ORNL-2896.txt

VASTER

ORNL-2896
UC-4 - Chemistry=-General

PHASE EQUILIBRIA IN MOLTEN SALT

BREEDER REACTOR FUELS.

. THE SYSTEM LiF-Ber-UF4-ThF4

C. F. Weaver
R. E. Thoma
H. Insley

H. A. Friedman

OAK RIDGE NATIONAL LABORATORY
operated by

UNION CARBIDE CORPORATION
for the

U.S. ATOMIC ENERGY COMMISSION
DISCLAIMER

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i

i~

" . ORNL-2896
UC-4 — Chemistry-General
TID-4500 (15th ed.)

Contract No. W-7405-eng-26

REACTOR CHEMISTRY DIVISION

PHASE EQUILIBRIA IN MOLTEN SALT BREEDER REACTOR FUELS.
I. THE SYSTEM LiF-BeF,-UF,-ThF,

C.-F. Weaver
R. E. Thoma

H. Insley

H. A. Friedman

DATE ISSUED

OAK RIDGE NATTIONAL LABORATORY
- Oak Ridge, Tennessee
operated by
UNION CARBIDE CORPORATION
for the
U.S. ATOMIC ENERGY COMMISSION
THIS PAGE
WAS INTENTIONALLY
LEFT BLANK
9!

iii

CONTENTS
Abstract..eveecerencees ceecssesesnes ceessscssecs st esssenensnes s cesens
1. Introduction.eceveesoseesvrecacese teessecescsseasanae ecesecreesanas .
2. Experimental Methods..... cicsiessransas crccesnasannonas .o ceee
2.1 Techniques and ApparatuS..ccecereersescescssscencsanss criesas .
2.2 MaterialS...eoesse e eceanes Cecseaseccesesacsasecenosssssens
3. Phase Equilibria and Related Phenomena.....c.eeveeensenss crssnne
3 ol The Components LiF, BeF2 ) ThF4, and IJF4 LI R R B A N N I I I N B A S
3. 2 T:h.e SyStemS BEF2 -lI':hF4 and. BeF2 "UF4 oooooooooo . s e e TR EEEE
3.3 The System LiF-Ber oooooooo e s 00 o e s s 00 s s 008000 N EERE R N .
3.4 The SystemLi:F'TI]F/'oo.-..ooa.ooo-ooo oooooooo s e 068 L] * e T e .
3.5 The SyStemLiF-UF4-.......-.....-. oooooooooooooooo 6 080 P
3.6 The S'y'StEITl .UF4"ThF4lo ooooo A EEEEREEREEER) .o T EEEEE] ¢ NN s e
3.7 The System LiF-BeFo-UF4eeueeereoneraececcacnasannans cesaas
3.8 Tlle System LiF-BeF2 "'ThFZ'_ oooooooo s o s s e s es e e Y . * e o e
3 . 9 The System Ber'ThF4-UF4 " e 9 e s eSS s RS SE SIS OISR TR ESER "e * . . e
3 llo Tkle System LiF—‘[J‘FZ',"T’.b.‘Fer ® 2 8 ¢ 6 9o 3 20 00 s e e s e e e o 000 00 L) .
3.11 The System LiF-BeF,-UF,-ThF, (Selected Portions)......eeee.
4. AcknowledgmentsS...eeeveecosersscanse cesesesessseetsstsnrerernenn
Appendix A Optical and Crystallographic PropertieS.ecesevccecces ceoe

Appendix B

Appendix C

X-Ray Dittraction Data f'or the Solid Phases

Observed in the Quaternary System LiF-BeF;-UF,;-ThF;.....

Specific CompositionS.eecececceosseses

Liquidus Temperatures and Primary Phases for

58
o

PHASE EQUILIBRIA IN MOLTEN SALT BREEDER REACTOR FUELS.
I. THE SYSTEM LiF-BeF,-UF,-ThF',

C. F. Weaver R. E. Thoma H. Insley H. A. Friedman

ABSTRACT

The phase equilibrium relationships for the systems limiting the
quaternary system LiF-BeF,-UF,-ThF, are described in detail along with
available information on the quaternary system itself. The implications
of the extensive solid solutions in the limiting systems are discussed
and experimental information supporting the conclusions is presented. U
The optical properties, crystallographic properties, and x-ray diffrac-
tion patterns for the phases occurring in these systems are tabulated.
Specific compositions of project interest to which references have been
made in the ORNL literature are given special attention. Reference is
made to literature reporting properties of these materials.other than

those discussed in this report.

~ 1. INTRODUCTION

Fluoride fused salts have attracted general interest for use in high-
tempefature reactors because: (1) fluorine has a very low thermal neutron
absorption cross section,® (2) fluorides have low vapor pressures at tem-
peratures and compositions of i.n.terest,2 (3) molten fluorides are very

2 and (4) there are no serious

resistant to damage by nuclear emissions,
corrosion probleme between many fluorides and nickel-based structural ma-
terial.? Specifically, uranium tetrafluoride, a fissile material, is of
interest because it is the only nongaseous fluoride of uranium which does
not incur serious metal container corrosion and/or fuel inhomogeneity as

3

an effect of high-temperature disproportionation. Thorium tetrafluoride,

1s. Glasstone, Principles of Nuclear Reactor Engineering, p 841,
Van Nostrand, Princeton, N.J., 1955.

°H. G. MacPherson, p 567 in Fluid Fuel Reactors, ed. by J. A. Lane,
H. G. MacPherson, and F. Maslan, Addison-Wesley, Reading, Mass., 1958.

3W. R. Grimes et al., p 577 in Fluid Fuel Reactors, ed. by J. A
Lane, H. G. MacPherson, and F. Maslan, Addison-Wesley, Readlng, Mass.,
1958.

a fertile material, is the only fluoride of thorium._4 The fluorides PbF,,
BiF3, Li’F, NaF, ZrF,, and BeF, have sufficiently low thermal neutron ab-
sorption cross sections, vapor pressures, and melting points to allow their
use as diluents for the UF, and ThF,. However, PbF, and BiF3; are unsuit-
able because the cations are readily reduced to the metallic'state by

5 The lower thermal neutron

structural metals such as iron and chromium.
absorption cross section of Ii”7 as compared with that of sodium allows
the design of reactors which have a smaller holdup of fissile material
and superior breeding performance.6

Fluid salt mixtures containing high concentrations of ZrF, are not
regarded as attractive reactor fluids because of significant vapor pres-
sure of ZrF, above 500°C. In a reactor system sublimation of Zng fol-
lowed by deposition as a solid limits the temperatures at which long op-
erating times are permissible. Comparable limitations do not occur in
mixtures containing BeFé rather than ZrF4.7 Molten salt reactor systems
which are designed to operate at sufficiently high temperatures that al-
kali fluoride—ZrF, solvents containing 30-40 mole % ZrF, can be employed
may offer advantages in the futuré, but present preference must be given
to BeF, on the basis of sublimation.® Consequently, mixtures containing
Li’F, BeF,, UF,, and ThF, which have liquidus values severallhundred de-
greesibelow the ThF, and UF,; melting points are the mdst promising éore
materials for a fused salt thermél breeder/converter reactor. A knowl-
edge of the liquidus values of such mixtures is necessary since as reac-
tor fluids fihey must remain wholly in the liquid state during reactor op-
eration. Liquidus data alone are insufficient because mixtures of solids
and liquids will be formed during some fuel handling operations. A knowl-
edge‘of‘the nature of the'melting-freezing process, of the ufanium-thbrium

partition or phase'separation during this process, and of the identity of

4Tbid.,-p 588.
°Tbid., p 570. '
®MSR Quar. Prog. Rep. Jan. 31, 1958 ORNL-2474, p 1.
" "H. G. MacPherson, ORNL, personal communlcatlon.
8. R. Grimes et al., p 582-84 in Fluid Fuel Reactors, ed. by J. A.
Lane, H. G. MacPherson, and F. Maslan, Addison- Wesley, Reading, Mass.,
1958.

i
b
solids formed on cooling of molten mixtures is also necessary. Thus, the
phase equilibrium relationships for the quaternary system must be under-
stood, especially near liquidus temperatures and at compositions which
may afford attractive core or blanket materials. Before the determina-
tions of the phase relationships can be made in a quaternary system, the
14 limiting unary, binary, and ternary systems must be understood. All
these limiting systems for the quaternary system LiF-BeF,-UF,-ThF, have
been reported and are described in detail in the body of this report along
with the available data on the quaternary system itself. It is remarkable
that these studies have not disclosed the existence of ternary or -of
quaternary compounds.

