
=T . : +p P 14
K, = (M(NOg) - q TBP ]/ [M""] [No P [TBP )]~ (2)
and the distribution coefficient
= -1P q :
D = K, {NOg]P [TBP |2 , (3)

Under constant aqueous conditiong, and at a sufficient dilution of TBP in an inert

diluent to make Eq. (2) valid, the distribution will be proportional to the éth power of

29
391

the TBP concer_ltration. Solovkin

has calculated distribution coefficients for this

system on a gemi-empirical basis and obtained good agreement with experimental data.

Tetra- and hexavalent Pu as well as other actinides have been shown to be di-

golvates in the organic phase.44

for Pu(IV) and Pqu(N03)2

the extracted complex is tri-solvated, Pu(NO3)3 - 3 TBP.

The extracted complexes are then Pu(NO3)4 -2 TBP
- 2 TBP for Pu(VI). Work with trivalent Pu has shown that

372 252

Laxminarayanan et al.

have shown that Pu(IV) in 2-4 M HNO, is associated with an average of 2.6 nitrate ions

and does not exist as undissociated Pu(N03)4 by combining solvent extraction data

from several solvents.

the organic phase. 170

There is direct evidence that the complexes are un-ionized in

Typical data for the extraction of a number of elements at trace concentration

into 19 volume % TBP 'in kerosene from nitric acid solution of various concentrations

are shown in Fig. 1.

The distribution coefficients riges steeply at low nitric acid

concentrations because of the strong salting-out effect of the nitrate ion (Eq. 1),

passes through a maximum, and then falls at higher acid concentrations.

Some

elements (e. g. Th and Y) pass through minima and rise again,

103

 

 

102

 

Np({VT) ™ Th

~ - ul(l)
./ /

 

~ LTI T T T T

 

S

N

 

102

 

 

Pu (OT)

R

 

 

 

 

 

_

[ | L 1 1 | | 1.1 |
5 10
EQUILIBRIUM

1073
0

 

15

HNO3z CONCENTRATION, AQUEQUS (M)

Fig. 1. Extraction of mitrates at trace
concentration into 19 volume % TBP in
kerosene at 25°C from nitric acid solutions.
Taken from McKay and Healy.2%9 The in-
dividual references are: yttrium390;
thorium ; zirconium<?2; uranium and
neptunium<9®: and plutonium44s

30

Several other studies of the ex-
traction of Pu from nitric acid solutions
have been reported. CarlsE!SOnF"B used
40% TBP in kerosene and paid partic-
ular attention to requirements to main-
tain Pu in the desired oxidation state.

He found that NaaLNO3 was necessary to
prepare pure Pu(IV) from an equilibrium
Figure 2
shows the effect of HNO3 concentration

disproportionated mixture.

on several reducing agents in the ex-
traction of an equilibrium Pu solution,
and the extraction curve for Pu(III)
alone. Ferrous sulfamate with added
hydroxylamine effects complete re-
duction of Pu(IV) to Pu(IlI) at up to 2 M
HNO3, but fails at higher acidities.
Ferrous ion plus hydrazine and hydrox-
ylamine fail to complete the reduction
at progressively lower acidities.
Carleson algo found that golid I{BrO3
did not oxidize Pu{IV) to Pu(VI) in 1.55
M HNO3
the oxidation was quantitative in 0.1 M

at room temperature, but that

BrOa_ after heating to 95°C for several
hours.

Codding et al. used 30%
TBP in kerosene, Rozen and Moiseenl-:o334

92, 93
and Shevchenko and FedeJ:'c-V3 64 used 20%
TBP in kerosene, and Bernstrom and
Rydberg®! used 100% TBP. All the
above workers measured the distribution
coefficients of Pu(IV) and Pu(VI}) as a
function of equilibrium agueous nitric
acid concentration with similar resultgs,
and several also studied the effect of

U(VI) competition on the extraction of

 

o™t 132
Pu(IV) and Pu(VI). Flanary derived
D equilibrium constants (defined by Eq.
(2)) for U(VI), HNO3, and Pu(IV) of 22,
0.18, and 3 respectively, while Rozen
l2and3 and Moiseenko®34 and Codding
— | et 21.92: 93 get about 1.5 for Pu(Iv).
-T2 fl‘%?fi’.flf,‘,’.fl!.’.?.‘fl”y"“"‘“"‘*°‘°° -0.02 These values illustrate the effective
10~2 :_'_::3:2%55:%2241:21:;::fi'.".°" competition of macro U{VI) over trace
Pu(IV) in the simultaneous extraction of
these species, resulting in a large re-
I 2 3 duction of the Pu distribution coefficients
M(HNO3z) H20 (see Fig. 5).

. The order of extractibility into
11b1::igm2Pu](Dl'}IS)t, ri;fizi&?’oirfijugg()vfiid Ii?;l__ TBP from nitric acid solutions for the
tures in the presences of several reducing actinides is M(IV) > M(VI)
agents in 40% TBP in kerosene and nitric o> M(III)fM‘ 258,26 pe extractibility

acid; after Carleson.
of the tetravalent actinides increases

with atomic number, i.e., Th(IV) < Np(IV)} < Pu(IV), while that of the hexavalent
actinides decreases with atomic number, i.e., Pu(VI) < Np(VI) < U(VI).44

Moiseenko and Rozen281 measured the effect of temperature on the extraction of
Pu(IV) as a function of nitric acid concentration and uranyl nitrate concentration (Figs.
3,4, and 5). In the absence of uranyl nitrate the distribution coefficient decreases with
temperature below 5 M HNOB, while at higher acidities it increases. This effect is
explained by a decrease in the equilibrium constant for the distribution reaction with
temperature, with a compensating increase in the activity coefficient of Pu(IV) at higher
acidities. This increase is ascribed to a decreased association of Pu(IV) with nitrate
ions at higher temperatures. Shevchenko and Federov364 have studied the same system
at nitric acid concentrations below 4 M with similar results.

Best et_al.43 ' measured the distribution of several tripositive actinides and
lanthanides from nitric acid solutions into 100% TBP. Sorme of their data are shown
in Fig. 6 plotted as a function of atomic number, along with the lanthanide data of
Hesford Lal.l'?'7 for comparison. The curves for the two homologous series are
approximately superimposable if adjustment is made to compare ions of the same radius.
This illustrates the importance of ionic radius on the chemical behavior of these
elements. '

31
 

 

1 |

5
Concentration
of HNO3 In aqueous phass, M

Fig. 3. Dependence of distribution co-
efficient of Pu{IV) into TBP on concentration
of nitric acid in aqueous phase (for 281
solutions not containing uranyl nitrate).
Curve 1-20°, curve 2-30°, curve 3-50°,
and curve 4-70°.

 

8
10 6
6
4
0.5 3
2
1
o I ] L ] |
20 30 40 50 €0 70
Temperdture,°C
Fig. 5. Dependence of distribution co-

efficient of Pu(IV) into TBP on temperature
with a uranium content of 0.42 Min the
aqueous phase. Concentration of
HNO3: curve 1-0-5N, curve 2-1N,

curve 3-2N, curve 4-3N, curve 5-4N,
curve 6-6N, curve 7-8N, and curve
8-10N.

32

 

 

 

 

 

20 30 40 50 60 TO
Temperature, °C

Fig. 4.
efficient of Pu(IV) into TBP on temperzafllre
in solutions not containing uranium.

Dependence of distribution co-

Concentration of HNOq: curve 1-0.5N,
curve 2-1N, curve 3-2N, curve 4-3N,
curve 5-4N, curve 6-10N, curve 7-5N,
and curve 8-6to BN.

 

 

 

 

10
O LANTHANIDES
A TRIPOSITIVE ,d%flfl
02— ACTINIDES ,.,‘d HNO3Z
i F :
i F
I.o
10 —
N /o D"T
R aZom
5 Y o0 HNO3
I £ o<
_'cf ~
o
o
10 A
10~2
Tol | | | | AmCmBRCr€ | | |

1
LaCe Pr NdPmSmEu GdTbDy Ho Er TmYb La

Fig. 6. Distribution coefficientasa
function of position in the lanthanide
and actinide series. 43,177

o Lanthanides
A Tripositive actinides
The salting-out effect of non-extractable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

§§\8M_ 19%V/VTBP In kerosene salts on the extraction of Pu and U has re-
0% W gfl::re: g:'fl%m":‘mrh;om ceived considerable attention. 189,43, 149,52
N In[dlu“d Typical results are gshown in Fig. 7 in which
\l % M Na(NO,) is used as the salting agent for
D am| N Pu(Iv).44. 258 At 5 constant total nitrate con-
10 | 7 N centration the distribution coefficient decreases
q2M / as the proportion of nitric acid is increased,
?7 gfl'r:: for HNQ3\\ but the distribution coefficient is always
greater than that of pure HNO3. This effect
| is caused by the reduction of competition for

0 5 10 TBP molecules by the lowering of the extract-
Aqueous nltric acld concentration M L . .
- able nitric acid concentration.

Fig. 7. Effect of NaNOj on the dis- Aluminum nitrate has been used as a

tribution of Pu(IV) between 19% TBP in

kerosene and nitric acid solutions.44, 258 salting-out agent for Pu in several TBP ex-

. 149, 165,52, 354
traction processes.

Applications of TBP-nitrate systems. Many papers have been written about

the application of TBP to the processging of irradiated U for
Pu195, 132, 93, 148, 325, 114, 202, 365,109, 133

and U(VI) away from fission products into TBP-kerosene from nitric acid solutions,

The process involvesg extracting Pu(IV)

stripping the Pu into a relatively concentrated nitric acid solution by reduction to Pu(III),
and finally stripping the U(VI) with water. Nitrous acid is added to the feed solution in
the first extraction to stabilize Pu(l'V).'76 Ferrous sulfamate was first used as a re-

ductant in the Pu stripping stage,335' 195, 132
209, 221, 67, 385, 353, 342, 38

although U(IV) as a reductant has been ex-

tensively gtudied. This reagent can be generated from

U(VI) and stabilized by volatile reductants, with the considerable advantage in large-
scale processing plants of not introducing non-volatile materials (e. g. irom) into the
waste streams, thus permitting a smaller waste volume. The behavicr of fission pro-

ducts and other elements in this process has received much attention, both in the primary

papers and others.BB‘ 161,431, 133, 367

A variant has been described in which the fission
products, Pu and U, are successively siripped from the TBP phase by stepwise lower-

. . . 203

ing of the acid concentration.

TBP was used in the isolation of naturally occurring Pu.315

144,114

Anr:tly‘tical362 and radiochemical procedures for Pu based on TBP ex-

traction from HNO3 have been given.

An interesting application is the use of TBP in reversed-phase chromatography for
- - 124, 156,157, 190
various heavy element separations,

: PuflV)andPufiH)huHNo3?8°

and for the separation of Pu(IIl),

TBP — other aqueous systems. Tetra- and hexavalent actinides extract well

into TBP from moderately concentrated HCIl solutions, while trivalent species are

33
essentially unextractable. Larsen and

 

0% 249
Seils measured the extraction of U

and Pu into 30% TBP in CCl, (Fig. 8),
and used this system as the basis of an

FETTT

I

analytical precedure for these elements
(Procedure 15, Sect. VIII). Both Pu(IV)
and Pu(VI) extract better at all acidities
than U(IV) and U{VI). The quadrivalent

actinides have higher distribution co-

(g3

efficients than the hexavalent above 5-6

M HCI, while the reverse is true at
lower acidities. These authors report a
digtribution coefficient of about 10_3 for
Pu(IIT) and 10 for Am(III) in 8 M HCI1

under the gsame conditions. The wvalue

T TTTTI]

for Am is congidered more reliable be-
cauge of possible partial oxidation of
the Pu(III) to Pu(IV). HCIL is much less
extractable than HNO3 into TBP. Larsen
and Seils report D = 0.01 at 6 M HC1 and
0.12 at 8 M HC!I into 30% TBP in
CC14,249
Selovkin et al. found that the
extraction of Pu(Iv)into 1.1 M (30%)
TBP in CCl4
appreciable. The disftribution co~

o~ 1 j 1 ] efficients varied from 0.0045 at 0.4 M
2 4 B 8 1 12 -

AQUEOUS HCl CONCENTRATION (M) HClO4 to 0.9 at 6.4 MHC104. The ex-

tracted complex was determined to be

I TTTTI

390

T

from perchloric acid was

 

 

 

 

Fig. 8. Extraction of U and Pu b\g/ 30%

TBP in CCI4 from HCL solutions. 24 di-solvated by TBP dilution experiments.

PuIV) and Pu(VI) extract well
intc TBP from trichloro- and trifluoroacetic acids.183 The distribution coefficients
decrease with increasing acidity, rather than the usual increase., The distribution co-
efficients for both Pu(IV) and Pu(VI) are about 4 to 5 times as great for CClBCOOH as
for CF3COOH at low acid concentrations. For extraction of Pu(IV) into 30% TBP in
Amsco-125 (a kerosene type diluent) fr~m an initial concentration of 0.5 M CCIBCOOH,
D = 21; for Pu(VI), D = 4.

The effect of addition of sulfuric acid and phosphoric acid to Pu(IV) or Pu(VI) —
nitric acid — TBP systems is invariably to lower the distribution Coefficient438’ 440, 437 _
sulfuric439 — phogphoric. This effect is presumably due to the formation of unextractable
sulfate and phosphate complexes of Pu. The effect is more pronounced in Pu(IV) than in
Pu(VI), and at lower nitric acid concentrations. For example, making the agueous phase
0.08 M in HZSO4 lowered D for Pu(IV) from 16 to 9.5 in 4 M HNOB; in 2 M I—INO3 the

corresponding decrease was from & to 1.4_437 On the other hand the lowering of D for

34
Pu(VI) by the addition of enough H,50, to 2 M HNO, to make the solution 0.1 M in
stO4 was only from 2.6 to 2.2. .
Sulfuric acid also decreases the extraction of Pu(IV) into TBP from HCl

441

solutions. A solution 1 M in HZSO4 lowered DPu approximately a factor of 10

throughout a2 change in HC1 concentration of 3-8 M.

Other neutral phogsphorous compounds. A wide variety of organo-phosphorous

 

compounds has been studied in an attempt tofind other extractants for Pu and U,
Higgins et al. 181 working with the butyl series found the order to be phosphate
((RO),;PO) < phosphonate (R(RO),PO) < phosphinate(Rz(RO)PO) < phosphine oxide
(RSPO). Thus the extracting power increases with the number of C-P bonds.

69,70

Burger confirmed this series and correlated the extracting power with the basisity

of the phosphoryl oxygen as measured by the P-O stretching frequency. Burger,sg’ 70

and Petrov et al:.318

found that electronegative substituents in the alkyl chain such as Cl and

phenyl strongly depressed the extraction. Sidda113

76 tound that increasing the length of
the alkyl chain in the phosphate series made little difference up to 8 carbon atoms for
quadrivalent and hexavalent actinides. The effect of branching the alkyl chain is to in-
crease the extraction of U, Np, and Pu, but to strongly depress that of Th. This effect
is atiributed to steric effects and possible tri-solvation of the Th complex at high ex-
tractant concentrations.

The extraction mechanism of these compounds is generally the same as that for

267 ppion-

TBP, but not necessarily with the same solvation number for all elements.
octylphosphine oxide (TOPQ) and tri-n-butylphosphine oxide (TBPO) extract Pu(IV) and
Pu(VI) as the di—solvate.zsg’ 408
10 for extraction of several elements into 0.1 M TOPO in cyclohexane from HNO3 and
HC1 solutions. Pw(IV}) and U(VI) are both extracted well (D = 4-30) from 3 M H,SO,
by 0.3 M TOPO. 187 The extraction of Pu(IV) as a function of nitric acid concentration
is similar to that for TBP, but very much higher, while that for U{(VI) and Pu(VI) show

different acid dependencies. White and Rc-ss427 have written a general review of the

The data of Martin andOckenden2%? i5 given in Figs. 9 and

extractive properties of TOPO.

Trace quantitieg of U have been separated from large amounts of Pu by extracting
the .U with TOPO under reducing conditions from 2 M HN03.34

Table IV-16 is a compilation of data for the extraction of Pu{IV) by a large number
of compounds of this type. The extraction coefficients were converted to 1 M extract-
ant by using the ''square law,'" that is by assuming that the extracted complex is di-
golvated in every case. The distribution coefficients were taken at 1 M HNO3 where
possible, but cases in which other ions were present or the acidity was different are
noted. The extractive power relative to TBP was calculated by direct comparison in the
same gseries of experiments where possible, or by comparison to other TBP data taken
under the same stated conditions. The conversion of the phosphine oxide datato 1 M
extractant generally required large extrapolations, since the experiments were done at
low extractiant concentrations. For this reason the numerical values of the distribution

coefficients and the relative extractive power are only approximate.

35
 

1000 ' 1000 Y
Ut

~py ¢ /.. *"0‘-{\%|

100

 

0

 

/

g

 

100 \

&

R

4
é-

 

 

 

 

/
R

 

 

 

0. L | P %t
o

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0 I L 1 1 ] 1 1
"0 2 4 6 8 10 12 14
.01 \ Hydrochlorlc acid molarlty
\ Fig. 10. Extraction of metal ions from
N hydrochloric _acid by 0.1 M TOPO in
0.001 1 ] ] L | * Am IIL CYC].Ohexane.

 

0O 2 4 6 8 10 12 14
Nitric acid molarity

Fig. 9. Extraction of metal ions from
nitric acid by 0.1 M TOPO in cyclo-
hexane.

Acidic Compounds

These compounds are the mono- and di-acidic esters of phosphoric
acid and related phosphonates and phosphinates. They have recieved considerable
attention in recent years during the search for more versatile or specific extractants.
In general, these compounds extract by an ion exchange type reaction anaslogous to
chelation. In many cases the chelate compound thus formed is further solvated in the
organic phase. For example the extracted complex in the extraction of Th(IV) with
bis-2-ethylhexyl phosphoric acid from several acids involves the anions such as NOs_,

Cl, and possibly 0104_ in extractions from the respective ar.:ids.312

Mono-acidic compounds. Di-n-butyl phosphoric acid (DBP) and bis-2-

 

ethylhexyl phosphoric acid (HDEHP) are the compounds that have received most
attention. They have been shown to be dimeric in the organic phase in a non-polar
golvent such as benzene?’.loThe dimerization is presumably due to hydrogen bonding to
the phosphoryl oxygen. 130 The extraction reaction can be formulated as

M+P + P(HA)Z(O) = M(HAZ)P(O) + PH', (1)

36
LE

TABLE IV-16. Compiled Data on Extraction of Pu(IV) by Neutral Organo-Phosphorous Compounds

 

 

 

Extractant Extractant Nitric Acid - Pu Datl1 M Relative
_— Concentration Concentration Conec. D Given Extractant Extractibility
Phosphates Diluent Vol, % (M) (M) (a) (M) in Paper {b) (TBP =1.0)(c) Reference

Tributyl (TBP) Kecrosene 19 (0.69) 1.0 p(d) 1,5 3.2 1.0 44
Gulf BT " 30 (1.09) T 3.0 2.5 92, 93
Kerosene 40 (1.46) T 3.5 1.6 76
Kerogene 20 (0.73) Bx107% 1,38 2.6 281
Benzene 20 (0.73) ~3.0 T 14.1 26.3 364
Mesitylene 6.4 11,9 364
Heptane 4,72 8.8 364
Nonane 5.46 10,2 364
—————— 100 (3.65) 1.0 T 36. 1.0 41
Xylene (1) 1.0 T 3.0 3.0 i 187
n -Dodecane 30 (1.09) 3.0 T 16.1 13.5 376

Dibutyl Carbon (0.5) 2 (initial) 0.0038 0.71 2.8 0.45 69

methyl tetrachloride

Dibutyl-decyl Carbon (0.5) 2 (initial) 0.0038 2.3 9.2 1.28 69
tetrachloride

Triigobutyl n -Dodecane (1.09) 3 T 11.8 9.9 0.73 376

Tri- n-amyl n -Dodecane (1.09) 3 T 15.6 13.1 0.97 376

Tri-igoamyl n -Dodecane (1.09) 3 T 17.8 15,0 1.10 376

Tri- n-hexyl n -Dodecane (1.09) 3 T 15.6 13.1 0,97 376

Tri- n-octyl n -Dodecane (1,09) 3 T 15,3 12.9 0,85 376

 

NOTES:
(a) Equilibrium agueous concentrations are listed except as noted, 142 ' _
(b) Calculated by assuming di-solvation and ideality in the organic phase; i. e., DlM = DxM (E) where x is the concentration of

the extractant. -
(¢) Calculated by comparing to TBP under the same conditions under the same experimental conditions where possible. Other-

wise the comparison is made indirectly. These cases are noted.
(d) T represents tracer quantities of Pu.
8t

Table IV-16.

(Continued)

 

. Extractant

 

Extractant Nitrie Acid Pu Dat1 M Relative
Concentration Concentration Cone. D Given  LExtractant Extractibility
Phosphates Diluent Vol. % (M) D) (2) (M) in Paper (b) (TBP=1.0){c) Reference
Tri-2-ethyl n -Dodecane (1.09) 3 T 25 21 1.55 376
hexyl '
Tri-2-butyl n -Dodecane (1.09) 3 T(d) 28 23.5 1.74 376
Tri-3-amyl n- Dodecane (1.09) 3 T 18.1 15,2 1.12 376
Tri-3-methyl- n -Dodecane (1.09) T 24 20 1.49 376
2-butyl
Tri-4-methyl- n-Dodecane (1,09) 3 T 22 18.5 1.36 376
2-amyl
Tri-sec-butyl Amsco 125-82 (0.3) 0.5+0.5M T7.1X 5 56 3.85 187,420
Al (NO3)3 1075

Tri-2-octyl Amsco 125-82 {(0.3) 4 44 3.07 187,420
Dibutyl ethyl Carbon (0.5) 0.8 M 4,2 X 2,62 10.5 0.62 182

tetrachloride AY(NO,) -4

3’3 10

Diethyl amyl 3.76 15,0 0.89
Diethyl n -butyl 3.73 14.9 0.88
Diethyl isobutyl 3.69 14,8 0.87
Phosphonates _ 0.6 +0.1 M (d) _
Dibutyl butyl CC14 0.7’ M UOE(NO:}); T 1.23 2.2 17.3 181

CC14 0.5 2 (e) 0.0038 32 128 20,4 69
Dibutyl mecthyl CCl4 0.5 2 (c) 0.0038 29 116 20.0 69
Dibutyl decyl cCl, 0.5 2 (e) 0.0038 35 140 22,3 69
Di-n -butyl (f) 1.0 1.0 T 3.2 3.2 1.0 187
phenyl
Di-sec-butyl () 1.0 1.0 T 5.1 5.1 1.6 187

phenyl

(c) Initial aqueous concentration,

(f) Diluent not stated, probably kerosene.
6E

 

 

 

 

 

 

 

 

 

 

 

 

Table IV-16, (Continued)
Extractant Extractant Nitric Acid Pu Dat1 M Relative
Concentration Concentration Conc. D Given Extractant Extractibility
Phogphonates Diluent Vol. % (M) (M) (a) (M) in Paper (b) (TBP=1.0){c) Reference
Dibutyl butyl n-Dodecane 1.08 1,0 T 160 137 22,0(8) 375
Di-2-amyl n-Dodecane 1,096 1.0 T 53 44 14,7(8) 379
2-butyl
Dibutyl methyl ~ CCl, 0.5 M 1.0 + 0,21 0.004 11.15 44.6 16.6 318
M UO,(NO,),
Di-~isoamyl 7.43 29,7 11.1
methyl
Di- n-hexyl 11.65 46,6 17.4
methyl .
Di- n-heptyl 10.95 43.8 16.3
methyl
Di- n-octyl 13.65 94.6 20.3
methyl
Di- n-nonyl 24,15 96.6 36.0
methyl
Di- n-decyl Y Y Y Y 21.65 86.6 33.3
methyl Y
Di-cyclohexyl CCl, 0.5 M 1.0(8) +0.21 0.004 17,35 69.4 25.9 318
methyl M UO, (NO,)
— 2 32
Diphenyl methyl 1.34 2.4 2.0
n -butyl 11.60 46.4 17.3
n -hexyl methyl
n -butyl n- 17.85 71.4 26.6
heptyl methyl
Di- n-butyl 7.58 30.3 11.3
cthyl .
Di-isobutyl 7.67 30.7 11.4
ethyl v Y Y Y Y

 

(g) Indirect comparison, i.e,, to TBP under the same stated conditions, but determined in a different experiment,
o¥

Table IV-16. (Continued)

 

 

Extractant Extractant Nitrie Acid Pu Datil M Relative
_— Concentration Concentration Conc. D Given  Extractant Extractibility
Phosphonates Diluent Vol, % (M) (M) (2) (M) in Paper (b) (TBP=1,0)(c) Reference
Di-n -butyl ccl, 0.5 M 1,0(e) + 0,21  0.004 8.65 34.6 12.9 318
Di-isoamyl 7.46 29.8 - 11.1
n -propyl
Di-n -butyl 9,46 37.8 14.1
n -butyl
Di-n -butyl 8.91 35.6 13.3
n -amyl
Di-isoamyl 8.00 36.0 13.4
n -amyl :
Di-igoamyl 7.69 30.8 11,5
isoamyl
Di-isoamyl _ 8,92 35,7 13.3
n -octyl
Di- n -butyl 1.91 7.6 2.8
benzyl
Di- n-butyl 1.186 4,6 1.7
methoxymethyl
Di—n -butyl 1,50 6.0 2,2
ethoxymethyl
Di 2-(n -butoxy) 3.26 13.0 4,9
-ethyl-1
Di 1-methyl-2- 2,35 9.4 3.5
(n -butylcarboxy)
-ethyl-1
Di 2-(n -butyl- 2.38 9,5 3.5
carboxy)-
ethyl-1
Tetra-n -butyl . 6.72 10.0

 

 

 

 

 

_;fil?;lgl?: nate v * + + '

 
¥

 

 

 

 

 

 

Table IV-16. (Continued)
Extractant Extractant Nitric Acid Pu Datl M Relative
Concentration Concentration Conc. D Given Extractant Extractibility
Phosphonates Diluent Vol. %{(M) (M) (a) (M) in Paper (b) (TBP =1.0){c) Reference
Tetra-igoamyl ccl, 0.5 M 1.0{®) + 0,21 0,004 8.45 12,6 318
methylene M UO,(NOy),
Phosphinates
Butyl dibutyl ccl, 0.75M 0.6 Fol 7{d) 49 87 69 181
oNU3l5
Butyl dibutyl ccl, 0.50 2 (e) 0.0038 170 510 108 69
Ethyl dihexyl ccl, 0.50 2 (e) 0.0038 200 800 127 69
Butyl dibutyl m-Dodecane 1.08 1.0 T 160 137
Phogphine Oxides
Tri-n-butyl ccl, 0TS M 08+01 @ 499 888 703 181
2\NU3/5
Tri-octyl Cyclohexane 0.1 1.0 T 236 23,600 ~100'8 269
Tri-n-butyl ccl, 0.5 %fi%fl?fl% | 0.004 299 1,196 446 318
2/ tNY3)9
Tri-isobutyl ccl, 0.5 1.0 +0.21 0.004 21.9 876 32.6 318
(UO,)(NO,),
Tri-butyl cel, 0.01 1.0 T 110 1.1 x 108 ~3 x 10° @) 408
Tri octyl Amsco 125-82 0.01 0.8 T 100 1,0 x 108 ~3 X 10° 187
Tri-2-ethyl- Amsco 125-82 0.1 0.6 T 200 2.0 x 10 ~6000 187

hexyl

 
In this equation, HA represents any monoacidic ester of phogphoric acid.

This equation has been shown to be correct for di- and trivalent ions, but tetra-
valent ions in general show a more complex behavior. The extracted complex is some-
times further solvated in the organic phase and nitrate, chloride, and even perchlorate
complexes may be involved in the extraction reaction, depending on the specific aqueous
conditions employed. Thus, no general reaction can be proposed which will account
for all of the observed behavior.

" Kosyakov Lal.238 studied the extraction of Pu(IV) and other actinides from
nitric acid solutions by several dialkylphosphoric acids. Their results for Pu(IV) are
shown in Fig. 11. The distribution coefficient increases as the length of the normal

|. Dibutylphosphoric acld (HDBP)
Dloctylphosphoric acid (HDOP)
Dinonylphosphoric acid (HDNP)
Didecyiphosphoric acid (HDDP)
Di-2-ethylhexylphosphoric {HDEHP)

  
 
 
   

o s wDw

4.0

5
o
> 35 é
-
30
|
2‘5 l I

 

 

-1.0 0 1.0
LOG HNO, CONCENTRATION (M)

Fig. 11. Extraction of Pu(IV) by dialkylphosphoric acids (0.5 M in isooctane) from

HN’O3 solutiong. 238

alkyl chain is increaged from butyl to decyl, but that for 2-ethylhexyl is greater than
any of these. The ndn—linearity of the slope of these extraction curves is ascribed to
nitrate complexing in the extracted species. The acid dependency was determined by
extraction into HDEHP from HC 104 solutions at a constant ionic strength of 1.0 and
found to be inverse first power in the region from approximately 0.05 to 1.0 M HT.
The Pu is probably exiracted as a hydrolyzed species at low acid concentrations. The
disgtribution coefficient wasg found to vary directly as the square of the HDEHP con- -
centration.

The distribution coefficients for the extraction of Am(II), Pu(IV), Np(V) and
U(VI) into HDEHP from nitric acid are shown in Fig. 12. The discontinuity in the Np(V)

42
Log D

 

 

- | A N L .
3 -1 o 14 : }
Log HNO; CONCENTRATION (M)

Fig. 12. Extraction of various actinides into 0.5 M HDEHP (isooctane diluent) from
HNO, solutions.238

curve at high acid concentrations is due to disproportionation of Np(V) into Np(IV) and
Np(VI), both of which are more extractable than Np{V). The minimum in the Am(IT)
‘curve at high acid concentrations is probably due to nitrate complexing of the extracted
Am species.

Horner and Coleman187 get a different result for the extraction of Pu(IV) by
HDEHP. As shown in Fig. 13, the extraction curve is concave downward with increasing
HNO3 concentration using 0.01 M HDEHP in Amsco 125-82. The mazgéisitude of distribu-
tion coefficients are very much larger than those of Kosyakov et al., if the second
power dependence on the extractant concentration is taken into account. Another dif-
ference is the decreased distribution coefficient at 0.1 M acid. Horner and Coleman
ascribe this decrease to hydrolysis of the Pu(IV). Horner and Coleman prepared Pu(IV)
by reduction to Pu(Ill) with hydroxylamine nitrate, and reoxidation and stabilization
with sodium nitrite, while Kosyakov La'l.zsa did not state their method of preparation of
Pu(IV).

Dreze and Duyckaerts121 investigated the extraction of Pu(IV) by di-n-butyl
phosphoric acid (HDBP) from nitrate solutions as a function of nitric acid concentration,
nitrate concentration, HDBP concentration, and ionic strength. Representative results
are shown in Figs. 14 and 15. These experimenters were able to invoke the known
stability constants of Pu(IV) nitrate complexes to fit the various functional dependencies.
They consider the extraction reaction to be

+4

Pu’" + 2(NO4)” + 2(HDBP)y ) = Pu(NO,), (H(DBP),), \ + on" (2)

2(o)

for which they calculate the equilibrium constant to be (1.7 £ 0.3) X 109 (m/1)2.
43
 

4 &
10 | T |

103

102

z[No;] -
6 M (HNOz + NaNOg)

 

 

 

 

| | |
'O | 1001 | 0

HNO, (equllibrlum), M

 

Fig. 13. Pu(IV) extraction by di(2-ethylhexyl)-phosphoric acid: effect of nitric acid
and sodium nitrate concentration. @ 0.01 MD2EHPA; (O 0.1 M D2EHPA; diluent,
Amsco 125-82. Plutonium reduced with hydroxylamine nitrate, reoxidized and stabi-
lized with 0.1-0.5 M NaNO,,. 187 ’

 

Log D

-20

 

 

 

-30 | [ | I | —
-2.0 -2.5 -30 -3.5 -40
Log 2 [Hz Aa]

 

Fig. 14. Variation of the distribution coefficient of Pu(IV) as a function of the con-
centration of the dimer, (HDBP)5 in benzene.121 HNOj3 + NaNO3 = 6 M; HNO3 con-
centrations:

Curve 1-0.5 M Curve 4-4 M
Curve 2-1 M Curve 5-6 M
Curve 3-2

(2=

44
 

Log D

-05

 

 

 

 

-0.2 (I)IO.IZ 04 06
Log [HNO.&]

Fig. 15. Variation of the distribution

08

0

coefficient of Pu(IV) from nitrate solu-
tions by HDBP as a function of HNOj3

concentration.

@® HNOg + NaNO3 =

WM HNO; + NaNOj

other workers are included also.

centration dependency for the same system.

 

S T | 04 1 AR

 

6 M
4 M

On the other hand, Shevchenko and
Smelov?’m3 interpreted their results on the
same system by assuming the extracted
complex to be nitrate free.

Early work on the Pu(IV)-HDBP-
HNO, system was done by Stewart and
Hicks,394 who found a strong lowering of the
distribution coefficient when dibutyl ether
was used as the diluent instead of hexane.

HDBP has been used as the extractant
in a procedure to determine py24l by
extraction and counting In a liquid scintil-
la‘tor.zss

Kimur3225 determined the acid de-
pendency of the distribution coefficients of
many elements extracted from 50 volume %
HDEHP from HCIl solutions. His results, in
the form of a periodic table, are shown in

Fig. 16 for comparison. Some results from

A later similar study was made on the solvent con-

226

 

[ [éil--IllP'.-IllS] -1 --cl--

 

 

 

 

 

 

 

~ 1PN\ % Er e
a1 1 2l 2L Ll a L i Al s g Lol 3
—E G m\r e R e R S B S A s.j 5]

| 4} 4t 4t 4t 4 !l | 4 i 1} 4+ L aamd b L
LIS N S \QA I ::\':'\:*\:: 1L A1 vt )
fi.l -fi--lselll- -llll- lll.l }l llLl- _:.-lll- rI\ l.-h- -jlll -l‘ll-F‘.ll -rllll- i l) F‘I{‘
| 5’4:Y:.i.z.’::ss£.:_:‘°" f‘fl:' RE PeSiE S '“z::’ fg;;* MY
SN e .\..::"‘:-\.; L Tk

 

 

 

 

 

 

 

 

 

 

 

 

9 r
el B[ L] TR W R o R R B T e Y B e A
O N I N1t —~ 11 I 1 A I cm‘:::§r-;L il ]
[ I -1 I === 1L Ir ik ;‘/\4’? 3 B ]
-.\ .-\ 1 1L - [ 1L 1L |- 1 1- '1 ] -lql i 1 ] ] ’

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- DFP Values basing on Data of DF.Peppard et al,
-=-CAB Data of CA Blaka et al.
Data of T.Ishlmorl .

=TI

==EN  Dalaof E.Nakamura.
Serubbing.

5

 

T 1. 1 T

 

™ T T ™ T TTTT --s

4

=0

R R
L 4} 4k 1rDFP\IL 4}
E p 4} L <k

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aclb — {|5= 'TISU'G'V [ PR Am][ )l B e R e M e
- 4k 4} 1 rose - 4+ 4t 4} S - 4+ 3 P -k
- 4 4} r 1F L 4k \-.. - 4F [ 1r
o 1 Jhe 0 ORI IR J ; :

1L Th;.. nan.-.- -_.__.. ] -E-.'-n -- - el A lol i

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fig. 16. Extraction of elements from HCI solution by 50% HDEHP in toluene as a
function of acid concentration.2

45
Di-acidic compounds. Mono-2-ethylhexylphosphoric acid has been most

 

extensively studied of this type of compound. It is polymeric in the organic phase in

310,130

a non-polar solvent, such as benzene and extracts primarilybythe ion exchange re-

action.
238 gtudied the extraction of Am(III), Pu(IV), Np(V), and U(VI)

by mono-2-ethylhexylphogphoric acid (H2MEHP) from nitric acid solutions with results

Kosyakov et al.
shown in Fig. 17. The distribution coefficients are in general higher for the same

aqueous conditions than those of HDEHP. Pu(IV) can be returned to the aqueous phase

by washing with a 5% solution of potassium oxalate.

5&JF7"-"'”‘“"----..._4L_________-__ITiEEEl-‘-_-.-

4.0 [ f}

.

 

 

 

o 2.0
=]
o
-~
1.0
0
-1.0
20 1 L | [
-.0 ~0.5 0 0.5 1.0

Log HNOz CONCENTRATION (M)

Fig. 17. Extraction of various actinides into 0.2 M HZMEHP {(isooctane diluent) from
HNO, solutions.238

Peppard et a.l.313’ 270 studied the extraction of several actinides by H2MEHP

from HCl solutions (Fig. 18). The distribution coefficient for Np(IV) at 12 M HCl is
over 103 and is a factor of 104 greater than the other non-tetravalent species studied.
Separation frorm Pu ig accomplished by.reduction of the Pu to the tripositive state.

Gindler et al. 146 236

used this method to purify Pu for fission counting. The Np{(IV) can
be returned to the aqueous phase by the addition of TBP to the organic phase, resulting
in a great reduction in the distribution coefficient because of anti-synergistic (or

antagonistic) effect of these reagents, (cf Mixed Extractants, p. 71).

Applications of acidic compounds. Acidic compounds have been used in
several applications in Pu chemistry. Kosyakov et a]L.za8 used HDEHP to purify Am(III)
from other actinides of higher valence state, and accomplish their mutual separation

46
 

Am(IIl), Pu, and U, are extracted from 0.01
M HNO, after stabilization of the Np in the
pentavalent state with NaNO,. Np(V) is then
oxidized to Np(VI) by an oxidizing agent and
extracted by HDEHP, and recovered from the
organic phase by reduction to Np{V) and
washing with 0.1 M HNOS. Am(IIT) is back-
extracted from the HDEHP by 3 M HNOB,

and the Pu recovered by reduction to Pu(III)
and back extraction with 3 M I-INO3.
the U(VI) is returned to the aqueous phase by

Finally,

Log D

back extraction with ~1 M ammonium
carbonate.

Chudinov and Yakovleva9 extracted U
and Pu away from Np(V) with HDEHP as a
preliminary step in the calorimetric
determination of Np(IV) with arsenazo (III).
They state a Np sensitivity of 0.04 ¥/m!l by
this method.

 

 

 

 

- DBP was used by Markin and McKay268
F HCI to prepare a pure Pu(V) solution in 0.2 M
Fig. 18. Extraction of some actinide HNOB' The method was to extract Pu(IV)

cations into 0.48 F HoMEHP in toluene from a mixture of Pu(IIl) and Pu{VI). The

as a function of HCL concentration.313 ,
reaction

Pu(VI) + Pu(IIl) = Pu(IV) + Pu(V)

is thus driven to completion leaving a pure Pu(V) solution in the aqueous phase.

Peppard et a1.311 used HZMEHP in various diluents, and tri-n-cctyl phosphine
oxide to effect 2 sequential separation of various tri-, tetra-, and hexavalent ions from
urine,

Peppard et al. 314

used HDEHP to separate Bk from other tripositive actinides
and from Pu. The Bk is oxidized to Bk(IV) in 10 M HNO, by 1 M KBrOg and extracted
away from tripositive actinides. The Bk(IV) is then back extracted into 8 M HNO3 by
reduction with HZOZ' Pu is not reduced to Pu(III) under these conditions and remains

in the organic phase.