The majority of the informdtion included in this report was derived
in the High Temperature Phase Equilibrium Group of the Reactor Chemistry
Division at the Oak Ridge National Laboratory. Some of the preliminary
studies of the phase equilibria in the limiting binary and ternary sys-

tems were begun as early as 1951.

2. EXPERIMENTAL METHODS
2.1 Techniques and Apparatus

The experimental techniques and apparatus used in the studies of
LiF-BeF,-UF,-ThF, phase equiiibria have been described in detaill else-
where.®"13 1In general, the data were obtained by thermal analysis of
slowly cooled melts and by quenching mixtures which had been equilibrated
at known temperatures. Commonly, fused-salt diagrams are based entirely
on information from cooling curves (temperature of the sample plotted as
a function of time). Changes in the slope of the cooling curve reflect
phase changes which occur on cooling, but.are prone to give misleading
or irrelevant indications because of the impossibility of maintaining

equilibrium during the cooling process. Consequently, predominant use

°%C. J. Barton et al., J. Am. Ceram. Soc. 41, 6369 (1958).

10c, J. Barton et al., J. Phys. Chem. 62, 665 (1958).

11y, A. Friedman, J. Am. Ceram. Soc. 42, 284-85 (1959),

12p, A. Tucker and E. F. Joy, Am. Ceram. Soc. Bull. 36, 52-54 (1957).
13L. J. Wittenberg, J. Am. Ceram. Soc. 42, 209-11 (1959).
has been made of the much more effective method of quenching.equilibrium .
samples and identifying the phases by examination with a polarizing light
mlcroscope and by x-ray dlffractlon techniques.

A thermal gradient furnace with a single movihg thermocouplel? is
used for equilibration in the temperature range 650-1200°C. . Five other
thermal gradient furnaces, operating at a maximum temperature of 900°C,
incorpérate 18 thermocoufiles.each. The independent readings from these
aré'used.to”determine a temperature calibration curve of the thermal .gra-
dient within the annealing area of the furnace. Malfunction of a single
thermoéouPle-becomeé readily apparent.. In quenching studies made at tem-
peraturésvbelow 900°C, sample tubes are distributed among the five fur- -
naces randomly, to achieve méximum reproducibility among independent tem-
perature readings. The region of temperature overlap, 650-900°C, is used
to monitor the single highfitemperéture furnace. 1In the absence of super-
cooling effects, the completely separate measurements in.the thermal.anal- .-
ysis furnaces agree within 5°C with those from the thermal :gradient. fur-
naces. This interlocking system, by which multiple'fhermocouples'within
five .of the furnaces and three typeé of furnaces are used, provides a
continuous-chéck on. the proper function of the equipment. ,

The accuracy of the temperature‘measurements'ileimited by the char=
acteristicé.of the. Chromel-Alumel thermocouples used.l4 The invariant
point temperature data are so precise that a standafd deviation of:l or

-~ 2° is obtained.

2:2 Materials

The LiF used for this work was reagent grade obtained from Foote
Mihepal Company and from Maywood Chemical Works. The UF4 was a product
of Mallinékrodt Chemical Works. The ThF, was obtained from Towa State
College and from National Lead Company. The BeF, was a product of Brush é%
Beryllium Company . No 1mpur1t1es were found in any ‘of these materials.
by x-ray diffraction or microscopic analy51s. Spectroscopic analy51s in- -

dicates less than 0.25 wt % impurities.

147, F. Potts, Thermocouple Research — Cold Work, ORNL CF-59-6-61
(June 15, 1959).

Because thorium!® and uranium fluorides are easily converted to ox-
ides or oxyfluorides at elevated temperatures it was necessary to remove
small amounts of water and oxygen as completely as possible from the
starting materials. In a few cases the molten mixtures were treated with
anhydrous HF. For the vast majority of preparations, however, NH,F-HF
was added to the mixture before melting. As such mixtures are heated

the watcer evaporates from the system. 'I'race quantities of oxide impuri-
ties are converted to products which have not yet been identified but

nl6,17 ypon further heat-

which are likely to be ammonium "fluometallates.
ing the ammonium "fluometallates" and the excess NH,F-HF decompose. The
products are metal fluorides and the gases NH3 and HF. These gases are
quantitatively swept from the system by dry helium. The samples were
melted and cooled to obtain thermal analysis data. The purified solids
were transferred to an argon-filled dry box which contained BaO as a des-

iccant. They wcre grofind to pass a 100-mesh screen and used in the S

quenching experiments. The heating cycles were conducted in closed cap- TG

sules or under an atmosphere of dry helium or argon.

3. PHASE EQUILIBRIA AND RELATED PHENOMENA

3.1 The Components LiF, BeF,, ThF,, and UF,

-
o

A special character can be assigned to the behavior of combinations
of the four compounds LiF, BeF,;, ThF,, and UF,, for in this grouping are
to be found a pair of metal cations in the lowest and a pair in the high-
est atomic number range. It might, therefore, be expected that the di-
verse physical and chemical properties of these four components would
contribute to the occurrence of phase behavior in which a wide variety
of phenomena would appear. The melting points of the components are
shown in Table 1.

Of the four components, only BeF, exhibits polymorphic transitions.

The equilibrium melting temperature and the nature of these solid-state

1°R. W. M. D'Bye, J. Chem. Soc. 1958, 196.
l'E’MSR Quar. Prog. Rep. Apr. 30, 1959, ORNL-2723, p 93.
178, J. Sturm, ORNL, personal communication (May 1960).

‘Table 1. "The Melting Points of the Components

Melting Point

Component ‘ (°c)
LiF g45%
BeF», 548b—d
ThF,, 1111578
UF,, 1035"

%7, B. Douglas and J. L. Dever, J. -Am. Chem. Soc. 76, 4824 (1954).
b

LiF- BeF2 ThF4," J. Phys. Chem , in press.
D. M Roy, R. Roy, and E. F. Osborn, J. Am. Ceram. Soc. 36, 185

R. E. Thoma et al., "Phase Equilibria in the Systems BeF,-ThF, and

(1953).
' @M. P. Boryenkova et al., Zhur. Neorg. Khim. 1, 2071 (1956).
R. E. Thoma et al., J. Phys. Chem. 63, 1266 (1959).

J. Asker, E. R. Segnit, and A. W. Wylie, J. Chem. Soc. 1952, 4470.

®A. J. Darnell and F. J. Keneshea, Jr., J. Phys. Chem. 62, 1143
(1958). ‘

’ hH. R. Hoekstra and J. J. Katz, p 177 in The Actinide Elements, ed.

by G. T. Seaborg and J. J. Katz, McGraw-Hill, New York, 1954.

transitions have been the subject of controversy for several- years. 18

The structure of Bng is analogous to that of S5i0Oz, as.was predicted by .

| Goldschmldt 19 211 known modifications crystalllze as S1i0,-type struc-

tures. Belng similar to 8102, Bng readily forms a glass upon cooling

_ from the liquid state. For this reason, establishing solid-state equl—
libria with BeF,, in which devitrification of this glass must be accom-

plished, is often a very slow process.