Amine Extractants

These compounds are long-chain alkyl or aryl primary, secondary, and
tertiary amines, and quaternary amine salts. Moore286 and Coleman Lz-:.l.g5 have
given general reviews of the extraction of inorganic species by these compounds. The
amines react with acids to form an ion-association complex which is soluble in the
organic phase, illustrated by a tertiary amine

+ - + -
R3N(O)+H +A =R4NH ... A (0) (1)

47
A may be either a simple anion or the anion of a complex metal acid. This complex
may undergo a further reaction with another anion in a manner analogous to anion ex-

change

+B =R,NHT...B, ., +A (2)

A (o) 3 (o)

RBNH

Much work has been done on Pu and other actinides with these compounds, in
process and analytical applications. They have much higher distribution coefficients
than TBP for U and Pu{IV), and show much less deleterious effects on the distribution
due to high radiation fields because the radiolysis products do not interact with the
extractant to produce synergistic mixtures, (cf Mixed Extractants, p. 71).

The treatment here will be in the order ni_trate, chloride, sulfate, and other.

The structure and nature of the amine exert a great influence on the extractability of Pu,

Nitrate Systems

The relative extractability of Pu in nitrate solutions is in the order
Pu(IV) > Pu(VI) > Pu(Ill) and the extractive power of the amines varies in the order
10°

quaternary > tertiary > secondary
> pr‘im:a.ry'.l87 Pu(IV) extracts very strongly

:;I(g and selectively in analogy with anion ex-
Th(DL

)) change,

Keder _Lal.zlg reported the extraction
of several actinide elements from HNO3
solutions by tri-n-octylamine (TOA) diluted
with xylene. Their regults for quadivalent
gpecies are shown in Fig. 19 as a function of
HI\T()3 concentration. Pu(IV) and Np(IV) are .
much more extractable than are Th and U.
These species show a second power depen-
dence on the amine concentration, indicating
that the extracted complex involves two amine

molecules. According to Egs. 1 and 2, the

 

extracted complex involves the M(NOs)fi=
o™ . ] _
O 2 4 € 8 10 I2 14 anion and is (TOA),M(NOg)., where M is any

Aqueous HNO3 Concentration, M quadrivalent actinide. No conclusions can

Fig. 19. The extraction of the be drawn about the nitrate species in the
quadravalent actiniéi(f nitrates by 10
v/o TOA in xylene. 21°

Keder et al.219 also determined the extraction properties of hexavalent, trivalent

aqueous phase, however,

and pentavalent actinides as a function of nitric acid concentration, with results shown
in Figs. 20 and 21. The maximum distribution coefficients for all these species is very
much less than for Pu{IV) and Np(IV), indicating an easy separation of these elements
from other actinide elements. For the hexavalent species, the amine concentration
dependencies of the distribution coefficients were between first and second power, per-
mitting no unambiguous assignment of the extracted complex. The slope of the Am(III)
curve was unity, while that for Pu(Ill) was approximately 1.5. No explanation of this

fact was given.

48
102

107t

 

D
D APa X Ref.(13)
1.0 m Pg (X)
¥ Np(X)
e Py (IIT)
oAm (1T
107!
|0
0 2 q 6 8 0 12 14 0 2 4 6 8 0 12 14
Aqueous HNO3 Concentration,M Aqueous HNOy Concentration,M
Fig. 20. The exiraction of the hexa- Fig. 21. The extraction of pentavalent
valent actinide nitrates by 10 v/o TOA and trivalent actinide nitrates by 10 v/o
in xylene.219 TOA in xylene. 219

Keder et :3.1.2]'8 determined that the extracted complex is M(NO3)62- for
quadrivalent actinides and M02(N03)3- for hexavalent actinides by spectrophotometric
measurements.

187 and Weaver and Horner"£20 have determined the dis-

Horner and Coleman
tribution coefficients of Pu(IV), Pw(IIl), and Pu(VI) for a number of amines from HNOg
solutions, with results shown in Figs. 22, 23, and 24. Their Pu(IV) results for unsalted
tri-n-octylamine (TOA) agree qualitatively with Keder Lal.219 and Baroncelli Lal.?’s but
reach the maximumn at a lower HNO3 concentration. The other classes of amines reach
a maximum at around 9 M HNOa. The effect of salting with l\TaNO3 at a constant nitrate
concentration is to increase the distribution coefficient at lower acidities. Pu(IIl) and
Pu(VI) show very much lower distribution coefficients with all classes of amines (Fig.

23) although Al(NO3)3 salting raises the DPu(III) to a relatively high value with tertiary
amines (Fig. 24).

Baroncelli 51:_3.1_.36 measured the distribution of Pu(IV) between HNO3 golutions and
"tricaprylamine' (TCA, sold as "Alamine 336," a mixture of n-octyl and n-decyl-amines),
with similar results. The amine was diluted in ""Solvesso 100," an aromatic naphtha.

The extraction reached a maximum of approximately D = 140 at 4 M HNOS, and was
strongly depressed by the presence of macro uranyl ion, which saturates the extractant.
In experiments varying the concentration of the TCA the formation of the hexanitrato
Pu(IV) complex is confirmed, but the slope of the log D Pu vs log TCA curve is 1.4 in the
presence of 1.5 M uranyl ion. The corresponding slope for U is 1, indicating the for- .

mation of a uranyl trinitrate complex.

49
 

104 — +

     

 

W Allguat X5 In xylere \

0 B=I0d In Amco - 8% TOA Q

HB-I04 in xylens o

© TIOA In Amco - B TOA J

V Ditridecyl In Amaca

X LA-1 in xylena
107 |- 4524 In Amco B

X NBHA in xylers :

& Primens JM In Amuco - 5% TDA
oz Q Qx
10° - w A i

a w \ Fig. 22. Pu(IV) extraction by 0.1
M amines: effect of nitric acid and
o L o | sodium nitrate concentrations.
, Amine clags: (Q) quaternary am-
2 ¢° '\ monium, (3) tertiary, (2) secondary,
x (1) primary amine. Pu(IV) stabilized
! /\ with 0.04-0.1 M NaNOs. Amsco
L g i 125-82, T]DI%'?: branched primary
2 A 2 tridecanol.
I [Noa] - L [NQJ] -
[HNOa] + 0.2 M NaNO, - 8 M(HMC)3 + NuNOa)
[ X 4
9 x

n.5lll|°|.| L 1 Jlllllll 1 1 ||ILll|Ja‘. 'Ol.zl IIIlLlII 1 1 Illlli

 

 

HNOS (EQUILIBRIUM), M

Baroncelli _fi?s also determined the separationfactorsfor Pu from initially 1.5
M U ion and 4 M HNO4 by amine extractions with tri-n-dodecyl amine ("tri-lauryl-
amine," TLA) in an aromatic diluent (''Solvesso 100") and a paraffinic diluent (''Shellsol
T'"), and found them to be similar, around 40. The TLA-Shellsol mixture had about
5% nonanol to prevent formation of a third phase by increasi'ng the solubility of the com-
plex in the organic phase. Valentini flil.‘mg achieve maximum separation from U by
extracting Pu from 2 M HNOs.

Other work with tertiary amine nitric acid systems with generally similar results
includes that of de Trentinian and Chesfiellsand Chesfie B4 on TLA extraction of TL(IV), U.(VI),
Np(IV), Np(VI) and Pu(IV); I{nochZE’2 and Knoch and Lim:].ne1:'231 on tri-iso-octylamine
extraction of Pu(IV), U(VI), Zr, and Ru. Bertocci42 found that, with tri-isononyl amine
(TNA, tri-3,5, 5-trimethylhexylamine), the DPu(l'V)
still increasing at 6 M HNO3, in contrast to work on other amines.
Wilson430 found that perchloric acid is a very good stripping agent for Pu(IV) in
TOA solutions. The Dp, value was 0.04, bothin 1 M HNO, + 1 M HC10,and 0.8 M
HNO3 +02M HClO4. Bertocci42 found that Pu(IV) was not stripped well from TNA
solutions by NHZOH- HCI solutions, in contrast to expectations. Valentini Lal.409
1 M Hy50, to strip Pu{IV) from TLA with good results.

Several processes for the separation of Pu and U from irradiated U using tertiary

Vs HNO3 concentration curve was

used

amines have been proposed. Wilson429 used TLA + 2% Octanol in kerosene to extract
Pu(IV) from 4 M HNO3, and stripped the Pu by reduction to Pu(Ill) with ferrous sulfamate.
Cheagne et 31.85 used the same extraction system, but stripped the Pu{IV) by a HT_'\TOB'-stO4

mixture..- Valentini et an.l.‘109 used the TLA—HNO3 gystem.

50
T¢

 

0.1 M Reogents:

o 8-104 in Amsco - 8% TDA

o TIOA in Amsco - 8% TDA

" TIOA in xylene

|  V 5-24 in Amsco

X NBHA in xylene

o Primene JM in Amsco =
5% TDA

] O~==Pu(l11)
10" gemeaPu(VI)

- E2 (Pu)
o

 

103 N

 

 

 

o} [
HNO:3 (EQUILIBRIUM), M

Fig. 23. Pu(lll) and Pu(VI) extraction by 0.1 M amines: effect
of nitric acid concentration. Amine class: (Q) quaternary am-
monium, (3) tertiary, (2) secondary, (1) primary amine.
duced with 0.03 M ferrous su&f,amate plus 0.05 M excess sulfamic

acid, or oxidized with AgO.!

(Pu)

EO

 

z-z/l

 

I [No3] = 6 N (AI(NO,); + HNO,) |
| o
- l_ 0 0.1 MTIOA in Amsco - 8% TDA
0 0.1 MTIOA in xylene
X 0.3 MTIOA in xylene
| ¥{0.3 MTLA in xylene
X 0.3 M Alomine 336 in xylene ’,/
/’.
1072 //
I,
Unsalted HN03 Solutions
10-3 1 | 1

 

 

0.01 al [
HN03 (EQUILIBRIUM), M

Fig. 24, FExtraction by tertiary amines from solutions of
Pu(IM) in nitric acid with and without aluminum nitrate

salting. Plutonium reduced with 0.03 M ferrous sulfamate
plus 0.05 M excess sulfamic acid, —
The fact that Pu(Ill) does not extract into tertiary amines has been made the
bagis of 2 Np-Pu separa.tion.%'7 The Np is extracted as Np(IV) away from Pw(III) in a
nitric acid solution.

Winchester and Maramr:m431 made a study of the decontamination of Pu in an ex-
perimental pyrometallurgical laboratory from Fe, Co, Zr, Mo, Ru, and Ce by both
TBP and amine extraction. A summary of their results in terms of decontamination
factors for Pu is given in Table IV~17. They concluded that the best separation of Pu
from these metals was obtained in the secondary amine system and described a batch
equilibration process for recovery of Pu on a 300-gram scale in a metallurgical
laboratory. '

The Pu and U complexes have limited solubility in the organic phase, and
separate as a third phase at high metal conceniration. The addition of a small fraction
of polar constituent, e.g. octanol;, into the organic phase, increases the solubility of
the extracted complex. Baroncelli i‘a_l.35 have made a study of this effect, and also
of the effect of nitrous acid added to stabilize quadrivalent Pu. They found that nitrous
acid can have either an enhancing or depressing effect on the distribution coefficient,
depending on the nitric acid concentration, while the long chain alcohol always has a
depressing effect. At equal molar nitrous acid and alcohol concentration in the organic
phase, the distribution coefficient is at a maximum. Thig effect ig explained in terms

of the formation of an alcohol-nitrous acid complex in the organic phase.

TABLE IV-17. Decontamination Factors for Impurities in Plutonium in Various
Solvent Extraction Processes.

 

 

 

 

Initial Decontamination factors for{a)
concentration Primary(b) Secondary(c) Tertiary(d) Quaternary(e)
Element (g/1) TBP amine amine amine amine
Fe 1.26 74 > 492 120 - -
Co 1.86 > 300 > 31 > 80 >60 > 52
Zr 0.34 44 > 22 92 31 > h2
Mo ~0.17 > 100 > 8 > 78 >18 > 9
Ru 0.98 1.3 12 38 16 13
Ce 0.36 2.1 25 > 67 >32 > 28
Pu 60.58 -- -- -- -- --
Notes:
(a)

Procedure consisted of 3 equal volume extractions with 35 vol. % reagent in Gulf
BT Solvent (aliphatic hydrocarbon) from 8 M HNOg3 solution (except primary amine
extraction in which 6 M HNO3 was used). The secondary, tertiary, and quaternary
amines had 10 vol. % decyl alcohol. The solutions were stripped with 3-1/3 volume
portions of 0.1 M hydroxylamine nifrate.

(b)

(c)
(d)
(e)

Rohm and Haas Company "Primene JM-T"
Rohm and Haas Company ""Amine 9D-178."
TIOA.

Sterwin Chermnical Company '""Roccal."

Maeck et a1.262 determined the distribution of a large number of elements for

quaternary ammonium compounds between various aqueous golutions and methylisobutyl

ketone ('"hexone"). The aqueous solutions considered were NaOH, HNO HZSO4, HC1,

3]

52
and HF. No extraction of PwIV) or Pu(VI) was found at any concentration of HZSO4,
NaOH, and HF. The results for HNO3 and HCI are given in Figs. 25 and 26 as percent
extractions from equal phase volurmnes as a function of aqueous acidity in the form of
periodic tables. Berkman and K:a.pla.n40 found that tetrabutylamrmmonium nitrate (TBAN)
added to Pu{IV) extracted into hexone caused the formation of a hexanitrate Pu(IV)
species, while in the absence of TBAN the tetranitrate appears to be stable. A pro-
cedure for radiochemical determination of Np and Pu based on this extraction system
using aluminum nitrate as a salting agent has been developed by Maeck e_til.261 They
report a better decontamination from fission products, particularly Zr, than is ob-
tainable in other amine systemas. '

The quaternary amine "Hyamine 1622'" has been used to extract Pu(IV) from HNO,

golutiong as part of an analytical procedure for Pu.48

Chloride Systems

Pu(IV) and Pu(VI) extract well from HCI solutions by amines, while
Pu(ITl) is poorly extracted, in analogy with the strong base anion exchange system.
Plutonium chloride systems have found application mainly in analytical and radio-
chemical work rather than in processes because of the corrosive properties of HCl
solutions.
Keder2
and U from HCI solutions into tri-n-octylamine (TOA). The dependence of the

17 measgured the distribution coefficients of tetra- and hexavalent Pu, Np,

distribution coefficients on HCI concentration is shown in Figs. 27 and 28. In every
case, the slope of the log D vs log TOA concentration curve is near 2, indicating that
the extracted complex has two TOA molecules for both valence states. Pu(IV) is much
more extractable than is Np(IV) and U(IV) under the same conditions. The hexavalent
actinides are more extractable than the tetravalent in this system.

Shevchenko Lla.l.366 .
distribution coefficient was approximately 0.005 for Pu(Ill) extracted into 20% TOA in

obtained similar results for Pu(IV), and found that the

xylene.

Moorezaz’ 283

extracted tracer Pu(VI) with 5% tri-isooctylamine (TIOA) in
xylene from 4.8 M HCI, using 0.01 M potassium dichromate as a holding oxidant.
Niobium and ruthenium extracted to some extent, but separation from these elements
is possible by scrubbing with 5 M HC1 and reductive stripping of the Pu. Th(IV) or
trivalent and lower speices did not extract. The tri-laurylamine (TLA)-HCl system

has been used to separate Pu(IV) before spectrographic analysis of other elernents.234

Sulfate Systems

Shevchenko and Zhdanova'73 investigated the extraction of Pu(IV) from
HZSO 4 solutions by TOA. They showed that the extracted complex contains 2 amine
molecules., The sulfuric acid dependence from 0.1 M TOA is shown in Table IV-18.
The decrease in the distribution coefficient at low acidity is ascribed to Pu(IV) poly-

merization. As the acid concentration is increased, the decrease in D is ascribed

Pu(IV)
to the formation of an amine bisulfate complex.

53
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

' HI EXTRACTION )96% ! r
i % é NOEXTRACTION <1 % L 8 €I N- e
r 515- L [
80|
- 5 HNOy  SYSTEM L | .
L N |} Mg o OFTEYY o Al o P 5
e[ N HNO, -\'n fi'ty .
X c # [[ B v &'L"" E['? T'E\B'E‘TH'E“H'E
L r X I dk b < 1F - o
. L&#L&Lfi& ety (SN - | S | S
] :"--T\ ) }
L " . | L L P L
" LR E T w LE R AL\ it
\ =~ \ —~J} t k
\\_ ") " s | wmeed | -
. “[f;;"&, *...a;,~[::_}'"~.£;¥_¥_n 2|l
1t L _--LL *eaanar R o -‘ . e, | Lo o
Fr Ra |} A ’1-.! ,:-b‘ 1|I'.ll'-.':u:\ +r=-
ey l..' :' —— (M4 N I
f .
- ——— (Butyl), N
[ f 7 (Propyl) Nt
L - ) T
I3 ,P‘?—"’ ’_‘.'-‘f"' =/ /Y || T opyly
= - CPP-8-1TOB

 

 

 

Fig. 25. Extraction of elements as tetraalkyl amine complexes from nitric acid.262

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

r HI EXTRACTION )>98% [
| L Qe 5 w00 NO EXTRACTION < % B c it w 0
I x). = oy . B . N
i = HCI SYSTEM
3 5 ) h-.--"-. L r
L Nlfl L Mg » “oirzden - Cr IAI{ s | P : 5
Mt - Non:tg.m = .
- r’\ I’.- [
e ¢ [FTNIE | el '
[ "‘ gt o8 0 42 2 . fi
-~ \\ r—\\‘ - }' --._. oIEEX ,f!
; §
o YUY AR R FR |
il .,'A__.
i X o s ';,:—
\ '
e o't o [ TR B |
¥ |l X T T R.E\' =
)
———— (Butyl)y Nt
eleusdden (Prop,l)4 N+
—oPr——rr o

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Fi .6%6. Extraction of elements as tetraalkyl amine complexes from hydrochloric
acid.

54
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

106 —a 103 102
E 3 : R
- > -
104L /A 1102 -
A ; I
af ’ 10
03, o :
o2} 1.0 -
- e U (V)
A - /}Z Do - B Nplvi)
10 E / {107 - A Pulvl)
.o fl / 4102
— p 3 10~k
A :_
Io_l - - |0_3 ™
F o uliv) K -
- B Np(IV) 3 n
- o PU“V) -
10™2L J10-4 102 l | | ] |
F 3 o | 2 3 4 5 6 7 B8 9 |0
- . M HCI
-3 ] 1 | L 10-3
10 O1 234 5678 910
M HCI _ Fig. 28. Extraction of hexavalent U,
Np, and Pu from HCI solution with 1.0%
Fig. 27. Extraction of U(IV) and TOA in xylene.217

Np(IV) by 10% TOA and Pu(71'V) by 1- 0%
TOA from HC1 solutions.?21

TABLE IV-18. Dependence of the Distri- Vdovenko et al.412 investigated the
bution Coefficient for Pu(IV) Between

Aqueous Sulfuric Acid and Tri-n-Octyl- extraction of Pu(IV) by a mixture of 7 to

 

amine.373 9 carbon primary aliphatic amines dis-
H2SO4 Concentration solved in chloroform. They determined
at equilibrium D that the extracted complex involves 4
(M) Pu(IV)

 

amine molecules, i.e. (RNH3)4PU(SO4)4.

0.01 11.3 , S
by the amine concentration dependence
0.037 15.2 . -
0 method, and by direct macroscopic
A1 43
3 g 2 measurements of the stoichiometry of the
0.32 i8.
3 reaction. From comparisons of the ad-
.88 0.415 ] .
sorption specira in the aqueous and
2,44 0.008

 

organic phases, they conclude that the
(a)Initial TOA concentration 0.1 M, Pu(IV) Pu(IV) exists primarily as a neutral sulfate
concentration 2.34 X 1074 M. - complex in the aqueous phase. Therefore,
they conclude that in this case the anion exchange process does not operate.

Extractions from mixtures of H2504 and HNO3 proceeded by the formation of the
gsame amine Pu sulfate complex above, but the distribution coefficient decreased with
increasing HNO3 concentration because of the formation of arnine nitrate complex. This

effect is illustrated by the data in Table TV-189.

55
TABLE IV-19. Distribution Coefficients of Pu(IV) from H2504 Solutions into Primary
Amines as a Function of Increaging HNO, Concentration. 2

 

Concentration of HNO4 (M) 0 0.05 0.10 0.20 0.30 0.50 0.90 1.50
Dpy(rv) 66.3 63.3 50.1 14.6 2.08 0.11 0.01 R

 

*Amine concentration 0.06 M, HQSO4 concentration 0.2 N.

By contrast, Horner and Coleman187 get a third-power dependence on amine con-
centration for extractions of Pu(IV) from H2804 solutions by primary amines. They
also determined distribution coefficients for Pu(IV) of several secondary and tertiary
amines. Their results are shown in Fig. 29, showing the successive lowering of the

distribution coefficients in going to more complex amine types. They report variable

 

104
/Prlrneno JM/Amco~
/ TDA, 3 M H,SO,
103 L Primena IM/xylens,
0.5 M H,SO
2.0 M (NH).SO
4 %4 /
102 . .
i 0> / 873 M 5O, pH~0.7 Fig. 29. Extraction of Pu(IV)
NBHA/Amco from sulfuric acid and acidic
—3 M Hy50, sulfate solution by primary, sec-

ondary, and tertiary amines.
Diluents: xylene, Amsco 125-82,
or 95% Amsco 125-82-5%

MN-benzyl-1-undecy|-lauryl/
/Amlflo, 3 MH2504

3 M SO, pH~0.7

Ditridecyl/Amsco-TDA, tridecanol. For primary amine
3 M H,S0, extraction, Pu reduced with
& hydroxylamine sulfate, reoxidized
i ' and stabilized at (IV) with 0.5 M
Amine 5-24/Amco, 1 - =
Aamun;o4, p/|-| -?7 NaNOQOsg. Others stabilized at (IV)

with 0.1-0.5 M NaNO,.187

 

 

Tri-Im~octyl/Amsco,
°3 Mso‘r pH~ 0.7

l 1 I 1
0.001 0.0l 0.1 | 10

AMINE CONCENTRATION, M

 

distribution coefficients for Pu(IIl) by primary amines from sulfuric acid solutions,
ranging from ~5 to >> 100 with 0.1 M amines. This behavior is attributed to partial
oxidation of Pu(III) to Pu(IV), even in the presence of holding reductants.
These authors propose a process for recovery of Pu from sulfuric acid decladding
3 . I . 188
solutions based on primary amine extraction.
The primary amine- sto system has been used for determination of Pu in

biological material, e.g. urine or solution of bone ash. 61

56
Other Systems

Moore285 found that the hexavalent actinides U(VI) and Pu(VI) could

be quantitatively extracted from 1 M acetic acid solutions and 1 M acetic acid — 0.1

M nitric acid solutions by 5% TIOA-xylene. Of the fission products only Ru, Zr, and
Nb extracted appreciably, and these could be scrubbed with 5 M HCl. A preliminary
ferric (or uranyl) hydroxide precipitation in the presence of niocbium carrier improved
the decontamination from these elements. The U and Pu were leached from the insoluble
Nb205 with 1 M acetic acid. The uranium could be stripped with dilute I—l'J.'\TO3 or HCI,
NH4OH or ammonium bicarbonate. The Puw(VI) could be stripped by these reagents

or reductively stripped, since Pu(IV) and Pu(Ill) do not extract under these conditions.

Alcohols, Ketones, Etherg, and Amides

These compounds have in common the fact that they contain a basic oxygen
atom which can solvate a proton or metal atom. This type of extractant was once very
popular, but the newer organo phosphorous compounds and amines have received more
attention in recent years. Nevertheless, they are still important in laboratory and
process separations. Indeed, one of the large-scale processes for the processing of
irradiated U, the '"redox' process, uses methylisobutylketone (MIBK or "hexone'’)
as the primary extractant for U and Pu251 as do several laboratory procedures. The
extractive properties of the ethers for U, Fe, and other elements have been known for
many years.

Nitrate systems have received by far the most attention as extraction media for
Pu. Both Pu(IV) and Pu(VI) are extractable at high nitric acid concentrations, or at
moderately high nitrate concentrations provided by a salt such as aluminum
nitrate. Pu(IIl) is practically inextractable at any nitrate concentration. The extracted
species depends on the aqueous phase composition. It has been shown that, for example,
the extraction of Pu(VI) from nitric acid solutions by dibutyl carbitol (DBC, the dibutyl
ether of diethylene glycol) the extracted species is the neutral plutonyl dinitrate at low
nitric acid ( < 0.8 N) is a mixture of dinitrate and trinitrate at intermediate acidities
(0.8-3N), is predominately trinitrate at higher acidities (3-6N), and finally is more
complex than irinitrate above 6N. 171 At these higher acidities the extraction must in-
volve the solvation of a proton to form the species H(DBC)2 Pu(NO3)3, rather ‘;}éa}rn
direct solvation of the Pu in the case of the extraction of the dinitrate sgpecies.

from 1.5 M HNOS and as HzPu(NOg)6
245, 246

Similarly, Pu(IV) extracts into hexone as Pu(N03)4
at 6 M HNO3, with intermediate composition of the organic phase in between.
The species extracted into triethyleneglycol dichloride at high nitrate concentration have
been found to be H2Pu(1\703)6 for Pu(IV) and H Pqu(NOB)3 for Pu(VI).7Ei Dibutyl ether
behaves similarly. 413 -
Pu extraction by hexone has received the most attention, undoubtedly because of
its use in processing. The extraction of Pu(IV) and Pu(VI) as a function of nitric acid
concentration and the concentration of various salts has been measured by several

groups.

57
    

 

0
|
0.0l
D
Q.00
D, _<0.00I
Cu<
0.000I DNU_O.OOI
La
g g a1
0.0000I I 2 3 2 5 e
M HNOj;
Fig. 30. The distribution ratios of T,

Pu(IV) and Pu(VI), Th, Zr, Ce(IV) and
La into hexone as functions of the equi-
librium concentration of HNO4q in the
aqueous phase. The Ce(l‘Vj curve is
taken from Glendenin et al.14

Py WI’,u(lV)

o
T III"I T
A

\J

 

 

D
Q.
-
001
- Ca
0.001 E % .
i Dyg < 0.001
1 L L L ] ] | 1 ] 1
00001 I 2 3 4 5 6

AQUEOUS HNO5 CONCENTRATION (M)

Fig 31. The distribution ratios of U,
Pu(IV) and Pu({VI), Th, Zr, La and Ca
intc hexone ag functions of the equilib- .
rium concentration of HNO4 in the aque-
ous phase. Concentration of Ca(NOg)y
4-3.5 M.343

58

343 measured

Rydberg and Bernstrom
distribution coefficients for several
elements including TU(VI), Pu(IV), and
Pu(VI) as a function of nitric acid con-
centration both with and without calcium
nitrate as a salting agent. Typical results
The effect

of salting with Ca(NO3)2 is to raise all the

are shown in Figs. 30 and 31.

digtribution coefficients, but at low acid
those of U and Pu are high enough to be
efficiently separated from other elements.
MacKenzie?®? extended the distribu-
tion curves to higher aqueous acidities for
Puw(IV) and Pw(VI) as shown in Fig. 32.
This curve was replotted from MacKenzie's
original data by Smith388 because the
original was reported in terms of organic
phase acid concentration. The conversion
to aquéofi"s'- phase original acid concentration
wag made by using data on nitric acid ex-

traction by hexone. Both Pu(IV) and Pu(VI)

pass through maxima and decrease above

approximately 7 M acid. A salting agent,
e. g ALNO,),, 271 193 ca(NO,),,343,
NH4NO3260 increases the distribution co-
efficient. A useful comparison of various
galting agents for Pu(IV) into hexone was
reported by Stewart3 23 (Fig. 33). The salts
increase in salting effectiveness at high
total nitrate concentration in this order:
ammeonium, lanthanum, nitric acid, mag-
nesium, aluminum, and mangafiese. A
similar comparison for Pu(VI) into diethyl
ether was made resulting in this order:
ammonium, calcium, lanthanum, nitric
acid.

Kooi236

found that .the distribution
curves for extraction of Pu(IV) and Pu(VI)
into hexone did not decrease at high HINOg4
concentrations, in contrast to other
workers. His distribution coefficient for
Pu(IV) reached the maximum value of

approximately 7 at 8 M initial HNOS
 

o
AR R

    

 

 

 

D 0.1 Pu(vI}(d Pu CONCENTRATION 2 2 mg/mi
" " #" , Dadjusted
PullV) ® Pu CONCENTRATION= 2 mg/ml
v " #Fuon yD adjusted
0.0l
~
_1 | I | | |
0.00l
0 2 4 6 8 10 i2 14

INITIAL AQUEOUS HND3 CONCENTRATION (M)

Fig. 32. Distribution of Pu(IV) and Pu(VI) into hexone from HNO4 solu‘cions.260

concentration. MacKenziezs0 found that the distribution coefficient for both Pu{IV) and

Pu(VI)} in nitric acid increased in the range 0.01-2 mg/ml, while Groot Lal.153 re-
port no dependence on Pu concentration from 0.00003 to 0.5 mg/ml for the extraction
of Pu(IV). Groot et al.!®3
either 0.03 M Na,Cr O, or 0.3 M sulfonic acid. These reagents are commonly used

271
as oxidizing and reducing agents in redox processes. Rider et al.332 has used hexone in a

also find that the distribution coefficients are not affected by

laboratory procedure to determine Pu and U in reactor targets.

Other Aqueous Systems

Stewart393 reports on the comparative extraction of Pu (unspecified

initial valence) by hexone from hydrochloric, nitrie, sulfuric, and acetic acids under
various conditions (Table IV-20). Plutonium (presumably a mixture of Pu(IV) and Pu(VI))
extracts well from 8 N HCI, but not from H2504

ig very low under reducing conditions for all these acids.

or acetic acid, while the extraction

59
 

100
90
B8O

Fig. 33. Effect of total nitrate
ion concentration on the extraction
of Pu(IV) by methyl isobutyl

TO

60

PERCENT Pu(lV) EXTRACTEDBY
EQUAL VOLUME METHYL-ISOBUTYL KETONE

 

 

 

 

ketone. 393
50 Curve
No. Aqueous Phase
II 1IN HNOj3 + NH4NOg
III 1N HNOg + Mn(NOj3)g
30 IV 3N HNOg3 + Mg(NO3)y, POy---
v 3N HNOg + A1(NOg)3, POy4---
50 VI 1M HNO3 + La(NOj)g
10
0 | I L 11
0O | 2 3 4 5 6 7T B8 9 101 12

TOTAL INITIAL NO3 CONCENTRATION
IN AQUEOUS PHASE

Other Extractants

Stewartag3 compiled a table of extraction data for a large number of
ethers, alcohols, ketones, etc. for Pu in the tri-, quadri- and hexavalant oxidation
states from ammonium nitrate-nitric acid mixtures. These data are reproduced in
their entirety as Tables IV-21, and IV-22, to show the variety of compounds
tried and to indicate the types of compounds which are efficient as Pu extractants. In
general, the ability of these compounds to extract correlates with the basicity of the
oxygen, nitrogen or other functional group. Thus, electronegative substituents in-
variably decrease the extractibility of Pu (see e. g. diethyl ether vs dichlorodiethyl-
ether).

TABLE IV-20. Distribution of Pu Between Various Aqueous Phases and Hexone.393

 

Distribution Coefficient for
Extraction from 8 N Acid

 

 

Composition of Aqueous Layer  HCI HNO, Hy50,  CH3COOH
Acid only 10 8.3 0.06 0.012
0 0.33 3.3 0.005  -----

Acid + 0.7 M UOz(NOS)z IEFH2
Same, saturated with 802 0.0012 0.2 = m==e- —=eea
Same, as 2 + 0.06 M hydroquinone 0.0033 -——— mm——= meeee

B W N o~

 

60
TABLE IV-21,

Volume of Various Organic Solvents.

Extraction of Plutonium from 10 M NH4NO3, 1 M HNO3 by an Equal

 

 

 

% Pu % Pu
extracted extracted
Solvent (II1)*  (IV) (VI) Solvent (II)* :(1v) (VI)
Ethers-Cellosolves Acids - Esters
Diethyl ether <1 <1 50 2-ethyl butyric acid <1 5.7 -
N-propyl ether <1 4.8(?)2-ethyl butyl acetate <1 1.5 -
Di-isopropyl ether 7 Ketones
Allyl ether 4 - m ethyl ketone
N-butyl ether 1 1.5 15% Xylene <1 79 -
Hexyl ether <1 1 1. Methy n-amyl ketone <1 52 -
Ethylallyl ether 2 - Methyl isobutyl ketone
Ethyl-n-butyl ether 1 (Hexone) <l 82 -
Dichloro ethyl ether <1 3 12  Measityl oxide 14 -
Phenyl cellosolve 21 - Acetophenone 83 -
Benzyl cellosolve 48 - Cyclopentenone 91 -
2-ethylbutyl cellosolve <1 71 - Cyclohexanone 72 -
Diethyl cellosolve 97 9  Methylcyclohexanone 82 -
Ethyl butyl cellosolve 66 73 Menthone 20 47
Dibutyl cellosolve 6 13  1sophorone <i 37 y
BA' Dibutoxyethyl ether 93 91(?) Hydrocarbons
Triglycoldichloride <1 72 - Cyclohexane 3
Dibutoxytetra-ethylene 73 - Cyclohexene 5
glycol Xylene (mixture of
Anisole 3 - isomers) 10 -
O-Nitroanisole 62 40 Pinene .6 -
p-Fluoranisole 1 - Indené 5 1
Resorcinildimethyl ether 1 Nitro Compounds
Dimethyldioxane 60(?) - Nitroethane 34 g1
Sulfur Compounds Nitromethane 1 58 70
Diethyl sulfide 43 - Nitro benzene a 28
Thiophene L Halogenated Compounds |
Carbon Disulfide 62 1 Methyl Chloroform 4 3.2(?2)
Alcohols Trichloroethylene 6 12
Hexanol 23 - Chlorobenzene 4 7
Heptanol 15 - Bromobenzene 2. 2.
Heptadecanol <1 10 - Iodobenzene 1. 1.7
2-ethyl-hexanol <1 1 - o-Bichlorobenzene 4 5
2-ethyl-butanol <1 16 - m-Dichlorobenzene 4.6 -
Methyl-isobutyl - Ethyl iodide 1 1
carbinol 42 - Isoamyl chloride 1.6 1
Methyl-amyl alcohol 1 42 - Tertiary amyl chloride 1 -
Miscellaneous
o Butyl phosphate 99 97

 

%
(II1) Values out of

61

5 W4 Cl, TN-HCI, Sat'd. with SO,.
TABLE IV-22.

Extraction of Plutonium into Miscellaneous Organic Solvents.

393

 

% Pu extracted
by equal volume

Composition of aqueous

 

 

phase before of solvent
Solvent equilibration (ITT) (IV) (VI)
Carbon tetra chloride Nearly saturated NH,NO, 1 1
Ethyl acetate Nearly saturated LiNOj 5 25
Chloroform Nearly saturated LiNOg 1 1.6
Ethylene dichloride Nearly saturated KNOjg 1
Ethyl bromide Nearly saturated LiNOg 1.6 2.1
Nitromethane Nearly saturated LiNOg 7.9 71
13
1-Nitropropane Nearly saturated LiNOj 20 81
30 69
2-Nitropropane Nearly saturated LiNO3 39.6 72
Nitroethane Nearly saturated LiNOg 72 83
Diethyl cellosolve 20% UO32(NO3)g- 6H50, 84
10 M NHNOg3 0.5 M HNOj3
Di-butyl cellosolve- 2 M HNOj, 5 M Ca(NO3)2 11
Di-butyl carbitol 20% UO4(NO3)s° 6H50, 0.05 48 8
' 10 M NH4NOj3, 1 M HNOg
2-ethyl-butyl 20% UO2(NOg)s" 6H5O, 0.03 46
cellosolve 10 M NH4NO3, 1 M HNO3
Diethyl cellosolve’ 20% UO2(NO3)9* 6H90, 0.3 48 52
10 M NH4NOg3, 1 M HNOjg
Dibutyl cellosolve 20% UO5(NO3)g" 6HO, 0.003 3 88
.10 M NH,NOj3, I M HNOg
Ethyl butyl cellosolve 20% UO2(NO3),* 6Hg0, 0.1 60
10 M NH4NO3, 1 M HNOq
Nitromethane 20% UO5(NOg)y' 6H50, 5.2 67
10 M NH,NO3, 1 M HNOg
Methyl-isobutyl 20% UO9(NOg)y" 6H0, 0.05 26
carbinol 10 M NH4NOj3, 1 M HNOj
2-ethyl hexoic acid 20% UO9(NO3g)q- 6H50, 0.03 1
10 M NH4NO3, 1 M HNOg
Methyl isobutyl 20% UO9(NO3)9' 6H,0, 0.1 47
carbinol acetate 10 M NEH4NOg, 1 _1\_/12HNO3
Xylene 3 M HNOg, 5 N Al(NO3)3. 0.001
Dissolved BiPOy4
Nitrobenzene 3 M HNOg, 5 N Al(NOg)j. 5 5.3
Dissolved BiPOy4
Nitroethane 3 M HNOs3, 5 N Al(NOg)3. 47.5
Dissolved BiPOy
Dibutyl carbitol 3 M HNOj3, 5 N Al(NO3)3. 99.8
Diasolved BiPOy4 '
Ethylene dichloride 2 M HNO4, 10 M NH4NOj 1 1
Anisole 10 M NHy4NOj 0.003

 

62
245,246 investigated a series of aliphatic ketones as efiractants for Pu(IV).

Kuca
His results, shown in Table IV-23, show that the distribution of Pu(IV) into hexone is
decreased by (1) increasing the length of the side chain for the methyl—n—aikyl series,
(2) increasing the branching of the side chain for the methyl- (n-, sec-, and tert-)
butyl series, and (3) increasing the symmeitry for the seven carbon atom series. These
resultis can be Qualitatively explained by the effect of the decreased basicity of the
carbonyl oxygen as the alkyl side chain is lengthened, and by steric effects in branched
alpha carbon atoms. Khalkin M'224 found that the distribution coefficient for the ex-~
traction of Pu(IV) from 5.0 M HNO3 was 11.5 by diethyl ether, and this was the highest
among a number of oxygen containing compounds. Pu(IV) was extracted as HéPu(NO3)6
at this acidity. K00i23® found that for extraction of Pu(IV) from 8 M HNO, the ex-
traction decreased in the order dibutyl carbitol (DBC) > diethyl ether (DEE) > hexone,
while for Pu(VI) the order was DBC > hexone > DEE. Branica and Bona54 found that

U(VI) and Th extract at a lower HNO, concentration with several cyclic ethers (e. g.

TABLE IV-23. Distribution Co- tetrahydropyran) than with diethyl ether or
efficients for Pu(IV) Extracted by

Various Ketones from 3.2 M HNO3.245 hexone, and these results are presumably

 

applicable to Pu also.