Opticél and crystallographic properties for the compounds fiiF, Bel'y,

ThF,, and UF, may be found in Appendix A. Their x-ray diffraction data
are listed in Appendix B. ' . ' '

187, V. Novoselova, Uspekhi Khim. 27, 33 (1959).
- 1%, M. Goldschmidt, Skrifter Norske Videnskaps-Akad. Oslo. I.
‘Mat.-Naturv. Kl. 1926, No. 8, p 7-156 (1927).
»

3.2 The Systems BeF,-ThF, and BeF,-UF,

The systems BeF,-ThF;?° (Fig. 1) and BeF,-UF,?! (Fig. 2) are similar

‘UNCLASSIFIED

ORNL-LR-DWG 245514

in that both possess no interme-

1300 —————————— x diate equilibrium compounds, have
e THERMAL ANALYSIS RESULT
1200 |- * NoF-BeF,~Thi, EXTRAPOLATION RESULT lowest liquidus values between
s THERMAL GRADIENT QUENCHING RESULT
100 | < 97 and 100 mole % BeF,, have a
- LIQUID 'y .. . .
€ 1000 T single eutectic invariant point,
w /(
o
2 500 7 and have an abrupt change in the
B /./ .
b -
Q. y—®
Z 800 I 20 1
- }// LIQUID +ThF, R. E. Thoma et al., "Phase
700 / Equilibria in the Systems BeFj,-
co0 g/ HOUD + BeFy ThF, and LiF-BeF,-ThF,," J. Phys.
Ve {Ber, +ThF, Chem. ; in press.
L a l g .
500 7 l 1T. B. Rhinehammer, P. A.
o 0 %0 %0 Mo S0 B0 To 80 s 1 Tucker, and E. F. Joy, Phase Equi-
2 ¢ . libria in the System BeF,-UF,,
Fig. 1. The System BeF,-ThF,. MILM-1082 (to be published).
UNCLASSIFIED
. ORNL-LR-DWG. 28598
oo ] T T T T T I T | T ] T I | | T [ T
1000} - o
_ LIQuip
900} - -
¥a00l- -
w : UF4 + LIQUID
>
[
<
w
0. 700 -
=
7Y
-
600} i
T %0—00—0000-0-0-0-0-0-00——0—05—v oo — ]
QMigH BeFa +UF,
400 | l 1 l i l | l 1 l | 1 l 1 l | l 1
0 10 20 30 a0 50 60 70 80 90 100
BoFp MOLE PERCENT UF4 UFs
FPig. 2. The System BeF,-UF,.
liquidus slope in the quadrivalent fluoride primary phase region. The
eutectic invariant points are at 2 mole % ThF,, 527°, and at 0.5 mole %
UF4, 535°, while the change in slope occurs near 12 mole % ThF, and 7

mole % UF; in the corresponding systems.

3. 3 The System LiF- Bng

A phase dlagram of the system LiF-BeF,22:23 (Fig. 3) has been derived
at ORNL from the results of thermal gradient experiments. A phase diagram

nearly identical with that shown has been derived independently at the

 22R, E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials,
ORNL-2548, p 33 (Nov. 2, 19597.
23R, E. Moore, C.. J. Barton, R. E. Thoma, and T. N.. McVay, ORNL, un-
publlshed data. ‘

UNCLASSIFIED
ORNL—LR—-DWG {6426R

900"
800 \‘\

' 700 —N\

%)

£ 600 [——LiF + LIQUID -

*:; \

[ .

- -

2 - \ . —

w C .

a .

S 500 .

/  BeFp + LIQUID
400 ‘ 2L|F BeFa\ -

LIQUID \\/

Lif + 2LiF - BeFp

by 2LiF - BeFp + BeF, (HIGH QUARTZ TYPE)
300 l@ | j
= 2LiF-BeF, W ! Lo o
~ T 2 9 LiF - BeFo+ BeFp (HIGH QUARTZ TYPE) '
UF-Ber, & 1 | 1 '
200 IF-BeFp 3 LiF - BeFo+ BeF2 (LOW QUARTZ TYPE) _
LiF 10 20 30 - 40 50 - 60 70 80 90 Bef,
BeFla (mole %)

Fig. 3. The.System -LiF-BeF,.
Mound La'boratory.24 These diagrams are revisions of those published by

earlier investigators:?° 27

Two equilibrium compounds occur .in the system
LiF-BeF,, the incongruently melting compound 2LiF.BeF, and the subsolidus
compound LiF.BeF,. Unsuccessful attempts have been made by the authors
to produce the reported compounds 3LiF.2BeF,28 and LiF-2BeF,2° by devitri-
' fication of LiF-BeF, glass and by solid-state equilibration of mixtures
of BeF, and 2LiF-.BeF,. Because the special purification techniques de-
scribed earlier in this report were not used by other investigators??:28
reports of the existence of 3LiF.2BeF, and LiF.ZBng should be considered
tentative.

The optical properties, crystallographic properties, and x-ray dif-
fraction data for the compounds 2LiF.BeF,; and LiF.BeF, are listed in Ap-
pendixes A and B. The compositibns and temperatures of the two invariant

points and one upper limit of stability may be found in Table 2.

Table 2. Invariant Equilibria in the System LiF-BeF,*

Mole % Invariant Type

BeF, in Temperature of Fhase Reaction at

2 .

Liquid (°c) Equilibrium Invariant Temperature
33.5 454 Peritectic "L + LiF = 2LiF.BeF,
52 355 Eutectic L = 2LiF.-BeF, + BeF,
- 280 Upper temperature  2LiF.BeF, + BeF, = LiF-:BeF,

of stability
for LiF.BeF,

*¥R. E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials,
ORNL-2548, p 33 (Nov. 6, 1959).

Cooling mixtures of LiF and BeF, slowly from the liquid to the solid

state rarely produces equilibrium solids, for the subsolidus reaction

243. F. Eichelberger, C. R. Hudgens, L. V. Jones, and T. B. Rhine-
hammer Mound Laboratory, unpuihlished data.
°D. M. Roy et al., J. Am. Ceram. Soc. 37, 300 (1.954).
2°A V. Novoselova et al., J. Phys. Chem. (USSR) 26, 1244 (1952).
27J. L. Speirs, Ph.D. thesis, University of Michigan, May 29, 1952.
28F, Thilo and H. A. Lehmann, Z. anorg. Chem. 258, 332-55 (1949)
Ceram. Abstr. 1950, 82f.
- ‘conditions.

10

Li,BeF, + BeF, — 2LiBeF3 proceeds very slowly. The compound LiF.BeF,
~ may be observed to grow slowly into solid'mixtures of LiF and BeF, which
are held for several days at temperatures just below 280°C. ‘The fofma—
tion of LiF-BeF, glass which devitrifies slowly also prevents compositions
rich in BeF, from reaching equilibrium.rapidly. Mixtures of LiF and BeF'5,
- containing more than 33.3 mole % BeF, regularly contain only Z2LiF-BelF,
and the low-quartz form of BeF, if fhey are cooled under nonequilibrium

29, 30

The compositions, liquidus temperatures, and primary phases for mix-
tures of LiF and BeF, which have been referred to in the ORNL literature
as C-74, C-112, and C-132 may be found in Appendix C.

Solubilities of NaF,3' RbF,32 zrF,,33 PuFs,3% CeFs,35 HF,3% and the

37

noble gases in LiF-BeF, solvents have been reported. The reactions M +

HF (M = Fe, Cr, or Ni),3® CeF; + Be0,3? and CeF; + Hp0%® in LiF-BeF, sol-

.. vents have been investigated, as have the exchange reactions between CelFj

~and CeO, and between HfC and HfF,.%1

2°R. E. Thoma, X-Ray lefraction Results, ORNL CF-56-6-25, item T-
1437 (JUne 4, 1956)
30R. E. Thoma, Results of X- Ray lefractlon Phase Analyses of Fused

Salt Mixtures, ORNL CF-58-2-59, item 1894 (Feb. 18, 1958).

_ 31R. E. Thoma (ed ), Phase Diagrams of Nuclear Reactor Materials,
ORNL- 2548, p 42 (Nov. 2, 1959).
°Tbid., p 44.
33MSR Quar. Prog. Rep Jan. 31 and Apr. 30, 1960, ORNL-2973, p 65.
34C. J. Barton et al., Reactor Chem. Ann. Prog Rep Jan. 31 1960,
ORNL- 293l, p 12.
30w, 1. Ward, R. A. Strehlow, and G. M. Watson, Chem. Ann. Prog. Rep.
June 20, 1958, ORNL-2584, p 82.