 

Distribution A number of other process applications
Ketone coefficient )

of this class of extractants are worth mention-
Methyl-n-propyl 10 L ; dib diethvleth

ing at this point. 8,8' - dibutoxydiethylether
Methyl-n-butyl 2.2 g P 8.8 yeethy

) ("Butex') has been used as one of the ex-

Methylisobutyl 1.6

tractants, along with TBP in a two-solvent
Methyl-t-butyl 0.12

process for purification of Pu and recovery
Methyl-n-amyl 0.62 450 188

: of U at the Windscale power reactor facility. :

Methyl-n-hexyl 0.22

The quoted advantages over hexone are (1)
Di-n-propyl 0.12

sufficient resistance to attack by high con-
Ethyl-n-butyl 0.23

 

centrations of HNO3 to permit use of the
acid as a salting agent, and (2) superior
separation factors of Pu from U. TBP is used as the second extractant because it gives

superior decontamination of the Pu from Ru.

Vdovenko and Kovalskaya.411 used a mixture of dibutyl ether and carbon tetra-

chloride in a Redo-type process with satisfactory results.

Dibutoxytetraethylene glycol (''pentaether') has been used as an extractant,lso

along with a 50% pentaether-50% dibutyl ether 1'nixtur<-:-.28
Sidda11377. 378

for tetra- and hexavalent actinides. The carbonyl oxygen in these compounds has en-

has pioneeredthe use of N, N disubstituted amides as extractants

hanced basicity because of the presence of the amido nitrogen, and therefore should be
analogous to the neutral organo-phosphorous compounds in extraction properties.
Typical results for a number of elements and amides are shown in Fig. 34 and Table
IV-24. He found that U(VI) behaved similarly to the phosphorous compounds (e. g.
TBP) in that the extracted complex involves two amide molecules. However, the

quadrivalent species (Pu, Th, etc.,) are extracted with more than two amides per

63
¥9

TABLE IV-24,

at 3 and 6 M HNO, (Ref. 379).%

Extraction of Actinides and Zirconium by Various N, N-Disubstituted Amides

 

— 3.0'M HNOj4 in the aqueous phase —

—6.0M HNO3 in the aqueous phase——

 

 

SExtraction coefficient is defined as moles/liter in the organic phasge divided by moles/liter in aqueous phase.

bA]_'l 0.50 M in toluene.

b Pu Pu- Np- U- Np-

Amide u(viy (av) (V) Np(IV) (VD) HNO; (VD) PuV) (IV) Th Zr  HNOq

N, N-Dihexylformamide 4,1 2.4 0.119 3.6 4.0 0.10 0.54 0.090
N, N-Dibutylacetamide 9.9 21 138 6.4 38 .74 .21 .102
N, N-Dibutylpropionamide 4.5 3.5 112 4.5 7.2 .11 .044 .094
N, N-Dibutylisobutyramide 2,4 0.080 0.23 0.024 1.2 .103 3.3 0.21 0.070 .0040 .0026 ,083
N, N-Dibutylpivalamide 0.60 0.0009 .051 0.33 .057 1.4 0.0048 .0001 <,001 .060
N, N-Dibutylbutyramide 5.3 . 4.0 .63 1,0 3.4 114 4.7 8.7 2,2 085 ,039 .095
N, N-Di-isobutylbutyramide 5.1 3.5 0.48 0.62 3.0 .108 4.8 7.1 1.6 .028 ,046 .088
N, N-Di-isobutylisobutyramide 2.0 0,057 0.0070 100 3.1 0.11 0,037 .0010 00,0012 .085
N, N-Dicyclohexylformamide 9.4 9.9 .150 4.8 11 .21 1.1 .100
N, N-Dicyclohexylacetamide 14 11 2.2 .142 8,3 16 .68 0,026 ,091
N, N-Dicyclohexylbutyramide 7.9 1,7 .148 5.1 2.9 .16 .010 .103
- N, N-Dibutyl-2-ethylhexanamide 4.0 0.19 125 4.1 0.29 .0043 .0022 .094
N, N-Dimethyldecanamide 4.9 10 115 4,4 39 .63 096  ,091
N, N-Diethyldecanamide 5.1 6.9 .120 5.0 16 .34 049 .096
1-Hexanoylpiperidine 7.2 B.7 .115 5.8 20 .32 077 .096
1-(2-Ethylhexanoyl)-piperidine 2.8 0.60 .087 4,2 1.5 .025 .011 ,080
N, N-Di-sec-butylhexanamide 5.5 .90 120 4,0 3.9 .092  ,0092 .0%4
N, N-Dibutylcyclohexanecarboxamide 3.1 .19 103 4 1.0 .0040 ,0034 .090
N-Butyl-N-phenylbutyramide 1.4 .23 .088 2.4 1,3 .0033 .0099 .085
N, N-Dibutylberizamide 0.86 .34 105 1.2 0.69 .0099 ,0070 .088
N, N-Dibenzylacetamide 3.3 0.22 0.077 4.3 1.0 0.014 0.021 0.077
metal atom at high nitrate concentrations. Zr exhibits a maximum distribution co-
efficient at about 7 M HNO, and decreases at higher acidities. A large decrease in the
distribution coefficient of quadrivalent Pu and Th occurs as the branching of the alpha
carbon atom is increased, while that of U(VI) is only decreased moderately. N, N-
dihexyloctanamide was superior to TBP in decontamination of Pu from Zr-Nb, but
slightly inferior for Ru decontamination. The potential uses of these compounds are
(1) as selective extractants for quadrivalent actinides, or (2) as selective extractants
for U(VI) in the case of amides with highly branced alpha carbon atoms (e. g. N, N-
dihexyltrialkylacetamide).

Chelating Agents
A large number of bi-functional reagents which form strong coordination
complexes with metal ions have been investigated. These complexes are more soluble
in non-polar organic selvents such as benzene or carbon tetrachloride than in the

aqueous phase, and are therefore extractable. Of these compounds the fluorinated

/ B-diketone, 2-thenoyltrifluorc acetone (TTA) and

 

100
the ammonium salt of N-nitrosophenylhydroxyl-

amine (''Cupferron') have been used most widely

T

in radiochemical and analytical applications.

uivn Thenovyltrifluoro acetone {TTA)

S

This compound has the structural

i) O
L) 8 e,

S

formula

FTTTTIT]

  
 

Th{lv) and exists primarily in the enol form in both

aqueous and organic solutions.
TTA forms strong complexes with many

metal ions, particularly those of high valence.

T T ITTT]

The general reaction for the extraction can be

written as

+m +
o /¢ M +mHT = MTm(o) + mH (1)

0.l (o) ~

and the equilibrium consgtant

T TTT

+,m
LM, )

g — (2)
(M+T™ (HT)IE:))

 

 

0.01 g L GL B where the quantities in parentheses are activ-

HNOz CONCENTRATION AT ities.
EQUILIBRIUM (M) Thus, if activity coefficients are neglected,
Fig. 34. Extraction of actinides and no aqueous complexing occurs, the distribu-

and Zr by 1.09 M N, N-dibutyloctan-
amide in n-dodecane at 30°.378

 

tion coefficient should show a direct mth power

65
dependence on the TTA concentration and an inverse mth power dependence on the
aqueous acidity. This expectation is borne out for many elements, including Pu.

The most comprehensive summary of TTA data is that of Poskanzer and

Forema_n324 who found that the extraction data for most elements could be fitted by the
equation
+.x
-p—HL 3)
&Py g o )
HT

in which K is a constant, [H+] is the activity of the hydrogen ion in the aqueous phase
(HT) is the concentration of the TTA in the organic phase, x is the observed TTA con-
centration dependence of the reaction, m is that of Eq. 1, and f is the organic phase

activity coefficient of the TTA. For benzene solutions of TTA

0.48 228 (4)

f =1-0.24 (HT)

HT

Equation (3) assumes that the activity coefficients of the TTA and the metal chelate
are equal in the organic phase.

These authors determined the parameters of Eq. (3) for all available experimental
data on TTA extractiones and calculated pH50, the pH at which 50% of the ion
is extracted by equal volume phases into 0.2 M TTA in benzene. They displayed some
of these data in the form of a periodic table to show the trends in extractability of the
elements (gee Fig. 35). In cases in which the pH50 value is negative only HCI data are
given, while other data may be for a variety of acids and acid-salt combinations. The
reader is referred to the original paper for more detail. However, this figure shows

that the quadrivalent ions are much more extractable than others.

 

ELEMENT
H.. OXIDATION STATE — \
LIZ|jBem PHsq 2l 8 c | n\olr‘
>® ||#**]  pHgy = pH. OF 50 % EXTRACTION WITH EQUAL VOLUME
NEGATIVE "pH,, ° ® —LOG HCI CONCENTRATION

No [l Mg . X~ COEFFICIENT OF pH DEPENDENCE OF LoG & D |AIIO(l SI P s cl
= OXIDATION STATE WHEN NOT INDICATED 2.4

 

 

 

 

 

 

 

 

 

 

 

K Call ||SeII||l TI v Cr Mn Fe CoIl || NITT||CuIX |) Zn Ga Ge As Sa Br
6.7 Y] Lo.eami| 4.1 || > 1.38

B

Rb SrJIlYIII ZrI¥|( Nb | Mo Te Ru Rh Pd Ag Cd |{{InIO|| Sn Sh Te 1
74 || 3.20 )[-1.o08 >s e

 

 

 

 

 

 

 

 

 

Cs |[BoII |[LaTO/IHI ) Ta w Rs Os || IrTOT|| Pt Au My TI [|PoII | BIOI| Peo At
334

8.0 4.24 || -1.O >7 3331 L8O || 0.8
{3.3) 2mm z)
0.5m

 

 

 

 

 

Fr [|ReTL | AeIdD
>7 || a57 L
(9 || ¢eo || PrIO|| NdIX|[PmIO
3sem| 3sa || xse || 342

 

SmII||[Eu IO|[\GdIX||Th L || Oy IX|[|Ho TX|| Er || TemIO|| YO IX||LuIX
3.20 (| 329 || 3.26 || 524 || 308 || 28 308 || 297 299

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ThIX AmII||CmII||IBk IX ||Cf II|| E IX || FmIX|| Mv | 102
0A8 ez || 3s 0 || A a 34

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—_

 

Fig. 35. Extraction of the elements with 0.2 M TTA in benzene.324

66
The extraction of Pu(IV) from nitric acid solutions was investigated by

Cunninghame and Milesllo' 111

using CCl4 and benzene as solvents primarily, al-
though other chlorinated hydrocarbons were used also. They find that, by neglecting

aqueous phase nitrate complexing of the Pu, the equilibrium can be expressed by the

equation
4
AHNO, 'pur,
€ Ppurw) 1 ;4 - %)
HT® g

They derive the f's from the TTA concentration dependence of.t.he distribution co-
efficient, and find that C is close to 1 X 10+5 over the range from 1 to 10 M HNO3 for
tracer Pu. Heisig and HiCkS,173 in a very extensive study of the kinetics of the ex-
traction of Pu(IV) from nitric acid solutions by TTA, in sec-butyl benzene, determined
that the rate of transfer of Pu chelate acrosa the organic aqueous boundary controls
the forward and reductive back extraction rates. They find that at low nitric acid
concentrations (0.5 M) the extracted species is PuT4, while at 4.9 M total nitrate con-
centration some partially nitrated complex such as PuNO, T, exists.

373
174 found that for Pu{VI) extractions into TTA-benzene from

Heisig and Hicks
nitric acid solutions the dependencies are direct second-power on the TTA concenira-
tion and inverse second-power on the hydrogen ion concentration, indicating that Eq.

(1) represents the reaction. These authors measured the distribution coefficients for

the Pu(IIl) obtained by reduction with 0.005 M ferrous perchlorate—-0.0l.l\_/I_ sulfuric acid as

a function of nitric acid and TTA concentrations. Theyobtaineda direct 2.3 power dependency
on T'TA concentrationand aninverse 2.6 power dependencyonhydrogenion. These solutions
were never stabilized in the presence of TTA, however. Since the distribution co-
efficient increased with time, extrapolations to time zero were made, and the extrap-
olated values were used. Plots of the distribution coefficients for Pu(IIl) and Pu(VI)
obtained by Heisig and Hicks are shown in Fig. 36.

Cunninghame and MJLleE'.111 determined the extraction properties of 2 number of
possible impurities in the development of a batch process for separating Pu from ir-
radiated U. Their results are shown in Fig. 37. Their procedure, which should be
easily adaptable to the laboratory scale, is to pre-extract the Zr from 0.5 M HNO3
while the Pu is reduced to Pu(Ill) with hydroxylamine, oxidize to Pu(IV) with NaNOz,
extract with 0.2 M TTA-benzene, scrub with dilute HNOB, and back-extract the Pu into
8 M [-INOB. They report a 99.4% Pu recovery on a 1-gram scale with decontamination
factors from Zr and U of 3000 and 667, respectively.

Other reporis on the use of TTA for processing irradiated uranium for Pu are
those of Crandall et al.'%® and cutler.1%?
to strip Pu from TTA solutions by reduction to Pu(Ill) or a combination of reduction

and displacement.342 The application of TTA to analytical and radiochemical pro-

An interesting variation is the use of U(IV)

cedures for Pu has been reported many times, either as the only purification

step287’ 50, 356 for rapid analysis (see for example, Procedure 2, Section VIII) or in

136, 351,50, 284 BiPO,, 341, 237
332,315, 168, 261

combination with co-precipitation steps involving LaF3,

chemisorption on a CaLF2 suspension,352 or other separation steps.

67
 

   

Pul{lll)

 

 

ol ] L | |
0 004 0.08 0.2 0.16 0.20
HNO3 CONCENTRATION (M)

 

Fig. 36. Extraction of Pu(III) and
Pu({VI) into TTA-benzene as a function
of I—INO3 concentration at constant total

nitrate concentration. LiNOj added.174

Pu(VD) Pu(III)

TTA conc. (M) 0,74 1,65
Total nitrate (M) 0.175 0.096
Agueous conditions 0.006 M
2 X 10-4 M KMnOy FelClOy),

 

oZr

 

1000

100 \

 

 

 

 

0.l

_Tatk/
0.0l ': y hx

 

/

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J | P o
0.001 I A W2
= \vog' i
PuI ‘
o.000|° | 2 3 4 5 6 7 8 % 01 12

HNOs MOLARITY

Fig. 37. Distribution coefficients of
various ions from nitric acid solutions
into 0.2 M TTA in benzene.110.111

TTA has been used to separate a

small amount of U from macro Pu,194 o

. 415
vice versa, to concentrate Pu from en-

r

3 352
vironmental water samples and to
determine the oxidation state of Pu in
environmental samples, including sea

136
water.

In the latter procedure, Pu(IV)
is extracted from 0.5 M HCI and the
acqueoug raffinate adjusted to pH 4.3 with

ammonium acetate from which the Pu(III)

and Pu(VI) are extracted together. On a second sample, the Pu(IV) and Pu(IIl) are

coprecipitated together with LaF
are then calculated by difference.

q- The relative amounts of the three valence states

TTA has been used to separate Pu from impurities for a spectrographic

. 411
ahalysis.

In this procedure an HCI solution of the metal is reduced to Pu(Ill) with

hydroxylamine and impurity elements extracted with TTA in hexone. The Pu in the
aqueous phase is then oxidized to Pu(IV) and extracted into TTA-hexone. By this pro-
cedure both extractable and non-extractable impurities can be determined.

TTA has been used for several procedures for the determination of Pu in bio-

logical material, expecially urine
Procedure 21, Section VIII).

125, 349, 360, 257,56, 316

(see, for example,
% EXTRACTION

Cupferron

N-nitrosophenylhydroxylamine or cupferron has been used as a pre-

cipitating agent for many metal ions for many years, and the solubility of these complexes.

in non-polar solvents such as chloroform was recognized at an early date.

The extrac-

tion reaction is analogous to Eq. 1, although little quantitative work has been done on

Pu. Furman et al. 138 have reviewed the subject and have given data for U(IV) and U(VI).

Kemp220

into chloroform from HCl-ammonium chloride solutions (g = 1.0 pH = 4.5 - 5).

found that Pu(IlI) required four cupferron molecules per Pu atom in extractions

He ruled

out oxidation of the Pu(IlI) by the reagent and postulated an "extra' cupferron molecule

in the organic phase to complete the eightfold coordination sphere.

The pH dependence

for Pu(Ill)from these solutions was found to be third power, in accordance with Eq. 1.

The pH dependence of Pu(Ill) with and without the presence of hydroxylamine and Pu(IV)

is shown in Fig. 38.
Kirk and Rodden229

report that most light elements are not extracted by cupferron-

CHCl and listed Fe, U(VI), U(IV). and Pu(IV) as extractable species. They report low

extraction for Pu(VI), but essentially complete extraction for Pu(IIl) and Pu(IV).

The

extraction of reduced Pu is lowered above pH 0.8 in HZSO4. Phosphate interferes with

the extraction, but a small concentration of iron is beneficial,

Nigon and Pennemr:m.304

the Pu in the presence of ferrous ammonium sulfate from 1 N HCI1 solutions.

 

 

   

 

 

 

100 |-
(3)
8ol (m pulim
(2) Pullil)INPRESENCE
OF HYDROXYLAMINE
(3 Pullv)
60
40
20
1 | 1 1 1
00 ! 2 4 6
pH
Fig. 38. Extraction of Pu(IIl} and

Pu(IV) from 1.0 M chloride into cup-
ferron-CHCl3. 220 Curve 1: Pu(IIl)
= 2.16 X 10-9 M, cupferron = 3.98

X 10-2 M; Curve 2: Pu(III) = 3.65

X 10-3 M; cupferron = 3.68 X 10-2 M,

10 w/v% hydroxylamine hydrochloride.

The curves are % extraction for equal
phase volumes va equilibrium pH.

report a separation of Pu and Am, based on extraction of

The fact
that the extraction rate of Pu is slowed by
cooling from room temperature to 5°C suggests
that oxidation from Pu(III) to Pu(IV) is taking
place in the presence of cupferron. They re-
port a separation factor of 10° with quantitative
recovery of both Am and Pu. A similar pro-

cedure has been used to separate Pu from
U 417

231 has used cupferron ex-

Kooi and Hallatein
tractions to concentrate Pu from environmental
Beaufait and Luken.'s37

corporated a cupferron extraction step in a

water samples. in-
general radiochemical procedure for Pu.
Cupferron has been used in several pro-
cedures to separate Pu before spectrographic
determination of impurity elements.zgs' 45
Finally, cupferron, has been widely used
in procedures to separate and concentrate Pu
from biclogical rnaterials.loz’ 387,.248,272
Chmutova M.BT

for determination of Pu by extraction from 3 M

developed a procedure

HNOg by a chloroform solution of N-benzoyl-
phenylhydroxylamine (BPHA), an analog of

69
cupferron, followed by back extraction of the Pu(IV) into sulfuric acid. It was
found that U, Am, Np(V), and fission products (except Nb and Zr) do not extract under
these conditions. The Nb and Zr are separated in the back extraction step.

Other Chelating Compounds

Many organic chelating agents were investigated in the Manhattan
Project for possible extractants for Pu, including acetylacetone, trifluoroacetylacetone,
and various other fluoridated diketones. Stewart393 has compiled extiraction data for
such compounds as well as many other complexing agents. Extraction data for several

chelating agents are shown in Table IV-25.

TABLE IV-25. Comparison of the Extractabilitg' of Plutoniurmn into Benzene
Phases Containing Various Fluorinated Diketones. 93

 

 

Pu(IV) _
, dlstr;butlon ratio Relative concentration
Code SngtltutEd group fl_%n_z}%r%_ needed to give same
name Rl(a) = 3 extraction of Pu(IV)
TFA CHgq 1.0 1
PTA CHSCH2 9.0 1/3
ITA (CH3)2CHCH2 ~ 100 1/5
~ 1/17
BTA CgHg ~ 100 /
TTA HC - CH 42 1/15
HC\ /C—
S
FBTA pFCE;H4 ~100 1/
NTA ~ 100 1/7
FTA CH - CH . ~100 1
HC\ C-
O/

 

(a)The general formula for these compounds is Rl—C(O)CHZC(O)CF3.

70
Pu(VI) and Pu(IV) complexes with pyridine-N-oxide-2-carboxylic acid which
precipitate at pH 2-3 have been prepared.176 These compounds are iso-structural
with TTA complex. A possible application ig the separation of U(VI) and Pu(VI) from
solutions of salts.

Mixed Extractants

Synergism

The term synergism is used to denote enhanced (or depressed) ex-
traction of metals by mixed extractants, as against the extraction by each extractant
taken separately. This subject has received considerable attention in recent years.

Pu has received its share {(perhaps more than its share) of the general research, and
while not many radiochemical applications have appeared for this phenocmenon, it is to
be expected that more will be found. Considered in this section are all cases of changed
extraction properties due to changes in the nature of the supposedly inert diluent, as well"’
as mixtures of different t{ypes of extractants such as TBP-TTA, TBP-DBP, etc. The
range of phenomena described under the term synergism is thus diverse, complex, and
in general not completely understood. The review of Marcus267 is excellent in this re-

gard, and the reader is referred to it for a more complete discussion.

Influence of Diluent

Taubeage' 397,398

polarity and polarizability of supposedly inert diluents on the extractability of tetra-

conducted extensive studies on the effect of the

and hexavalent actinides with verious extractants, including hexone, TBP, DBC, TTA,
TLA, and TBAN. Examples of diluents used are polar (P): chloroform, non-polar (L.):
carbon tetrachloride, non-polar but polarizable (H): benzene., He found that the nature
of the diluent exerted a large influence on the extractability, and proposed a theory
based on (1) the interaction between the dipole of the organic molecule and the diluent
dipoles, and (2) mutual interaction between permanent dipoles in the diluent mixture
giving rise to structure in the organic phase. The effects can be large; e. g., DPu(IV)
increases a factor of three in going from pure CHCl3 to pure benzene in TBP
extractions. In general, the extraction of a non-polar complex (Pu(IV) and Pu(VI) with
hexone, TBP, TTA, etc.) is favored by a non-polar diluent, In the case of the highly
polar Pu(IV)-TBAN complex, the extraction is favored by a polar diluent; however, the
presence of a polarizable diluent increases the extraction. The extraction as a function
of the mole fraction of H-type diluent thus exhibits & maximum. This is explained by
disruption of the agsociation of the dipoles in the P-type diluent, followed by participa-
tion of the induced dipoles in the H-type diluent in the extraction.

Shevchenko E’fl.afig' 371 found that the extractability of U(VI), Pu(IV), Zr(IV); and
Ce(IIT) decrease with increasing polarizability of the diluent by TBP solutions from 3
M HNO,.

Far greater effects are observed when two different classes of extractants are

mixed. The enhancement (or depression) of the distribution coefficients may be 10% or

71
more. Siekierski and Taube,381 and Taube400 have proposed a systern for synergistic

mixtures based on classification of extractors as anionic (A™), neutral (BO), or cationic
(C). Anionic extractants are acidic compounds such as TTA, DBP, HDEHP, etc. that
act as organic anions in the extracted complex; similarly neutral extractants (TBP,
TOPO, etc.) are neutral compounds that form complexes through a basgic oxygen atom,
and cationic extractants are strongly basic-compounds (TOA, TBAN, etc.) that act as
cations in the extracted complex. In general the synergistic effect is small in mixtures
of compounds of the same class, and may be small or large in mixtures of different
clasges. These authors define a synergistic coefficient as

D
g = log' 1,2, exp

(1)
D; 2. aad

Dl, 2, exp is the experimental distribution coefficient of a mixture of extractants 1 and 2,
and Dl, 2. add is the calculated distribution coefficient based on additivity of the individual
distribution coefficients. Additivity is based on the assumption that (1) no interaction be-
tween the extractants occurs, and (2) no mixed complex of the extracted metal ion with
the two extractants occurs. Both assumptions are commonly not true when extractants

of different types are mixed. A summary table of examples of synergistic mixtures

for U and Pu extraction is given in Table IV-26, based on this clagsification system.

Taube400 has made an extensive survey of mixed extraction systems.

Synergism in the system M-TTA-P, where M is an actinide and P is a neutral

phosphate compound has been studied by Irving and Edg‘lng‘ton,lgfi_zoo in nitric acid

and Healy169 in HCl. Healy found no evidence of participation of chloride in the ex-

traction. The extraction reaction is thus
X = +
M™ + x HT(o) +y P(o) =M (T)x (P)y(o) +x H . (2)

Values of y ranged from 1 to 3 for various di-~, tri-, and hexavelent ions. Th(IV) had
a y value of 1 as did U02++, except in the case of TOPO where a value of 3 was also
obtained at high P concentrations.

Irving and Edgington found that 1 or 2 nitrates could enter into the complex,
depending on the nitric acid concentration. With tributyl phosphine oxide (TBPO) the
species identified were M(IV) T3(N03)P1, M(IV) TZ(NO3)2 P,, and M(III) T, (NO3)P2,
whereas with P = TBP they were M(III) T3P2, M(IV) TB(N03)P1, and M(VI) T2P1,
where M is an actinide. Thus the complex is influenced by the basic strength of P.
These authors postulate that the reaction mechanism for hexavalent species ig the re-
placement of a water molecule in the complex by P, giving a coordinately unsaturated
product, thus

MOZTZ H20 + P = MOZTZP(O) + HZO‘ (3)
In the case of tetravalent species, one or more chelates are displaced by P molecules,
with nitrates added to preserve electrical neutrality, thus

MT4 + rnHNO3 + mP = MT4_m(NO3)um + mHT. (4)

72
TABLE IV-26.
U and Pu Extractions.3

Synelé-gistic and Antagonistic Effects in Two Extractant Systems in

 

Synergism or

 

 

antagonism Exampleg for plutonium and References
System OCCUrs uranium extraction and remarks
A7+ A S>0 ?
anionic + 59
anionic S << 0 U(VI), HG9PO + HaGPO Blake, 1959
At Be S>> 0 U(VI), H,S04, D2EHPO + TBPO Blake, 195929
anionic + UVI), HNO,y, TTA + TBP Irving, 1960196
non-ionic Pu(VI), HN(gg, HDEHP + TBPO Blake, 195999
Pu(VI), HpSO4, DNNSA + TBP Oak Ridge, 1960443
Pu(VI), HNO3, TTA + TBP Irving, 1961198
Taube, 1961400
S<< 0 U(VI), HoSO4 DDPA + TBP Blake, 195999
Pu(VI), Pu(IV), HpSO4, DBP + TBP Taube, 1961400
A +cCt S>>0 U(VI), HpSO4, DBP + TOA Deptula, Minc
anionic + 1961115
cationic U(VI), HDEHP + tertiary amines Blake, 195928
Pu(VI) H3SO4, DBP + TOA Taube, 1961400
S<0 Pu(IV), H,SO,, DBP + TBAN Taube, 1961400
B + B, 5> 0 U(VI), TBP, TiBP _ 376
non-ionic + 5<0 ? Siddal 1960
.. no data
non-ionic
B° +C+ Pu(VI), Pu(IV), HNOs, TBP + TOA Taube, 1961400
non-ionic + S~ 0 Pu(VI), Pu(IV), HNO3, TBP + TBAN Taube, 1961400
cationic
cf+c;
cationic + S~ 0 Pu(IV), HNO,, TOA + TBAN Taube, 1961400
cationic '
SYMBOLS G* general alkyl group

D2EHPO di-2-ethylhexyl phosphine oxide

TBPO tri-n-butyl phosphine oxide
DNNSA dinonylnaphthalenesulfonic acid
TBAN tetrabutyl ammonium nitrate
TiBP triisobutyl phosphate

The trivalent species are considered to become 8-coordinated by either addition of two

P molecules or replacement of two water molecules. The addition reaction is

MT:3 + 2P = MT3P2.

The synergistic effects discussed so far are for relatively small concentrations
of P.

synergism or antagonism sets in.

Ii the P concentration is increased to about 1 M and above, a strong negative-
The P dependencies for several M/TTA/P/HCl

systems as quoted by Healy169 are shown in Table IV-2T7,

Thus it is possible by
judicious addition of one of these compounds to effect the selective return of ions to

the aqueous phase.

73
TABLE IV-27. Slope of the Dependehce of the Distribution Coefficient on the
Concentration of the Added Reagent for Mixtures of Phosphorous Esters, Amides,
Alcohols and Ketones with TTA.41

 

 

Ion Valence Synergism region Antisynergism region
Th v +1 -2
Am, Pm o1 +2 -4
UO2 VI +1 -2

 

Fused Salt Systems

Some research has been done on the solvent extraction properties of
actinide and other elements in relatively low-temperature eutectic mixtures of fused
salts because of their potential use in homogeneous power reactors. Gruen ia_l.154
give a general discussion of oxidation states and spectra of actinides in LiNOs—ICNO3
mixtures, and indicate that TBP extracts a number of elements efficiently from the
eutectic mixture. Isaac %-201 determined the distribution coefficients between
Co(II), M(III) (where M is a trivalent actinide or lanthanide), Np(V) and Np(VI), and
U(VI) in this eutectic mixture (MP 120°C) and dilute golutions of TBP in a mixture of
polyphenyls at 150°C. In general, the distribution coefficients were a factor of 102 or
103 higher than the corresponding concentrated aqueous nitrate solutions. The dis-
tribution coefficients all showed the same TBP concentration dependency a8 in acqueous
solutions, indicating that the extraction mechanism is the same, the higher distribution
being due to the increased salting-in effect. The effect of added chloride was to lower
the distribution coefficients. Quadrivalent actinides would be expected to behave
gimilarly, although none was determined.

Borkowska iai.m used a KC1-CuCl eutectic mixture at 180° to study the ex-
traction of Pu, U, and Am by solutions of TBP, TOA, and HDBP in diphenyl. For TOA

they find the extractability is in the order

<< D

Dpyam < Pamm < Puwn Uavy

In this system a maximum in the D vs concentration of TOA curve occurs at ~40%
TOA, where DU(IV) ~3. TBP shows similar behavior. The maximum in this case is
at §7% TBP,2 where DU(IV) ~50. For U(].'V)’ HDBP is similaer to TBP.

Moore measured the distribution of a number of ions between the immiscible
galt pair LiCl—A1C14_K+ at 650°C. [t is perhaps not proper to speak of this system as
extraction; however significant distributions (Kd > 1 on a mole fraction basis) in favor
of the LiCl phase were noted for UCl4 (for which SnCl2 was added as a reductant),
PuC14, and FeC13. The ratio of the distribution coefficients for tri- and tetravalent
actinides was > 40. Since the SnCl2 used fo stabilize the U(IV) also reduced Pu to
the trivalent state, an easy separation is possible in this system. Similar results were
cbtained by Moore and Lyon290 for the system KCl-AlClB-Al. In this case the
separation factor for U from Pu and Th is approximately 100, while that for Th from
Pa is up to 800,

Cafasso gt_a_l.73 determined the partition coefficient of a number of elements,
including U and Pu, between liquid lead and zinc at 703°C. The results (Zn/Pb) are
Pd:600, U:21.5, Pu:7.3, Ce:3.4, Sr:0.05,

74
D.3 Ion Exchange

The phenomenon of ion exchange is of great utility in the radiochemaical separa-
tion of Pu. Cationic Pu in dilute, non-complexing, acid solution will readily adsorb
on cation resin in the hydrogen or alkali metal form. On the other hand Pu(IV) and
Pu(V]) form anionic complexes in moderately concentrated nitric or hydrochloric acids
and s0 will adsorb on anion exchange resins. Anion and cation exchange methods are
thus both usable to separate Pu. The anion exchange separation is especially valuable
in the laboratory because of the simple equipment required, the ease of manipulation,
and the excellent decontamination from fission products by the use of redox cycles.

Recently synthetic inorganic cation exchangers such as zirconium phosphate have
been developed,

A good introduction to the subject of ion exchange in the actinides is contained in
Chapter 7 of Seaborg and Katz.l The review of Hyde 17 is valuable for ion exchange
separations of the actinides. The general gsubject of ion exchange has been reviewed
many times. The books of Helfferich175 and Samuelson348 are good references
to the theory and applications of ion exchangers. Samuelson has a good review of
recent work done on actinides. Helfferich gives a table of the names and properties
of commercially available J".on-exchange materials. Kraus and Nel.":zon241 reviewed
the general subject of ion-exchange separations in 1957, while [—Iard.y162 reviewed
the ion exchange data for actinides in 1858,

Cation Exchagge

The general cation exchange reaction for an exchanger in the hydrogen

form (acid solution) is

M'P + bHR = MR, + bH" . 1)
In this equation R is an exchanger site. The exchange reaction is favored by a low
acid concentration or conversely, high acid can be used to displace the metal from the
exchanger by mass action. Anocther way to remove metal ions from the exchanger is
to decrease the concentration of M+b by complexing. In general, the absorbability of
cations on ion exchangers increases with increasing charge and decreasing hydrated
radius. Thus, the order of absorbability on cation exchangers for Pu is Pu(IV)
> Pu(Ill) > PU(VI). For example, Schubert 358 found the following adsorption affinity
for the strong base cation resin Amberlite IR-1: Th(IV)> Pu(IV)> La(Ill) Rare
Earths > Y(III) Rare Earths > Ba(II)> Cs(I)> Sr(II) > U02++. All Pu species are
absorbed well at low acld concentration, and are desorbed at high acid concentrations,
However, many anions form neutral or anionic complexes with Pu in all of its oxida-
tion states, and therefore Pu may be desorbed by reaction with the anion of the acid,
as well as the massg action displacement.

The sulfonated cross-linked polystyrene resins have been by far the most
popular materials for the separation of inorganic species, including the actinides.
Typical of these is Dowex-50. This resin is usually specified ag "X 4" or "X 12,” ete.,
which means 4% or 12%, etc. divinylbenzene was added to the styrene in the

75
-

polymerization of the resin to provide the crogs linkage. In general, the low-cross-
linked resins have the advantage of faster kinetics, but also have the disadvantage of
greater volume change with changing ionic milieu,

As mentioned above, under non-complexing conditions, i.e., dilute acidic
solution, the absorption of Pu is esgentially independent of the anions present. How-
ever, many anions form Pu complexes at moderate concentrations, which makes the
elution behavior of Pu variable.

The elution behavior of Pu on cation resin is summarized in Fig. 39,
where the distribution coefficient for Pu(Il), Pu(lV), and Pu({VI) on Dowex-50 is plotted
ag a function of the acid molarity,

 

 

 

 

 

 

 

 

 

 

 

 

104 104 0% T
Pul¥ Pud¥dL
! /
103 103 _ 1031 — /
: /
\ /
2l 2
D 100 ' HCl 0T /hciog
\ |
0 [¢ H 10 |-\
.\__ \. NOs 2 Hnos
\ \ cl
v L s ) 1
O 2 4 6 B0 O 2 4 6 B0 0 2 4 6 8 10

MOLARITY OF ACID

Fig, 39. Typical distribution coefficients of Pu on Dowex 50 in common acidic solu-
tions.

These data are intended to be only illustrative of the behavior of Pu. In
some caseg, the data of other actinides (e. g.-Am(II), U(VI)) were adjusted to corre-
pond to Pu in the same valance state. The data in every case were taken from litera-
ture mentioned later in this section.

' In general, the slopes of the curves are steeper for HNO3, H2504, and
HCI1O, than for HCl. A strong increase in the distribution coefficient in HC1O, at high
acidities is shown for Pu(Ill) and Pu(VI). This increase occurs in a great number of
elements,soo and probably also for Pu(IV).

The classic work on cation exchange of the actinide elements in HC1 solu-
tion was done by Diamond et al. 117

whose principal results are shown in Fig, 40 as
a plot of relative volumes required to elute tracer amounts of the ions from a Dowex-
50 column 10 cm long by 1 or 1.5 mm in diameter. These data are proportional to the
distribution coefficients, and illustrate the separations obtainable in this system.

The points for the. Pu species have been connected to make a crude elution pogiton vs
HCl concentration plot. The exireme decrease of the Pu(IV) elution position in going
from 3.2 to 9.3 M HCI is undoubtedly due to the formation of 'an anionic chloride
complex. The tetravalent actinides elute in this sequence: Pu, Np, U, Th; i.e., Th
has the highest distribution coefficient at any HCIl concentration. This order of elution

is in accord with the decreasing hydrated radii in going from Pu to Th. Th(IV) was not

76
3.2M HCI

 

 

 

 

 

Th(IV) —e=
! Ll oyl N g
Np(¥) Pu{iD| UTZ Cs YbSrY CmTPuCoLnRu Ac Pu(lY) —==
/ Np (D / Am _ -
/ /’ -
/ / -
/ 6.2 M/ HCI -~
[ w/ L ||/|||u/'|/| -
T T T 1 T T T T ¥ Th
Np D futam csvp Y cs mI)os/Lua:1Ru| fe w
Pu(¥D Am .~  PullVINp(IX)
I
! 7
r > 93M HCI
L1 L |
t Th(¥) —e=
PulD
’U’(%c. Puluabflp élfll |Eu Src. Lu Ac
Pu[ID Am uay
| I
| ' /
L byl Th (D) —=—
Np(¥) Cs Pu(I'V)CI!)AmCEEYI: RoY EuBa C|LuSr Ac
Um(&n Pu
Pu
| L |I|||||l| ] L1l ] Lol
| 100 1000

VOLUME OF ELUTRIANT

Fig. 40. Relative elution peak position of actinides and other ions in varigus HC1
concentrations. The positions of the Pu ions have been connected by lines, 117

eluted at all under the conditions of the experiment. A plot of the elution position of
the tetravalent actinides under slightly different conditions is shown in Fig. 41 to show
the relative elution position of Th(IV). The well-known separation of the trivalent
actinides and lanthanides is illustrated by the increase in the elution positions of the
lanthanides at high acidities,

Nelson _eifl.So summarized the cation exchange behavior of most of
the elements in HC1l, The summary is in Fig. 42 as a periodic table of DV ve HCll
concentration. Dowex-50 X 4 resin was used. Although relatively few data for Pu are
included, the curves for Th(IV), U(VI), and Am(OI) permit a normalization to the data
of Diamond et al. 117

Strelow 395 jnve stigated the cation exchange behavior of 43 elements on
Dowex-50 X B resin at HCl concentrations up to 4 M with results in general agreement
with those above. He arranged the elements in decreasing order of the equilibrium
distribution coefficients in 1 M HCl. The values ranged from 7250 for Zr{Iv) to 0.3
for Hg-H-. The distribution coefficient of Th(IV), the only actinide studied, wag 2049,

just below Zr.

1
 

1000 Oc—
* [ Th
B [
.o -
o
c -
=
= 100
s t Fig. 41, Elution peak position of the
= - tetrapositive ions vs hydrochloric acid
= [ Y molarity, 117
g | >
¥
5 10 Pu
a =
=2 -
o |
'—
> -
|
w

I I j — 1

 

 

 

6 9
HCI MOLARITY

 

[ ELEMENT |
AND

Fox10ATION ]
STATE

 

 

oAl
o 4 8 2
MOLARITY =0

 

 

LOG DISTR. GREPF., 0,
o

 

 

 

n
LI

 

Fig. 42. Volume distribution coefficient of the elements vs HCI concentration for
Dowex 50 X 4 cation exchange resin, Tracer concentrations of the elements were used
for the most part. :

78
Prevot et al.st. determined

coefficients of Pu(Il) and Pu(lV), along
with other ions as a function of HNO'3
concentration (Fig. 43)., They used
C- 50 resin (similar to Dowex-50).
Pu(IT) and Pu(IV) are expected to absorb
very strongly below 1 M acid. The
distribution coefficient is very low at
I—lNO3 concentrations < 4 M, since the
U(VI) and Fe(Ill) curves are flattening
out. A partial separation frbm these
ions can be achieved in the elution of
the Pu. -

Nelson e_‘t_il.300

used I-IClO4 as the aqueous medium in

also

their survey of cation exchange behavior.