36J. H. Shaffer and G. M. Wetson, Reactor Chem. Ann. Prog. Rep. Jan.
31, 1960, ORNL-2931, p 31. .

37N, V. Smith et al., Reactor Chem. Ann. Prog. Rep. Jen. 31, 1960,
ORNL-2931, p 28.  ~ |

38¢c. M. Blood et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL—2931, p 39. T -

397, H. Shaffer, G. M. Watson, and W. R. Grlmes, Reactor Chem. Ann.
Prog. Rep.. Jan. 31,. 1960, ORNL-2931, p 86.

401pig. , p 88.
4TF H. Shaffer and G. M. Watson, Reactor Chem. Ann. Prog. Rep. Jan.
31, 1960, ORNL- 2931, p 82-84.

11

3.4 The System LiF-ThF,

One congruently melting compound (3LiF.ThF,) and three incongruently
melting compounds (7LiF-6ThF,, LiF-2ThF,, and LiF.4ThF,) are formed in
the system LiF-Tth,42 (Fig. 4). Optical properties, crystallographic

properties, and x-ray diffraction
UNCLASSIFIED
ORNL-LR-DWG 265354

150 — data for these compounds are listed
(050 . //”// in Appendixes A and B. The com-
950 ////// positions and temperatures of the

five invariant points and one con-

/// gruent melting point may be found

750 AN /
\\ // in Table 3.
650 \
\»q/ Binary LiF-ThF, mixtures con-

3LiF - Thiy—{ 7LiF-6ThF—~= LiF- 2Thi—

TEMPERATURE (°C) -

LiF-4ThE,

taining more than 25 and less than

| | l
450
LUF 40 20 30 40 50 60 70 80 90 Thg, 66.7 mole % ThF, regularly contain
Thf, (mole %)
‘ 3LiF.ThF, and LiF.-2ThF, if cooled

Fig. 4. The System LiF-ThF,. from the liquid state under non-

43

equilibrium conditions. The solidification temperature is not signifi-

cantly changed by the failure of 7LiF¥F.6ThF, to form.%? The equilibrium

“2R. E. Thoma et al., J. Phys. Chem. 63, 1266 (1959).
43R. E. Thoma, Results of X-Ray Diffraction Phase Analyses of Fused
Salt Mixtures, ORNL CF-58-2-59, items 1854, 1873, and 1894 (Feb. 18, 1958).

Table 3. Invariant Equilibria in the System LiF-ThI',*

Mole % Invariant Type Phase Reaction
ThF, in Temperature ~ of at Invariant
Liquid (°c) Equilibrium Temperature
23 565 Eutectic = LiF +
' 3LiF-ThF,
25 . 573 Congruent mp L = 3LiF.ThF,
29 568 Eutectic L = 3LiF.ThF,; +
7LiF-6ThF,,
30.5 597 Peritectic LiF.2ThF, + L ==
7LiF-6ThF,
42 762 Peritectic LiF«4ThF, + L =
LiF-2ThF,,
58 897 Peritectic ThF, + L =
LiF-4ThF,

XR. E. Thoma et al., J. Phys. Chem. 63, 1267 (1959).
.t
Rark 2k~ FPIRNILITN

12 B - @

condition will be readily establlshed if the LiF-ThF, mixtures are held D ’

for a short time at temperatures Jjust below the solidus.

KA

" The comp081t10n, liquidus temperature, and prlmary phases for the
mixture of LiF and ThF, referred to in the ORNL literature as C-128 may
be found in Appendlx C.

| 3.5 The SyStem LiF-UF,

Three incongruently melting compounds (4LiF.UF,, 7LiF.6UF,, and
LiF.-4UF,) are formed in the system LiF-UF,° (Fig. 5). The metastable

UNCLASSIFIED ]
’ ORNL —LR-DWG 17457 -
{100

700 \\\ : : /

-

TEMPERATURE (°C)

600 : N\

| 500 - - /

s <

LA = 3 E
aLiF-ug,—" = W -

~ -}

400 - — : . .
LiF " 10 20 30 40 50 60 70 80 90 UF,
UF4( mole To)

Fig. 5. The System LiF-UF,. _ N

compound 3LiF-UF,; is readily formed from melts containing approximately
25 mole % UF, at temperafures above the indongrfient melting point‘bf |
4LiF-UF, when these_mixtures are rapidly cooled from fhe liquid state.
The cooling curves of samples,in”thie composition range differ remarkably
from one another depending upon thé maximum temperature of the-mirture . e

just prior to cooling.
13

The optical properties (except for 3LiF.UF,), crystallographic prop-
erties, and x-ray diffraction data for these compounds may be found.in
Appendixes A and B. The compositions and temperatures of the four in-
variant points and the lower temperature limit of stability for 4LiF-.-UF,

may be found in Table 4. The systems LiF-ThF, and LiF-UF, are similar

Table 4. Invariant Equilibria in the System LiF-UF,*

Mole % Invariant Type of
UF, in Temperature oG Phases Present
. o Equilibrium
Liquid (°c)
- 470 Lower stability LiF, 4LiF-UF,,
limit for 7LiF«6UF,
. 41IAF.UF,
26 500 Peritectic LiF, 4LiF.UF,, liquid
liquid
40 $10 Peritectic 7LiF+-6UF,, LiF-4UF,,
liquiad
57 775 Peritectic LiF+4UF,, UF,;, liquid

*C. J. Barton et al., J. Am. Ceram. Soc. 4L, 63-69 (1958).

in that in each the lowest liquidus temperatures are found between 70 and
80 mole % LiF, and in Both systems compounds with alkali fluoride ratios
of 3:1, 7:6, and 1l:4 are formed. The compounds 7LiF.6ThF, and 7LiF.6UF,
form a continuous series of solid solutions as do the compounds LiF.4ThF,
and LiF-4UF,. These solid solutions are described in Sec 3.10 and Ap-
rendix A.

The solubilities of NaF,%* KF,%> RbF,%® and UF3%7 in LiF-UF, solvents
have been investigated. The vapor pressures of LiF-UF, mixtures containing

10 and 20 mole % LiF have been reported.*8

44R. E. Thoma et al., J. Am. Ceram. Soc. 42, 21-26 (1959).

45R. E. Thomalrgdtj, Phase Diagrams of Nuclear Reactor Materials,
ORNL-2548, p 98 (Nov. 6, 1959).

461pid., p 102.

47C. J. Barton et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 26. T
48g, Langer, Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960, ORNL-2931,

p 51.
14

IS

3.6 The Systeni UF,-ThF, - S S K

The isostructural components ThF4 and UF4 form a contlnuous serles

- .
1)§

UNCLASSIFIED of solid solutions w1thout max1-

ORNL-LR-DWG 27913R

1200 mum or minimum*® (Flg 6). The .
£ 1100 teses—— — LIQuio 1nd1ces of refraction of the
l&" -‘\‘ m:‘:m__ 1

. b EEE == . .

2 1000 LIQUID + ThF, - UF, SOLID SOLUTION ThF,-UF, solid solutions change
a
Lu ’ ’ » X . 3 '
= 900 The, - UF, SOLID SOLUTION . regularly with composition but
= . . . .

800 | l | not linearly.  The optical prop-

ThE, 10 20 30 40 50 60 70 80 90 UF, . o : .
) UF, (mole %) * erties for these solid solutions

Fig. 6. The System UF,-ThF,. may be found in Appendix A.

3.7 The System LiF-BeF,-UF,

Nolternary compounds form within the system LiF-BEFg-UF450’5l (Figs.
7 and 8). Consequently, the solid phases occurring in the system are
those of the components or binary compounds described above (Secs 3;1,
3.2, 3.3, and 3.5). The compositions and temperatures of the five in-
.variant poinfis may be found in Table 5. Thé equilibrium phase behavior
of selected compositions of LiF-BeF,-UF, is given in Table 6 and.in Ap-
‘pendix - Co When mixtures of LiF, Bng, and UF, cool slowly from the lig-
uid state, equlllbrlum is rarely, if ever, achieved. 1In the comp081tlons
c-75, C-126, C- 130, C-131, and C-136 solids have been routlnely observed

in the cooled.melts Wthh are indicatlive of nonequlllbrlum cooling. 352=54

490, F. Weaver et al.,rPhase Equilibria in the Systems UF,-ThF, and
L1F UF4-ThF4, ORNL-2719- (Aug. 17, 1959), J. Am. Ceram. Soc. 43 213 (1960).