The results shown in Fig. 44 show some
striking differences from the HCI data.
In high HC1O, concentrations > 2 M)
most elements have increasing distribu-
tion coefficients after having gone
through minima, These authors state
that essentially all the actinides in what-

ever oxidation state have appreciable

 

 

 

 

 

 

 

 

 

 

l. 17150
|
|
L\
)
\\ Pull¥)
D 100
\\W
\ %
\
\ \\ cu
NN \
10 Aw — A ™~
.\\ \ "‘—--U(ID
Fe (D™
Pu (I ~_
IO | 2 3 4N

NITRIC ACID“S()DNCENTRATION

Fig, 43. Distribution of Pu(lII) and
Pu(IV) and other ions between nitric acid
solutions and the catloréggsm C-50
(similar to Dowex-50).

distribution coefficients at high HClO concentration, and that this phenomenon might

be made the basis of an actinide group separation,
Neill and Higgins 299 getermined distribution coefficients for Pu(Ill) and

Pu(IV) for several regins in sulfuric acid solutions.

Their results are shown in Table

IV-28. They used Dowex-50 resin to demonstrate a process for recovering Pu from

sulfuric acid decladding solutions which contain stainless steel,

The Pu is normally

trivalent in dilute sulfuric acid solutions, and is adsorbed from 0.5 M acid, scrubbed

with 0.5 M sulfuric acid, wasghed with water to remove sulfate, and eluted with 6 N

HNO

primarily iron and chromium.

3 The product Pu solution contained 5% of the original stainless steel materials,

The most common applications of cation exchange techniques for Pu are

(1) concentration from a dilute solution, or (2) separation from nonabsorbable

impurities, such as hydrazine. 419

concentration of Pu from solvent exiraction plants have been developed.

processes should be easily adapted to the laboratory gcale.

Several processes for final purification and

Thesge

Bruce 60 describes the

process-as adsorption of Pu(lll) from 0.25 M I—INO3 by Dowex-50 X 12 from a 0.15 g/1
golution of Pu(IlI) which is 0.1 M in hydroxylamine sulfate, washing with 0.1 - 0,25 M
HNO3 containing 0.05 M hydroxylamine sulfate, and eluting with 5.7 M HNO3 containing

0.3 M sulfamic acid to prevent oxidation to Pu(IV).

Bruce reports a concentration
 

 

 

 

 

 

 

480
o=

 

Fig. 44, Volurne distribution coefficient of the elements vs HClO4 concentration for
Dowex-50 X 4 cation exchange resin.

TABLE IV-28. Distribution Coefficients for Pu for Various Cation Resins

 

 

in H,SO, Solutions 299
Resin Concentration (M) Pu(II) Pu(IV)
Duolite C-65 0.5 5.3 35
Dowex 50 X 8 0.5 360 --
3.6 3.6 --
Dowex 50 X 12 0,25 144 --
0.5 1470 -

 

factor of 330 for Pu in this process. Decontamination factors of approximately 20 to
30 for Zr and Nb, and 2.4 tc 8 for most other ions were obtained.

During the entire process the Pu is kept trivalent for several reasons;
among these are (1) the Pu isg initially trivalent as it is stripped from TBP in the
Purex process, (2) oxidation during adsorption liberates gasses which may channel the
resin and (3) Pu(OI) is more eagily desorbed, permitting a higher concentration factor.

Durham and Aiken 119 describe essentially the same process. Prevot

325 255 and Sikl{eland382 elute with 6~8 M HCI in preparation for

et al. Lingjaerde

80
anion exchange in an HCl system. The latter workers use an additional 2 M HCI wash
to elute the U(VI) and sorme fission products before elution of the Pu, Pm and Ce were
the major contaminating fission product activities in this procedure (see procedure
insert VIII). Den Boer and Dizdar 114 used the same general scheme except 1.5 N
[—INO3 wasg used to elute the U02++ and hydrazine was the reductant, and the Pu(Ill) was
eluted with 8 M [—INO3.

Chetham-Strode 5 investigated the behavior of NH, (), Fe(lI), P{IV), and
Al(ITI), which are common contaminants in the laboratory purification of trivalent
actinides for spectrometer sources. His results are shown in Fig. 45 with Am(ITI)
as a typical actinide. His procedure was to adsorb the ions from a very dilute HCI1
solution, wash with 1 M HCI, and elute with 6 M HCI.

 

0OO05M
HCI

©
=

6M HCI

I
0

+
ol

+4 , 43

prtd af t+3

=
I
by

af-mme e - =
m
@

CONCENTRATION

Fig. 45. Separation of Am
from some common impuritieg by
elution with HC1. The abcissa is
drop number for a 0.3-cm diam-
eter by 10-cm column. The 86
resin used was Dowex 50 X 4,

 

 

e - e e — e A e —— e ——————

10 16
DROP No.

Zolotov and Nishanov 436 report the separation of Np from U, Pu and

fission products by elution of Np(V) ahead of U(VI) by 1 M I-INO3 from the cation ex-
change resin KU-2. In the presence of 1 M HNOS, Np(VI) is reduced to Np{(V) on the
resin. The Pu(IV) is then eluted with 3 M HN03.

Zagral and Sel' chenkov 435 separated Np and Pu by elution from cation
resin (KU-1 and KU-2) with 0.02 M hydrofiuoric acid after reduction to Pu{Ill) and
Np(IV) with SO, for 20 minutes at 90-100°C.

The preparation of cation exchange resin beads with scintillating properties
was reported by Heimbuch and Gee. 172 Polyvinyl toluene-divinylbenzene rnixtures
were polymerized with p-terphenyl and 1, 4-bis- 2-(5-phenyloxyazolyl) -benzene as
scintillators. The resin beads were then surface-gulfonated, to give capacities rang-
ing from 0.01 to 0.1 milliquivalents/gram, Srgo, Pu239, find P0210 have been
adsorbed with this resin and counted with efficiencies from 30 to 50% of the adsorbed
activity. Several applications are suggested:

1. Easy sample preparation for adsorbable radionuclides.
2. A combination of concentration of ions from dilute solution and sample preparation.
3. Rapid qualitative analysis for radionuclides in dilute solutions.

Kennedy et al. 222 prepared and tested phosphorylated resins, which are

analogous to acidic phosphorous compounds in solvent extraction systems. They found

that these resinsg are between carboxylic and sulfonic resins in acidity. The adsorption

81
affinity of geveral ions was Th(IV), U(IV)> U(VI), Fe(ll)> La(OI)> H > Cu(1),
Co(Il), Ca(m})> Na+. Pu was not measured, but Pu(IV) would presurnably be with Th
and U.

Inorganic Ion Exchangers

 

Although inorganic ion exchangers have been long known, they have been
largely superseded by the synthetic resins, principally because of the higher
capacities and more tractable physical characteristics obtainable in the synthetic
exchangers. However experimentation has continued on natural and synthetic com-
pounds. In the actinide field this work has proceeded primarily toward the finding of
better geparations from fission products, The inorganic exchangers are also quite
resistant to radiation damage, which is an advantage in process applications.

A general discussion of the ion exchange properties of hydrous oxides has

been given by Kraus et al. 242 Inorganic phosphates as ion exchange materials have
been reported. 31, 1.3 The use of zirconium phosphate to separate Pu, U, and

fission products has been reported by Gal and Ruvarac. 140

Equilibrium distribution
coefficients for a number of ions are shown in Fig. 46, plotted against nitric acid
concentration. The solution containing U, Pu and fission products was loaded onto a
column at 0.5 M I-INC_)3 +0.02 M NaNO2. The U, Ce, Sr, and Ru pass through the
column. After washing the column, the Pu and Cs are removed with 8 M HNOa. The
Zr and most.of the Nb stay on the column. Of the ions studied, only Cs follows the
Pu and must be separated by an additional step.

Ahrland et al. 21,22

and proposed a separation of Pu, U and fission products similar to the one described

studied the behavior of several ions on silica gel

for zirconium phosphate above. The distribution coefficients are plotted as a function
of pH in Fig. 47, revealing an easy separation of Zr, U, Pu, and other ions by pH
and valency adjustment,

Rydberg 341 separated Zr-Nb from Pu by adsorption of the former on
silica gel from a 6 M HNOj3 solution (see Procedure 11 in Sect. VIII).

112

Cvjetcanin extracted Pu(VI) and U(VI} with hexone in the presence of

gilica gel to effect a Zr-Nb separation.

Cvjetcanin and Cvjetcanin 113

uged a column of MnO2 to separate U and
Pu from long-lived fission products. The method is adsorb the fission products from
0.1 N H_NO3, while pasging U(VI) and Pu(VI) through the column. QOver 99% of the Zr,
Ru, and Cs activity was adsorbed on the column. The capacity for zirconium for
MnO2 dried at 110°C was determined to be 1 milliequivalent/gram.

An exchanger eomposed of Zr and Si oxyhydrates has been prepared and
applied to Pu separations. 291

Pu has been concentrated from environmental water samples by chemi-

352 (see Procedure

sorption of Pu(IV) on calcium fluoride from a nitric acid solution
13 in Sect. VIO). '
Kennedy et al. 223 describe the absorption of Pu(IV), U(VI), Ru, Zr,

and Nb from aqueous carbonate solutions by hydrated titanium oxide (HTO). About

82
 

  

Zr(IV)+ NB (¥)

 

 

 

 

HNO 3 CONCENTRATION (M)

Fig. 46. The dependence of the distribution coefficients of several ions on zirconium
phosphate on the aqueous HNOg concentration. All adsorbates present in tracer amounts.
Solutions of Pu({Ill} were 0.005 M in sulpharmc acid and 0.015 M in l}g'drazine; solutions of
Pu(IV) 0.02 M in NaNO and solutions of Pqu 0.02 M in KBI‘Og

 

T

- 2riv 7]
+Nb
u(vn

®

ulivy/ feutivy —
Co

Na

of _

1 ] 1;
o

LOoG D

 

 

 

pH

Fig. 47 Log D for some metal ions as a function of pH on silica gel (KEBO, 50-100
mesh).2

83
95% of Pu(IV) was removed from a 0.5 M Na,COjg solution by passage of 2000-bed
volumes at a flow rate of 1. ml/cm /mm of the seclution through an HTO column. The
abgorption of Pu(lV) was not affected by the presence of 5 mg/1 of U(VI). The absorp-
tion of Pu(VI) was only 20% in 1000-bed volumes under the same conditions. A possible
application of this system to recover Pu and other ions from carbonate wastes in

processing plants is discussed.

Paper Chromatography

Clanet 0 determined paper chromatographic Rf values for Pu(IIl), - Pu(IV)

and Pu(VI), U(IV), and U(VI), and Am(III) in HCl-butanol mixtures (1:1) ranging from
1to 10 M HCl. The Rf values reached a maximum around 6 M HCI and ranged from
0.27 for U(IV) to 0.50 for U(VI), the other ions falling in between. The ions of lower

valency tended to have lower Rf values,

 

Bildestein ‘_at;al.fl geparated U and Pu by several paper chromatographic
methods, using different combinations of solvent and acid. The use of ion-exchange
paper to separate U and Pu was also reported by these workers. For example, with
Whatman ET-20 using 6 M HC1 as a developer, the R, values are 0.56 and 0.98 for U
and Pu, respectively. The oxidation states of the U and Pu were not specified.

‘F'ink and Fink 131 investigated many combinations of solvent and acid to
develop paper chromatograms of both Pu(IV) and Pu(VI). In most systems Pu(lV)
failed to move or streaked, but in a few cases moved quantitatively. The resgults
indicated Pu(VI) and U(VI} might be separated in a methyl ethyl ketone — dilute nitric

acid system.

Anion Exchange

The behavior of the actinide elements in various oxidation states on a
strong base anion exchange resin (typically Dowex 1 or 2) in HCl is shown in Table IV-
29. Strong adsorption of the actinides in the higher oxidation states (IV-VI) occurs at
HC1 concentrations above 6 M while desorption occurs below 2 M HCI,

TABLE IV-29, Absorption and Desorption of Actinides on Strong Base Anion
Exchangers in HCI Solutions

 

 

 

Oxidatiop _State of %%Concentratlon M) for —57
Actinide Absorption Desorption
1 Not abgorbed | -
Iv 6-8 2-4
v 6-8 2-4
Vi 2-3 0.1-1

 

@)k 4 = 10-100 for absorption.

(b)Kd = 0.1-1.0 for desorption.

A convenient way of separating Pu from other actinides and most other
elements is to adsorb Pu{IV) or Pu(VI) onto such a resin from> 6 M HCI solution,
wash with HCl, and desorb by reducing the Pu to the trivalent with a suitable reducing

84
agent. This method is so simple and effective that it has become one of the standard
laboratory methods for the separation of Pu, as well as in larger scale process plants.
Pu(IV) may be also adsorbed from 7 M HNO3 solutions and desorbed either
by dilute acid or by reduction. The distribution coefficients and separation factors
from fission products are higher than in the HCI system, but the room temperature
reactions are slower, resulting in some loss of convenience, 325
Many of the procedures collected in this volume are based on anion ex-
change,
Wigh and Rowell 432,433, 434
coefficients for several actinide and other elements for Dowex-2 in HC], HNOB,
H2804, and HC1-HF solution with results shown in Figs. 48-51. Although no Pu data

in I-INO3 was obtained by these workers, the curves are included for comparison.

have determined equilibrium distribution

Dowex-2 is made by addition of dimethylethanol amine to chloromethylated polystyrene,
while Dowex-1 is made with trimethylamine, 175 The equilibrium distribution data for
434,240 55 that the behavior of the
actinides in Dowex-2 is also valid for Dowex-1. The behavior of the ions in the HC1-

the 2 resins is quite similar, e.g. for U(VI)

HF mixture shows the effect of strong HF complexing in Zr and Pu. These workers
geparate Pu from Zr and other elements by eluting the Zr with 11 N HCI - 0.06 M HF,
and the Pu and Np together with 6.5 N HC1 - 0,000¢ N HF.

Marcus 266

measured distribution coefficients for macro amounts of T,
Np. and Pu in the tetra- and hexavalent states on Dowex-1. The oxidation states of
the ions in these experiments were measured spectrophotometrically both in the solu-
tion and in the resin pPhase. The results, which differ somewhat from those above are
shown in Fig. 52 as volume distribution coefficients, Dv’ obtained by multiplying the
usual D by the resin bed density, 0.45, in thig case.

Hardy 162

hag summarized equilibrium data for the actinides in HNO3 and
HC1 solutions for various strong base quaternary anion resins. These are shown in
Fig. 53. The Pu(IV) data in HNO4 show significant differences for different resins
and different workers. The species adsorbed from 7 M HNO3 has been shown to be

= 337,120 —
Pu(NO3)Ei .
Data for the adsorption of other elements on Dowex 1 from HCI1 solutions 240

and [—INO3 solutions 127

are shown in Figs. 54 and 55. The great specificity for
actinides in the higher valence states is shown by Fig. 55.

Many examples exist of the use of anion exchange resins for Pu separations,
both in HC1 and HNO, solutions. Adsorption in 8 to 12 M HCI and elution by reduction
to Pu(IlD) with NH,I in 8 M HC1, 108 382, 447,185,383 o5, by 45 concentrated HC, 185 293
or with NHZOH and NH4I in concentrated H%19:31155are common procedures. An

: is to adsorb Pu(lV) from 7 M
HNOS, wash the column first with 7 M [-I.NOa, then with concentrated HC1, and finally
strip in 10 M HC1 - 0.5 M HI or NH,I solution. This method combines the advantages

of the somewhat greater selectivity and removal of iron of the nitrate system with the

alternative procedure which has been used

ease of reduction to Pu(Ill) of the chloride system with resulting small strip volume.
The elution of Pu(IV) by HC1-HF mixtures has been mentioned before, 432, 433 These

85
104

K =
o D

STRIBUTION COEFFICIENT)
=
L

Ep (DI

(™
.
o

 

167
0 2 L 6 8 10 12 1y

Irig. 48. Equilibrium distribution coefficients for Dowex g in HCI solutions. 432, 433

(Mo, Zr, and Nb curves furnished by L. R. Bunney et al.b

36
2100

 

o 8 10 12 14

N HNO,

Fig. 49, Absorption of various iong by Dowex 2 from nitric acid éolutions.433

. 87
1049

103

102

Kp

100

Qi

 

N H,SO,

Fig. 50. Absorption of various actinide ions from H2804 solutions by Dowex 2.433

88
 

0 2 L 6 8 10 12 1k
N HC1 CONTAINING O.3N HF

Fig. 51. Equilibrium distribution coefficients of various ions on Dowex 2 in HCI ~
HF solutions. ,

85
 

1000 - 1T 1 Np (3M, Pu (¥I)
500 |

 

U (¥D)

200

100

50

 

 

| R A N

0 | 2 3 4q 5 6
HCI CONCENTRATION (M)

 

Fig. 52. Volume distribution coefficients, Dv, for tetra and hexavalent U, Np, and
Pu between Dowex 1 and hydrochloric acid solutions.

90
ANION EXCHANGE ANION EXCHANGE ANION EXCHANGE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IO‘ T T =T T
DEACIDITE FF f‘HflB,‘%ROL'TE (9] DeACIDITE FF e)
(fl) J/—s -(\
103
im foro T
D o2 // I/ Dowex !
' Pol¥ | — M T
oL LA g | o AnSeLTe e
7/ o N /23000
/ ‘ alL polTH
| [ 1
Q 2 4 6 810 0O 2 4 6 B O 0 2 4 6 6 10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

M,HNO : M,HNO3 M,HNO3
o4 T T . I T - I | 10 T T
DOWEX | AMBERLITE IRA 400 FRENCH A 300D
D yor b} no~gTRONGLY d) FoarroNeLY | (f)
103} apsonmep -ADIORBED AT 102 apsoreep }
[ >6 W MGl >eH
0100 /
10 | # o] Pu
10 [ 7
//flm um Np Pum
1 ol |
0O 2 4 66 8 10 0 2 4 & 8 10 0 2 4 © B 10
MHCI M, HCI M,HCI

Fig. 53. Equilibrium distribution coefficients for actinides on various strong base
anion exchangers, 162

Individual references:
63

Th and U; Carswell 80

240

2) Pa; Hardy et al.1
b)
c,d)

e)

Kraus and Nelson
Ward and Welch (unpublished data)

De-acidite FF; Phillips and Jenkins
23

319

Dowex 1; Aiken

Amberlite 1 RA 400 and French A 300 D; Prevot et al.
325

Prevot et al.

325
f)

91
 

o

I

no ads. - NO ADSQRPTION 0.4 <« M HClL.<12
sl. ads, - SLIGHT ADSQORPTION IN 12 Af HCI
(035D <g1)

 

"

 

 

LOG DISTR. GOEFF., D,

| i

a + 8 12
MOLARITY HGI

 

 

sir.ads. - STRONG ADSORPTION D, > {

 

1l ads.

 

Fig. 54. Adsorption of the elements from hydrochloric acid solution by Dowex 1.2%0

NGO \DE. - NO ADSORPTION FROM |-14M HNOy
BL. ADS. ~ JLIGHT ADSORPTION

o 4 1i2i4
MOLARITY HNOp .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[

 

Fig. 35. Removal of elements from solution in 1 M nitric acid with strongly basic
anion-exchange resin.127

u2
methods have been incorporated in sequential separation schemes for Pu and many

108,432, 433,434

other elements. Np and Pu have been separated by reduction of the

Pu with NH4I before adsorption on the resin, 204
The removal of macro amounts of Pu before analysis of other elements is

280,405, 319, 55

commonly done by anion exchange either from HNO, or HCI1 solutions

for example . ’

The separation of Pu irom U by adsorption of U(VI) on anion exchange regin
in 60% ethanol which is 2 M in HCl has been reported. 298 Pu is reduced to Pu(Ill)
with hydroxylamine and is not adsorbed in this form. The advantage of this system
over a pure aqueous one is low shrinkage of the resin and rapid adsorption and de-
sorption of the U(VI).

In the nifrate system Pu is usually adsorbed from 6 to 8 M HNO3 because
the distribution coefficient decreases above this concentration and because resin de-
gradation becomes a problem at high acid concentrations. The applications are either
to separate Pu, or to separate other materials from Pu.

Roberts and Brauer 333 separate Am, Pu, and Np by adsorbing the Pu
and Np from 8 M HNOS, eluting the Pu with 0,02 M ferrous sulfamate, and finally
eluting Np by oxidation with Ce(IV) sulfate in 0.25 M HNOS. In another method, Th is
included in the separation scheme by adsorption of Th(IV), Pu(IV) and Np from 8 M
HNOS, elution of the Thby 12 M HCl, of Puby 12 M HCI - 0.1 M NH4I, and of Np by
4 M HCl. These authors report a clean separation with greater than 95% yields by
both methods.

Buchanan et al. 66 report separations of U, Mo, Ce, and Zr from Pu by
anion exchange methods in analysis of Pu-"'fissium" binary alloys for these elements.

Other eluting agents for Pu adsorbed on anion exchange resin in the nitrate
159, 419,319,189 ;14 0,36 M HCI - 0.01 M HF, 243

243 used a "slurry-column" technique for the

system are hydroxylamine

Kressin and Waterbury
rapid separation of Pu from other ions. The 7 M I—INO3 solution of the ions ig slurried
with about half of the resin to adsorb the bulk of the Pu before placing in a column
containing the other half of the resin. The solution can then be run through the column
at a more rapid rate without Pu breakthrough, because most of the Pu is already
adsorbed. Thesge authors used a low cross-linked resin (Dowex 1 X 2) to speed the
kinetics of the adsorption reaction. They report greater than 99,9% recovery of the
Pu by this technique when mixed with substantial quantities of over 40 elements, The
Pu is desorbed with an HC1-HF mixture, again to speed the elution. |

Anion exchange from HNO, solutions is used ag a unit process in a number

3
of large scale processes of different types. Among these are: (1) the concentration

and purification of Pu following a solvent extraction separation; 338, 339, 340, 325, 255

(2) the recovery of Pu metal scrap; 336, 331

23, 57

and (3) the main separation step from

fission products.
207

The separation of Pu and Th in HCI1 solutions has also been
described.
Anion exchange methods have been used in several procedures for the

33, 404 205, 74, 254, 421

determination of Pu in biological material, especially urine.

93
Toribara et al. 403

used a liquid scintillation technique for counting Pu [rom bio-
logical materials, The counting was done by a single-phase mixture of sample in

aqueous solutions, absgolute alcohol, and liquid scintillator,

Electrolytic Separation Methods

 

Separation methods based on electrolysis have been used for radiochemical
applications, but are not common because of the relative complexity of the method.

In very early work, Cook 101 found that Pu could not be separated from Np and U by

electrodeposition from acetate solutions at pH 6-~7. However, Samartseva 344 found
that U, Pu, and Np could be separated by electrolysis from nitric acid 'solutions by
varying the pH. His results are shown in Fig. 56 as a plot of % yield vs pH for the
gtated conditions. Optimum conditions _f(_Jr the separation are stated as (1) current
density 750-1000 ma/ cmz, (2) plating time 2 to 3 hours, and (3) solution volume 20 to
40 ml.

Samartseva also found that electrolytic separation of Pu was successful against
many competing ions in concentrations up to 0.5 mg/ml. Among the ions tested were
Fe, Al, La, Ba, Cr, Mn, Ca, Mg, Bk, and Na, Of these only Fe interferred with the
separation to an appreciable extent. Oxalic acid at 0.002 M concentration was added

to complex the Fe.

On the other hand, Sinitsyna et al.384 found that the deposition of U and Pu

was strongly dependent on pH and current density, but that quantitative separations
could not be achieved at any pll from nitric acid solutions and acetate buffers.

Rein Qt_g_l_.azg separated Pu from Cr, Co, Ni, FFe, Pb, Mn, Sn, and Zn by
deposition of these elements on a Hg cathode [rom 1 N HCI. Por’l:ersz1 found that
Pu metal could be deposited on a mercury cathode from an organic solution, and
determined that dimethyl sulfoxide solution saturated with the metal chloride was the

best solvent among those investigated.322

Np

60

U,Np & Pu YIELD, %

    

 

1 L
7 9

Fig. 56. Relation of element yield to solution pH. The current density on the
cathogif‘lwas 100 rnA/cm2 and the electrolysis time, 2 hr. The solution was nitric
acid.

94
Clanet et al.gl separated U(VI), Pu(IV), Am(III), and Cm(III) by paper electro-

phoresis using 10 M HN03 as the electrolyte. A plot of a radioactivity scan of their
"electrophoretogram' is shown in Fig. 57, which gives the experimental conditions,
U(VI) would lie between Pu{IV) and Am(III) in this plot, according to the measured

mobilities in this system.

cm (i) 100 Pu{IV)

Amd{inn)

a -~
Qo

ACTIVITY
(COUNTS/min)
N
0

1 A 1 1™~ 3 11
2 4 6 8 IO

 

m

DISTANGE {cm)

Fig. 57. Separation of Pu(IV)-Am(III)-Cm(I11).91 Electrolyte: 10 NHNOj.
Support: "Millipore" HAWP paper. Development voltage: 250 volts. Time: 6 hours.

95
V. DISSOLUTION OF PLUTONIUM SAMPLES FOR ANALYSIS
A. Metallic Plutonium

Plutonium metal dissolves in HCl and other halogen acids, but not in H'NO3 or

concentrated H,SO,. Dilute H,SO, attacks Pu slowly.! The addition of HF to HNO,

274
renders Pu svr::luble.428 Sulfamic acid has been used to dissolve Pu metal.zlo

Pu-Al alloys can be dissolved in 6 M HNOS -0.056 M Hg‘(NO3)2 - 0.02 M HF,
as well as HCI1 and HC104. An alternative method is to dissolve the Al in a solution

of NaOH - NaNO,. The Pu and other actinide elements can then be dissolved in boiling

3
HNO3 or HCI1 after filtrE).‘cion.317‘166

317

B. Other Compounds

Pqu, if ignited, dissolves only with great difficulty in the usual acids. Boiling
with concentrated nitric acid plus 0.005 M HF,445’328 with B5-100% H3P04 at 200° or
with 5-6 M HI451 have been recommended methods. Another method is fusion with

ammonium bifluoride, followed by treatment with aqueous aluminum nitrate or

107,62

acid. Ignited Pu oxalates and fluorides have been dissolved by fusion with

potassium bisulfate, dissolving the residuein water to precipitate Pu(OH)4, and finally

263 The sealed tube method of Wichers et alfl53 has been

454

dissolving the hydroxide.
used to dissolve Pu-containing samples.

C. Biological and Environmental Samples

The Pu in thece samples ranges {rom readily soluble in the case of metabolized
plutonium in excreted samples, to extremely refractory in the case of fallout samples.
Nielsen and Beas‘.ley303 describe methods for dissolving various biological samples.
Most procedures for dissolving fallout or other environmental samples involve treat-

ment with HF or a basic fusion step which renders the Pu soluble in acids.

VI. SOURCE PREPARATION AND COUNTING METHODS
A. Source Preparation

A universal problem in Pu radiochemistry is the preparation of sources suitable
for counting. Owing to the short range of alpha particles in matter, the thickness of
foreign material on the counting sample is limited to approximately one mg/crn2 for
counting without serious loss. The requirements are much more severe if the ratios
of alpha-emitting isotopes are to be determined by energy analysis. This is so because
an alpha particle will be degraded in energy by interaction with the surrounding medium,
and the resulting pulse height distribution will be smeared out.

Most of the methods used for preparing alpha counting sources in use today were
developed in the Manhattan Project. Jaffey and Hufford and Scott189 summarize the
project experience. Source mounting techniques are, in general, a trade-off of
quantitativity on the one hand with thinness on the other. In assay work it is very

important to be quantitative but not so important to have a "thin'" sample. On ihe other

26
hand, for the separation of alpha particle energies by energy analysis the thinness of
the source is paramount, while guantitativity is not required, at least in the case of
isotopic dilution analytical methods.

Table VI-30 is a surnmary of the project method for alpha source preparation. The
reviews mentioned above are the primary source of this information and should be con-
sulted for more detail and literature references. Other general reviews may be con-
sulted for a discussion of the problem of mounting thin sou.r'ces.mz’a86’307

Two of the most widely used methods for preparation of alpha sources on a metal
backing for counting or spectroscopyare (1) direct evaporationof an aqueous or organic
solution and (2) electrodeposgition. Other methods, such as volatilization of the sample in
a vacuum, adsorption from an agqueous solution, are not so widely used. However, the
method of vacuum 'flashing' from a tungsten filament produces very satisfactory sources

and is in routine use in some laboratories. (See for example Procedure 4 in Sect. VIII.)

A.l Direct Evaporation

 

This method has the advantage of speed and simplicity and the disadvantage of
tending to concentrate any mass present in the solution to produce local thick areas. The
classic ”LaF3”
of LaF

VII). In general, the method is satisfactory if only total alpha counting is to be done.

method for the determination of Pu utilizes direct evaporation of a slurry

446 (Procedure 1 in Sect.

3—Pu, followed by alpha counting to determine the Pu
However, in methods which depend on alpha energy analysis, direct evaporation of even
a ""carrier free' solution will not be completely satisfactory. The reason for this failure
lies in the above mentioned concentration effect to produce an effectively "thick' plate.
The great advantage of other methods in this regard ig that the Pu and impurities in the
solution to be plated are spread evenly over the entire area of the plate.

Tucl-:qt06 describes a method for evaporating organic solutions of alpha-emitting ma-
terials by heating only the edge of a circular plate, thus confining the liquid to the center.

The same principle was used by \a‘Vestru.m426 to evaporate sulfuric acid solutions.

A. 2 Electrodeposition

This method has the advantage of producing thin uniform plates suitable for energy
analysis of the alpha particles, and the disadvantage of requiring a relatively complex
apparatus and relatively greater effort. The time to produce one sample can be as much
as two hours.

K0233

Cm. He chose a buffered solution of formic, perchloric or sulfuric acid and ammonium

gives specific conditions for electrodeposition of the actinides from Th to

formate and achieved high yields for up to 100 ug of Pu at current densities of 100-300
rnA/crnz. The deposition of all these elements occurs as a precipitation reaction ai the
cathode. In the case of Pu, the compound precipitated is Pu(OH)4 (hydrated). Moore
and SmithzBB also used an acid solution of ammonium oxalate to electrodeposit Pu.
Mi’cchellfl""-:'2 gives a rapid method for electroplating trace quantities of actinides from
HCl-ammonium chloride solutions. He gets essentially queanlitative deposition in 15
minutes from a ¢.1-0.2 g/ml chloride solution at pH about 1 using a current density of
1 A/cmz.

97
86

TABLE VI-30. Source Preparation Methods for Alpha Radioactivity Measurements(a)

 

Method and Principle

. Normal Evaporation - Placing 1,

solution on a suitable backing,
usually Pt, and evaporation

under a heat lamp, and igniting, 9
Solution may be pipetted quanti- ’
tatively if desired.

. Slurry Transfer of Carrier

 

Salts - Co-precipitation with
suitable salt, transfer to
plate, spread, evaporate and
ignite,

. Electrodeposition - Electrolytic

reduction of plutonium at a
platinum cathode.

. Low Temperature Sublimation

 

in Vacuum - Prepare volatile
compound, place in low temp-
erature oven in vacuum, collect
vapor on suitable cold plate, The
volatile compound is rendered
non-volatile and the organic
material destroyed by ignition,

. High Temperature Sublimation

 

in Vacuum - Place material in
oven with suitable orifice,

evacuate and volatilize at high
temperature. Collect on a cold
plate. The oven may be a dimpled
W or Ta strip heated by resisiance
heating. In this case the plate need
not be cooled,

Applications

Preparation of sources
for alpha counting from
agueous solution,

Preparation of sources
for alpha counting from
organic solution,

Volume reduction for
cases where solvent
extraction or ion ex-
change methods are not
applicable.

Preparation of sources
for energy analysis.

Preparation of extrcmely
thin sources for highest
resolution alpha energy
analysis,

Preparation of high-
quality thin samples for
alpha energy measure-
ments.

1-

Advantages

Rapid, convenient,
quantitative.

Easier to get uni-
form spreading.
Organic may not
have refractory
impurities,

Relatively fast,
easy method,

Very thin, uniform
films are attainable.
Method can be made
quantitative,

Excelient sources -
any kind of backing
may be used.

Very good sources
obtainable. Resist-
ance heated strip
method applicable to
routine lsotopic
dilution analysis.

Disadvantages

Sample not uniformly spread
if > 25 ug of material. May
cause error due to self
adsorption.

Same as 1 + more difficult
to prevent loss over edge of
plate. May require edge
heating or stippling small
volume at a time,

Co-precipitation and transfer
may not be quantitative,
Requires at least 0.3 mg of
carrier. Self absorption
losses may be serious.

Requires special preparation
of solution, requires rela-
tively long time to prepare 1
sample,

Only a small fraction of
sample collected. Volatile
compounds are difficult to
handle and constitute a
health hazard. Not a routine
method.

Not quantitative, however
under favorable conditions
~ 90% yield can be obtained,
Yield is usually about 50%.
The apparatus is relatively
large and expensive.

 

(a)Cornpiled from References 206 and 189,
Miller and Broun3276

give a detailed procedure for electrodepositon of Pu(VI) from
1-2 N KOH solution. The Pu was oxidized with ozone. This method has the disadvantage

that all elements which precipitate in basic solution interfere with the deposition.
A. 3 Other Methods

El Guebely and Silfl:kca-land]'22 report an interesting method for preparation of ex-
tremely thin Pu sources. The basis of the method is adsorption of Pu(IV) onto glass or
metal plates from dilute (~0.01 M) HCIl solutions, presumably as the polymeric form.
The method is not quantitative. Sa.I:".h..':n:'tseva347 reports that adsorption of Pu(IV) is 97-
! t0 1077 M HNO, solutions.

Carswell and MilfiteadB1 made thin sources of U and Pu by electrostatically .

98% complete on Pt from 10~

focussing a jet of the material to be plated which was dissolved in a volatile solvent.

B. Counting

The subject of the determination of the amount of alpha radioactivity has been re-

viewed by JnsmffeyzoEi and recently by Johnson et a.l.,z13 169

and Hanna. These accounts
should be consulted for details of the various detection systems and literature references.
Table VI-31 lists the major types of counting systems with applications, advantages, and
disadvantages of each.

The ratios of the isotopes of Pu can be determined by making use of the difference
in the energies of the alpha particles in alpha pulse analysis.

The isotope Pu236 is very useful as a tracer in this method. This isotope is pre-

pared by the reaction

0?3 (4, n) Np236_E . 36
using highly enriched 1235 1o make the Pu23f 4g pure as possible. Since Pu236 is not
made by any neutron reaction on U, an unspiked sample need not be run if the Pu236 is

isotopically pure. Since the alpha energy Pu236

occurring isotopes (Pu239, Pu‘?40 238

is higher than that of the other commonly
), care must be taken that the added Pu236
activity is not very much greater than the activity of the other Pu isotopes. The reason

. and Pu

for this precaution is that imperfections in the sample and detecting instrument always
result in low-energy alpha particles which appear as a continuum or low energy ''tail" in
the spectrum. The subtraction of this tail becomes difficult if higher energy isotope pre-

dominates.

C. Other Methods
242 as the tracer and a

mass spectrometer as the detecting instrument. Highly enriched Pu242 is a product of

239
39

Another isotopic dilution method uses the rare isctope Pu

long reactor irradiations of Pu

-Pu240 isotopic ratio must be made if the specific

A determination of the Pu2
activity of a particular sample is needed. This determination must be made by meang of
a mass spectrometer since the alpha particle energy of these 2 isotopes is the same.

Schwendiman and Healy360 have described a nuclear emulsion technique for low-
level Pu analysis. Nielsen and Bea:s.lejyrs03 have reviewed the radiochemical determination

of Pu in biological materials and include a critical comparison of various counting systems.

29
001

TABLE VI-31.

Techniques for Measuring Alpha Radioactivity.

 

Method
Total Alpha Activity

Air ionization chamber

I'ree-electron-gas ionization

chamber (A, A—COZ, He, Nz, ete,)

Alpha proportional counter

Scintillation alpha counter

Low-geometry counters

Nuclear Emulsions

Application

Total assay -~ survey
instrumentas,

Total assay.

Total assay.

Total assay.

Total assay.

Total assay.

Advantages

Simple, easily repaired
and cleaned, reliable,
inexpensive,

Sharp pulses permit high
count rates and tolerance
to B activity. Not micro-
phonic, Reliable and
stable. A known relatively
unchanging geometry,

High signal-to-nois¢ ratio,
good B discrimination,
Not at all microphonic.

Very low background,

Can count sources of
greater activity. Count-
ing rate not so sensitive
to sample thickness.
Reproducable and reliable.
No low-angle back scatter-
ing correction.

Great sensitivity and
stability. Very simplce
apparatus.

Disadvantages

Long decay time of pulse
makes inherently wide
pulses - limited to low
counting rates. Low
tolerance to B activity.

Signal-to-noise inferior
to proportional counters,
therefore more prone to
spurious counts. Must be
corrected for low-angle
back scattering.

Count rate sensitive to
applied voltage., Requires
pure gas for stability.
Difficult to maintain
stability for long periods.

Lower tolerance to 8
radiation than ionization
chamber or proportional
counter, Greater sensiti-
vity to sample size, and
position.

Not suitable for low activity.
Sensitivity to sample posi-
tion and area.

Limited accuracy, consider-
able technique required in ex-
posing and developing emulsions.
Counting tracks is time con-
suming and tedious.
101

TABLE VI-31,

Techniques for Measuring Alpha Radioactivity (Cont'd)

 

Method

Alpha Energy Measurement

Magnetic deflection alpha
spectrometer

Total ionization and pulse
analysis, I'risch grid
ionization chamber

Semiconductor charged
particle detector

Application

Energy measurement -
mainly for determination
of energy spectrum.

Energy measurement -
determination of iscotope
ratios.

Energy measurement -
isotope ratios.

Advantages

Very high precision
and accuracy.

Convenient, easy to
use. High geometry -
up to 50%. Tolerates
large area sources,
Resolution can be
improved by collima-
tiom.

Very convenient -
capable of high
resolution,

Disadvantages

Large, expensive equip-
ment. ‘Requires photo-
graphic technique for
recording data. Count-
ing tracks is tedious and
time-consuming. Very
low geometry. Thin
sample required.

Requires gas purifica-
tion.

Requires low geometry
for high resolution,
Detector may become
irreversibly contaminated
by volatile radioactivity.

 
Solvent extraction of Pu into a liquid scintillator has been proposed aa a method to

135, 403 The determination of

256

eliminate source preparation in radiochemical procedures.
the B activity of ZE"u241 in low-level biological samples by this method has been reported.
The incorporation of a scintillator in the polymerization of an ion-exchange resin
has been ::-el:gi)rtedl'72 (see page 81 for details).
Scintillation counting of the weak 0.4 MeV gamma-ray in Puz'?'9 by Nal detectors

has been used to monitor the concentration of Pu in process strea.ms.123

VI. SAFETY CONSIDERATIONS

Hazards to personnel who work with Pu in the leboratory arise primarily from two
causes. First, Pu is extremely poisonous becruse of its high specific alpha activity,
long biological half-life, and tendency to concentrate in the bone. Second, inadvertent
criticality may occur. A full discussion of these hazards is beyond the scope of this re-
view, but some general comments concerning precautions and techniques can be made.
The subject of personnel monitoring and radiation surveying has been treated by Mt:;rg‘an.291

Appleton and Dunster32 bave writien a manusl on the safe handling of Pu.