°0L. V. Jones et al.,- Phase Equilibria in the LiF-BeF,- UFfi»Ternary
Fused Salt System, MLM—lO8O (Aug. 24, 1959)..

51R. E. Thoma (ed. ), Phase Dlagrams of Nuclear Reactor Materials,
ORNL-2548, p 108-9 (Nov. 6, 1959).

°2R. E. Thoma, Results of Examinations of Fused Salt Mixtures by -3
Optical and X-Ray lefractlon MEthods, ORNL CF-58-11-40, item 1925 (Nov.
14, 1958).

23R. E. Thoma, Results of ‘X-Ray Diffraction Phase Analyses of Fused -
Salt Mixtures, ORNL CF-58-2-59, items 1873 and 1894 (Feb. 18, 1958)."

°%R. E. Thoma, Results of Examinations of Fused Salt Mixtures by
Optical and X- -Ray Diffraction Methods, ORNL CF-59-10-18, 1tems 2006
2019, 2036 2056, 2061 and 2074 (Oct. 7, 1959) : .

15

Solid-state equilibrium is readily established if the solid mixture is

annealed for a short time at temperatures near the solidus.

UNCLASSIFIED
MOUND LAB. NO.
1035 56-141-29 (REV)

UF,

ALL TEMPERATURES ARE IN °C

£ = EUTECTIC
P = PERITECTIC LiF'4UF4
UF, | = PRIMARY PHASE FIELD

Fig. 7. The System LiF-BeF,-UF,.

Numerous investigations of the interactions of molten mixtures of

LiF, BeF,, and UF, with other substances have been reported. The solu-
2LiF - BeFp+BeF,

LiF- Ber + BCFZ
LiF +2LiF - BeF,
2LiF - BeF,
2LiF-BeF, +LiF - BeF,

Fig. 8. The System LiF-BeF,-UF,.

BBFZ

Table 5. Invariant Equilibria in the System LiF-BeF,-UF,*

Composition of

il Tempera- Solid Phases
e (mole %) ture TYP? O? Present at
(*g) IRt Invariant Temperature
LiF BeF, UF,
72 6 22 480 Peritectic (de- 4LiF-UF,, LiF, and
composition of 7LiF.6UF,

4LiF-UF,; in the
ternary system)

69 23 8 426 Eutectic LiF, 2LiF+BeF;, and
7LiF«6UF,

48 51.5 0.5 350 Eutectic 7LiF<6UF,;, 2LiF-BeF,,
and BelF',

45.5 54 0.5 381 Peritectic LiF-4UF,, 7LiF-6UFy,
and BeF's,

29.5 70 045 483 Peritectic UF,, LiF-4UF,;, and
BeF',

*¥R. E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials,
ORNL-2548, p 109 (Nov. 6, 1959).

17

Table 6. Phase Behavior of Selected LiF-BeF,-UF, Compositions

Tem%fé?ture Phases Present

Cc-75: 67 LiF-2.5 UF,~30.5 BeF, (Mole %)

464—450 LiF and liquid
450426 LiF, 2LiF-BeF,, and liquid
Below 426 LiF, 2LiF-BeF,, and 7LiF.6UF,

C-126: 53 LiF-1 UF,—46 BeF, (Mole %)

400-350 2LiF+BeF,, 7LiF.6UF;, and liquid
350-280 2LiF-BeF2, 7LiF’6UF4, and BeF;
Below 280 2LiF+BeF,, 7LiF+6UF,, and LiF-BeF,

C-130: 62 LiF-1 UF,-37 BeF, (Mole %)

40—414 2LiF+BeF, and liquid

414~381 2LiF+BeF,, 7LiF+6UF,, and liquid
381280 2LiF+BeF,, 7LiF-6UF,, and BeF,
Below 280 2LiF-BeF,, 7LiF-6UF,, and LiF+BeF,

Cc-131: 60 LiF—4 UF,—36 BeF, (Mole %)

450~415 7LiF+6UF, and liquid

415381 7LiF+6UF,, 2LiF-BeF,, and liquid
381-280 7LiF-6UF,, 2LiF-BeF,, and BeF,
Below 280 7LiF.6UF,, 2LiF-BeF,, and LiF-BeF,

C-136: 70 LiF-20 UF,—10 BeF, (Mole %)

500-465 7LiF+6UF, and liquid
465426 7LiF+6UF,, LiF, and liquid
Below 426 7LiF.6UF,, LiF, and 2LiF-BeF;

18

bilities of PuFs3,1? CeF3,°° LaF;,°° and SmF3°° in LiF-BeF,-UF, solvents
and the reactions of Be0’® and steam’” on these solvents have been in-
vestigated. The exchange of SmF; (dissolved) and CeF; (solid),”8 the
exchange of Hf in HfF, and HfC,”° and the effect of AlF358 on the solu-
bility of the rare-earth trifluorides in LiF-UF,-BeF, molten mixtures
have been studied. In addition the effect of thermal cycling on segre-
gation,6o the effect of radiation on static corrosion of graphite and

3 64

of INOR-8,6l graphite per.meation,62 dehydration,6 and purification

have been reported for LiF-UF,-BeF, mixtures.

3.8 The System LiF-BeF,-ThF,

The phase equilibria in the system LiF-BeF,-ThF, (Figs. 9%-15) have
been described in a recent report.20 One aspect of the phase equilibria
in this system which is of significance is the formation of a solid so-
lution in which beryllium replaces both lithium and thorium in the
3LiF-ThF, lattice. The single-phase composition area for this solid so-
lution is limited as indicated in Table 7. This results in the forma-
tion of phases at the solidus whose compositions are not so diverse as

those which would have been formed if the substitutional solid solution

°R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 77. T

57, H. Shaffer, G. M. Watson, and W. R. Grimes, Reactor Chem. Ann.
Prog. Rep. Jan. 31, 1960, ORNL-2931, p 84.

57Tpid., p 87.

>8R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 77-80. ~—

°9J. H. Shaffer and G. M. Watson, Reactor Chem. Ann. Prog. Rep. Jan.
31, 1960, ORNL-2931, p 83.

60G. J. Nessle and J. Truitt, Reactor Chem. Ann. Prog. Rep. Jan. 31,
1960, ORNL-2931, p 17-19.

6ly. E. Browning and H. L. Hemphill, Reactor Chem. Ann. Prog. Rep.
Jan. 31, 1960, ORNL-2931, p 74-75.

®2R. J. Sheil et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 69.

63c. J. Barton et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 20. o

64J. E. Eorgan et al., Reactor Chem. Ann. Prog. Rep. Jan. 31, 1960,
ORNL-2931, p 64. T

19

- UNCLASSIFIED
ORNL-LR-DWG 37420R2

Thi, 1414

TEMPERATURE IN °C
COMPOSITION IN mole 7o

LiF-4ThE, | ,

LiF-2Th,

" P 762 A 850

e

& D wo N ————— " \\;£ 576
(o) N> — = = g
LiF O\/ \ \\ \\\f A VA ) 5 \V X AVA > Ber

845 2LiF-BeF, 5001450 400 400 450 500 548
P 465 £ 370

Fig. 9. The System LiF-BeF,-ThF,.

Table 7. Limits of Single-Phase in 3LiF+.ThF, were not to occur.
3LiF+ThF, Solid Solution*

Composition in mole %

This is a way of saying that when

such mixtures are used as reactor

fuels, the segregation of the tho-

. LiF BeF, ThF,
rium-containing phase or phases
! 75 0 25 from the LiF-BeF, solvent on cool-
58 16 26 ing will be less than one would
59 20 2% expect without a knowledge of the
solid solution.
3 *¥R. E. Thoma (ed.), Phase Dia- R i aRREaRTE
grams of Nuclear Reactor Materials, Y P
ORNL-2548, p 81 (Nov. 6, 1959). formed in the system. Conse-

quently, all the solid phases formed in the system, except for members
of the 3LiF.ThF, solid solution, are the components or binary compounds
described above (Secs 3.1, 3.2, 3.3, and 3.4). The compositions and the

temperatures of the six invariant points may be found in Table 8.
UNCLASSIFIED
ORNL-LR-DWG 43437

°
Q
Q
Q
(=2
%
o
., b 2
N,
S Q
o 9
& o 5 h s ©
S & ;
S o s °
S EXOF K
(@]
o/ a S
S %
0 BeF,+LIQUID S A o Y
b ThE, + LIQUID & € o)
¢ ThE, + BeF, = d s A
d 2LiF-BeF, + BeF, - f e A\
e 2LiF-BeF,+LIQUID L e a
f LiF + 2LiF-BeF, [
g LiF +LIQUID 500 / o
h LiF-4ThF, + LIQUID g / TEMPERATURE IN °C
/' TLiF-6Thi, + LIQUID 600 COMPOSITION IN mole %
J 3LiF-ThE, ss + LIQUID
k LiF-2ThF, +LIQUID 700
/' 3LiF-ThF, + LIQUID
m LiF + 3LiF ThE, 800 v
A 3LiF-ThE,+ 7LiF-6ThE, L
0 LiF-4ThF, + The, 565
p LiF-2ThF, + LiF - 4ThF,
g TLiF-BThF,+ LiF-2ThE,

Fig. 10. The System LiF-BeF,-ThF,.

The equilibrium phase behavior which will occur in several selected
LiF-BeF,-ThF, compositions is described in Table 9.

When mixtures of LiF-BeF,-ThF, are cooled slowly from the liquid
state, equilibrium is rarely, if ever, achieved. In compositions C-127,
Cc-133 (or C-1lla), and BeLT-15, solids have been routinely observed in

the cooled melts which are indicative of nonequilibrium cooling.®”:66

6°R. E. Thoma, Results of X-Ray Diffraction Phase Analyses of Fused
Salt Mixtures, ORNL CF-58-2-59, item 1854 (Feb. 18, 1958).

66R. E. Thoma, Results of Examinations of Fused Salt Mixtures by
Optical and X-Ray Diffraction Methods, ORNL CF-59-10-18, item 2095 (Oct.
7, 19597,

21

UNCLASSIFIED
PHOTO 32551

Fig. 11. The System LiF-BeF,;-ThF,.
UNCLASSIFIED
ORNL-LR-DWG 40224

BeF,

2LiF-BeF,

Flg. 12.
BeF,-ThF, ¢

The System LiF-
550°C Isotherm.

UNCLASSIFIED
ORNL-LR-DWG 40223R

?LiF-BeF,
<

FPig. l4.
BeF,-ThF, ¢

The System LiF-
444°C Isotherm.

22

UNCLASSIFIED
ORNL~-LR-DWG 40222R

LiF-4ThE,

LiF-2ThF,
7LiF-6ThE,

"y \
7

LiF

2LiF-BeF,

Fig. 13.
Bng-ThF4 H

The System LiF-
497°C Isotherm.

UNCLASSIFIED
ORNL-LR-DWG 40224R

Thig

LiF- 4TI’\F4

LiF-2The

7LIF-6ThE,

3LiF-Th, ,,
) 4

W w‘g&

4

2LiF-BeF2

LiF é—

Fig. 15.
BeF,-Thl :

The System LiF-
433°C Isotherm.

Solid-state equilibrium is readily established if the solid mixture is

annealed for a short time at temperatures near the solidus.

The system pairs LiF-BeF,-ThF, and LiF-BeF,-UF, are very similar.

In both, the primary phase fields of the LiF-BeF, compounds occupy a small

area, and the lowest liquidus temperatures are very near those in the sys-

tem LiF-BeF 2

A rather low temperature region exists on the liquidus

surfaces in the vicinity of 70 mole % LiF. The liquidus surfaces in the
Table 8. Invariant Equilibria in the System LiF-BeF,-ThF,*

Composition of Liquid

Invariant

(mole %) Type of Solids Present
Tem€fg?ture Invariant at Invariant Point
LiF BeF, ThF,,
15 83 2 497 Peritectic ThF,, LiF.4ThF,, and
Bng
33.5 64 2.5 455 * Peritectic LiF-4ThF,, LiF-2ThF,,
' and BeF;
47 51.5 1.5 356 + Eutectic 2LiF-BeF,, LiF.2ThF,,
and BeF,
60.5 36.5 3 433 % Peritectic LiF-2ThF,, 3LiF-.ThF,ss,
and 2LiF-.BeF,
65.5 30.5 4 b4bidy Peritectic LiF, <ZLiF-BeF,, and
3LiF°ThF4SS
63 30.5 6.5 448 + Peritectic 3LiF+ThF,ss, 7LiF-6ThF,,
and LiF+2ThF,
E. Thoma (ed.), Phase Diagrams of Nuclear Reactor Materials, ORNL-2548, p 80 (Wov. 6, 1959).

*R.

£c
24

Table 9. Phase Behavior of Selected LiF-BeF,-ThF, Compositions

Tem?sg?ture Phases Present

C-127: 58 LiF~7 ThF,~35 BeF, (Mole %)

460~-430 - LiF+2ThF, and liquid
430-356 LiF-2ThF,, 2LiF‘BeF,, and liquid
356~280 ‘ LiF:2ThF,, 2LiF-BeF,, and BeF,

Below 280 LiF.2ThF,, 2LiF.BeF,, and LiF.BeF,

C-133: 71 LiF-13 ThF4~l6 BeF, (Mole %)

500470 ?nvqf  _ ; - 3LiF-ThF,ss and liquid
470-444 ~ 3LiF-ThF,ss, LiF, and liquid

Below 444 3LiF-ThF,ss and 2LiF.BeF,

BeLT-15:% 67.5 LiF-15 ThF,~17.5 BeF, (Mole %)

500-465 3LiF+ThF,ss, 7LiF-6ThF,, and liquid
465440 3LiF-ThF,ss and liquid

“Below 440, 3LiF-ThF;ss and 2LiF.BeF,

: *R. E Thoma, Crystallization Reactions. in  the Mixture- L1F BeF2 ThF4
(67.5-17.5-15 MOle %), BeLT-15, ORNL CF-59-4-49 (Apr. 13, 1959).

system_LiF-Ber-ThF4 tend to occur at somewhat higher temperatures than
those in fhe system LiF-BeF,-UF,.

-~ Several investigations of the interactions of molten mixtures of
LiF,vBéFg;'and ThF, have been reported. The precipitation of ThO, from
LiF-BeFé-ThF4 mixtures by steam*® has been studied. Attempts to remove
barium from‘LiFJBer;ThF4 mixtures by adding Cr,03 or BeO were unsuccess-
ful, -as'wéré'attempts to remove cerium by adding BeO or Al,03.% The
segregation effect of thermal cycling on LiF-BeF,-ThF, mixtures has been

reported. 0, 63
3.9 The System BeF,-ThF,-UF,
The great similarity of the binary systems BeF,-UF, and BeF,-ThF,
(Sec 3.2) and the continuous solid solution between UF, and ThF, (Sec 3.6)
indicate that the phase equilibria in the system Bng-ThF4-UF467 are es-
sentially predictable from the limiting systems. This has been confirmed

experimentally (Fig. 16). The system is dominated by the primary phase

UNCLASSIFIED
ORNL - LR - DWG 50123R
ThF‘l

144

400 ‘

COMPOSITION IN male %
1075 o, TEMPERATURE IN °C

PRIMARY PHASE AREAS
(0) UF,-ThE,ss
(b) BeF,

BeF,
548 €535

850 (o)

de / VANV \/ .
548\j . 1035

Fig. 16. The System BeF,-UF,-ThF,.

area of the UF,-ThF, solid solution. The only solid phases existing at
equilibrium are BeF, and the UF,-ThF, solid solution. The properties
of these solids are given in Secs 3.1 and 3.6 and in Appendixes A and

B. The system possesses a single boundary path and no ternary invariant

67c., F. Weaver, R. E. Thoma, H. A, Friedman, and H. Insley, J. Am.
Ceram. Soc., in press.
26

points. All mlxtures with lquIldU.S temperatures below 550°C contaln more

than-97 mole % Bngo‘

N . e b
". . ' .‘-' r

3. lO The System LiF-UF,- ThF4

The system LlF-UF4-ThF449 (Flgs. 17 and 18) 1s characterlzed by ex-

tenns1ve ternary solid SOlU.‘Pl_Ol’lS which. are shown -;h Figs. 19-22. The

t.