A. Radioactive Safety

The primary hazard is due to the posgibility of ingestion, since the alpha particles
are easilglr shielded and the gamma rediation associated with the common long-lived
lsotopes is slight. The hazard is better stated in terms of the activity level rather than
the mass, since the biological damuge is done by the alpha radioactivity and the isotopic
composition of Pu varies widely. Table VII-32 lists body burdens and maximum per-
missable concentrations (MPC) of Pu isotopes for continuous occupational exposure.
These data are taken from the National Bureau of Standards Handbook 69, which should
be consulted for details.

TABLE VII-32. Health Hazard Data for Plutonium Isotopes.

 

. Maximum Permissable
Maximum Permigaasble Concentration for 40-

 

Body Burden in Bone hour week
Isotope (microcuries) (microcuries/ecc)
Water Air

Pu23? goluble 0.04 1074 2 x 10712
py238 p 240 242

insoluble —_— 8 x 10-4 (@) 3 x 10-11 ®)
Pu??! goluble 0.9 7 X 1073 s x 10”11

insoluble — 0.04 (&) 4 X 1078 ®

 

(a)Assuming the gastiro-intestinal tract to be the critical organ.

(b)

Assuming the lung to be the critical organ

102
The most common control practice is total containment of high activities of
alpha-emitting isotopes by means of an enclosure which is maintained at a negative
air pressure with respect to the laboratory atmosphere. Operations are done either
with remote manipulators or with arm length gloves gealed to the enclosure,

In an intermediate or high-level alpha activity laboratory, a variety of
auxiliary equipment and practices in addition to the primary enclosure of the activity,
are necessary to insure personnel safety. Among these are:

1. Adequate monitoring of the accidental release or "spilling" of radioactivity.
This monitoring can be done by hand-held survey instruments, by continuous filtering
and monitoring of the laborat-ory air, and by persocnnel monitoring instfu.ments placed
at exits to the working area,

2. Protective devices and clothing. In most high-level radiochemical labora-
tories, special clothing is part of the laboratory practice. The availability of
respirators to prevent inhalation of airborne radioactivity in the event of a spill is
esgential.

3. Procedures for normal operation of the laboratory as well as emergency
procedures must be worked out in advance and understood by all personnel, ""Good
housekeeping," or the maintainance of a clean and orderly work space, should be
especially emphasized.

The kind, amount, and distribution of protective devices, as well as laboratory
practices for normal and emergency operation, vary considerably in detail from
laboratory to laboratory. This very brief introduction to the subject of the handling
and manipulation of large amounts of alpha activity iz intended to serve mainly as a
warning to the uninitiated. The subject of enclosures for radicactive materials is
treated fully in a review by Garden and Nielsen, 142

Low activity can, of course, be handled in an ordinary radiochemical laboratory.
The limit beyond which total containment becomes a necessity is not very well defined.
The concentration of the alpha-active material, as well as the nature of the operation
and the skill and care of the operator, are factors which must be considered. At
the level of one microcurie, ordinary laboratory procedures can be done if
reasonable care is taken, while at higher levels the operations become more and
more limited. At the millicurie level total containment becomes necessary for any

chemical operation. In any case, proper monitoring of the activity is essential.

B. Criticality Safety

This hazard is most generally met in the radiochemistry laboratory bjr only
permitting an "always safe'' amount of Pu in any room or area. This is an amount
which will not be a critical mass in any configuration or dispersed in any medium,
While the determination of the always-safe amount in a particular situation is beyond
the scope of this review, Table 32 gives basic data for Pu239, This table was ex-
tracted from the USAEC Publication "Nuclear Safety Guide" *4%

sulted for further information on this subject.

which may be con-

103
TABLE VII-33. Basic Data for Criticality Hazard for Plutonium-239.

 

Mass of Isotope (kg) which is maximum

 

 

Form of Isotope Recommended for Safety Minimum Critical
Metal, & phase(a) 2.6 5.6
Metal, 6 phase(a) 3.5 7.6
Solution 0.22 0.51

 

(a)

The metal is assumed to be surrounded by a thick hydrogenous layer.

104
VIII. COLLECTION OF PROCEDURES
A. Introduction

The literature of Pu is replate with radiochemical and analytical separation
procedures. A survey disclosed 54 papers with procedures which were written in
enough detail to do justice to the name, and many more methods which could easily be
developed into procedures by making the directions quantitative or more complete.

Of the 54, 26 survived screening and are included in this collection. The basic

criteria for screening were fourfold: (1) distinctivenegs in chemistry, (2) completeness
in detailed instructions, (3) generality in application, and (4) utility. In some cases

a rather arbitrary choice had to be made between procedures which met these

criteria equally well,

The procedures are divided into (1) general radiochemical procedures, (2)
special purpose separation procedures, and (3) urinalysis procedures.

The procedures in the first group are concerned with purifying Pu from other
alpha emitiers and from fission products sufficiently for the purpose at hand, usually
for alpha counting or alpha pulse analysis. The starting materials range from reactor
target dissolver solutions of varying ages to fresh samples of nuclear explosion debris
to very dilute environmental samples. There are 13 of these procedures included.

The second group of procedures ig concerned with a specific separation involving
Pu. Two examples are the separation of Np and Pu and the removal of Pu before
analysis for impurities in Pu metal.

Urinalysis is a separate category, primarily because there are so many pro-
cedures in the literature, all purporting to do the same thing. The chemistry after
the initial separation step is, of course, similar to that in the other categories. The

urinalysis procedures included were chosen primarily for distinctiveness of chemistry.

B. Listing of Contents

General Radiochemical Procedures

 

Procedure Author
No. (principal) Title or method Page

1. Welch Determination of Pu when large amounts 108
of Fe and Cr are present (LaF3 method)

2. Moore Separation and determination of Pu by 112
TTA extraction

3. Maeck Separation and determination of Pu in 114 -
U-fission product mixtures (extraction
of quaternary alkylammonium-plutonyl
nitrate complex into hexone-TTA extraction

4. Morrow Plutonium (anion exchange) 116

5. Hoffman Plutonium (anion exchange) 118

105
Procedure
No.

6.

Oa,

9b,

10.

11.

12.

13.

Author
(principal}
Hart
(No author)
Rider
Lingjaerde

Rydberg

Rydberg

Geiger
Sheidhauer

Kooi

Special Procedures

14,

15,

16.

17.

18.

Larsen

Trowell

Trowell

Jackson

Zagrai

Urinalysis Procedures

 

18.

20.

Brooks

Perkins

Title or method

Separation and determination of Pu from
U and fission products in irradiated
reactor targets (anion exchange — TBP
extraction)

Pu (CeFy4-LaFjg cycle, TBP extraction,
anion exchange%

U and Pu determination in highly irradiated
fuel. (Hexone extraction, TTA extraction)

Pu from irradiated U (cation exchange, anion
exchange)

Separation of Pu from U and fission
products (BiPQg4 precipitation, TTA ex-
traction)

Separation of Pu from U and fission
products (adsorption of Zr-Nb on silica gel,
preciditation of CuS, TTA extraction)

U and Pu from environmental sampleg of
soil, vegetation and water (TBP extraction)

Pu from environmental water samples
{chemisorption on Can, TTA extraction)

Pu from environmental water samples
(BiPO4 precipitation, co-extraction with
ferric cupferride)

Separation and spectrophotometeric
determination of Pu from U-Pu-fission
element alloys (TBP extraction from HCl
solution)

Separation of Pu before spectrographic
analysis of impurities in Pu metal (anion
exchange

Separation of Pu before spectrographic
analysis of impurities in high purity Pu
metal (extraction chromatography using
TBP)

Separation of Np and Pu by anion exchange

Separation of Np and Pu by cation exchange
chromatography

Determination of Pu in urine (ferric
cupferride extraction)

Determination of Pu in urine (PrF3 pre-
cipitation, TTA extraction)

106

Page
122

124

126

129

132

134

137

140

142

144

148

149

150

153

155
Procedure

No.

21,

22.

23.

24.

25.

Author
{principal)

Everett

Bokowski

Campbell

Weiss

Bruenger

Title or method

Determination of Pu in urine (LaFj
precipitation, TTA extraction)

Determinaiion of Am in urine in the
presence of Pu (BiPO, precipitation,
LaF'g precipitation extraction of Pu into
di-(2-ethylhexyl) phosphoric acid

Determination of Pu in urine (alkaline
earth phosphate precipitation, anion
exchange

Determination of Pu in urine {(co-crystal-
lization with potassium rhodizonate,
LaF g precipitation, anion exchange)

Determination of Pu in urine and bone ash

(extraction by primary amines from HoSO0y
solution)

107

164

166
Procedure 1. Determination of Pu in solutions containing large amounts of Fe and
Cr. G. A. Welch et al. (Ref. 446).

Qutline of Method

Hydroxylamine is added to the sample to reduce plutonium and chromium
to the trivalent state. The acidity of the solution is adjusted and lanthanum nitrate
carrier added. Lanthanum fluoride is precipitated by adding a limited amount of
ammonium fluoride and carries the plutonium with it, By strictly controlling the
amount of fluoride added the precipitation of iron and chromium is prevented. The
precipitate is separated by centrifuging, washed and mounted on a {lat stainless-steel
counting tray, and the a-activity measured with a scintillation counter calibrated
against standard sources.

Reagents

All reagents are analytical reagent quality where available.

1. Ammonium hydroxide, 9M

2. Nitric acid, 2M

3. Hydroxylamine hydrochloride, 5% w/v

4, Lanthanum nitrate solution, 5 mg La/mil.
Digsolve 7+ 8 g of lanthanum hyxahydrate in 500 ml of distilled water.

5. Ammonium fluoride solution, 12+ 5% w/v
Store in a polythene bottle,

6. Cellulose lacquer.
Dilute "ZAPON" lacquer with amyl acetate,

7. Standard Pu solution, 05 ug/ml.
Dilute a solution of known Pu concentration. The exact Pu concen-
tration of the diluted solution need not be known, but the isotopic
constitution should be eséentially the same as that of the samples

requiring analysis.

Eguipment
1. a-scintillation equipment,
Type 1093A or B scintillation unit with associated equipment,
2, Counting trays.

Stainless steel, flat, mirror finish, 1-1/16 in, diameter,

Prepare for use by heating in a flame until the surface is straw coloured.
Allow to cool and paint a ring of cellulose lacquer round the edge. Allow the lacquer

to dry and store the p:t.'epared trays in a closed container,
Procedure

1. Transfer a suitable portion of the sample to a 3 ml glass centrifuge
tube. Wash out the pipette with 2M nitric acid and add the washings
to the tube. [Note (a)].

108
10.

11.

12.

13.

Notes

(a)
(b)

(c)

(d)

Add 0- 15 ml (3 drops} of hydroxylamine hydrochloride solution
and stir well. [Note (b)].

Adg 9M ammonia solution until a faint permanent precipitate is
formed,

Add 2M nitric acid until the precipitate just redissolves, then
add 0-1 ml (2 drops) in excess.

Add 0-1 ml (2 drops) of lanthanum nitrate solution (5 mg La/ml),
dilute the solution to about 2 ml and stir well,

Add 0-15 (3 drops) of 12+5% ammonium fluoride solution, stir
well and centrifuge for 10 min,

Remove the supernatant liquor [ Note (¢)] with a transfer pipette
[Note (d)] and wash the precipitate twice by stirring with a
mixture of 1 ml of water, 01 ml of 2M nitric acid and 0*25 ml
of ammonium fluoride solution. After each wash, centrifuge for
5 min before removing the supernatant liquor.

Slurry the precipitate with 2 drops of water and transfer it to a
prepared counting tray with a transfer pipette. Do not allow the
slurry to enter the wider part of the tube. [Note (e)].

Wash the centrifuge tube with 5-10 drops of distilled water and
transfer the washings and the residual precipitate to the counting
tray. Spread the slurry evenly over the tray within the cellulose
lacquer ring and break up agglomerations of solid matter with
additional drops of water where necessary.

Dry the slurry beneath a radiant heater and ignite the counting
tray in a flame to a dull red heat to drive off excess ammonium
fluoride and burn off the ""ZAPON" ring. Allow to cool.

Measure the activity on the counting tray using stable a-scintilla-
tion equipment [ Note (f)].

Using a clean counting tray, measure the background of the equip-
ment and correct the counting rate of the sample source for back-
ground, [ Note (g)].

Calculate the concentration of Pu in the sample solution from the
relation Pu (dpm/ml) = 100 Cel/EE2 V [Note (h)].

Usually not more than 500 gl should be used.

After each addition of reagent the mixture should be well stirred
with a platinum wire,

About 0-1 ml of liquid should be left behind at this stage and
after each wash to ensure that the precipitate is not disturbed,

A piece of glass tubing drawn out to a capillary and attached to a
rubber teat,

i08
(e) The precipitate is easily washed from the narrow portion of the
tube, but it is difficult to remove it if it is allowed to dry on the
wider part of the tube.

(f) The stability of the counter may be checked statistically using a
standard plutonium source (see Appendix IT).

{g) The background should not normally exceed 2 cpm,

(h) The ratio E;/Eg may be replaced by the ratio of the counting rates
of the plutonium control source at the time of standardizing and at

the time of sample count provided that the same control source is

used,
Where C = Counting rate of sample source corrected for background as cpm.

V = Volume of sample in ml,

E = Percentage efficiency of the counting equipment for the standard
plutonium source (Appendix I).

E1 = Percentage efficiency of the counting equipment for the Pu control
source at the time of calibration (Appendix I).

E2 = Percentage for the Pu control source at the time of sample count
(para. 11).

APPENDIX I. Calibraiion of the e-counting equipment,

 

Using 500 ul of the standard Pu solution (0.5 ug Pu/ml) (see Section B,
para. 7) obtain a series of standard sources by the procedures described in Section
D, paras. 2 to 10. '

Measure the counting rate of each source and correct for background.

Determine the disintegration rate of each source using an a-proportional
counter of known efficiency. (This efficiency is measured with a source calibrated in
a low geometry counter.)

Calculate in each case the ratio

Corrected counting rate as cpm
Disintegration rate as dpm

 

and calculate the counter efficiency E = 100 mean ratio.

APPENDIX II, Preparation of the Pu control source,

Prepare a standard Pu solution containing about 10 pg/ml of Pu. Transfer
approximately 20 mg of this solution from a weight pipette to a clean prepared counting
tray, ensuring that the liquid forms a small spot in the center of the tray. Evaporate
the liquid on the tray fo dryness by warming gently beneath a radiant heater. Allow
the tray to cool and add just sufficient of a solution containing 10 ug/ml of collodion
in acetone to cover the spot of activity. Allow to dry at room temperature, Determine
the counting rate of the control source and determine the disintegration rate using an
a-proportional counter of known efficiency. Calculate the efficiency of the couniing
equipment, -

110
100 Corrected counting rate (as cpm)

Efficiency = Disintegration rate (as dpm)

NOTE: The procedures of Appendix I and Appendix II are carried out at the

same time and E the efficiency of the equipment for the control source at the time

1 J
of calibration of the equipment, is obtained. The counting rate of the control source
is measured with each set of sample determinations and E2 , the efficiency of the
equipment at the time of sample count, is calculated using the previously obtained

disintegration rate,
Procedure 2. Separation and determination of Pu by TTA extraction., F, L.. Moore
and J. E. Hudgens, Jr. (Ref. 287).

Outline of Methond

The_sample is pre-treated if necessary, with either I—_INO3 or by precipita-
ting LaF g and dissolving in Al{NO3)3-HNO,. The pre-treatment destroys any polymer
which may be present and assures the proper valence state (IV) for the TTA extraction.
Pu(lV) is extracted from 2 M HNOg and stripped into 10 M HNO,, evaporated onto a

plate, and counted. Yield is quantitative.

Reagents

Hydroxylamine hydrochloride, 1 M, is prepared by dissolving 68.5 grams

of C.P. grade end diluting it to 1 liter.

Sodium nitrite, 1 M, is prepared by dissolving 69 grams of C. P. grade and
diluting it to 1 liter.

2-Thenoyltrifluoroacetone-xylene 0.5M, is prepared by dissolving 111 grams of
the ketone and diluting it to 1 liter with C. P. xylene. (2-Thenoyltrifluoro acetone
may be obtained from Graham, Crowley, and Associates, Inc., 5465 West Division
St., Chicago 51, Iil.)

Pretreatment

Nitric acid method. A suitable allquot of the sample solution is pipetted
into a 100-ml volumetric flask containing 13 ml of concentrated nitric acid. The solu-
tion is heated carefully to a low boil on a hot plate and the temperature is held just
under boiling for 5 min. The solution is then made to a known volume with distilled

water, The nitric acid concentration of this solution should be approximately 2M.

Fluoride method. A suitable aliquot (1 ml) of the sample solution is
pipetted into a 5-ml centrifuge cone, After addition of 0.4 ml of concentrated
hydrochloric acid and 0.1 ml of lanthanum carrier (5 mg per ml) the solution is
mixed well. Then 0.3 ml of hydroxylamine hydrochloride (5M) and 0.4 ml of hydro-
fluoric acid (27 M) are added and the solution is stirred with a platinum stirrer,
After a 5-min digestion at room temperature, the solution is centrifuged for 3 min.
Next, 0.1 ml of lanthanum carrier (5 mg per ml) is added and the supernatant is
stirred, care being taken not to disturb the precipitate.” After another 5-min digestion
at room temperature, the solution is centrifuged for 3 min and the supernatant is
removed with mild suction. The precipitate is washed twice with 0.5-ml portions of
1M nitric acid — 1 M hydrofluoric acid, centrifuging each time for 3 min. The
lanthanum fluoride precipitate containing the Pu is then dissolved in 0.3 ml of 2 M
aluminum nitrate and 1 ml of 2M nitric acid.

This treatment not only aids in depolymerizing Pu(IV) but offers a method of
removing the Pu from interferences, as sulfuric acid, before performing the extrac-
tion. The liquid-liquid extraction technique described in this paper has been applied

successfully for several years to the purification and isolation of Pu isotopes.

112
Procedure

The choice of the sample gize is governed by the magnitude of the con-
centration of Pu activity and of the beta and gamma ray emitters in the original
solution. The presence of high levels of radiocactivity must be congidered because of
the health hazard involved and because a beta ray counting rate of over 109 counts
per minute will interfere with the alpha counting on the Simpson proportional alpha
counter,

One ml of the sample solution (pretreated if necessary) is pipetted into
a 10-ml beaker., Three ml of 2 M nitric acid and 1 ml of 1M hydroxylamine hydro-
chloride solution are added. The solution is mixed thoroughly and heated at approxi-
mately 80°C. for 5 min, The volume of the solution is adjusted to approximately 4 ml
by the addition of several drops of 1 M nitric acid. The solution is transferred to a
30-ml separatory funnel using 2 ml of 1 M sodium nitrite, mixed thoroughly and
allowed to stand until gas evolution ceases. The aqueous phase at the time of extrac-
tion should be approximately 1 M in nitric acid.

The solution is extracted for 10 min with an equal volume of 0.5 M 2-thenoyltri-
fluoroacetone-xylene. When the two phases have disengaged, the aqueous phase is
drawn off and discarded. The organic phase is washed by mixing with an equal volume
of 1 M nitric acid for 3 min. After the phases have settled, the aqueous wash solution
is discarded, care being taken not to lose any of the organic phase. The Pu is then
stripped from the organic phase by mixing thoroughly for 2 min with an equal volume
of 10 M nitric acid. If the aqueous strip solution is too high in gamma radicactivity
for alpha measurement, the last traces of radiozirconium and protactinium may be
removed readily by a 5-min re-extraction of the 10 M nitric acid strip solution with
an equal volume of 0,5M 2-thenoyltrifluoroacetone-xylene. Pu remains quantitatively
in the aqueous phase, The small percentage of iron extracted (produces a red color)
remains in the organic phase when the Pu is stripped into 10 M nitric acid. The
aqueous strip solution is drawn off into a centrifuge tube and centrifuged for 1 min,

A suitable aliquot is pipetted onto a platinum (or stainiess steel) plate and evaporated
to dryness under an infrared heat lamp, The plate containing the evaporated sample
aliquot is heated to a dull red heat over a Fisher burner to destroy organic matter
and counted in a suitable alpha counter. In this laboratory, the methane flow propor-

tional alpha counter is used almost exclusively,

113
Procedure 3. Separation and determination of Puin U — fission product mixtures.
W. 8. Maeck, G. L. Booman, M. E. Kussy and J. E. Rein (Ref. 261).

Outline of Method

Plutonium is oxidized to Pu(VI) with permanganate and quantitatively
extracted as a tetraalkylammeonium complex into methyl isobutyl ketone from an acid-
deficient aluminum nitrate salting solution. Pu is stripped from the organic phase and
reduced to Pu(lll) with a hydroxylamine-iron(Il) mixture, oxidized to Pu(IV) with
nitrite, then quantitatively extracted into TTA.

Yield

Overall recovery of Pu is 98.8%.

Decontamination

Overall figsion product decontarnination is greater than 1 X 104; U

carry-through is less than 0.05%.

Reagents
Reagent grade inorganic chemicals, Eastman Kodak Co. White Label

tetrapropylammeonium hydroxide, and thenoyltrifluoroacetone obtained frorm Peninsular

Chemical Research, Inc., Gainesville, Fla,, were uged without purification.

Aluminum nitrate salting solution. Place 1050 grams of aluminum nitrate
nonahydrate in a 2-liter beaker and add water to a volume of 800 ml. Warm on a hot
plate. After dissolution, add 135 ml of concentrated (14.8 N) ammonium hydroxide
and stir for several minutes until the hydroxide precipitate dissoclves. Cool below
50°C. Add 50 ml of 10% tetrapropylammonium hjrdroxide reagent and stir until
dissolution is complete, Transfer to a 1-liter volumetric flask and dilute to volume
with water.

The 0.2 M ferrous sulfate and 0.22 M sodium nitrite solutions should be pre-
pared fresh daily, The 1.25M hydroxylamine hydrochloride and 0.05M potassium
permanganate solutions are stable for a month or longer. The potassium perman-
ganate solution is stored in a dark bottle.

Unless otherwise stated, the Pu levels in ex-tractibns were approximately
100,000 disintegrations per min (dpm). The stock solution was prepared from high
purity Hanford metal dissolved in 6 N hydrochloric acid. The isotopic composition
of the metal was 95,40% Pu239, 4,31% Pu240, 0,28% Pu24l, and 0.01% Pu242,

Equipment
The methyl isobutyl ketone (4-methyl-2-pentanone) extractions and strips
were made in 15 X 125 mm test tubes with polyethylene stoppers. An end-for-end
extraction wheel was used. Thenoylirifluoroacetone extractions were made in 50 ml

centrifuge cones with a motor-driven wire stirrer. The samples plates were 1-in.
stainless steel. An alpha scintillation counter was used for gross counting and a

Frisch grid chamber, 256-channel analyzer system, for pulse height analysis,

Procedure.

Add 6 ml of salting solution to a test tube containing 0.1 ml of 0.05 M
potassium permanganate, Pipefte 1 ml or less of sample into the tube. Add 3 ml
of methyl isobutyl ketone, stopper the tube, and extract for 5 min on the extraction
wheel. Centrifuge to facilitate phage separation. Pipette 3 ml of 3.125M nitric acid,
2 ml of 1.25 M hydroxylamine hydrochloride, and 2 ml of the above organic phase
into another 15 X 125 mm test tube. Stiopper the tube and strip for 10 min, and then
centrifuge. Carefully transfer 2 ml of the aqueous strip phase to a 50-ml centrifuge
tube containing 0.1 ml of freshly prepared 0.2 M ferrous sulfate and allow the mix-
ture to stand for 5 min. Add 3 ml of freshly prepared 0.22 M sodium nitrite and let
stand until gas evolution ceases. Add 5 ml of 0.5 M thenoyltrifluoroacetone-xylene
and stir vigorously for 20 min. Remove an aliquot of the organic phase and dry on a
planchet under a heat lamp. Ignite and count.

115
Procedure 4. Plutonium R. J. Morrow (Ref. 293)

 

Outline of Method

The Pu is co-precipitated from acid solution with La{OH)3 with NH;OH.
The precipitate is washed with NaOH solution, dissolved and the co-precipitation
repeated using La(IOg)g as the carrier. The hydioxide precipitation is repeated and
the Pu adsorbed on an anion resin column from 8 M HNOg. The column is washed
successively with HNOj3 and 2 portions of 10 M HCl. Finally, the Pu is eluted with
a mixture of HCl and HI and mounted for counting,

Purification

This procedure is designed primarily for separation of Pu samples to be
alpha-counted; it does not yield samples highly purified from beta- and gamma-
emitters. Samples containing 1013 - 1014 atoms of Pu have been isolated from four-
day old solutions of 5 X 1013 figsions. No foreign alpha activities could be detected,
and the beta content was 107 dpm or less,

Yield

60% if an electroplating technique is used for the final step, and 35% if

vacuum volatilization is used.

Procedure

One operation can do 12 samples in 6 hours, exclusive of volatilization
or electroplating.
1. To an acid solution of mixed activities in a plastic centrifuge cone

add ~1 mg La*3

carrier and an appropriate amount of standardized
Pu alpha-emitting tracer, the isotope added and its level of activity
depending upon the isotope sought afid its estimated level of activity.
Add 2-3 drops sat. NaNO2 solution and heat in a hot-waler bath for
five minutes.

2, Add enough conc. NH4OH to make the solution basic. Stir, and digest
at 60°C in a hot-water bath for five minutes. Centrifuge and discard
supernatant solution.

3. To the precipitate add 5 ml 25% NaOH solution, Siir and digest for 5
min at 60°C in a hot-water bath, Centrifuge and discard the supernatant
solution,

4. The hydroxide precipitate is then dissolved in a minimal volume of 3M
HCl and a volume of 0.5 M HIOj3 is added of the order of 4-5 times the
volume of HCI solution.

5. The precipitate is then digested for 10 min in a hot water bath.

§. The sample is centrifuged and the supernatant solution is decanted,
after which the precipitate is washed with 0,1 M HIOgq.

7. The sample is again centrifuged and the supernatant golution decanted.

116
8I

10.

11.

12,

13.

14.

A minimal amount of concentrated HCl is used to dissolve the

precipitate with stirring.

After dissolution the sample is precipitated with sodium hydroxide

and centrifuged.

The supernatant solution is discarded and the precipitate is washed

with HyO and centrifuged after which the supernatant solution is again

discarded.

To precipitate, add enough 8 N HNOj saturated with HgBOg (usually

~5-10 drops) to dissolve. Heat in hot-water bath if necessary.

Pipet the solution onto a 3 mm i.d. X 6 em long Dowex A-1 (1 X 8)

anion exchange resin column (previously washed thoroughly with 8 N

HNOQ,) and discard effluent. Wash column twice with 2 ml 8 N HNOg

each time, and twice with one ml portions of 10 N HCl, Disgcard all

washes.

To column add 2 ml of a solution 10 N in HCI and 0.5 N in HI, collect-

ing eluate in a 50 ml Erlenmeyer flask or a 40 ml centrifuge tube,

Either of two alternatives may now be followed:

a. Boil the solution to a very small volume and pipet the remainder
onto the central depression of the tungsten filament of vacuum bell
jar apparatus. Carefully boil the remaining solution to dryness in
the filament in air by application of current through filament,
Evacuate system and flash the contents of the filament onto a

platinum disc located about 1/4 in. - 1/2 in. from filament.

b. Evaporate the solution to dryness and redissolve residue with

three drops of conc. HCl, Transfer to an electrolysis cell suitable
for 1-in. diameter plates. Rinse tube successively with three more
drops of conc. HCI and three drops of water adding the rinses to the
solution in the cell, Carefully adjust acidity to the methyl red end
point with cone. NH,OH, then make barely acidic with two drops of
2M HCl. With a 1-in, Pt disc as cathode, and a volume of roughly

1 to 2 ml, plate at 5-6 volts with about 2.5 amps for roughly fifteen
min. Before stopping the current, add 1 ml conc. NH,OH. Shut

off current, remove solution and wash the disc first with water, then

with acetone. Mild flaming of the plate is desirable.

117
Procedure 5, Plutoniurmn D. C. Hoffrnan (Ref. 185)

 

QOutline of Method

The essentially gpecific procedure for Pu utilizes the almost quantitative
carrying of Pu(IV) on lanthanum fluoride and also the great difference in ability of
Pu(Ill}) and Pu (IV) in 12 M HCl medium to be absorbed on a Dowex A-1 anion resin,
One cycle of the procedure serves to separate Pu from other o-emitters, and two
cycles usually gives complete decontamination from B-emitting fissian products.

The initial lanthanum fluoride precipitation, carried out in the presence
of hydroxylamine, is an excellent volume-reducing step and also eliminates many
elements (notably iron) which may interfere in the subsequent adsorption of Pu on
the resin column, After dissolution of the lanthanum fluoride precipitate in 12 M
HCI1, adsorption on the anion resin column of Np, Pu, and any traces of Fe and U
present is effected, while the rare-earths Am and Cm pass through the column. Pu
is eluted from the column after reduction to Pu(Ill) with hydriodic acid; Np is not
reduced to the +3 state and remains quantitatively behind. (A solution containing 15
ug of U235 was run through the procedure, and no fission counts above the usual
background of 0.1 - 0.2 smidgins (1 smidgin = 10-6 mg) could be detected.)

The Pu is collected directly from the resin column on 2-in. Pt plates
which are flamed, o-counted, and, if necessary, pulse-analyzed., The plates are
usually very clean and may be @-pulse-analyzed with a resolution of 1 - 1.5%.

Samples are usually run in quadruplicate and yields are determined in
one of two ways. Pu236 tracer to the extent of about one-fourth to one-half of the
total Pu @ -activity expected may be added to one or two of the original aliquote, On
completion of the analysis, the fraction of Pu236 in the sample is determine by pulse
analysis, thus permitting the calculation of yield. Yields may also be determined by
spiking two of the four samples with a standardized solution of Pu activity which is
at least five times as active as the aliquot to be analyzed. The average of the number
of cpm in the two unspiked samples is subtracted from the average in the two spiked
samples. The resulting value divided by the number of cpm in the spike gives the
yield. The chemical yield is usually about 97% and for a set of four aliquots analyzed
simultaneously is constant to within +1%. In analysis of solutions of very high ionic
strength the yields are somewhat lower (90-97%), probably because under these con-
ditions the lanthanum fluoride carrying step is less efficient, Quadruplicate analyses

can be performed in 3 h,

Reagents
La carrier: 5 mg La/ml (added as La(NO,), - 6H,0 in H,O)
Pu?36 standardized tracer solution (in 3 N HCI),
or
Pu standardized spike solution (any mixture of Pu isotopes in 3N HCl).
HCl: cone. (12M)
HCl: 3M

118
HF': conc.

HF-HNOg: equal volumes of 2 M solutions

H3B03: saturated solution

NHoOH - HC1: 35% by weight in H20

Solution I: 0.1 ml conec. HNO3 per 15 ml conc, HC1

Dowex A-1 (10% cross-link, Nalcite SBR) anion resin slurry in H20.

Preparation

The 200-400 mesh moist solid is washed about three times with successive
poriions of water and conc. HCl, After each wash the resin is allowed to settle and
the liguid decanted by siphoning or by means of a vacuum pipet. The resin is then
stirred thoroughly with several times ita volume of water in a large gfaduated
cylinder, and the following fractions are withdrawn on the basis of sedimentation
rates: < (1 cm/min, <5 cm/min, <10 cm/min and > 10 cm/min, The <10 cm/min

fraction is employed in the procedure.

HI stock solution. Distill HI (Mallinckrodt analytical reagent grade,
5.5M in HI, 1.5% H3P02 preservative) under nitrogen. The HI cannot be used with-
out distillation, since the H‘.‘,‘PO2 preservative appears to cause the eluted drops to
attack the Pt coliection disks and make the samples unguitable for pulse analysis,
Commercial preparations of HI without preservative usually contain enough free
iodine to make them unsuitable. Even after storage under nitrogen, distilled HI is
slowly oxidized. Oxidation is inhibited by the addition of sufficient hydrazine (up to
20% by volume of 64-84% NyH, in H20) to decolorize the HI solution. The final
solution is about 4.4 M in HIL .

HI-HCI elutriant. 1 ml of HI stock solution is added to 9 ml of conc, HCI
to give a solution about 0.44M in HI. The precipitaté which resulté from the hydrazine
present is removed by centrifugation and the supernate is saturated with gaseous HCI.
The solution is permitted to come to equilibrium at room temperature before use and

since the solution is readily oxidized, fresh reagent is required every few days.

Equipment

Centrifuge

Block for holding centrifuge tubes

Fisher burner

Heat lamp

Pt digks: 2 in, diameter

Pt wire stirring rods

Transfer pipets and syringes

Vacuum trap for withdrawing supernates (optional)

10-cm glass ion exchange columns (see_* Note 4, Np procedure) (one per
sample) '

40-m]l conical centrifuges tubes: Pyrex 8140 (one per sample)

118
Procedure

Step 1. Pipet the samples (2 M in HCl or HNO,) into 40-ml long taper
conical centrifuge tubes. (1-ml aliquots are used if possible, although aliquots as
large as 25 ml can be taken if necessary). If tracer or spike is added to 1 or 2 of -
the samples, make the others up to the same volume with a solution of acid strength
identical to that of the tracer or spike. Stir,

Step 2. Add 1-2 drops of La carrier and then 2~4 drops of NH20H- HCl
per ml of solution. Make the solution at least 2.5M in HF by addition of conc.
reagent (Note 1). Agitate the solution and permit to stand for 5 min after the addi-
tion of each of the above reagents.

Step 3. Cén‘trifuge and digcard the supernate,

Step 4. Wash the precipitate with about 0.5 ml of 2M HF-2M HNO

solution. Stir, centrifuge and discard the supernate.

3

Step 5. Dissolve the LaF3 precipitate by adding 1 drop of saturated
H3BO3 gsolution, stirring, and then adding conc. HCI to a volume of 1.5-2.0 ml, The
solution may be warmed if necessary.

Step 6. Transfer the solution to a 5-cm Dowex A-1 regin column (see
Note 4 of Np procedure) which has been washed with 1-2 column volumes (Note 2) of
Solution I (Note 3). Wash the centrifuge tube with two l—m.'l' aliquots of Solution I.
The washes may be driven through the column with air pressure if so desired. The
effluent solutions from these washes may be used for the Am and Cm determinations;
if not to be so used the washes are discarded.

Step 7. Wash the sides of the centrifuge tube with 1.5 ml of conc. HC],
wash and remove the Pt stirring rods, centrifuge and pass the solution through the
column with the use of pressure.

Step 8. Add a few crystals of NH20H- HC] directly to the top of the resin
column. (This helps to prevent immediate oxidation of the HI solution by any traces
of HNO3 remaining on the column, ) Wash the centrifuge tube with 1.5 ml of cone.
HCI1, transfer the washings to the column, and permit them to pass through. The
column should not be permitted to run dry while air pressure is being applied to it,
since air bubbles will be forced into the column and channeling and erratic elution of
activity may occur,

Step 9. . 1-2 ml of the HI-HCI elutriant is put on the top of the column and
no pressure is applied during elution. The dark band of the elutriant may be seen
migrating down the column, The activity appears to be concentrated about the lower
edge of the elutriant band and most of it comes off in a 6- to 8-drop peak. However,
to obtain quantitative ylelds, drop collection is begun on a 2-in. Pt disk when the band
is about 0.8 cm from the end of the column, and collection is continued for 10-15
drops after the band has reached the end of the column. This allows for possible
irregularities in the band or misjudgements regarding its position. The drops taken
before the band reaches the end of the column are arranged on the periphery of the Pt
disk, and those which are expected to contain most of the activity are collected near

the center. The drops are not permitted to run together.

120
Step 10. Place the Pt disk under a heat lamp and allow the drops to
evaporate. Heat the plate to red heat in an open flame and cool; @-count if the
origifial aliquot was spiked, and pulse analyze and e-count if Pu236 tracer was
employed (Notes 4 and 5). '

Notes

1. When an appreciable quantity of Fe is present, en'ou.gh HF must be
added not only to complex this element (thus decolorizing the solution) but also to
precipitate La carrier.

2. The column volume is defined as about one-half the volume calculated
from the actual dimensions of the column, The column volume may, of course, be
measured experimentally in each case if the interfaces can be clearly seen.

3. The presence of conc, HNO3 in Solution I is necessary to destroy the
reducing properties of the original resin and thus avoid premature reduction of Pu(IV)
to the tripositive state.

4, If it is desired to fisgsion count the Pu, plates may be prepared by
taking the activity directly from the column. However, if any drops are permitted
to run together giving an extreme ''bathtub effect," the figsion counting results are
invariably toc low. To avoid such effects atiributable to sample thickness, the
following procedure for plate preparation is employed.

The Pu activity is evaporated on a 1-mil W filament under a heat lamp,
but the filament is not flamed. It is then placed in a vacuum evaporating apparatus
constrficted at this Laboratory. The chamber of the apparatus is evacudted to
5 X 10-4 mm or less of Hg pressure and the filament is heated rapidly several {imes
to about 1300°C to remove readily volatile material. A 1-in, diameter collector
plate is then placed in position directly above the sample (1/4 to 1/2-in, away) and
the filament is heated to 2000°C for a few seconds to violatilize Pu. The Pt disk is
then flamed and mounted for fission counting. The yields vary, depending upon the
size of the sample being evaporated and also upon the distance between the filament
and the disk, but are ugually about 40%. By careful control of the W filament tempera-
tures, plates having no visible deposit and checking to within 0,1% are ordinarily
obtained.

5. The Np activity whcih quantitatively remains on the column after
elution of Pu may be removed in the following manner:

Step 1: By means of pressure, run conc. HCI containing several
drops of HNO3 per ml through the column until the dark color has been removed,
Discard the effluent, (During this process the column may separate as a result of
bubbling, etc,, but can be resettled by means of pressure.)

Step 2. Wash the resin with conc, HCI and pressure, permitting the
column to rebed itself,

Step 3. Elute the Np with 0.1 N HCl, If the yield is very low after
only one elution with 0,1 M HC], about three cycles of elution alternately with ¢,1 M
HCI and conc. HCI usually give yields up to 85%. '

121
Procedure 6, Separation of Plutonium from Uranium and Fission Products in

 

Irradiated Reactor Targets R. G. Hart, M. Lounsbury, C. B. Bigham, L. P. V. Corriveau,
F. Girardi (Ref. 167)

 

Qutline of Method

The Pu is adsorbed on anion exchange resion (Dowex 1) from 7-11 M
HNO3 , the U and most of the fission products passing through. The Pu is then
eluted by reduction with 1 M N'H20H- HNO3 and impu.rit_.ies are extracted into TBP
while the Pu remains as Pu(IlI). The Pu is then precipitated as the hydroxide, dis-
solved in HNO3 and extracted into TBP. Finally, the Pu is back-extracted by
NHZOH . I-I'NO3 ,

This procedure describes two specific types of analyses to be done on
240 followed
followed by @

precipitated as hydroxide, and dissolved in HNO3 for analysis.

digssolved, irradiated, U targets. These are (1) isotopic dilution by Pu
by mass spectrograph analysis, and (2) isotopic dilution by PuZBB

pulse analysis. These analyses are described before the separation procedure is given,

Procedure

Total Pu, isotopic dilution with Pu240.

Two aliquots, one containing

~ 800 ug of Pu and the other containing ~ 400 ug of Pu, are removed from the dissolver
solution. Only the second aliquot need be measured accurately. To the second aliquot
is added ~ 400 ug of Pu containing a high percentage of the heavier isotopes. This
aliquot must be accurately measured and the Pu concentration and isotopic composi-
tion must be accurately known. The samples are allowed to stand for 4 or 5 days to
allow the spiked sample to reach isotopic equilibriurn:l and are then carried through

the Separation procedure. The purified Pu is then mass analysed. From the isotopic

 

compositions of the standard, the unknown and the mixture, and the total Pu content

of the standard, it is possible to calculate the total Pu concentration in the unknown.,

238

Total Pu, isotopic dilution with Pu Two aliquots, one containing

 

~ 100 pug of Pu and the other containing ~ 50 ug of Pu, are removed from the dissolver
solution. Only the second need be meeasured accurately. To the second aliquot is
added ~0.19 ug of Pu238, This aliquot must be accurately measured and the Pu238
digintegration rate of the solution must be accurately known. Both samples are
diluted to 15 ml with 7 M nitric acid, and are allowed to stand for 4 or 5 days to
allow the spiked sample to reach isotopic equilibr-iurn.2 The two samples are now
carried through the Separation method and ¢-counting discs are prepared from each
as described in the following section. From the ratios of Pu238 to Pu23? in the
spiked and unspiked samples, the total disintegration rate of the standard Py238
solution, and the isotopic composition of ungpiked sample, it is possible to make an

accurate calculation of the total Pu content of the solution.

 

1No detailed study has been made to determine the length of time required to
reach isotopic equilibrium, but it is known that some considerable time is necessary,

2See Footnote 1,
122
Preparation of @-counting plates. An aliquot containing about 50 ug of U

 

was transferred to a stainless steel source tray in the usual manner, The micropipette
used was then washed three times with a solution of tetraethylene glycol (TEG) in dilute
nitric acid (4 drops of TEG in 10 ml of 1 M nitric acid). The solution on the source
tray was then evaporated to dryness under an infrared lamp and the disc was ignited

to redness, The evaporation must take place very slowly to avoid decomposition of

TEG by hot nitric acid. Two to three hours are necessary for the drying.

Separation procedure

 

(1) The aliquot, in 7-11 M nitric acid, was passed through a 1-ml column
of 250-mesh Dowex 1 in the nitrate form to absorb the anionic Pu
nitrate complex.

(2) The uranium and fission products were washed through the column
with 20 ml of 7.5 M nitric acid. The strong acid was then displaced
with 1 ml of 1 M nitric acid.

(3) An aliquot of the effluent containing ~40 mg of U was retained for U
isotopic analysis and the remainder wasg discarded.

(4) The Pu was eluted from the column with 4 ml of 1,0 M hydroxylamine
nitrate.

(5) The Pu solution was extracted five times with 2 ml portions of 30%
TBP-solirol to remove any U left with the Pu,

(8) The Pu was precipitated from the aqueous phase with concentrated
ammonium hydroxide, dissolved in 100 A of concentrated nitric acid,
diluted to 0.5 ml and extracted with two 0.5-ml portions of 30% TBP-
soltrol,3

{7) The Pu was then backwashed from the organic phase with 3 half-volume
1 M hydroxylamine nitrate washes, precipitated with ammonium hydro-
xide, washed once with water, and dissolved in 20 A of concentrated
nitric acid. The solution was then diluted to 100 A with 1 M nitric

acid.

 

3The TBP extraction is necessary to separate the plutonium from resin decompo-
sition products.

123
Procedure 7.

Determination of Pu (Ref. 447)

 

Outline of Method

This procedure used an oxidized CeF

4—reduced LaF3 cycle and extraction

of Pu(VI) into hexone, in addition to two cycles of adsorption of Pu(lV) on anion resin

from concentrated HCl and desorption by reduction with NH4I.

Procedure

1.

10.

Add 5 mg Fe' ' and 1 ml HNO, to the acid solution containing the Pu
activity. Boil the solution down to about 3 ml and transfer to a 50-ml
lusteroid tube,

Make the solution ammoniacal to precipitate Fe(OH)3. Digest for a
few minutes on a 75°C water bath. Wash the hydroxide with 5 ml
water containing 1 drop NH4OH. Discard the supernate and wash.
Dissolve the Fe(OH)3 in 3 drops HNO3 and dilute with water to a

- volume of 15 ml (Note a). Add 3 mg Ce™ and 2 granules of

NaZCr207 . Sti.r well and heat for 5 min on a 75°C water bath. Cool
in tap water until sample reaches room temperature.

Precipitate CeF4 by adding 10 drops HF treated with dichromate
(Note b), Stir well and centrifuge immediately. Wash the precipitate
with 2 ml 1 N HT_\TO3 1 N HF. Decant the supernate and wash into a
clean 50-ml lusteroid tube.

Make the solution basic with 8 N NaOH. Let stand 3 min and centri-
fuge. Wash the Fe(OH)3 with 10 ml water. Discard the supernate and
wash. Dissolve the hydroxide in 3 drops of I-_INO3.

Add 5 mg La, 1 mg of Zr and dilute to 10 ml with water. Heat the
solution for 3 min on a 75°C water bath. Add 20 mg NaHSO3 a little
at a time, to insure complete reduction, Continue to heat for 5 min.
Add 10 drope HF with stirring, and heat for a few minutes. Cool and
centrifuge. Wash the LaF3 with 2 ml 1N HCl1 -1 N HF. Digcard the

supernate and wash,
Slurry the LaF3 in 1 ml saturated H3BO3 and heat on a 75°C water
bath for a few minutes. Add 1 ml HCl and 1 ml water and continue

to heat on the water bath to obtain a clear solution, Transfer the
solution to a 40-ml glass tube with water washes,

Add NI-I4OH to precipitate La(OH)s. Digest in a hot water bath for a
few minutes. Centrifuge, and wash the precipitate with 5 ml water
containing 1 drop NH4OH. Discard the supernate and wash.

Dissolve the L.EL(OH)3 in 1 ml HC1 and 2 drops HNO,. Heat the
solution for 3 min in a hot water bath, Cool the solution in an ice
bath, and saturate with HCl gas. Allow io come to room temperature.
Transfer the solution to a prepared Dowex AG 1-X8 (100-200 mesh)
colurnn, Prepare a wash solution containing 15 ml HCI and 1/2-ml

124
11,

12,

13.

14,
15.

16.

17,

18.

19,

20,

21.

Notes

a.

HNO3 . Rinse the tube with several 1-ml portions. of this sclution.
Transfer these washes to the column. Wash the column with the
remaining solution in 2-ml portions. Wash with 15 ml HCI in 2-ml
portions. Discard the effluents and washes.

Prepare an eluting solution containing 20 ml HCl and 75 mg NH 41.
Elute the Pu from the column into a 50-ml beaker with 2-ml portions
-of thig solution, allowing the first 2-ml portion to pass through. Add
the second 2-ml portion and plug the top of the column with -a piece of
pressure-sensitive tape for 5 min. Remove the tape and continue to
elute in 2-ml portions. Pass through 6 ml of HC1 in 2-ml portions.
Add 2 mg of La and evaporate the solution to approximately 5 ml.
Transfer to a 50-ml lusteroid tube and dilute to a volume of 10 ml.
Add 20 mg NaHSO3 a little at a time.

Add 10 drops HF with stirring, and allow to stand for a few minutes.

Cool in an ice bath, centrifuge, and wash the LaF, with 2 ml 1 N HCIl

X 1N HF. Discard the supernate and wash, ?
Repeat Steps 7 through 11.

Evaporate the solution in the 50-ml beaker to approximately 5 mls with
addition of HI\‘IO3 to drive off all iodine. Transfer the solution to a 40
ml centrifuge tube.

Add 5 mg Fe' " and precipitate Fe(CH), by addition of NH,OH.

Digest in a hot water bath for a few minutes. Céntrifuge, and wash

thé precipitate with 5 ml water containing 1 drop NH4OH. Digcard the
supernate,

Disgolve the Fe(OI’-I,'v3 iIn5ml6éN HNO3 . Add 4 drops saturated NaBrO
solution. Warm on a hot water bath for a few minutes. Saturate the
solution with NH,NO,, crystals, add 5 ml hexone (methyl isobutyl

4 73
ketone) and stir with a mechanical stirrer for 3 min, Centrifuge to

3

separate the phases, and withdraw the hexone (upper) layer with a
transfer pipet. Transfer the hexone to a clean, dry 40-ml centrifuge
tube.. Repeat the extraction twice, adding 1 drop of saturated N:;.BrO3
and more N'H4N03 if necessary.

241

Record the time of extraction as the '"Final Separation of Pu and

Am241."

Wash the hexone phases by stirring with 5 ml 6 N HNO3 . Stir for 2
min, centrifuge, withdraw the acid (lower) phase and combine with
original aqueous phase,

Back-extract the Pu from the hexone by stirring for 3 min with 5 ml
0.1N HN03. Centrifuge, and transfer the aqueous phase into a 50-ml
beaker. Repeat twice and combine the agueous phases,

The solution is now ready for electroplating.

Do not continue step 3 unless there is enough time to carry the

procedure completely and rapidly through step 5.

b.

Dissolve 1 granule of Na,CR,Oy with 1/2 ml HF in a Pt dish.
125
Procedure 8, Uranium and Plutonium Analysis B. F. Rider, et al., (Ref, 332)

 

QOutline of Method

Sample of dissolved irradiated fuel contain highly radioactive fission

products., For this reason, U and Pu are geparated before analysis. The procedure

described here gives a good yield, together with a good decontamination factor.

Reagents

1.

Distilled conc. H'NO3 -

2, 2M HI\TO3 - distilled conec, HNO3 , double distilled H,O.

3. U233 solution, standardized,

4, Pu.236 Solution, standardized,

5. KBrO3 - crystals, reagent grade. Low natural U blank,

6. 8M NH4NO3 in2 M HNO3 - Place 200 ml distilled 16 M HNO3 + 100
ml double distilled Hzo in a large beaker. Bubble l\iI'I-I3 gas through
solution until basic to pH paper. Boil off excess NH3 (solution neutral).
Transfer to mixing cylinder, add 50 ml of distilled 16 M HNO3 , dilute
t0.400 ml, Check density of solution (1.31 £ 0.01 @20°C).

. Hexone - distilled.
HCl - C.P. reagent. Low natural U blank,
. I M HNO3 - distilled conc. HN03 , double distilled HZO'
10. 30% H202 - meetg A. C. S, specification, low natural U blank,
11, 0.2 M TTA in xylene - 4,44 gm TTA dissolved in 100 ml digtilled
xylene,
12, Xylene - distilled.
13, Ether - distilled,
14, 0.05 M HNO:3 - distilled conc. HNO3 , double distilled HZO'
15. HZO - double distilled.
Glassware

All glassware used is Pyrex which has been soaked overnight in 50%
HNO:3 and rinsed with double distilled water. Pipets are rinsed with 50% HNO3 and
double distilled water before being used.

Separation and Decontamination Procedure

1.

Place the aliquot for analysis in a 15-ml cone and evaporate to about
1 ml., Add a suitable U233 and P1.1236 spike, one drop conc, nitric
acid, and several KBTOBH_ crystals. Allow to stand for 1 hr to allow
oxidation of Pu to Pqu.

Add 1.5 ml 8 MNH4NO:'3 in 2 MHNOS,
Prepare two scrub solutions in separate 15-ml cones, containing 1 ml
of 8 M NH4NO3 in 2 M HNO, and about 10 mg KBrO;. Preoxidize
about 10 ml Hexone with 2 ml of 2 M HNO3 and KBrO

until ready for use.

and evaporate to about 2 ml,
Keep covered

3-

126
10.

11.

12,

13.

14,

Extract the U and Pu four times for 5 min with 2-ml portions of
hexone (methyl isobutyl ketone), adding 1 drop of 16 M HNO, to the
original solution after each extraction. Scrub each extract in turn
with the two solutions prepared in step 3.

Strip the combined hexone extracts with five 2-ml portions of HZO‘
Evaporate the combined aqueous portions to dryness, add a few drops
of H'NO3 and HCI1, take to dryness. Evaporate to dryness with HNO3
under a gental stream of pure nitrogen on a boiling water bath.
Prepare 3 ml of 1 MHNO3 and 1 drop of 30% H202, add 1 ml to the
Pu and U residue from step 5 and two 1-ml portions to separate 15
ml cones.

Extract immediately the Pu two times for 20 min with 2-ml portions of
0.2 M TTA (thenoyltrifluoroacetone} in xylene. Scrub each in turn
with solutions prepared in gtep 6. Save the aqueous phase for U.
Combine the TTA extracts and add a few crystals of trichloroacetic
acid.

Mount the combined TTA extracts on a Pt plate for o-pulse analysis.
After pulse analysis, remove the Pu for mass analysis as follows:
Cover disk with HF'. Evaporate to dryness under a heat lamp. Again
cover disk with HF and evaporate to dryness. Cover disc with cone.
HNO3 and evaporate to dryness. Repeat three or four times. Cover
disk with conec, nitric, reflux a few seconds, and transfer with a
pipette to a 15-ml cone. Repeat three or four times,

Evaporate the combined conc. HNO3 refluxes to dryness. Treat
residue with aqua regia and evaporate to dryness. Evaporate to
dryness with cone. HNO3 on a bolling water bath several times. Add
50X of 0.01 M HNO3 to the evaporated sarmple and submit sample for
mass spectrographic analysis.

Wash the original 1 M HNO3 U fraction (step 7} with xylene. -Add 1
drop of HNO3 and 3 drops of HCI to the washed 1 M HNO3 and reflux
for about 1/2 hour to destroy the organic present., Evaporate to
dryness, flame gently to destroy organic matter and dissolve the
residue with 2 drops of HNO3 and evaporate to dryness on a water bhath,
Pipette three 1-ml portions of 8 M NH4N03 in2 M HNO3 . dissolve the
evaporated U fraction in one 1-ml portion. Place the other 2 portions
in two 13-ml cones for scrub solutions,

Extract the U with four 2-ml portions of diethyl ether, adding 100 A

of conc. HNO3 before each extraction. Scrub each extract in turn
with two scrub solutions prepared in step 12.

Evaporate the combined ether extracts over 1 ml of HZO in a 15-ml

cone. Ewvaporate to dryness.

127
15. Add 3 drops of HC1 and 1 drop of HNO:3 , and evaporate to dryness
repeatedly until the organic is destroyed. Flame gently to expel
ammonium salts. Then dissolve in H'NO3 and evaporate to dryness -
on a water bath, Add 50X of 0.05 M HNO3 to the dry cone and submit

sample for mass spectrographic analysis.

Plutonjium Calculation

To determine the amount of Pu in the original sample, it is necessary to

measure in a Frisch chamber the ¢ spectrum of the plate prepared in step 8. The

239 and Pu240 activity to Pu236 activity is calculated. If the ratio is

236 239

ratio of. Pu

multiplied by the original activity of Pu
Pu240

obtained. The specific activity of the mixture is calculated from that of the individual

239 plus Pu240 activity can be converted to Pu239 plus Pu2.40

added, the original activity of Pu

can be obtained. From the mass analysis a Pu239 to Pu240 atom ratio is

plus

isotopes. The Pu weight

by dividing this activity by the specific activity of the mixture.
Uranium Calculation

The ratio of the various U isotopes to U233 from the mass spectrometer
data is rnultiplied by the amount of U233 spike originally added to the sample to obtain

the amount of each U isotope present in the original sample.

128
Procedure 9a. Separation of Plutonium from Irradiated Uranium R. O. Lingjaerde
(Ref. 255)

Outline of Method

The Pu, U and figsion products are adsorbed on a cation exchange column
from 0.3-0.5 M HNO3 and washed with 0.5 M HNOS. The U and fission products are
then eluted with 2.0 M HC], and the Pu is stripped with 8 M HCl. The Pu is then
adsorbed onto anion exchange resin, washed with 8 M HCl, and finally stripped with
2 M HCI.

Procedure

5 ml of stock solution {containing about 15 ug Pu), 5 ml of 4.0 M HNO,
and Smlof 1.0 M NaNO2 were mixed in a flask, and made up to a volume of 50 ml
with water, NOZ‘ reduces Pu(VI) to Pu(IV), Care has to be taken that concentration
of HNO3 is not allowed to fall below 0.1 M, since Pu then will hydrolyse and conse-
quently coagulate on the column.

This solution was adsorbed on Dowex 50 (140-160 mesh) and the column
was washed with 0.5 M HN03.
ing fission products. The washing with 2.0 M HCl wasg continued until the S8-activity

Then 2.0 M HCl was applied to elute U and accompany-

was close to background.
Pu and remaining fission products were eluted with 8 M HCI, a small
3 + some NaNOZ added (to oxidize Pu(Ill) to Pu{IV)), and

this fraction was transferred to another column containing Dowex 1 (50-100 mesh),

amount of concentrated HNO

which beforehand had been washed with concentrated HC1 containing a little concentrated

HNO3.
After the sorption step, the column was washed with 8 M HCI (containing a

little concentrated HN03) until the effluent was practically free from B-activity.

T"inally the Pu was eluted with 2.8 M HCI.

129
Procedure 9b,

Separation of Plutonium from Uranium Metal, J. Rydberg (Ref. 341)

Qutline of Method

This procedure makes use of the co-precipitation properties of the different
oxidation states of Pu on BiPO4. The Pu is first oxidized to Pu({VI) which does not

carry on BiP04, and then reduced to Pu(IV) which carries, An additicnal purification

step is provided by extraction into TTA. Yield is greater than 60%.

Procedure

1.

The U sample is dissolved in hot conc, HNO3 and kept at 90°C for 30
min, giving a solution of U(VI) and Pu(IV).

The solution is diluted to 5 M in HNO, and solid NaBiO3 is added to
oxidize Pu to the +6 valency state.

The solution is made 0.1 M in HNO, (if it becomes turbid, HNO, is
added until the solution is clear) and 0.1 M in phosphate. The BiPO4

precipitate is centrifuged off. This precipitate carries most of the

3

fission products, and especially those with a chemistry similar to
Pu(IV).

The supernatant solution containing Pu(VI) ig made 1 M in HNO3 ,

0.05 M in NoH, and 0.005 M in Fe''. In this solution Pu is rapidly
reduced to Pu(III).

The solution is diluted to 0.1 M in HNO, and made 0.1 M in phosphate.
Bi™1 is then added (1 drop 0.1 M Bi' ' for each ml solution) to
precipitate BiPO4 , which carries all the Pu, The precipitate, which
ig usually contaminated with some U is centrifuged off and washed,
The phosphates in the precipitate are converted into hydroxides by
treating with warm ~10 M KOH. After centrifuging the solution is
drawn off, and the precipitate is washed and dissolved in hot conc.
HNOa. .

After some hours at room temperature, the solution is diluted to 1

M HNOS,

acetone in benzene. This gives a pure Pu(IV) solution in the benzene

and extracted with an equal volume of 0.3 M thenoyltrifluoro-

phase, leaving the rest of the U and the fission products in the aqueous

phase.

. If desired, the Pu(IV) can be back-extracted in to the aqueous phase

with 10 M HNO, or HCI0

phase with benzene.

4 after a two-fold dilution of the organic

130
Procedure 10,

Purification of Plutonium from Uranium and Fission Products

J. Rydberg (Ref, 341)

Oufline of Method

The method takes advantage of the fact that Zr and Nb are adsorbed very

well on silica gel from strong nitric acid solutions. Further decontamination from

fission products is achieved by precipitation of CuS from a 0.5 M HNO:3 solution.
Pu(IV) does not carry. Finally the Pu{lV) is extracted into TTA. Yield is greater

than 90%. Purification is approximately 106 from B—y radiation of fission products.

Procedure

1.

2.

The U03 sample is dissolved in hot conc. HNO3 and kept at 20°C for
30 min, giving a solution of U(VI) and Pu(IV),
The acidity of the cooled solution is adjustied to 6 M in HNO3 , and the

. solution is run through two columns of SiO2 gel. This removes most

of the Zr and Nb. The columns have a dimeter of 0.8 ¢cm and a

length of 10 cm.

Cu-H-, La*tt and ZrO-H- (1 drop 0.1 M carrier for each ml of solution)
are added to the solution, and it is then diluted to 0.5 M in HN03. On
the addition of HZS‘ CuS precipitates and carr’ies most of the fission
products with sulfides insoluble in 0.5 M HNOS. The precipitate

i's centrifuged off,

The solution is evaporated almost to dryness and then kept for 30

min in hot ~10 M HNO
valency state.

The solution is diluted to 1 M in HNO3

volume of 0.3 M thenoyltrifluoroacetone in benzene. Under these

3" This removes H28 and restores the Pu(IV)

and extracted with an equal

conditions practically only Pu(IV) and Zr(IV) are extracted, leaving
U, Th(UXl) and the rest of the fission products in the aqueous phase.
After a two-fold dilution of the organic phase with benzene, Pu(IV)
can be extracted back into an aqueous phase with 10 M HNO3 or
HClO4 . This provides an additional purification from Zr. In

practice it has not proved necessary to use this step,
Procedure 11. Uranium and Plutonium from Environmental Samples of Soil, Vegetation
and Water E, L. Geiger (Ref. 144)

Outline of Method

. The samples are pre-ireated to bring the Pu into solution as Pu(IV) in
Al(N03)3 - HNOS. The U and Pu ia then extracted together into 50% TBPF in tetradecane,
washed with 4 N HNO3, and back-extracted into water for mounting and counting as total U
and Pu, Yield is approximately 80 £ 15 (S, D. of mean)%.

Procedure

Preparation of samples

Vegetation. Cut oven-dried vegetation into small pieces and weigh 10.0 g
into a 150-ml beaker. Heat the sample at 600°C, starting with a cold muffle furnace.
When only white ash remains, remove the beaker from the muffle furnace and allow to
cool. Carefully add 2 ml of water, then add 10 ml of 8 l\T_HNOB—O.5 MAI(NOa)3
tion, Cover the beaker with a watch glass and boil the solution for 5 min. Allow to
cool, add 1 ml of 2 M KNO2
tube. Use 4 N HNO3 to complete the transfer. Centrifuge and decant the supernate

solu-
solution and transfer the sample to a 100-ml centirifuge

into a 125-ml cylindrical separatory funnel graduated at 30 ml. Wash the residue
with 4 N HNOS, centrifuge, and decant the wash solution to the separatory funnel. The
acid normality of the combined solutions at thig point ig 4-6 N and the total volume

should not exceed 29 ml. Proceed to the extraction procedure.

Soil. Grind 5 g of oven-dried soil with a mortar and pestle until the
entire sample can pass through a 200-mesh sieve. Weigh 1.0 g of the 200-mesh soil
into a 50-ml Pt crucible and heat the sample at 800°C for 4 hr. Remove the sample
from the muffle furnace and allow to cool. Add 3 ml of 70% HNO3 and 10 ml of 48%
HF, then stir the sample for 2-3 min with a Pt rod, Heat the sample in a 200°C sand

bath until all traces of moisturs are removed. Repeat this HNO,_-HF treatment, being

careful that the sample is completely dry before proceeding to tl?;e next step. Allow
the sample to cool and then add 15 ml of 6 N HN03-0.25 M AI(NO3)3 solution, Cover
with a watch glass and heat in the sand bath for 5 min. Allow to cool and decant the
solution through a filter, such as Whatman No, 40, into a 125-ml cylindrical separatory
funnel graduated at 30 ml, Leave as much of the residue as possible in the crucible
and repeat the hot 6§ N I-I'N03—0.25 M AI(NO3)3 treatment. Allow to cool and then filter,
Proceed to the extraction procedure.

Water. Place 1 liter of the sample in a 1.5-liter beaker and if basic,
neutralize with nitric acid. Add 15 ml of 70% HNO3 and evaporate to 30-40 ml.
Decant the solution through a filter, such as Whatman No, 40, into a 100-ml beaker.
~ Wash the 1.5- liter beaker, the residue and the filter with 4 N HNO,. Evaporate the
combined solution in the 100-ml beaker to 5 ml. Add 20 ml of 4 N HNO,, cover with
a watch glass, and heat for 5 min. Transfer the sample to a 125-ml cylindrical
separatory funnel graduated at 30 ml. Wash the beaker with 4 N HN03

to the separatory funnel, being careful that the total volume in the separatory funnel

and transfer

does not exceed 29 ml. Proceed to the extraction procedure.

132
Extraction.

Add 1 mlof 2 M KNO, to the sample in the 125-ml cylindrical separatory
funnel. Dilute to the 30-ml mark with 4 N HNO, and stir the solution briefly. Add
30 ml of 50% TBP in n-tetradecane. Agitate the solution vigorously for 4 min with
an air-driven stirrer. Discard the acid portion (lower layer). Wash the TBP portion
with 4 N HN03 and again discard the acid portion. Back extract with seven 15-ml
portions of distilled water, collecting the sirip solution in a 150-ml beaker., Evaporate
the combined aqueous portions to 10-15 ml, then quantitatively transfer the solution to
a flamed stainleas steel planchet. Allow to dry under a heat lamp, flame the planchet
to burn off organic residue, and count on an ¢-counter. Retain for pulse-height analysis
if the e¢-count exceeds a specified level,

133
Procedure 12. Plutonium from Environmental Water Samples J. Scheidhauer,

L. Messanguiral, and A. M. Meiraneisio {(Ref. 352)

 

Outline of Method

Pu(IV) is spearated by chemisorption on solid Can as the concentration
step, and further purified with two TTA extraction cycles. The chemisorption step
has been shown to be quantitative and very efficient. The sensitivity can be made very

-11

great, as low as 0.7 X 10  Ci/ml by taking a large sample.

Reagents
Concentrated nitric acid (d = 1.38)
10 N nitric acid
2 N nitric acid
1 N nitric acid
Concentrated hydrofluoric acid
Concentrated perchloric acid
Ferric nitrate
Hydroxylamine hydrochloride
1 M hydroxylamine hydrochloride
Sodium nitrite
Ammonium thiocyanate
2M Al(NO3):3 -05N HNO3
Calcium fluoride
Solution of 111 g/1 TTA in xylene

Procedure

1. Place 3 liters of filtered water to be analyzed in a beaker and add 5 g each
of ferric nitrate and hydroxylamine hydrochloride.
2. Heat and agitate with a glass stirring rod to about 60-70°C.

T+ is reduced by spot

Let the sclution cool down, making sure the Fe
testing with several crystals of ammonium thiocyanate from time to time.

4. Pour this solution in a plexiglass column which is closed at one end and
edd water to within 0.5 cm of the top. Start agitation with a magnetic
stirrer.

5. Add 10 g sodium nitrite. After several minutes add 60 ml concentrated
HNO3 (d =1.38), then 45 ml concentrated HF when the HNO3 has redis-
solved the ferric hydroxide which has formed.

6. Then add 0.2 g calcium fuloride powder and place the filtration system on
the column (see Fig.58).

7. After agitating for 1 hr, invert the column over a 5-10 liter plastic receiving

vessel. The filtration may be speeded by maintaining pressure by means
of a laboratory pump.
8. Wash the filter cake two times with 250 ml of distilled water introduced

into the tube under pressure.

134
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

k L

 

 

 

 

Fig. 58. Cross sectional view of the agitation column. The material is "Altuglas
MZD" throughout except for the brass screws. The diffuser plate has a total of 213
holes drilled on 8 concentric circles. The inside dimensions of the column are 8.0 c¢m
diameter by 60 cm high. The reader is referred to the original paper for a more de-

tailed drawing.

135
10.

11.

12.

13.

14,

15.

186.

17.
18.

19.

20.

21.

22.

23.

24,

25.

28.

~the organic phase two times with 3 ml 10 N HNO

After disassembly of the filtration apparatus the filter membrane is placed
in a 100-ml beaker. The apparatus is washed briefly with distilled water

which is poured into the beaker.
Add 4 ml of the 1"—\1(N03):3 - HNO:3
volume is reduced to approximately 20 ml, remove the filter and wash it

solution and bring to a boil. When the

with water. Continue to evaporate to about 15 ml.

Add 4 ml 1 M hydroxylamine hydrochloride and let cool. Make sure the
Fe+++ is completely reduced by spot testing (with ammonium thiocyanate).
Add 0.5 sodium nitrite and start agitation. Add 1.5 ml 10 N HNO3
make sure by spot testing that the ferrous ion is oxidized. Expel the

and

nitrous vapors.

Add 15 ml TTA-xylene solution. Agitate so that the two phases are well
mixed for 1/2 hr.

Perrmit the phases to separate and draw off the aqueous phase with a pipette.
Wash two times with 5 ml I N HNOB.

Back-extract the Pu(IV) by agitation with 5 ml 10 N HNO,, for 1/2 hr. Wash

3
3
The 10 N HNO,, phases are combined in a 30-ml beaker and evaporated to

dryness.

3

Take up with 2 ml fuming HNO3 and 3 ml HClO4 and evaporate to dryness.

Stop heating and add 1 ml 1 M hydroxylamine hydrochloride when the tem-

perature permits,

Let the solution cool and verify that Fe'*" ig reduced by spot testing using
a very thin glass rod.

Add 1 mi 1N HNO3 and transfer to a 30-ml separatory funnel, washing the
beaker two times with 1 ml of 1 N HN03.

Add 0.15 g NaNO, to the funnel. Wash the beaker again with 1 ml 2 N HNO
and 0.5 ml 2 N HNOS. Combine these washes in the funnel.

Stir slowly for 5 min to expel the nitrous vapors.

3

Add 5 ml TTA-xylene and stir for 20 min at maximum speed.

Let the phases separate and eliminate the aqueous phase. Wash two times
by agitation for 10 min with 3 ml of 1 N HNO3.

The Pu is next re-extracted by agitation for 20 min with 5 ml of 10 N HNO
and the organic phase is washed two times with 2 ml of 10 N HNOa.

3!

The combined aqueous phase is evaporated on a watch glass and counted.

136
Procedure 13. Plutonium from Environmental Water Samples J. Kooi and U. Hollstein
(Ref. 237).

 

QOutline of Method

B:i_PO4 is used to concentrate the Pu after reduction to Pu(IV) with SO2
9 The
Pu is further purified by co-extraction into ferric cupferride as Pu(III) from dilute

gas. The solution is heated to 100°C for several minutes to expel excess SO

nitric acid, Finally, the organic matter is destroyed by wet-ashing with stO4 and
HNO3 and the Fe'' ¥ precipitated as the hydroxide, mounted and counted.

6

Yield. Approximately 99% from solutions containing 0.8 X 10" ° g CiPu/ml.

Procedure

1. Acidify a 500 ml sample of water with 15 ml of 2 N nitric acid and add
10.4 mg of Bi°T,

2. Bubble 502 gas, technical, gently through the solution for 20 min, using a
wide capillary.

3. Heat the solution to boiling and keep it boiling at 100°C for some minutes

9- Add slowly 60 ml of a 1 M solution of

orthophosphoric acid under continuous stirring with a glass rod and leave

to expel the excess of the SO

the suspension at 90°C for 30 min with occasional stirring. Allow the
precipitate to settle for at least 2 hr, by preference overnight.

4, Filter through a fine-fritied funnel, the stem of which has been drawn
into a wide capillary. Use 25 ml of 8 N HCL in total to rinse the beaker
and the glass rod ahd to dissolve the precipitate on the funnel. Suck the
solution through the funnel directly into a 50-ml narrow-necked flask placed
in a filtering flask with cut-off bottom, resting on a ground-glass plate.

5. Transfer the Bi-Pu solution to a 250-ml beaker, rinse the flasic with a
little distilled water and add 5 ml of freshly prepared 10% hydroxylamine
hydrochloride solution. After 15 min make up to about 100 ml with distilled
water. _

6. Using a pH meter, adjust the pH to 0.7-0.8 by addition of 70-90 ml of 2 N
ammonia. Add 0.1 mg of Fet

7. Transfer the solution into a 1~-1 separatory funnel, lubricating the stopcock
with any kind of grease that can be completely removed by the oxidation as
described in 14-16. Add 2 ml of a freshly prepared 5% cupferron solution
in water, shake, and let stand for 45 min.

8. Add 30 ml of purified chloroform. Shake the mixture repeatedly for 1 min
and run the chloroform extract through a 4-5 ¢m No. 41 Whatman filter
paper into a 250-ml separatory funnel, using the same kind of grease for
the stopcock.

9. Shake the chloroform solution with 20 ml of 0.3 N hydrochloric acid con-
taining 1.5 g of cupferron per liter, and run the chloroform layer through
a No. 41 Whatman filter paper into a 250-ml roundbottom flask with ground
joint. Transfer the water layer of the lower separatory funnel into the upper

one,
137
10.

11.

12.

13.

14.

15.

186.

17.

18,

19,

20.

21.

Add to the solution in the upper funnel 0.1 mg Fe™ and 2 ml of a 5%
cupferron solution, shake, and let stand for 45 min.

Repeat the whole extraction procedure twice (8 and 9) with 25 ml of purified
chloroform. Transier the water-layer resulting from the first repetition
from the lower to the upper funnel. Discard both water-layers in upper and
lower funnel after the second repetition,

Wash down the sides of the two filter papers into the roundbottom flask with
as little chloroform as possgible io remove traces of red-brown iron-cupferrate,
Distill off the chloroform until about 20 ml is left and remove the remainder
of chloroform by gentle blowing or suction, as shown in F1g 59.

Add 1 ml of concentrated sulfuric acid (C. P. grade) and attach to the round-
bottom flast a 15-c¢m condenser. Reflux for 30 min.

Add 2 ml of fuming nitric acid (C. P. grade) and heat until the solution
appears light yellow.

Remove nitrous vapors and sulfur trioxide first by heating, later by
sucking air through an attachable tube, creating slight turbulence in the
bulb and the neck of the roundbottom flask. Two burners should be used,
one to keep the bulb hot, without heating the dry residue to a red glow,
however; and the other to prevent condensation in the neck of the round-
bottom. If the dry residue does not appear snow-white after cooling,

repeat 14 and remove sulfur trioxide by heating as above,

Dissolve the white residue in 1 ml of concentrated HCL while gently
heating. Some time may be needed before the solid is completely dis-
solved, |

The final sample for counting is deposited on a Pt tray of 35 mm diameter
and 1 /8 cm thick. Determine the counter background with the tray in
counting position. Place the tray under a radiant heater and, using a
drawn-off pipette, transfer the green-yellow solution onto the tray,
covering about half of the area. Rinse the flask with a second ml of con-
centrated HCL and {ransfer the washing onto the tray. Repeat with 1 ml

of water. After evaporation to near dryness, add a few drops of water,
Enclose the tray and two 10-ml beakers filled with 10-15% ammonia in a
large beaker upside down. I.et stand for at least 5 min to ensure the
formation of ].-'-‘e(OH):3 to be completed., Evaporate to dryness.

Place the tray in a porcelain dish, cover it with a second dish, and ignite
for 10-15 min to convert the hydroxides to oxides.

Count the sample under an @-counter. A simple counting device consisting
of a photomultiplier and a ZnS screen, provided with a light trap for insert-
ing samples without switching off the high voltage, showed to be very re-
liable and satisfactory. Efficiencies up to 47-50 percent may easily be ob-
tained. Calculate the Pu concentration according to the formula

S

- -S A
Cp, = 9.01 X 107" & pe/ml

P
where A = activity of sample in counts per minute and E = percentage

efficiency of counter.
138
 

~ ~
\\
Y
* )
,I
(a) (b)
Fig. 59. Roundbottom flask used for destruction of organic matter. (a) Set-up

used for refluxing (----) and removal (—) of nitric acid. (b) Set-up used for removing

chloroform and sulfur-trioxide vapors.

139
Procedure 14. Separation of Plutonium in Uranium-Plutonium Fission Element
Alloys by TBP Extraction from Chloride Solutions R. P. Larsen and C. A. Seils, Jr.
(Ref. 249)

 

Qutline of Method
The U and Pu are reduced to U(IV) and Pu(Ill) by contact with Mg turnings
in 2 2 M HCI solution. The U is then extracted into TBP. The Pu is then oxidized to
Pu(IV) with NaNO3 and exiracted into TBP and back-extracted with 0.1 M HCl. The
Pu is then precipitated as the hydroxide and taken up in HNO:3 for spectrophotometric

determination.

Reagents

Unless otherwise stated, reagent grade materials are used.

1. Tributyl phosphate, 30-volume % in carbon tetrachloride.

2. Tributyl phosphate, 30 volume % in Amsco-140 {a kerosine distillate).

3. Dilute 300 ml of tributyl phosphate (Commercial Solvents Corp.) to 1
liter with carbon tetrachloride (or Amsco-140). Scrub once with 200 ml
of 0.5 N sodium hydroxide to remove traces of mono- and dibutyl phos-
phate. Scrub four times with distilled water and filer through a large dry

filter paper to remove cloudiness.

Procedure

Dissolve the alloy sample, using the procedure described by Larsen® for
this type of material, and dilute to volume.

Pipette an aliquot containing 10 to 20 mg of Pu into a 50-ml Erlenmeyer
flask. For 20% Pu alloys, there will be 35 to 70 mg of U, more than enough for its
determination. Convert to a chloride medium by evaporation to near dryness (3X)
with 12M hydrochloric acid. Adjust the volume to 10 ml and the hydrochloric acid
concentration to about 2M. Add approximately 0.1 g of Mg turnings over a period of
several minutes. Using a double layer of glass fiber filter paper in a filter chimney
assembly, separate the precipitated Group VIII elements by filtration, and catch the
filtrate in a 60-ml cylindrical separatory funnel. Rinse the flask and filtering assem-
bly with three 5-ml portions of 12M hydrochloric acid. Add 15 ml of 30% tributyl phos-
phate in carbon tetrachloride and shake for 1 min. Allow the phases to separate and
transfer the U-béaring organic phase to a second 80-ml separatory funnel.

Repeat the extraction with 10 ml of 30% tributyl phosphate in carbon
tetrachloride and combine the U-bearing organic phases in the second separatory
funnel. Treat the Pu—beafing aqueous phase by the procedure outlined in the next
paragraph. Add 15 ml of 0.5M hydrochloric acid to the combined organic extracts
and shake for 1 min. Allow the phases to separate and drain the stripped organic
phase into a 60-ml separatory funnel. Add 10 ml of 0.2M hydrochloric acid and repeat
the stripping operation. Discard the organic phase and combine the aqueous strip
solutions in the second separatory funnel, Add 5 ml of carbon tetrachloride and shake
30 sec to wash out dissolved tributyl phosphate from the aqueous phase, Discard the

organic layer. Rinse the U solution into

 

*Larsen, R. P., Anal. Chem. 31, 545 (1859).
140
a 50-ml Erlenmeyef flask and evaporate to dryness (2X) on a sand bath after addition
of 2-ml portions of 16M nitric acid. Add 5.0 ml of 16M nitric acid to dissolve the U.
Transfer to a 50-ml volumetric flask with water and make up to volume. Determine
U x-ray spectrometrically. For samples containing less U, use proportionately
smaller volumes of nitric acid and volumetric flasks (down to 5 ml).