- 68The phrase "ternary SOlld solution" as used here 1mp11es that the
solid solution composition, lies within the system TiF- -UF,4-ThF, .+ Each of
the solid solutions in this system, however, may. be formed from mixtures
of two end members and in this sense is a binary series.

ThF,

M4 S UNCLASSIFIED
Lo ORNL-LR-DWG 28215AR3

. " PRIMARY-PHASE AREAS
TEMPERATURE IN °C

COMPOSITION IN mole T

(@) UF,-ThF, (ss)

(b) LiF-4UF,~LiF-4ThF, (ss)

. () LiF-2Th{U)F, (ss) .

LiF-4ThE, - ' (d) - 7LiF-6UF,~7LiF-6ThF, (ss)
-2 (e) 3LiF-Th(U)F, (ss)

(f) LiF

LiF-2ThF,
P 897 AN
/N
7LiF-6ThF, ‘
P 762 . )
‘ >
P 597 A \
£ 568
3LiF-ThF,
£ 565 \
Q P 609
Alf)

2
3 O
_ e ] \
845 aLiF-ury” P500" '£490 P 610 j\ P 775 . LiF-4UF, 055
. TLIiF-6UF, :

Fig. 17. The System LiF-UF,-ThF,.
UNCLASSIFIED
PHOTO 32550

Fig. 18. The System LiF-UF,-ThF,.
28

UNCLASSIFIED
ORNL-LR-DWG 27915AR

& THERMAL BREAKS
© QUENCH DATA SEPARATING REGIONS (2)(4)(¢) AND (¢)
1100 THE SYMBOLS BELOW INDICATE CHANGES WITH
DECREASING TEMPERATURE
o (a) TO (&)
® (5) TO (¢)
®(c) TO (2)
< | e (5) TO (d) (@)
1000 ]
\\‘ A
3
& I(m
= LIQUID + UF, — ThF, ss
& 900 }
s
= ILIOUID+ UF, =ThFy ss + LiF+4 UF, —LiF - 4 ThF, ss
™ .
s S
800 -
(d) t e
LiF - 4UF4 —LiF - 4ThF, ss
700
0 10 20 30 40 50 60 70 80
UF, (mole %)
Fig. 19. The System LiF-UF,-
ThF,: 20 Mole % LiF Section.

points are listed in Table 10.

The temperatures and compositions

equilibrium phase behavior of a
ternary system involving solid
solutions can be clearly and un-
ambiguously described only by an
extensive series of isothermal
sections, fractionation paths in
the primary phase areas, and tie
lines in the subsolidus regions.
Four isothermal sections which il-
lustrate the invariant and the
subsolidus phenomena are shown in
Figs. 23-26.

paths for the primary phase areas

The fractionation

of the solutions may be found in
Fig. 27. Tie lines for three of
the subsolidus two-phase regions
are shown in Fig. 28.

of the three ternary invariant

The compatibility triangles associated

with these invariant points are shown in Fig. 29 and Table 10.
TEMPERATURE (°C)

1100

1000

900

800

700

600

500

(@)
(b)
()
(d)
(e)
(#)
(g)
(h)

29

UNCLASSIFIED

ORNL-LR-DWG 35506R
UFa — ThFs ss + LIQUID
LiF - 4UF, ~ LiF - 4ThF, + LIQUID
UF,—ThF, ss + LIQUID + LiF - 4UF, = LiF - 4ThF, ss
LiF - 2ThF, ss + LIQUID + LiF- 4UF, — LiF - 4ThF, ss
LiF - 4UF, —LiF- 4ThF, ss + LIQUID + 7LiF- 6 UFy — TLiF- 6ThF, ss ~
LiF- 2ThF, ss | ' |
LiF- 4UF,—LiF - 4ThF, ss + 7LiF - 6 UF4— 7LiF - 6ThFa ss
LiF - 4UFy —LiF-4ThF, ss + 7LiF - 6UF, ~7LiF - 6ThF, ss +LiF- 2ThF, ss

A THERMAL BREAKS
® QUENCH RESULTS
O TIE LINE INTERSECTION

(@) -7 o~
‘\ LIQUID (£) (T
\ -
A
NQ (o) R T ——— ‘
A \
.\‘_\\
\--\‘C
\\Ҥ
(b)
' A\
(£) \}-‘ll/ (€)
I (9
I
|1t
0 10 20 30 a0 50 60 662,
UF, (mole %)
Fig. 20. The System LiF-UF4-ThF,: 33-1/3 Mole % LiF Section.
TEMPERATURE (°C)

850

800 $=

700

650

{a)
(b
(c)
(&)
(6)
(7)

30

LiF - 4UF, = LiF ~.4ThFy ss + LIQUID
LiF - 2ThF, ss + LiF - 4UF, —LiF-- 4ThF, ss + LIQUID

LiF - 2ThF, ss + LIQUID _
LifF -2ThF, ss + 7LiF - 6UF, — 7LiF - 6ThF, ss + LIQUID

7LiF - 6UF, — TLiF -6 ThF, ss + LIQUID
7LiF - 6UF,— 7LiF - 6 ThF, ss

UNCLASSIFIED

ORNL-LR-DWG 27917AR

A THERMAL BREAKS
® QUENCH RESULTS
© TIE LINE INTERSECTION

LIdUID

(@)

()

Fig. 21. The System LiF-UF,-ThF,: 53.8 Mole % LiF Section.

20

25

UFy (mole %)

30

35

" 40

45 46.2

o
Fig. 22. The System LiF-UF,-ThF,:

TEMPERATURE (°C)

575

550

525

500

475

450

31

UNCLASSIFIED
ORNL-LR-DWG 35503R

LIQUID + 3LiF ThF, ss

LiF+ LIQUID

LiF + 3LiF - ThF, ss + LIQUID

LiF + 7LiF - 6 Thf, — 7LiF - 6UF, ss + LIQUID
4LiF-UF, + LIQUID + LiF

4LiF - UF, + LIQUID

4LiF-UF, + 7LiF-6ThF, —7LiF-6UF, ss + LIQUID
3LiF- ThFy ss

3LiF - ThF, ss + 7LiF - 6 ThF, — 7LiF - 6UF, ss + LiF
LiF + 7LiF - 6 ThFy— 7LiF - 6 UF, ss

LiF + 4LiF -UF, + 7LiF -6 ThF, — 7LiF - 6 UF,; ss

4 LiF - UF, + 7LiF - 6 ThF, — 7LiF - 6 UF, ss

T i
A THERMAL DATA
® QUENCH DATA

p -
v:\ . O TIE LINE DATA
<

LIQuUID

(c)

(M

/ ()

® (d)

1
(Y2 VA IS
) Vo™

AN

o
(6]

10 15 20

UF, (mole %)

25

75 Mole % LiF Section.
32

UNCLASSIFIED
ORNL—LR—DWG 35742

a
{a} CONTAINS:
1) LiF- 4 ThE,— Lif- 4UFy ss
2} LiF - 2ThF,ss
3) 7LiF- 6 ThF, — 7 LiF- 6UFss
4) LIQUID
LiF - 4ThF, ’
Y t
L ]
o. _
. (’-i\ .
¥ N )
LiF -2ThE, AL
’. <. 44\ [ 0
e N ¥ . '
. \ L) =4
e © . A %
.. ’;X 4('\ .. z\;\
O. g\ po .. P\ \o v
o))
(gfi '.“{'s\ ;‘\{}\ o (,‘qp%
. a . 7 % » ‘
D x Za % /// . =S
% Te %S W e
/” 4 .
/! .o
[ ]
By >
/s 7/ ¢ .
/7 = .
/7 7 < it
Y o, %
VA ) e
/s 7 A *
'y { ?(\P\ [
,’l,/“o. P\A (’.&\ o.
\ X A% <. @ %
(6('*"43 % G %
LIQUID X & %, .
. C.’«‘“'o . fal %
LiF v\ e o .
') [ ]
+ ¢ % %
_LIQUID .
LF v, \/ VARRCOURY, \/ \/ LY V uF,
7LiF -6 UF, ' Lif - 4UF,
Fig. 23. The System LiF-UF,-ThF,: 609°C Isothermal Section.