Add approximately 100 mg of sodium nitrite to the agueous raffinate from
the U separation to oxidize the Pu to the quadrivalent state. Add 20 ml of tributyl
phosphate-Amsco-140 and equilibrate 1 min. {(Amsco-140 is used as the inert diluent
to give a light organic phase.) Discard the lower aqueous raffinate., Add 15 ml of
0.2M hydrochloric acid and equilibrate 1 min. Allow the phases to separate and irans-
fer the aqueous phase to a 50-ml Erlenmeyer flask. Add 10 ml of 0.2M HCL to the
organic phase and repeat the stripping operation. Combine the aqueous strip solutions,
add 2 ml of 12M hydrochloric acid, and evaporate on a sand bath to reduce the volume
to approximately 2 ml. Transfer the solution to a 15-ml glass centrifuge cone with a
transfer pipette and dilute to 7ml with water. Add 0.5 ml of 20% hydroxylamine hydro-
chloride and let stand 15 min with occasional mixing. While mixing with a Pt stirring
wire, add 10M sodium hydroxide dropwise until plutonium hydroxide precipitates. Add
10 drops of sodium hydroxide solution in excess and let stand for 5 min. (Evaporation
is not a satisfactory volume-reduction step, as it does noi remove chloride. With the
nitrate introduced in the next step, oxidation of the Pu to the sexivalent state would
occur.) Centrifuge for 5 min and discard the clear supernate, Wash the precipitate
with water, centrifuge for 3 min, and discard the wash solution. Add 2.0 ml of 16M
nitric acid and stir to dissolve the precipitate. Heat the nitric acid solution in a
boiling water bath for 20 min. (This treatment will destroy any polymeric Pu which
may be present and ensure complete oxidation of the Pu io the quadrivalent state, If
the precipitate were digsolved in hot 3M nitric acid, some oxidation to the sexivalent
state would occur.) Allow the solution to cool and dilute to volume in a 10-ml volu-
metric flask with water. HRead the absorbance vs a reagent blank in 1-cm cells at
475 mu and a slit width of 0.02 mm. Calculate the Pu present from a calibration
factor prepared from a series of standards carried through the hydroxide precipitation
step only.

141
Procedure 15. Separation of Pu before Spectrographic Analysis of Impurities Anion

 

Exchange Method F. Trowell (Ref. 405)

Qutline of Method

Pu metal is dissolved in HCIl and an excess of 8 M HNO, ig added. Pu
ig adsorbed on an anion exchange column from the resulting mixture and the column
is washed with 8 M HNO3. The solution and wash is evaporated to dryness, taken up
in 6 M HCI, and spectrographically analyzed for Al, Be, Ca, Cd, Co, Cr, Cu, Fe,
Mg, Mn, Mo, Ni, Ti, and U.

Reagents
1. 8 M HNO, (Note a).
2. 6 M HCI (Note b).
3. Resin (Note c).

Procedure

1. Weigh duplicate portions of 0.25 g of Pu metal and dissolve each by tipping
into 1 ml 6 M HCI in 50-ml silica beakers.

. 2. When all traces of metal have dissolved, add 5 ml 8 M HNO3 and mix well.
Note (d).

3. Transfer the resulting green solutions to the ion exchange columns (Note
(e)) using the minimum volume of 8 M HNO, to rinse out the beakers.

4. Place 50 ml silica beakers containing 1 ml of 100 yg/ml Sc solution under
the columns to collect the eluted solutions. Allow the Pu solutions to
drain down to the top of the resin.

5. Add 15 ml 8 M HNO

through.

3 to the columns and allow this eluting acid to drain

6. Transfer the silica beakers to the fume cupboard and evaporate the solu-

"~ tions to dryness. Note (f),

7. Add 1 ml 6 M HCI to the dry residues and warm slightly to ensure com-
plete solution; draw into polythene ampules. Note (g)

8. Prepére duplicate reagent blanks using the procedure and reagents above
but omitting the Pu,

9. Pass 0.3 M HNO, through the columns until all traces of green color have
been removed (Note (h)). Recondition the column for further use with 8 M
HNOa. Note (i).

Notes

{2) Prepared from concentrated HNO3 (redistilled from silica) and deionised
water.

(b) Prepared from gaseous HCI1 and deionised water.

(c) Deacidite FF (SRA 68). Remove fines by stirring with water. Allow to

settle for 10 min and decant off any resin still in sugpension; repeat this

142
procedure until all fines are removed. Use 3 ml wet resin in a 6-mm
bore gilica column fitted with a quartz wool plug. (See Fig. 60).
for dimensions. } _ '

(d) At this stage the color changes from blue to green.

(e) Condition the columns immediately before use by allowing 10 ml 8 M
HNO3 to run through them.

(f) This solution contains the impurities free from Pu.

(g) This solution is ready for analysis by the polythene funnel method.

(h) Collect the washings and transfer to the appropriate residue bottle.

(i) Add about 10 ml 8 M HNO3

perspex rod until it is in suspension and all air bubbles have been

and stir the resin with a pointed 1/8-in.

removed. Allow to settle for 10 min and decant off any resin still in

suspension. Add fresh resin to bring the total resin volume to 3 ml.

- I.5¢cm BORE

  

4cm
4cm BORE

Bem
20 em 6émm BORE

QUARTZ WQOL PLUG

Fig. 60. Ion exchange column.

143
Procedure 16. Separation of Plutonium Before Spectrographic Analysis of
Impurities. Extraction Chromatography Method Using TBP ¥. Trowell (Ref. 405)

QOutline of Method

Pu in 8 M HNO, solution is adsorbed on a KelF/ TBP chromatographic
c¢olurnn and the impurities eluted with 8 M HNO3. Sc is added as an internal standard
to the eluted scolution which is then concentrated by evaporation and analyzed by the
graphite spark technique for Al, Co, Cr, Fe, Ga, Mn, Ni, and Ti.

Applicability. This method is intended for the analysis of high-purity Pu.
The concentration range covered is from 0.5 to 10 ppm. The lower limit of analysis
may be restricted by the reagent blank.

Equipment

1. Column (for dimensions and preparation see Appendix).

Reagents

. 6 M HCl. Note (a).
2. 16 M HNO,. Note (b).
8 M HNO,.
0,32 M HNO,.
2 M HF. Note (c).
CC14. Note {d).
Tri-n-butyl phosphate. Note (e).
KelF. Note (f).
Grease solution. Note (g).

= 3 s W

Procedure

1. Weigh 2 g of Pu and dissolve by tipping into 5 ml 6 M HCl in a 50-ml
silica beaker. Cover with a clock glass and warm. Note (h).

2. When all traces of the metal have dissolved, rinse and remove the
clock glass, rinse down the sides of the beaker, and evaporate the
solution to dryness.

3. Cool (Note (i)), add 5 ml 16 M H'NOS, warm and add 5 drops 2 M HF
to ensure complete solution. Evaporate to a moist residue. Note (j).

4. Redissolve this regidue in 10 ml 8 _I\gHNOa, warming to ensure
complete solution.

5. Transfer the solution to the KelF/TBP column using the minimum
volume of 8 M HNO3 to rinse out the beaker. WNote (k).

6. Place a 50-ml tall-form silica beaker containing 1 ml 20 gg/ml Sc
solution under the column. Note (1).

144
Notes

10.

11.

12.

13.

(a)
(b)

(c)
(d)

(e)
(f)
(g}
(h)
(i)
(j)

(k)
(1)

Allow the solution from (5) to drain down to the top of the
chromatographic column maintaining a flow rate of approximately

0.5 ml/min. Add40ml 8 M HNO, and allow to drain through the
column at the same rate.

Transfer the eluted solution to a 100-ml separating funnel and wash
with 10 ml conditioned CC14, repeat the wash with two further
portions of 10-ml CCl4.

Transfer the washed solution to the 50-ml beaker and evaporate to
dryness in a fume cupboard. Note {m).

Redissolve the residue in 1 ml 6 M HCl while the beaker is still
warm.

Duplicate reagent blanks are prepared using the procedure and re-
agents above, but omitting the Pu.

Prepare the electrodes for sparking by pipetting 0.1 ml of the solution
from (10) on to the tops of a pair of waterproofed graphite electrodes,
dividing the aliquot equally between the two electrodes, and dry under
an infrared lamp. Prepare duplicate pairs of electrodes for each
standard sample and reagent blank golution. Note (n).

Remove the adsorbed Pu from the column by eluting with 0.32 M
HNO3 {Note (o)) and then wash the column with water to remove the

HNO,. Note (p).

Prepared from gaseous HCl and deionized water,

HNO, AR redistilled from silica apparatus. Diluted with deionized
water.

Prepared from HF AR and delionized water.

CC14 AR conditioned before use by shaking with an equal volume of
8 M HN03.

Commercial TBP purified by steamn distillation and alkaline washing
(see Appendix).

Low density KelF moulding powder, less than 100 mesh (see
Appendix).

0.1% Apiezon M in CC14.

Each sample should be done in duplicate.

A vigorous reaction occurs if addition of concentrated HNO3 is made
to hot residue.

If the residue is allowed to go to dryness it will be difficult to re-
dissolve,

See Appendix for column preparation.

Vitrosil tall-form beaker nominally 50 ml capacity in fact has a

volume of about 75 ml.

145
(m}

(n)
(o)
(p)

The activity of the solution is due almost entirely to the Am content
of the Pu metal. In general this is sufficiently low to allow a number
of solution to be evaporated to dryness at one time without exceeding
the tolerance limit allowed in a fume cupboard.

Each sample and reagent blank will thus have four exposures.
Transfer the solution to the appropriate residue bottle.

The column life is limited as some TBP is washed off with each run.
The effect of this is that the adsorbed Pu layer becomes longer with
each run and the column must be replaced when the danger of Pu

break-through becomes apparent.

Purification of TBP

Appendix
1.
2.
3.
4.

Place 250 ml commercial TBP and 100 ml 0.5 M 'NaOH in a 1-litre
flask fitted with a splash head for steam distillation. Heat the mixture
to 80°C, but take care not to heat above this temperature. Note (a).
Remove the source of heat and steam distil for 3 hr, rejecting the
distillate. Note (b).

Pour the hot TBP/NaOH mixture into a separating funnel and reject
the (lower) aqueous phase. Wash the TBP with two 100-ml portions
of hot deionized water and then with two 100-ml portions of cold
deionized water. Note (c).

Filter (Whatman 541 paper) the washed TBP into a clean dry reagent
bottle,

Preparation of KelF Powder

 

1.

Chill KelF low density molding powder with solid CO2 and grind in a
microhammer mill. Note (d).

Sieve the milled powder and collect the material passing 100 mesh
(BSS). Note (e).

Wet the powder with acetone, transfer to a 1-liter beaker and add
excess of 6 M HCL (Note (f)). Allow the KelF/HCl suspension to stand
overnight. '

Pour the KelF/HC1 suspension into a funnel fitted with a cotton wool
plug and allow the acid to drain away. Wash the KelF free from acid
by pouring deionized water through the funnel.

Finally, dry the washed KelF by pouring acetone through the funnel
and then spreading the powder out onto a polythene sheet and allowing

the acetone to evaporate.

Preparation of Column

1.

Mix 12 g KelF powder and 12 g TBP to a smooth paste, add about 10

ml deionized water and mix to a slurry.

146
Notes

(a)
(b)

(c)

(d)
(e)

()
(g)

(h}

Transfer about a quarter of this slurry to the column (Note (g)) filled

with water and gently press small quantities of this slurry down with a
glags plunger so that an evenly packed column of the KelF/TBP is formed.
Note (h).

Repeat this procedure with further portions of the slurry until the

column is complete.

Keep the column filled with water until required for use and condition
with 40 ml 8 M HNO3 when required.

TBP/NaOH mixtures bump violently.

This removes most of the free n-butyl alcohol from the TBP; the
remainder is removed by washing.

The initial sepafation and washings must be done hot to avoid
emulsification.

Chilling assists the grinding process.

Making the powder just moist with acetone will prevent it sticking to
the sieve.

To remove any metallic impurities. . ,

28 cm X 1.2 cmn Pyrex calumn, 2-mm bore tap and fitted with a
quartz wool plug.

Care must be taken in the preparation of the column, loose packing
may result in Pu breakthrough during elution; tight packing will give

a very slow flow rate.

147
Procedure 17. Separation of Np and Pu by Anion Exchange N. Jackson and J. F.
Short (Ref. 204)

 

QOutline of Method

This procedure is desgcribed for macro amounts of Pu and Np. Tt is based
on the fact that Pu(IIl) is not adsorbed on anion exchange resin, while Np(IV) is
strongly adsorbed at high HC1 concentrations. The valence adjustment is done before
adsorption on the column by dissolving the hydroxides in a concentrated HCI solution
which has been saturated with NH4I. The Np is removed from the column with 2 M
HCl. The separation is quantitative and complete.

Procedure

The purification of 2.3 g of Np237 from approximately50mg of Pu239 was

then undertaken. The Np and Pu were precipitated as hydroxides, cenirifuged, and
dissolved in 210 ml of conc. HCI1 sat. with NH4I. The solution was allowed to stand
for 30 min and poured onto a Deacidite FF anion column 20 ¢m long and

2.5 cm diameter while a flow rate of 1 ml/min was mainta.ined. The first 200 ml of
effluent were pale blue [Pu(IIl)]. The. column was then washed with 100 ml conc.
HCl and the wash collected separately. No activity was found in a drop collected at
the end of the washing.

The Np was finally eluted with 2M HCl. It was possible to follow the dark green
band of the Np down the column and the first 40 ml of eluate was included with the
conc. HC1 wash. The whole of the Np was collected in the next 50 ml of eluate, No
activity was found in any eluate after this stage. Some 8-y activity was detected on

the glass wool at the top of the resin column and was assumed to be Pa233, the

daughter of Np237.

148
Procedure 18. Separation of Np and Pu by Cation Exchange Chromatography V. D.
Zagrai and L. I, Sel'chenkov (Ref. 435).

 

Qutline of Method

Np(IV) and Pu(IlI) are adsorbed on the cation resin KUl or KU2 from 0.25
M HCI1 solution after reduction with SOZ at boiling water temperatures. Np is eluted
with 0.02 N HF and the Pu stripped with 0.5 N HF.

Procedure

1. To 6-8 ml of 0.25 N HCI containing ug amounts of Np and Pu, add
about half of the resin in the hydrogen form required to fill the plexi-
glass column (1 mm diameter X 90 mm high) and 1-2 ml of water.

2. Pass SO2 gas through the solution vigorously for 15-20 min while
heating on a boiling water bath.

3. Allow the solution to cool to room temperature and transfer the resin
to the column with a pipette. Plug the top of the column with cotton
and pass the remaining solution through the column.

Wash the resin with 10 ml of 0.25 N HCI, followed by 10 ml of H,O.

5. Elute the Np into a Pt dishor a Teflon beaker with 40-60 ml of 0.02 N
HF.

6. Elute the Pu with 4-5 ml of 0.5 N HF.

149
Procedure 19. Determination of Plutonium in Urine R. O. R. Brooks (Ref. 56)

 

QOutline of Method

A 24-hr gsample of urine is dried and ashed and the residue dissolved in
dil. HCl and adjusted to a pH of 1. The Pu is reduced to the trivalent state with
hydroxylamine hydrochloride solution and co-precipitated on iron cupferride. This is
extracted with chloroform, the chloroform is distilled off, and the cupferrides residue
is wet oxidized. Thé iron carrying the Pu is finally mounted wi;ch conc. HCI, dried,
precipitated with ammonium hydrOxide, dried again, and flamed off to Fe203. This

233

procedure is based on that described by Smales et al. Differences in the two

procedures are given at the end of this procedure.

Reagents
Ferric chloride solution. 145 mg of FeC13/1iter (i.e. 50 mg Fe/liter).
Hydroxylamine hydrochloride solution. 50 g of NHZOH-HCI/liter.
Cupferron. 5% aqueous solution, renewed weekly.

 

 

Procedure

1. Evaporate a 24-hr sample of urine overnight in a 2-liter porcelain
basin under infrared lamps.

2. When dry, scrape out and quantitatively transfer the regidue to a
200-ml sgilica dish with washings of 4 N HCI, and re-dry it under
infrared lamps.

3. Place the sample in a muffle furnace at 500°C, and hasten oxidation
by periodic additions of 3-ml lots of conc. HNO3 to the dish when it
is cool.

4. Dissolve the white residue in ~30 ml of 4 N HCI, transfer to a 250-ml
beaker and make up with alternate 4 N HCI and water washings to
about 100 ml to a final acidity of 2 N. Stir until only an insoluble
silica residue remains. Add 5 ml of FeCl3 sclution and 10 ml of
NHZOH' HC1 solution followed by a few drops of cresol-red indicator.

5. Adjust the pH of the solutionto 1 (with a pH meter until the operator
can correctly do it visually) with 2 N NH4OH added dropwise from a
burette with constant stirring. It is essential that no phosphate
precipitate forms, as this may reduce recoveries. Allow the solution
to stand for 1 hr to ensure reduction of Pu(VI) to Pu(IIl).

6. Transfer the solution to a 500-ml separating funnel and add 2 ml of
5% cupferron solution, Shake the contents thoroughly and let stand
for 3/4 hr to allow complete formation of iron cupferride.

7. Add 30 ml of chloroform and shake the funnel thoroughly. Allow the
chloroform layer to settle and then run it off through a 7-cm Whatman
No. 41 filter paper into a 100~-ml scparating funnel. Wash the
chloroform by shaking with 20 ml of distilled water and run the

150
10.

11.

12.

13,

14,

chloroform into a 250-ml round-bottomed flask through a 7 cm

No. 41 filter paper as before. Return the water to the original aqueous
golution and add a further 5 ml of FeCla and 2 ml of 5% cupferron as

2 scavenge. After shaking, leave the solution to stand for another

3/4 hr.

Extract the cupferrides with three 15-ml lots of chloroform — or

until the chlorlform remains colorless — and filter each lot separately
into the 100-ml funnel. Wash the filter paper with chloroform from

a pipette to remove the ring of cupferrides which forms around the

top, and collect the washings in the 100-ml separating funnel.

Add 20 ml of distilled water to the chloroform extracts, and shake the
funnel. After they have settled out, filter the extracts into the 250-ml
round-bottomed flask and wash the filter papér with chloroform.
Evaporate off the excess chloroform in a fume cupboard using an
"Electro-Thermal'" mantle. Remove the final drops by blowing in air.
Add 3 ml of conc. H2304
heat. Evaporate the final traces of HZSO4 by blowing in air. If the

and 1 ml of conc. HNO3 to the residue and

residue is not white, add further aliquots of the acids and take to dry-
ness again.

Dissolve the residue in 3 ml of conc. HCI and transfer by means of a
pipette to a Pt tray previously counted for background. Use two
further 3-ml aliquots of conc. HCI to obtain a quantitative transfer.
Dry the final solution, then take up in a few drops of water and add
enough 2 N NH 4

Spread this precipitation evenly over the tray (15 c:m2 effective surface)

OH toensure complete precipitation of ferric hydroxide.

using a glass rod with a fine tip.
Dry the tray, and finally heat it over a bunsen to form the red oxide

Fe203 before counting.

Counting Procedure

Count the tray '"background'" and sample each for one period of 8 hr in an

a-scintillation counter.

Calculating Maximum Permissive Level in Urine

 

Maximum permigsive level in the body is 0.04 uc for Pu239 (solution),

Excretion rate assumed is 0.01% per day.

Corresponding Maximum Permissive Level in Urine is .. 4 puc

 

With a method recovery of 90% and a counter efficiency of (say) 35%, the

maximum permissive level in urine = 2.8 cpm above "background."

151
Reporting Results

Results are reported in puc/24-hr sample in the following ranges:

< 0.1 pyuc
<1l >0.1uuc
> 1 puc (exact figure reported with standard deviation).

NOTE:
Deviations from this report in steps 4, 7, and 8 above were made for reasons

of economy. The use of smaller quantities of reagents were found not to
affect the overall recovery. By using the amounts of HZSO4 and HNO3 quoted

in step 11 above, a more rapid oxidation was achieved.

152
Procedure 20. Determination of Pu239 in Urine (Small Area Electrodeposition

Procedure) R. W. Perkins (Ref. 316)

QOutline of Method

This procedure describes a method for the rapid separation of Pu239 from
200 ml (or smaller) urine samples, and the subsequent electrodeposition of the Pu239
on an E!—rnm2 area of a stainless steel disk. The yield for a set of five samples was

85.2 percent +3.6 percent standard deviation.

Procedure

1. Place the urine sample (200 ml or less) in a 1-liter Erlenmeyer flagk,
add 50 ml of concentrated HNOB, 40 mg of Pr carrier (Note (a)} and
evaporate to about 20 ml. Add 20 ml of HZO and cool under running
water, then transfer the solution to a 100-ml Lusteroid test tube (using
about 20-30 ml of wash water) containing 5 ml concentrated HF and
stir.

2. Allow the sample to stand 30 min, centrifuge 2 min, discard the super-
nate and dissolve the precipitate in 50 ml of 2 N I-1'NO3. Add 5 ml of
concentrated HF and stir. Allow the sample to stand 5 min,
centrifuge 2 min, discard the supernate and digsolve the precipitate
in 5 ml of HZO and 20 ml of 2 MAI(NO3 3—0.5 N HN03.

3. Transfer the solution to 2 120-ml separatory funnel and shake 5 min
(or until clear). Add 0.25 mlof 2 M Na.NO2 and shake 15 min. Add
10 ml of 0.45 M TTA (100 g/liter) in benzene and shake for 20 min.
Discard the agueous phase and wash the organic phase with two 10-ml
portions of 0.5 N HNOs, 5 min each. .

4. Add 10 ml of 8 N HCI and shake 15 min. Collect the aqueous layer in

~a 50-ml beaker. Add 5 ml of 8 N HCI to the organic phase and shake
5 min. Collect the aqueous phase.

3. Combine the aqueous layers, add 5 ml of concentrated HNO3, 3 ml of
concentrated HC104, l1mlof 0.1 M KNO3 and evaporate to dryness.
(Use low heat for final evaporation.)

6. Dissolve the regidue in 7 ml of 0.5 EHNO3 (Note 2). Rub sides of
beaker with policeman to make sure all of the residue is in solution.
Wash policeman with water, adding washings to the sample, then
evaporate the solution to 3-4 ml.

7. Add 4 ml of electrolyte (0.26 M (NH4)2 C204), transferring the solution
to an electrodeposition cell with an 8-mm? stainless steel cathode area
(Note 3).

B. Electrodeposit overnight at 110 mA.

The electrodeposited sample may be counted directly on a low back-
ground o counter, or exposed to a nuclear track film and the o tracks

counted under a microscope* io provide a greater sensitivity.
L. C. Schwendiman and J. W. Healy, Nucleonics 16, No. 6, 78, 80-82 (1958) June.

153
Notes

The element praseodymium as purchased (from the Lindsey Chemical
Division of the American Potash and Chemical Corporation, West
Chicago, Illinois) could be used directly without causing 2 high back-
ground; whereas, the use of lanthanum' as a carrier resulted in a
high backgrbund.

At this point, the sample can be evaporated on a counting dish for
direct counting if small area deposition is not required.

The eléctroly'tic cells consist of lucite cylinders which are threaded
at one end for stainless steel caps which contact the stainless steel
cathode plating surfaces. A beveled lucite disk fits between the cap

and cylinder and-defines the electrodeposition area.

154
Procedure 21, Determination of Plutonium in Urine R. J. Everett et a1.125

Outline of Method

Micro amounts of Pu are isolated by lanthanum fluoride coprecipitation,
thenoyltrifluoroacetone (TTA) extraction, and electrodeposition. The a activity is

measured by proportional counting or by autoradiography.

Evaporation and Electrodeposition

Reagents and equipment.

Electrodeposition apparatus and cells,

Stainless steel disks, 0.5-in. diam X 0.005-in. thick, polished stain-

lesa steel.

Aluminum nitrate solution — Dissolve 378 g Al(NOB)a- 9H20 in 800 ml
distilled water; add 23 ml conc. HNO:3 and dilute to 1 liter with
distilled water.

Conc. ammonium hydroxide — NH4OH(30% NH3).

Ammonium hydroxide, 10% golution— Dilute 10 ml conc. NH4CH to
100 ml with distilled water.

Conc. hydrochloric acid, 36% HCI.

Conc. hydrofluoric acid, 48% HF.

Conc. nitric acid, 70% HNO3

Conc. phosphoric acid, 85% H PO4

1 N nitric acid — Dilute 63 ml conc. HNO3 to 1 liter w1th distilled
water. _

2 N nitric acid — Dilute 125 ml conc. HNO3 to 1 liter with distilled
water.

8 N hydrochloric acid — Dilute 667 ml conc. HCI to 1 liter with dis-
tilled water. .

8 N potassium hydroxide — Dissolve 112 g KOH in 250 ml distilled water.

2 N potassium hydroxide — Diggolve 28 g KOH in 250 ml distilled water.

Sodium hypochlorite — 5% solution NaOCl.

Sodium nitrite solution — Dissolve 1.2 g NaNO, in 10 ml distilled
water. Prepare fresh imrnediately before use.

Hydroxyldamine hydrochloride — NH20H- HCI.

Lanthanum nitrate solution — Dissolve 6.2 g La(N03)3- 6H,0 in 100 ml
1N HNOS. 1 ml = 20 mg La.

Thenoyltrifluoroacetone solution — Disgolve 5 g thenoyltrifluoroacetone
(TTA) in 100 ml benzene.

Procedure

1. To 1 liter urine in a 2-liter beaker, add 20 ml conc. HN03, 5 ml
conc. H3PO4, and heat to 85°C.,

2. While stirring, add conc. NH4OH until precipitation occurs. Add
10 ml excess and continue heat and stirring for 1 hr.

155
10.

11.

12.
13.

14,

15.

16.

17.

18.

19.

20.

21.
22,
23.

Cover the beaker and let settle overnight.

Decant the supernate, being careful not to disturb the precipitate.
Filter the precipitate onto Whatman No. 50 filter paper. Wash
the precipitate with 10% NH4OH. Discard the filtrate.

Place filter and precipitate in 50~ml Vycor crucible and ignite at
800°C for 1 hr.

Cool residue and add 25 ml 2N HNO,.
Transfer to centrifuge tube with 2N HNO3 wash, and keep volume

Warm to dissolve residue.

less than 50 ml.
Cool to room temperature and add 1 g NH,OH- HCL. Stir until it
disgolves.
Add 1 ml LEL(NO3 )3 golution and adjust volume to 75 ml with 2N
HNOgj.
Stir and add 7 ml conc. HF. Let stand 2 min, then remove
stirring rods.
Let stand 3 min more, then centrifuge and carefully discard the
supernate. To residue, add a few ml 25\1_ HNO3 and stir vigorously.
Add 2§ I-INO‘.3 in portions, while stirring, until volume is 75 ml.
Repeat LaF3 precipitation by adding 7 ml conc. HF as in step 9,
then let stand for 3 min. Centrifuge, and discard the supernate.
Break up precipitate with stirring rod and add 2 ml Al(N03)3
solution. Stir vigorously and add 38 ml more Al(N03)3.
Transfer the solution to a separatory funnel. Add 5 drops NaNOQ,
solution and mix. Let stand 15 min.
Add 10 m]l TTA solution and extract 20 min. Let phases separate
and discard aqueous layer.

Note: For a rapid analysis, the TTA can be evaporated on a

planchet for counting. Otherwise, proceed to step 17.
Add 20 ml distilled water and extract 5 min. Let phases separate
and digcard aqueous layer. Add 10 ml distilled water and repeat.
Add10ml 8N HCl and extract 20 min. Let phases separate and
drain HCI layer into 50-ml beaker. Repeat extraction.
Carefully evaporate the two HC1 extracts to 1 ml. Do not boil or let
go dry. Cool and add 8N KOH by drops until a pale reddish-brown
color appears. Add 5 ml 2N KOH and 2 ml 5% NaOCl solution.
Evaporate carefully to one-half original volume. Transfer to
electrodeposition cell, washing the beaker once with 1 ml NaQOCl
solution and three times with distilled water. ,
Connect cell to electroplater and electrolyze 5 hr at 80 mA.
Remove cell without interrupting current. Discard solution.
Remove disk from cell and wash with distilled water. Let dry and
flame lightly. The disk can now be ¢-counted or autoradiographed.-

156
Autoradiography

Reagents and equipment.

Developer, Kodak D-19.

Fixer, Kodak F-5

Nuclear-track alpha (NTA) plates — 1-in. X 3-in. glass slide with 25-u
emulsion.

NTA exposure camera.

Microprojector — arc illuminated, with 21X objective and 20X ocular.

Chromic acid solution — Dissolve 0.2 g CrO3 in 1 liter distilled water.

Plate preparation
1. Fill staining dish two-thirds full of CrO3 solution.

2. In darkroom with red safe light, remove slides from box and place
in staining-dish rack. Immerse rack and slides in CrO3 solution
for 4 min. Let drain 5 sec. Turn off red safe light and wash in
ringe tank 20 min.

3. Remove rack from wash tank and let slides dry.
Autoradiographic procedure

1. In darkroom with Series AO light filter, load NTA plate in slide
depression of camera. Place disk positioner over NTA plates,
and drop disks face-down into holes of positioner.

2. Fit top securely on camera, and place camera in dark box. Expose
for 1 week. )

3. After exposure, develop NTA plates 10 min in D-19 developer at
68°F. Rinse in distilled water and fix 20 min in F-5 fixer.
Wash plates for 1 hr and let dry.
Count the ¢ tracks with the microprojector- Each projection covers
an area of 0.1409 mmz, which is called one field. The total area of
the exposed NTA plate is 38.82 mm?> or 277 fields. Tracks are
counted on a predetermined number of fields on each plate. "Tracks
found are compared with a standard curve prepared from urine

spiked with known amounts of Pu.
Calculation
Since 1 liter urine sample was used, dpm Pu/liter urine = dpm
from standard curve.
References

S. M. Sanders, Determination of Plutonium in Urine, DP-146, March 1956.
.. C. Schwendiman and J. W. Healy, '"Nuclear-Track Technique for Low-Level

Plutonium in Urine," Nucleonics 16, 78 (1958).

157
Procedure 22. Determination of Americium in Urine in the Presence of Plutonium
D. L. Bowkowski (Ref. 53).

Outline of Method

The Pu is co-precipitated with BiPO4 from acidified urine, the BiPO4
is wet-ashed with HNOB, and the Pu is co-precipitated with LaF3 from an HCl
solution. The LaF3 co-precipitation is repeated and the fluoride is metathesized with
KOH. Puis extracted into di(2-ethylhexyl)phosphoric acid from a 2 M HNO3 solution,
and the aqueous phase i8 mounted for counting.

This procedure is included to illusirate the extraction of Pu(IV} into acidic
phosphate extractants. The procedure could presumably be used for a simultaneous
determination of Pu and Am in urine, by back-extraction of the Pu either into strong

acid or a reducing solution.

Reagents
Bromthymol blue indicator solution — Dissolve one g of reagent grade
indicator in 500 ml of distilled water made alkaline with one pellet of sodium hydroxide.
3)3- 5H20-AR]
in 660 ml of concentrated HNOB.and dilute to one liter with distilled water. This

Bismuth nitrate solution — Dissolve 231.2 g of bismuth nitrate [Bi(NO

solution contains 0.1 g of Bi per ml.

4 N HCl — Add 344 ml of conc. HCI to approximately 500 ml of digstilled water in
a volumetric flask and make up to 1 liter with distilled water.

6 N HCl — Dilute 510 ml of conc. HCI to 1 liter in a volumetric flask.

8 N HC1 — Dilute 688 ml of conc. HCI to 1 liter in a volumetric flask.

Lanthanum nitrate solution — La(NO3)3' as received from the Lindsey Chemical
Company, West Chicago, Illinois, is freed from actinum o-emitting impurities on a

*

Dowex 50X12 cation exchange resin column by the method of Farabee. The lanthanum

nitrate stock solution obtained is used to prepare working solutions containing 25 mg of
La+++/ +++

are used.

ml. Only solutions containing 0.05 d/min or less of ¢ activity per mg of La

2 M Hydroxylamine hydrochloride — Dissolve 139.0 g of C. P, grade hydroxylamine
hydrochloride and dilute to one liter. Store in brown bottle.

2 N Sodium nitrite solution — Dissolve 13.8 g of sodium nitrite (NaNO,-AR) in
distilled water in a 100-ml volumetric flagk and make to volume with distilled water.
Prepare fresh.before use.

0.1 M DZ2EHPA — Add 32.3 g of di(2-ethylhexyl)phosphoric acid (Union Carbide
Chemical Company) to chloroform-AR in a 1-liter volumetric flask and make to volume
with chloroform.

8 N KOH — Dissolve 65.3 g of potassium hydroxide (KOH 86%-AR) in distilled
water and dilute to 1 liter,

All other chemicals are either of reagent or C. P. quality.

*L. B. Farabee, 5th Ann. Meeting-Bioassay and Analyt. Chem. Grp., Oct. 1-2,
1959 (USAEC Report TID-7591 Nov. 1960 p. 78).

158
Sample Pretireatment

 

The volume of a "24-hr equivalent' urine sample (two morning and two
evening voidings) is measured and the sample transferred to a 2-liter beaker. The
volurne and the liquid level are denoted on the beaker with a china-marking pencil
or marking pen. Several glass beads, 1 ml of octyl alcohol and 200 ml of concentrated
nitric acid are added. The beaker is covered with 2 Speede-Vap and placed over an
asbestos pad on a hot plate at high heat. The sample is digested by gentle boiling

until it attains a clear appearance.

BiPO 4 Coprecipitation

 

A stirring bar is added to the cooled solution and rapid stirring initiated
over a magnetic stirring motor. Approximately 130 ml of concentrated ammoniumn
hydroxide are added cautiously, followed by 1 ml of bromthymol blue indicator solution.
Neutralization is completed by addition of concentrated ammonium hydroxide to the
yellow-green endpoint. If necessary, the sample volume is readjusted to its oi'iginal
value with distilled water. Concentrated nitric acid is added to make the solution
0.15 M in HNO, (Table VIII-1). 500 mg of hydroxylamine hydrochloride are added to
the solution and the beaker placed in a steam bath heated to 80 +5°C. Concentrated
phosphoric acid is then added to a concentration of approximately 0.09 M (Table VI‘I_‘[-l)I.
An amount of bismuth nitrate solution, equivalent to 60 mg bismuth per 100 ml, is
"added dropwise to the heated, stirred solution. . |

The precipitate is digested by an
BigéBL}iEe‘figi;tfiiiluuon Requirements for additional hour of stirring at 80 + 5°C.
4 .

The sample beaker is removed from the

 

TUrine Conc. HNO3

 

solume Tor 6.15 M H,PO, Bi(NO,), water bath and allowed to stand un-
(m1l) (ml) (ml) soln, (ml) . disturbed for a minimum of 3 hr. The
500 4.8 3.0 3.0 supernatant solution is carefully
600 5.9 3.8 ‘3.6 . . . . ..
700 68 4.9 4.9 agpirated off (avoid disturbing precipitate)
800 7.2 4.8 4.8 and the precipitate transferred to a 90-
900 8.7 5.4 5.4 . . .
ml Pyrex centrifuge tube with a distilled
i?gg 1gg gg gg water rinse. The precipitate is cen-
1200 11.6 7.2 7.2 trifuged for 5 min at 2000 rpm and the
300 7 g '
1480 iggg 8.2 gg supernate carefully discarded. The
1500 14.4 9.0 9.0 sample beaker walls are then rinsed down
1600 15.0 9.6 9.6 with 4 N HCI from a wash bottle and the
iggg igg 1328 133 ringe transferred to the 90-ml tube. The
1900 18.5 11.4 11.4 final volume in the tube should be approxi-
2000 19.2 12.0 12.0

 

mately 50 ml.

Wet-ashing of Bismuth Phosphate

 

Several drops of coctyl alcohol are added to the HC1 solution in the 90-ml
tube; it is placed in an aluminum block af approximately 100°C, and the solution taken
to dryness. The dried sample is then repeatedly wet-ashed with several drops of

159
concentrated nitric acid in a block heated to 350°C. After the sample has ashed to
whiteness, itis evaporated twice with 8 N HCI.

Lanthanum Fluoride Coprecipitation

 

The bismuth chloride ash is dissolved in 8 ml of 8 N HCI and the solution
is transferred to a 25-ml conical centrifuge tube. The walls of the 90-ml tube are
rinsed with an additional 2 ml of 4 N HCI and the ringe added to the centrifuge cone.
After addition of 0.1 ml of La(N'O3)3 solution, the tube contents are mixed thoroughly.
Two ml of concentrated hydrofluoric acid (27 M) are then added, and the solution
stirred with a Pt stirrer. The tube is allowed to stand for 5 min and then centrifuged
at 2000 rpm for 3 min. The supernatant is carefully aspirated and the precipitate dis-
solved in 2 ml of concentrated HCI.

Following the addition of 2 ml of distilled water, L:-LF3 is reprecipitated by
addition of 2 ml of 27 M HF. The preceding digestion and centrifugation steps are
repeated. Five ml of 8 N potassium hydroxide are added to the precipitate and care-
fully heated to boiling. After cooling the mixture is centrifuged for three minutes and

the supernate carefully drawn off.

D2EHPA Extraction

Following solution of the precipitate in 6 ml of 2 N HNOS, one ml of 2 M
hydroxylamine hydrochloride is added, and the sample is heated in a water bath at
70°C for 5 min. The tube is then removed from the water bath and 2 ml of 2 M sodium
nitrite solution are added with swirling. When bubble evolution ceases, the solution is
transferred to a 30-ml separatory funnel. The centrifuge tube is rinsed once with 3 ml
of 2N nitric acid and the rinse added to the separatory funnel. The aqueous layer is
then extracted thrice with 5-ml portions of 0.1 M D2EHPA in chloroform for 5-min
periods. The chloroform extracts are removed and the aqueous layer is shaken for 3
min with a 5-ml portion of toluene. The aqueous portion is then withdrawn through
the funnel stem into another 25-ml conical centrifuge tube. Lanthanum fluoride is pre-
cipitated by addition of 2 ml of 27 M HF. The solution is allowed to stand 5 min
centrifuged at 2000 rpm for 3 min and the supernatant drawn off and discarded. Shake
the precipitate with 10-15 ml of 1:100 hydrofluoric acid wash solution and centrifuge
at 2000 rpm for 5 min.

Sample Planchetting

 

Aspirate the supernatant and invert the centrifuge cone quickly over ab-
sorbent tissue. Drain 15 min. Slurry the precipitate with distilled water and transfer
to a stainless steel planchet with a disposable capillary pipette. Dry the disk under
an infrared lamp and flame the dried planchet to red heat. The o activity is then counted
with a low-background proportional counter for 150 min.

160
Procedure 23. Determination of Plutonium in Urine by Anion Exchange E. D.
Campbell and W. D. Moss (Ref. 74)

Outline of Method

Pu is concentrated from urine by co-precipitation with alkaline earth
phosphates. The precipitate is dissolved in 7.5 N nitric acid and the Pu absorbed
from that solution onto Dowex 1 X 2 anion exchange resin. Interfering anions ab-
sorbed on the column are removed with 12 N HC1l. The Pu is eluted from the column
with specially prepared hydrochloric and hydriodic acids, and the o activity determined
by direct planchetting or by electrodeposition of the eluate, followed by standard a-

counting techniques.

Equipm ent

Ion exchange column. The ion exchange column container consists of a
glass reservoir, 2-5/8 in. long by 1-3/32 in, i.d., capacity 40 ml, on a chromato-
graphic column tube 3 in. long by 5/16 in. i.d., constricted at the tip.

Solutions

Hydriodic acid stock solution. Prepared by distilling hydriodic acid
(analytical reagent grade, 5.5 M in hydriodic acid, 1.5% hypophosphorous acid pre-
servative)under nitrogen. The hypophosphorous acid preservative interferes with the
electrodeposition step and also with the preparation of satisfactory planchetted samples.
Oxidation of the prepared hydriodic acid solution is inhibited by adding enough hydrazine
(up to 20% by volume of 64% to 84% hydrazine in water) to decolorize the hydriodic
acid solution.

Hydrochloric acid-hydriodic acid elutriant. Prepared by mixing 1 ml of
hydriodic acid stock solution with 9 ml of concentrated hydrochloric acid. The pre-~
cipitate formed by hydrazine is removed by centrifuging; the supernatant then is
saturated with gaseous hydrogen chloride. The reagent must be prepared every few

days because it decomposes easily.

Reagents

All other reagents used in the procedure are prepared from analytical
grade chemicals.

Preparation of Ion Exchange Column

 

A glass wool pledget in the tube supports the resin. The tube is filled
with from 2-1/2 to 3 in. of a distilled water slurry of Dowex AG1-X2. chloride form,
50 to 80 mesh, anion exchange resin (Bio-Rad Laboratories, 32nd and Griffin,
Richmond, Calif.). The resin in the column is converted to the nitrate form by
washing with at least two 5 ml portions of 7.5 N nitric acid before adding the sample

gsolution. The resulting column flow rate is 1 ml/min.

161
Preparation of Sample

 

The 24-hr or equivalent urine sample is transferred to a 2-liter graduated
cylinder with concentrated nitric acid (50 ml of acid per liter). The cylinder is heated
in a steam bath at 75 to 80°C, and stirred with a magnetic stirrer, for 30 min. One
ml of phosphoric acid is added to the sample, then enough concentrated ammonium
hydroxide to form a copious precipitate, and the sample is digested, with continuous
stirring, for 1 hr. After 30 min of digestion the stirrer is stopped, the precipitate is
allowed to settle for several minutes, and the clear supernatant is treated with several
ml of ammonium hydroxide to be sure precipitation is complete. Should more precipitate
form, an excess of ammonium hydroxide is added, and the stirring is continued for
the remaining 30 min. After the cylinder is removed from the wadter bath and the
stirring bar from the cylinder, the sample is allowed to remain undisturbed overnight
at room temperature,. .

The following morning the supernatant is aspirated from the precipitate and dis-
carded. The alkaline earth phosphate precipitate is transferfed to a 90-ml centrifuge
tube with distilled water and centrifuged. The supernatant is discarded, the cylinder
is washed with dilute (20%) nitric acid, and the'v;fashings are combined with the pre-
cipitate in the tube. The material in the tube then is evapprated to dryness in an
aluminum heating block at 85 to 90°C, and the residue finally. is -whitened with con-
centrated nitric acid at approxiinately 300°C,

Ion Exchange. Isolation of the Pu

 

The ashed residue from the alkaline earth phosphate precipitfite is dis-
solved in 25 ml of 7.5 N nitric acid. The residue may be t:iissolved with heat if
necessary, but will dissolve easily at room temperature ovérnight (preferred method).
.The acid solution is transferréd to the reservoir of a prépared ion exchange column
and allowed to drain completely. The centrifuge tube is rinséd with three 5-ml portions
of 7.5 N nitric acid,. each rinse being allowed to drain through the column before the
next is added. The column reservoir then is washed down with 5 ml of 7.5 N nitric
acid, which is allowed to drain'through the column completely.. Three ml of concen-
trated hydrochloric acid are added carefully to the top of the resin without disturbing
the resin, keeping dilution from the 7.5 N nitric acid to a minimum, and allowing the
hydrochloric acid to drain completely.” All effluents from the absorptlion and washing
steps are discarded.

One to twe ml of 0.5 N HCI are added to the top of the column, the first several
drops discarded, and the remaining eluate retained in a 15-ml centrifuge tube. The
column then is eluted with two 5 ml portions of 0.5 N HCI and allowed to drain completely
into the ceritrifuge tube.  Finally, several crystals of hydroxylamine hydrochloride are
added to the top of the resin and 2 ml of h'ydribdic—hydrochloric_acid solution drained
through the column and collected. | _ -

NOTE: The hydroxylamine hydrochl'oride is e_ldded to the column to prevent

immediate oxidation of the hydriodic acid. An excess of hydriodic-hydrochloric acid

162
golution should not be used because of possible interference in the electrodeposition
step. The eluate in the tube then is evaporated to approximately 1 ml in an aluminum
heating block at 75°C.

Electrodeposition
The residue from the vaporation is neutralized with 8 N potassium
hydroxide using phenolphthalein as indicator. When the solution is neutral, 2 ml of
sodiurmn hypochlorite and 5 ml of 2 N potassium hydroxide are added to the tube, and
the contents of the tube transferred to an electrodeposition cell with distilled water,
(The final concentration of the alkali is 1 N.) The Pu is electrodeposited on 1/2 in.
polished stainless steel disks at 200 mA for 5 hr. The apparatus and techniques for

K
the electrodeposition of Pu are described by Schwendiman et al.

Determination of Alpha Activity

 

The o activity on the stainless steel plates can be determined either by’
the NTA (Nuclear Track Alpha) emulsion method or by the standard electronic
counting method. The background of the NTA method is 0.007 dpm, with an accuracy
of 1.6 dpm. A method of choice for more rapid evaluation of results is the electronic
determination of the ¢ activity by the phosphor-coated mylar method described by
Hallden and Harley.** The phosphor method uses a 1-in. photomultiplier tube and an
all-transistorized amplifier and counter system designed by P-1 (the Electronics
Group of the Los Alamos Scientific Labhoratory's Physicg Division), similar to that
described by Graveson et al.”>  The background of this system is 0.015 cpm when
adjusted to an optimum efficiency of 45%. The precision of this counting is satis-

factory for 0.1 dpm.

 

*L. C. Schwendiman, J. W. Healy, D. L. Reid, and G. E. Hanford, HW-22680
(1951). :

“*N. ‘A. Hallden and J. H. Harley, Analyt. Chem. 32, 1861 (1960).

*SR. T. Graveson et al., AEC New York Operations Office, Rpt. NYO 1523 (1950).
(TID ORE, Oak Ridge, Tenn.)

163
Procedure 24. Determination of Plutonium in Urine by Co-crystallization with
Potassium Rhodizonate W. H. Shipman and H. V. Weiss (Ref. 374)

 

Qutline of Method

Pu is co-crystallized with potassium rhodizonate by adding an equal
volume of ethyl alcohol to a pH 9 solution of the reagent in urine. The Pu is further
purified by co-precipitation with LaF, and adsorption on an anion exchange resin.
The Pu is eluted with 6 N HCL - 0.2 N HF, electrodeposited and a-counted.

Reégents
Potassium rhodizonate (Paul B. Elder Co., Bryan, Ohio).
Dowex anion exchange resin AG1-X8 (Bio-Rad Laboratories, Richmond, Calif.).
Lanthanum carrier solution. Lanthanuwn nitrate was dissolved in water and
purified from interfering « activity be passage through the anion exchange column
after adjusting the HCI content to 10 N. Excess HCl was removed by evaporation and
the salt was dissolved in 2 N HNO,

All other chemicals were either of reagent grade or C.P. quality.

to a final concentration of 5 mg of La-!_H- per ml.

Procedure

Based upon the experimental results, the following analytical procedure
was evolved: The procedure is described for a 500-ml sample volume. For a dif-
ferent volume, reagents are used in proportionate amounts.

Add 1 g of potassium rhodizonate to the sample. (If the urine is not fresh,
solubilization of the reagent may be difficult. Under such circumstances acidification
of the sample with HC1 to pH 2 to 3 effects rapid solution.) Adjust to pH 9 with 5§ N
NaOH and crystallize the rhodizonate with 500 ml of absclute ethyl alcohol. Let stand
for several minutes and isolate the crystals by centrifugation.

Dissolve the crystals in 50 ml of 2 N HNOa.
mg of La+++ per ml) and precipitate with 30 ml of 27 N HF. Centrifuge. Without

Add 1 ml of lanthanum carrier (5

separating the precipitate from the liquid, add 0.5 ml of lanthanum carrier with
stirring to the supernatant liquid and centrifuge. Discard the supernatant liquid.
Dissolve the precipitate in 5 ml of saturated H3BO and 5 ml of concentrated

3
HCl. Add about 10 ml of distilled water and make alkaline with concentrated NH ,OH.

Centrifuge. Without separating the precipitate from the liquid, add 0.5 ml of lan‘}thanum
carrier with stirring to the supernatant liquid. Centrifuge. Discard the supernatant
liquid.

Dissolve the precipitate in a small volume of concentrated HNOS, add about 15
ml of water, and reprecipitate with concentrated NH4OH. Centrifuge. Without
separating the precipitate from the ligquid, add 0.5 ml of lanthanum carrier with
astirring to the supernatant liquid. Centrifuge. Discard the supernaiant liquid.

Dissolve the precipitate in concentrated HNOg. Add about 3 ml of concentrated
HZSO4 and heat to dryness.

Dissolve the salts in 10 to 15 ml of 6 N HCl. Add 0.5 mlof 0.4 N NaNO2 and
make 9 N with concentrated HCIl. Let stand 5 min.

164
Pour the solution through a Teflon column, 4 X 0.62 ¢m anion exchange resin
AG 1-X8 (Cl: 0.297 to 0.144 mm) previously washed with 10 ml of 9 N HCl. Adjust
the flow rate to 2 ml/min.

Wash the column with 15 ml of 9 N HC!l. Elute with 30 ml of 6 N HC1-0.2 N HF.
Collect the eluate in a Teflon beaker which contains 15 mg of NaCl. Evaporate to
dryness. Dissolve the salt in concentrated HNO3 and transfer to glass. Add 3 ml of
HClO4, 2 ml of H2504, and heat to dryness.

Dissolve the salt in 1 ml of water and transfer to the electrodeposition cell
fitted with a tantalum disk. Add 4 mlof 6 N NH4C1 golution and 2 drops of concentrated
HC1. .

Electrodeposit at 2.5 to 3.0 A for 20 min. Quench the cell with 1 ml of con-
centrated NH4OH. Wash the solution from the cell with distilled water and dry the
tantalum disk on a hot plate.

Alpha count.

165
Procedure 25. Determination of Plutonium in Urine and Bone Ash by Extraction with
Primary Amines F. W. Bruenger, B. J. Stover, and D. R. Atherton (Ref. 61)
Qutline of Method

Concentrated urine, or a solution of bone ash is made 1 M in H2504 and
Pu is extracted by a mixture of highly branched primary alkyl amines. The Pu is then
back-extracted with 8 M HCIl-and counted.

Reagents and Equipment

 

The o-detection instrument is a 27 proportional counter of conventional
design capable of accepting 2-in. stainless steel planchettes; counter performance is
checked with a U3OB standard supplied by the National Bureau of Standards.

Primene JM-T, a mixture of tert-alkyl primary amines, 5% by volume in xylene,
was purchased from Rohm and Haas, Philadelphia, Pa. The Primene solution is

washed with half its volume of 1 M HZSO4 before use.

Procedure

Urine analysis. Urine is collected in polyethylene bottles over 10 ml of
concentrated formic acid to avoid excessive hydrolysgis of urea, which would render
the specimen basic and could result in loss of Pu by adsorption on the wall of the con-
tainer. An aliquot of urine is transferred to a Kjeldahl flagk containing enough 5 M
sto4 to attain an acid concentration of 2 M in the final sample. The solution is
boiled without charring for about 1 hr. Thus far, volumes up to 500 ml have been
extracted. For larger volumes, amounts of reagents are increased proportionally.
The following amounts of reagents are used for 100-ml aliquots. The sample is
filtered through borosilicate glass wool into a separatory funnel and is allowed to
cool to room temperature, Twenty ml of a 5% solution of Primene JM-T in xylene is
added to the sample and the mixture is8 shaken for 15 min. After separation of the two
phases, the aqueous phase is put aside for a second extraction. The organic phase is
waghed twice with 25 ml of 1 M H2804. Pu is removed from the organic phase with
two 20-ml portions of 8 M HCl. The aqueous phase is again extracted with 20 ml of
5% Primene, and Pu is back-extracted from the Primene with 20 ml of 8 M HCL. The
combined HCI fractions are dried under a heat lamp and then the organic contaminants
are destroyed by heating over an open flame or in a furnace at 500°C. The Pu residue
is dissolved in concentrated HNO, and transferred to a 2-in. -diameter stainless steel

3
planchette for ¢ counting.

Bone analysis. Bone is ashed for 4 hr at 600°C and, after cooling, is
dissolved in as little HNO3 as pogsible and diluted with H20 to a known volume, and a
suitable aliquot of this solution is taken for analysis. The amount of bone ash should
not exceed 250 mg for every 75-ml volume of the aqueous phase. The aliquots are
evaporated to dryness under a heat lamp to minimize the amount of HNO3 and then put
in solution with 4 ml of concentrated HCOOH, and a 60-ml portion of 2.5 M H,80, is
added. This solution is heated in a water bath until it. is clear, and then transferred
to a separatory funnel. Transfer is completed with a 10-ml rinse of distilled water.
Any (33504 that forms does not interfere. Pu is extracted as described above.

166
Glossary

A/CONF. 8/ Vols., 1-17 — Proceedings of the International Conference on Peace-
ful Uses of Atomic Energy, held in Geneva, August 1955 (United Nations,
New York, 1958). |

A&CONF. 15/1 English Ed. Vols, 1-33 - Proceedings of the Second United Nations
International Conference on Peaceful Uses of Atomic Energy, held in Geneva,
September 1958 (United Nations, Geneva, 1958).

AEC — Atomic Energy Commission
AEC ~ Manhattan District and later Washington, D.C, AEC declassified

Teports. ' '
MDDS—Manhattan District, Oak Ridge, Tenn.

TID — Technical Information Division, Oak Ridge, Tenn.
AECL - Atomic Energy of Canada, Ltd,, Chalk River, Ontario.
(also CEI- and CRDC- prefixes followed by number.)
ANL - Argonne National Laboratory, Illinois.
CEA — France. Commissariat a 1'Energie Atomique, Paris.
CEA-TR — Series assigned by the AEC to translations received from CEA.
DP — E, I. du Pont de Nemours and Co., Savannah River Laboratory,
Aiken, So, Carolina.
EURAEC — United States — Euratom Joint Research and Development Program.,

HW — General Electric Co., Hanford Atomic Products Operation, Richland,
Wagh. ,
JENER - Joint Establishment for Nuclear Energy Research, Kjeller, Norway.
KAPL — Knolls Atomic Power Laboratory, Schnectady, New York.
LASL — Los Alamos Scientific Liaboratory, New Mexico,
(LA-, LAMS-, and LADC- prefixes followed by number, )
ORNL — QOak Ridge National Laboratory, Tennessee,

USNRDL - U.S. Naval Radiclogical Defense Laboratory, San Francisco, Calif.
UKAEA -~ United Kingdom Atomic Energy Authority. '
AEEW — Research Group, Atomic Energy Establishment, Win.t‘rith; Dorset.
AERE — Atomic Energy Research Establishment, Harwell, Berks.
AHSB(RP) — Health and Safety Branch, Radiological Protection Div., Harwell,
Berks,
AWRE ~ Great Britain Atomic Weapons Research Establishment, Aldermaston,
Berks. '
DEG-INF-SER — Development and Engineering Group, Risley, Warrington, Lancs,
IGO & IGR — Industrial Group Hdqgtrs,, Risley, Warrington, Lancs,
PG — Production Group, Risley, Warrington, Lancs.
Books Referenced:
"The Transuranium Elements" (McGraw-Hill Book Co., Inc., New York, 1949),
G. T. Seaborg, J. J. Katz and W. M. Manning, Eds.

167
""The Actinide Elemeénts'" (McGraw-Hill Book Co., Inc., New York, 1954).
G. T. Seaborg and J. J. Katz, Eds,

"Progress in Nuclear Energy Series III. Process Chemistry' (McGraw-Hill Book
Co., Inc., New York, 1956-61).

"Progress in Nuclear Energy Series V. Metallurgy and Fuels' (Pergamon Press,
Ltd., London, 1956-61).

168
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NOTE: The first 19 references are contained in Sections I and II at the begin-

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20.

21,
22.
23.
24,
25.

26.

27.

28.
29,
30.
31.
32.
33.
34.
35.

36.
37.

38.

39.
40,
41.
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44,
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46,
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U

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H

 

 

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169
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o2,
93.
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56.

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58,
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60.
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62.
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65:

66.

67.
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62.
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72.
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D. H. Boase, J. K. Foreman, and J. L. Drummond, Talanta 9, 53 (1962).
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M. Bonnevie-Svendsen, ''Reprocessing Analysis'', JENER-59, 1959,

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D. F. Bowersox, LASL, 1LLAMS-2884, Feb. 1963.

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R. O. R, Brooks, UKAEA, AERE-AM-60, (see also, Smales et al.,

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R. E. Brooksbank and W, T. McDuffee, ORNL -3566, 1964,

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E. Bruns and C. W. Nilsen, HW-70084, June 1961,

A. Brunstad, HW-51655, July 1957,

A. Brunstad, HW-54203, 1957.
A
R

-

. Brunstad and R. C. Smith, HW-52796, Sept. 1957,
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C. Carnigiia, Clinton Labs.,, Oak Ridge, Tenn., CN-3339, Aug. 1945.
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UshraQgmg-CrC

 

170
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1958,
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85. A. Chesné, G. Koehly, and A. Bathellier, Nucl. Sci. Eng. 17, 557 (1963).

86. A. Chetham-Strode, Jr., Lawrence Radiation Laboratory, Berkeley,
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87. M. K. Chmutova, O. M. Petrukhin,and Yu. A. Zolotov, Zh Analit, Khim,
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88. E. L. Christenson, C. W. Kellrey, A. J. Bearmint, and J. R, Humphrey,
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9. E. G. Chudinov and G. N. Yakovlev, Radiokhimiya 4, 506 (1962). In
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90. F Clanet, J. Chromatog. 6, 85 (July 1961). In French.

91, F. Clanet, J. Clarence, and M. Verry, J. Chromatog. 13, 440 (1964).

In French,

92, J. W, Codding, W, O. Haas, Jr., and F. K. Heumann, KAPL-602,
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93. J. W. Codding, W. O. Haas, Jr., and F. K. Heumann, Ind. Eng. Chem.
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94, A. S. Coffinberry and M. B. Waldron, Progr. Nucl. Energy Ser. V, Vol. 1,
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85. C. F. Coleman, K. B. Brown, J. G. Moore, and D, J. Crouse, Ind, Eng.
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96. C. A. Colvin, HW-79354, Oct. 1963.

97. A. E. Comyns, Chem. Rev, 60, 115 (1960).

98. W. V. Conner, Dow Chemical Co., Rocky Flats Div., Golden, Colo.
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99. R. E. Connick, J. Am. Chem, Soc, 71, 1528 (1949).
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(English transl, HW-TR-45.)
104, D. A, Costanzo and R. E. Biggers, ORNL-TM-585, July 1963.
105. H. W. Crandall, J. R. Thomas, and E. Zebroski, AEC-TID-10022, Aug, 1947.
106. I. H. Crocker, AECL, CRDC-697, May 1957 (AECL.-488).
107. H. W. Crocker, HW-68655, Feb. 1961.

171
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110. J. G. Cuninghame and G. L. Miles, J. Inorg. Nucl. Chem. 3, 54 (1956).

111. J. G. Cuninghame and G. L. Miles, J. Appl. Chem, 7, 72 (1957).
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112. D. Cvjetcanin, “Separatiofi of U(VI), Pu(VI), and Pu(IV) from Zr and Nb
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113, D. Cvjetcanin and N. Cvjetcanin, "Separation of U and Pu from Zr, Nb,
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114, D. H. W. den Boer and Z. [. Dizdar, "On the Isolation of Pu by a Solvent
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115. C. Deptula and S. Mine, Nukleonika 6, 197 (1961}.

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117. R. M. Diamond, K, Street, Jr., and G. T. Seaborg, J. Am. Chem, Soc.
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118. G. A. Dupetit and A. H. W. Aten Jr., Radiochim., Acta 1, 48 (1962).

119. R. W. Durham and A. M. Aiken, AECL, CEI-55, Feb. 1953. (Reprinted
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120. R. W. Durham and R. Mills, AECIL, CEI-62, (Rev.), Revised and
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121. Ph. Dreze and G. Duyckaerts, Liege Universite, Brussels, EUR-436.f. 1963.

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124. H. Eschrich, Institutt for Atomenergi, Kjeller, Norway, KR-11, 1981,

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126. L. B. Farabee, Clinton Labs., Oak Ridge, Tenn., MON-H-218, 1947,

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128. P. Faugeras and M. Heuberger, ""Nouveau Traite de Chemie Minerale,"
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129. C. Ferradini and J. Corpel, CEA-791, 1958,

130. J. R. Ferraro, G. W. Mason, and D. F. Peppard, J. Inorg. Nucl. Chem,
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131. R. M. Fink and K. F. Fink, University of California, Los Angeles,
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132, J. R. Flanary, A/CONF.8/9, pp 528-31, Paper/539.

133. J. M. Fletcher, Progr. Nucl, Energy Ser. ITI, Vol. 1, Chap. 4-1, p 105,

 

 

172
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135. A. Fontaine, L. Baude-Malfosse, and M. Cunz, CEA-1977, 1961,

136. S. C. Foti and E. C. Freiling, USNRDL-TR-444, July 1960. [See also
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137. E. L. Francis, UKAEA, IGR-161 (Rd/R), 1959.

138. N. H. Furman, W. B. Mason, and J. S. Pekola, Anal, Chem, 21, 1325
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139. I. J. Gal and O. S. Gal, A/CONF/15/1, Vol. 28, p 24, Paper/468.

140. I. Gal and Aleksandar Ruvarac, Bull. Inst. Nucl, Sci. ""Boris Kidrich"”
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141. M. Ganivet, CEA-1592, June 1960. In French,

-

 

142, H. B. Garden and E. Nielsen, in "Annual Review of Nuclear Science,"
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143, N. R. Geary, UKAEA, RISLEY-8142, 1355,

144. E. L. Geiger, Health Phys. 1, 405 (1959).

145. A. S. Ghosh Mazumder, P. V. Balakrishnan, and R. N. Singh, Lawrence
Radiation Laboratory, Livermore, California, UCRL-trans-938(L).
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146. J. E. Gindler, J. Gray, Jr., and J. R. Huizenga, Phys. Rev. 115, 1271
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147. L. E. Glendenin, K. F. Flynn, R. F. Buchanan, and E. P. Steinberg,
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148. B. Goldschmidt, P. Regnaut, and I. Prevot, A/CONF.8/9, pp 492-7,
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150. D. W. Grant, J. Inorg. Nucl. Chem. 6, 69 (1958).

151. V. I. Grebenshchikova and V. N. Bobrova, Radiokhimiya 3, 544 (1961).

 

 

In Russian.

152. V. I. Grebenshchikova and N. B. Chernyavskaya, Radiokhimiya 4, 232
(1962). In Russian. '

153. C. Groot, I. M. Rehn, and C. M. Slansky, HW-19303, Dec. 1950.

154. D. M. Gruen, S. Fried, P. Graf, and R, L.. McBeth, A/CONF, 15/1,
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155, J, E, Guthrie and W. E. Grummitt, AECL, AECL-1745, May 1963,

156, R. Gwozdz and S, Siekierski, Polish Academy of Sciences, Inst. of
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157. E. Haeffner and A. Hultgren, Nucl. Sci. and Eng. 3, 471 (1958).

158. G. R. Hall and R. Hurst, UKAEA, AERE C/M 88 (Rev), 1950.

173
159.
160.

161,

162,

163.

164.

165.

166.

167.

168.

169.

170.

171.

172,

173.

174.

175.

176,

177.

178.
1782,

180.

181.
182,
183.
184,
185,

J. W. Handshuh, HW-66441, 1960,

G. C. Hanna, in "Experimental Nuclear Physics' (John Wiley and Sons,
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W. H. Hardwick and F. Bedford, UKAEA, AERE-C/M-112, 1961,

C. J. Hardy, Progr. Nucl. Energy Ser. OI, Vol. 2, Chap. 8-2, p 357.
C. J. Hardy, D. Scargill and J. M. Fletcher, J. Inorg. Nucl, Chem. 7,
257 (1958), '

K. M. Harmon and W. H. Reas, Progr. Nucl, Energy Ser, I, Vol. 2,
Chap. 4-8, p 184. (Also HW-49597 A.)

R. G. Hart, AECL, CRDC-630, 1957,

R. G. Hart, AECL, CRDC-822, 1959,

R. G. Hart, M. Lounsbury, C. B, Bigham, 1., V. P. Corriveau, and

F, Girardi, AECL, CRP-761, 1959. [See also Talanta 6, 94 (1960).]

S. Havelka and M. Beran, Collection Czech. Chem. Commun., 28,

1603 (1963). In German. '

T. V. Healy, Nucl. Sci, Eng., 16, 413 (1963). (Also UKAEA, AERE-R-4191,)
T. V. Healy and H. A, C. McKay, Trans. Faraday Soc. 52, 633 (19586).
T. V. Healy and A. W. Gardner, J. Inorg. Nucl, Chem. 7, 245 (1958).
(See also UKAEA, AERE-C/R-800.)

A, H. Heimbuch and H. Y. Gee, AEC New York Opns. Office, NY0-9138,
1962,

D. L. Heisig and T. E. Hicks, Lawrence Radiation Laboratory, Berkeley,
Calif., LUCRI.-1169, 1952,

D. L. Heisig and T. E. Hicks, Lawrence Radiation Laboratory, Berkeley,
Calif., UCRL-1664, Feb, 1952. |

F. Helfferich, "Ion Exchange" (McGraw-Hill Book Co., Inc., New

York, 1952). .

A. Heller, R. Elson and Y. Marcus, Israel Atomic Energy Comm.,,

Tel Aviv, JA-736,

E. Hesford, E. Jackson and H. A. C. McKay, J. Inorg. Nucl. Chem, 9,
279 (1959).

E. Hesford and H. A, C. McKay, Trans, Faraday Soc. 54, 573 (1958).
E. Hesford, H. A. C. McKay, and D. Scargill, J. Inorg, Nucl. Chem. 4,
321 (1957).

T. E. Hicks and H. W. Crandall, LLawrence Radiation Laboratory, Berkeley,
Calif., UCRL-912, Sept. 1950.

C. E. Higgins, W. H. Baldwin, and J. M. Ruth, ORNI.-1338, Aug, 1952.
. Hill and F. J. Leitz, HW-21663, 1951.

. Hill and F. J. Leitz, EEW-23160, pp 24-5.

. Hindman, A/CONF. 15/1, Vol. 28, p 349, Paper/941,

. Hoffman, LASL, LA 1721 (Rev), 1954, pp 271-279,

—_— =

 

 

 

 

 

 

 

 

 

9200
00 oo

174
186,
187,
188.

189,

190,
191,
. 192,

193.
194,

195.
198,
197,
198,
199,
200.
201.

202,

203.
204,
205,

206.
207,
208.
208,
210.
211,
212.

213.

214.
215.
216,

D, E. Horner and C. ¥, Ccleman, ORNL-2830, Nov. 1959,

D. E. Horner and C. F. Coleman, ORNL-3051, March 1961,

G. R. Howells, T. G. Hughes, and K. Saddington, Progr. Nucl. Energy
Ser, II, Vol. 3, Chap. 3-2, p 151. (See also A/CQONF.15/1, Vol. 17,

p 3, Paper/307.)

D. L. Hufford and B. F. Scott, in "The Transuranium Elements,"

p 1149, Paper/16.1.

A, Hultgren and E. Haeffner, A/CONF.15/1, Vol. 17, p 324, Paper/144,
G. J. Hunter and R. B. Chenley, UKAEA, AERE-AM-19, 1959,

E. K. Hyde, "The Nuclear Properties of the Heavy Elements. II. Detailed
Radioactivity Properties' (Prentice Hall, Inc., New Jersey, 1964) pp 804-838,
C. H. Ice, HW-10277, June 1948.

M. G. Inghram, D. C, Hess, P. R, Fields, and G. L. Pyle, '"Hzalf-life of
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H R A< =B

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176
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251,

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253.
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255,
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258,

260.
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262.

263.
264,
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266.
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C. F. Metz, Anal. Chem, 28, 1748 (1957).

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G. F. Milis and H. B. Whetsel, Carbide and Carbon Chemicals Co, K-25
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F. J. Miner, Dow Chem. Co. Rocky Flats Plant, Denver, Colo. RFP-3517,
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B> QWA <

 

177
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282,
283.
284,
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2871.
288.
289.
290,
291.

292,
293.
294,
295,
296,
297.
298,

299,
300,

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302,

303.
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308.
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310,

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G. H. Morrison and H. Freiser, "Solvent Extraction in Analytical Chemistry"

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D

D

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178
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D. F. Peppard, M. H. Studier, M. V. Gergel, G, W, Mason, J. C. Sullivan,
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M. J. Rasmussen and H, W. Crocker, HW-72285, Jan. 1962,

J. E. Rein, A. L. Langhorst, Jr.,, and M. C. Elliott, LASL, LA-229],
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Reference eliminated.

A. E. Reisenauer and J. L. Nelson, HW-59983, April 1959,

B. F. Rider, J. L. Russell, Jr., D. L. Harris, and S. P. Peterson, Jr.,
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F. P. Roberts and F. P. Brauer, HW-60552, June 19359,

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Oz 9

 

 

 

 

 

 

179
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345.
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347.
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349,
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351,
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354,
355,
356.
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361,
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368.

369,

J. L. Ryan and E, J. Wheelwright, HW-55893 (Del), Feb. 1959, _

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J

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A. G. Samartseva, Radiokhimiya 4, 526 (1962). In Russian.

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D. Scargill, K. Alcock, J. M. Fletcher, E. Hesford, and H. A. C, McKay,
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C. S. Schlea, M. R, Caverly, H. E. Henry, W. R. Jenkins,and W. C. Perkins,
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Reference deleted.

R. A. Schneider and K, M. Harmon, HW-53368, Feb. 1961.

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K. Schwabe and-D. Nebel, Z. Physik, Chem. 219-220, 339-54 (1962),

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V. B. Shevchenko, N. S. Povitski, and A, S. Solovkin, Progr, Nucl,

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T. Sikkeland, JENER-38, 1955,

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A. A. Smales, L. Airey, G. N. Walton, and R. O. R. Brooks, UKAEA,

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ARAad

 

 

 

USSR Soviet Ministrov. Glavnoe Upravlenie po Ispol' zovaniyu Atomnoi

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405,
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408.
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410.
411,

412,

413.

414.

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416.

4117..
418,
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422,
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H. H. Van Tuyl, HW-28530, 1953,
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Paper/2216. (See also Progr. Nucl. Energy Ser. III, Vol. 3, p 221.)
. M. Vdovenko, A. A. Lepovskii and S. A. Nikitivo, Radiochemistry (USSR)

 

EERERE

 

 

 

 

 

v
3, 143 (1962). [Transl, from Radiokhimiya 3, 396 (1961).]

V. M. Vdovenko, A, A. Lepovskii, and S8, A. Nikitivo, Radiochemistry (USSR)
2, 44 (1960). [Transl. from Radiokhimiya 2, 307 (1960).]

A. F. Voigt, A. Kant, N. R. Sleight, R. E. Hein, J. M. Wright, F. J. Walter,
and H. D. Brown, in '"The Transuranium Elements," p 162, Paper/3.8.

A, M. Vorobev and V. P. Kuzmina, Gigiena i Sanit., No. 9, 54 (Sept. 1963).

In Russian,

 

R. Wagner, Process for the Reduction of Plutonium. (to Commissariat a 1t
Atomique Energie, Paris) Canadian Patent 626, 591, Aug, 29, 1961.
B. Warren, LASL, LA-1567, Sept. 10, 1954, Rev. Nov. 1955,

C. G. Warren, LASL, LA-1843 (Del), July 1953,

K. Watanabe, J, At. Energy Soc. Japan. 3, 497 (1961).

B. Weaver and D. E. Horner, J. Chem. Eng. Data 5, 260 (1960).
H. V. Weiss and W. H. Shipman, Anal. Chem. 33, 37 (1961).

H. V. Weiss and W. H. Shipman, USNRDL-TR-541, Oct. 1961.

I. Walls, UKAEA, AERE-CE /M-19, Nov. 1950,

A, W. Wenzel and C, E., Pietri, Anal. Chem, 35, 1324 (1963).

L. B. Werner and G, E. Moore, Clinton Labs,, Oak Ridge, Tenn.
CN-1630, 1944.

E. F. Westrum, Jr,, in '"The Transuranium Elements,”" p 1185, Paper/16.2.

 

 

182
427.

428.
429,

430.
431,

432.

433.

434.

435.

436,

4317.

438,

439,

440.

441,

442,

443,

444,

445,

446.
44'7,

448,

449,
450,

J. C. White and W. J. Ross, National Academy of Sciences, Nuclear Science
Series NAS-NS-3102, 1961.

V. J. Wilkinson and J,. A. Peacegood, UKAEA, RDB-(W)/TN-77, June 1953.
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Nucl. Energy Ser, III, Vol. 3, Chap. 3-5, p 211))

A. S. Wilson, HW-68207, 1961.

R. S. Winchester and W, J. Maraman, A/CONF, 15/1, Vol, 17, p 168,
Paper/530.

L. Wish, Anal. Chem. 31, 326 (1959).

L. Wish, USNRDL-TR-185, Oct. 1957.

L. Wish and M. Rowell, USNRDL-TR-117, Oct. 1956.

V. D. Zagrai and L.. I. Sel'chenkov, Radiochemistry (USSR) 4, 161 (1962).
[Transl. from Radiokhimiya 4, 181 (1962).]

Y. A. Zolotov and D. Nishanov, Radiochemistry (USSR) 4, 217 (1962).
[Transl. from Radiokhimiya 4, 241, (1962).]

 

 

(Noauthor), "Separations Processes, Progr. Report February-April 1951,"
KAPL-523, p. 17 Secret. (Quoted in DP-700, p 47, Ref. 28,)

{No author), '""Chemistry Tech. Div. Quarterly Progress Report for Period
Ending August 20, 1951," ORNL 1141, 1952, Secret. (Quoted in DP-700,
p.47, Ref. 20.)

A. H. Bushéy, "Quarterly Progress Report — Chemistry Unit, January-
March, 1953," HW-27727, 1953, Secret.

(No author), '"Report of the Chemistry & Chemical Engineering Section for
August-October '1953," KAPL-1002, 1953, p 42, Secret.

(No author), '"Chemical Engineering Division Summary Report for January-
March, 1954," ANIL.-5254, pp 11-15, Secret.

Reference deleted, '

(No author), '""ORNL Reactor Fuel Processing,' 1260, Vol. 3, p 16.

(No author), '"Nuclear Safety Guide," AEC Oak Ridge, Tenn, TID-7016, Rev. 1,
1961.

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& Societe Belge pour 1l'Industrie Nucleaire, Brussels, 1962,"" EURAEC-708.
(No author), UKAEA, PG-372-W, 1962.

(No author), "Procedures for Np and Pu," excerpt from Tracerlab Quarterly
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(No author), "Semiannual Progress Report (On Chemistry) for the Period
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183
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452,
453,

454.
455,

C. E. Holley,Jr., R. N. R. Mulford, E. J. Huber, Jr., E. L. Head, F. H.
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H. Evans, private communicaiion.
R. Ko, Anal. Chem. 28, 274 (19586).

184

USAEC Divhilon of Technlcal Informotion Exterslon, Oik Ridge, Tewmames
MONOGRAPHS IN THE RADIOCHEMISTRY AND THE RADIOCHEMICAL
TECHNIQUE SERIES

Copies of the following monographs are available from the
Clearinghouse for Federal Scientific and Technical Informa-
tion, National Bureau of Standards, U. S. Department of Com-

merce, Springfield, Va. 22151

Aluminum and Gallium, NAS-NS-3032, $0.50

Amerncium and Curium, NAS-NS-3006,
$0.75 -

Antimony, NAS-NS-3033, $0.50

Arsenic, NAS-NS-3002, (Rev.)1965 $1.00

Astatine, NAS-NS-3012, $0.50

Barium, Calcium, and Strontium, NAS-NS-
3010, $1.25

Beryllium, NAS-NS-3013, $0.75

Cadmium, NAS-NS-3001, $0.75

Carbon, Nitrogen, and Oxygen, NAS-NS-
3019, $0.50

Cesium, NAS-NS-3035, $0.75

Chromium, NAS-NS-3007, (Rev.}1964 $0.75

Cobalt, NAS-NS-3041, $1.00

Copper, NAS-NS-3027, $0.75

Fluorine, Chlorine, Bromine, and Icdine,
NAS-NS-3005, $0.50

Francium, NAS-NS-3003, $0.50

Germanium, NAS-NS-3043, $0.50

Gold, NAS-NS-3036, $0.50

Indium, NAS-NS-3014, $0.50

Iridium, NAS-NS-3045, $0.50

Iron, NAS-NS-3017, $0.50

Lead, NAS-NS-3040, $1.75

Magnesium, NAS-NS-3024, $0.50

Manganese, NAS-NS-3018, $0.50

Mercury, NAS-NS-3026, $0.50

Molybdenum, NAS-NS-3009, $0.50

Nickel, NAS-NS-3051, $0.50

Niobium and Tantalum, NAS-NS-3039, $0.75

Osmium, NAS-NS-3046, $0.50

Palladium, NAS-NS-3052, $0.75

Phosphorus, NAS-NS-3056, $0,50

Platinum, NAS-NS-3044, $0.50

Plutonium, NAS-NS-3058, $2.00

Polonium, NAS-NS-3037, $0.75

Potassium, NAS-NS-3048, $0.50

Protactinium, NAS-NS-3016, $1.00

- Radium, NAS-NS-30567, $2.25

Rare Earths— Scandium, Yttrium, and Ac-
tinium, NAS-NS-3020, $3.00

Rare Gases, NAS-NS-3025, $0.75

Rhenium, NAS-NS-3028, $0.50

Rhodium, NAS-NS-3008, (Rev.)1965 $1.00

Rubidium, NAS-NS-3053, $0.50

Ruthenium, NAS-NS-3029, $1.00

Selenium, NAS-NS-3030, (Rev.)1965 $1.00

Silicon, NAS-NS-3049, $0.50

Silver, NAS-NS-3047, $0.,75

Sodium, NAS-NS-3055, $0.50

Sulfur, NAS-N8-3054, $0.50

Technetium, NAS-NS-3021, $0.50

Tellurium, NAS-NS-3038, $0.50

Thorium, NAS-NS-3004, $0.75

Tin, NAS-NS-3023, $0.75

Titanium, NAS-NS-3034, $0.50

Transcurium Elements, NAS-NS-3031,
$0.50

Tungsten, NAS-NS-3042, $0.50

Uranium, NAS-NS-3050, $3.50

Vanadium, NAS-NS-3022, $0.75

Zinc, NAS-NS-3015, $0.75

Zirconium and Hafnium, NAS-NS-3011,
$0.50

-

Activation Analysis with Charged Particles,
NAS -NS -3110, $1.00

Applications of Computers to Nuclear and
Radiochemistry, NAS-NS-3107, $2.50 -

Application of Distillation Techniques to
Radiochemical Separations, NAS-NS-
3108, $0.50

Detection and Measurement of Nuclear Ra-
diation, NAS-NS-3105, $1.50

Liquid-liguid Extraction with High-
molecular-weight Amines, NAS-NS-
3101, $1.00 :

Low-level Radiochemical Separations, NAS-
NS-3103, $0.50

Paper Chromatographic and Electromigra-
tion Techniques in Radiochemistry, NAS-
NS-23106, $0.50

Processing of Counting Data, NAS-NS-
3109, $1.75

Rapid Radiochemical Separations, NAS-NS-
3104, $1.25

Separations by Solvent Extraction with Tri-
n-octylphosphine Oxide, NAS-NS-3102,
$0.75