&
33

UNCLASSIFIED
ORNL—LR—DWG 357414R

TLIF-6Thfy £ (@) CONTAINS:
1) TLiF- 6UF; — 7TLiF- 6ThF;ss
2) 3LiF- ThF, ss
3) LiF
4) LI1QUID

(5} CONTAINS:

1) 7LIF- BUF, — 7LiF - 6 ThF, ss
2) LiF- 4UF4—LiF-4ThF455
3} LiF- 2 ThF,ss

3LiF-ThF ss +

SLIF-Thf, 7LiF - BUF, —7LiF - 6ThF, ss .

LiF +
3 LiF - ThF4 5S

Pt e LiouiD + .
PP b Oy TUF-BUE — R
Pt LiF + LIQUID C. TLiF- 6ThF,ss % T
/’:”’ © .. %\
- - Y
LiF L2V \/ v AV \/ v Y V VAN
7LiF- BUF,

Fig. 24. The System LiF-UF,-ThF,: 500°C Isothermal Section.
34

UNCLASSIFIED
ORNL —LR—DWG 35738

(6) CONTAINS:
1) 7LiF+ 6UF, — 7LiF- 6 ThF,ss
2) 4LiF- UF,
3) LiF
4) LIQUID

() CONTAINS:
1) TLiF - 6UF, —7LiF-6ThF, ss
2) LiF - QUF, —LiF- 4 ThF, ss
- 3) LiF- 2 ThRyss '

| 3LIF-ThE, ss + e
7LiF BUFy — 7 LiF- 6ThF, 55

LiF + . .
3LiF - ThF, . ———TT
- Thigss %o e - . S
—— - . 'éfi
//‘ ”’ . .. P.s\
-7 BLIF-Thigss + -~ o5
-
g TLIF-6UF, — ”,— . CA;‘\
L7 TLiF -6 Thf 55 -~ O LiIF+ .
L77 HUF -7 TLIF-6UR — TLIF - 6ThE,ss %

4 LiF - UF,

Fig. 25. The System LiF-UF,;-ThF,: 488°C Isothermal Section.

#
35

UNCLASSIFIED
ORNL—LR—DWG 35739

ThF,

{g) CONTAINS:

1) LiF- 4UF, —LiF - 4ThF, ss

2) 7 LiF-8UF, — 7TLiF- 6 ThF, ss
3) LiF- 2ThE,

{L) CONTAINS:

1} 7Lil- GUFZ — 7 LiF: GTth L1
2} 3LiF- ThE, ss
3) LifF

{c) CONTAINS:
1) 3LiF - ThF, ss
2} LiF

[ ]
3LiF- ThF,ss*, , 2N )
+7LIF-BUF, =%, 4 IR o

——

- LiF + . %

P [ ]
[ o LR BU = /L b ing s S, ",
- L N -
I/,’/ A o.
I’ .
LiF \/ Vi \/ v v Vi v °/ Vi U,
7 LiF - 6UF, LiF -4UF,

Fig. 26. The System LiF-UF,-ThF,: 450°C Isothermal Section.
36

UNCLASSIFIED
ORNL-LR-DWG 358505R

ThF,

LiF - 4ThF,

LiF-2ThF,

: P

P //
_ \\94 / .
2

\/ ‘g‘, >-45\/ \/ N, \/

aLIF-UE, PE P TLIF-BURy LiF: QUF,

LiF UF,

Fig. 27. The System LiF-UF,-ThF,: Fractionation Paths.

A

L1
37

UNCLASSIFIED
ORNL—LR—0OWG 35740R

50% ThF,

7LiF-6ThF,

® PHASE COMPOSITION.
4 QUENCH COMPOSITION

3LiF - ThF,

-
—

-
-——

4 Lif - UF, _ — UF, 7LiF-6UFR,

Fig. 28. The System LiF-UF,-ThF,: Tie Lines.
38 -

Table 10. Invariant Equilibria in the System LiF-UF,-ThF,*

Composition of

Invariant Point Invariént . Type Solid Phases

. . C in Equilibrium
(mole. %) ' '-Tempfrature O? . at the Invariant
(°c) Equilibrium Temperature
LiF UF,  ThF, - |
63 19 18 - 609 Peritectic LiF«4ThF,-LiF-4UF,ss
' . containing 28
mole % UF,, -
LiF-2Th(U)F ss

containing 23 mole
% UF,, 7LiF<6ThF,-
7LiF.6UF,ss con-
taining 23 mole %
4 UF,; .
72.5  20.5 7 500 Peritectic 7LiF+6ThF,, -

- . o o 7LiF.-6UF,ss contain-
ing 31 mole % UF,,
3LiF-Th(U)F,ss con-
taining 15.5 mole %
UF,, LiF |

72 26.5 1.5 488 . Eutectic 7LiF +6ThF, -~
| | 7LiF-6UF,ss contain-
ing 42.5 mole % UF,,
LLiF-UF,, LiF

*C. F. Weaver et al., Phase Equilibria in the Systems UF,-ThF, and
LiF-UF4-ThF,, ORNL-2719 (Aug. 17, 1959); J. Am. Ceram. Soc. 43, 213
(1960).

39

UNCLASSIFIED
ORNL-LR-0WG 35504

Thf,

LiF - 4ThF,,

LiF - 2ThF,

7LiF - 6ThF,

——609°C

3LiF . ThF4 (c)

LiF 4LiF - UF, 7LiF - 6UF, LiF- qUF, UF,

Fig. 29. The System LiF-UF,-ThF,: Compatibility Triangles.

3.11 The System LiF-BeF,-UF,-ThF, (Selected Portions)

Detailed phase equilibrium studies for an entire quaternary system
require such a vast amount of time and money that they aré usually cuuw-
pleted over a number of years if at all. The system LiF-BeF,-UF,-ThF,
is no exception in this respect, and consequently the experimental work
was directed toward compositions which posses sufficiently low liquidus
and viscosity values to be of project interest.

The similarities between the systems BeF,;-ThF, and BeF,-UF,, the
systems LiF-ThF, and LiF-UF,, and the systems LiF-BeF,-''nt, and LiF-BeF,-
UF, have been discussed in Secs 3.2, 3.5, and 3.8 of this report. Within
the systems 1JF,-ThF, and Li¥F-UF,-ThF, extensive solid solutions are formed
between corresponding compounds. The existence of these similar systems

and of solid solutions between analogous compounds leads to the hypothesis
40

that UF, and ThF, are very nearly interchangeable in the quaternary mix-
turestwith respect to their liquidus values and that the phase relation-
ships in the quaférfiary system will be very much like those in the ternary
systems LiF-BeF,-ThF, and LiF-BeF,-UF,. Four sections of constant mole |
per cent LiF and BeF, were studied experimentally as a means of partially N
verifying this hypothesis. These sections contain 70 LiF and 10 BeF,,
67.5 LiF and 17.5 BeF,, 70 LiF and 6 BeF,, and 65 LiF and 25 BeF, (mole
%). The first two sections include the compositions C-136 and BeLT-15
(see Appendix C). The experimental results of these experiments may be
found in Table 11. The liquidus values along the first three joins are
nearly linear functions of the composition (Figs. 30-32). The deviation
from linearity in the fourth join (Fig. 33) is in the direction of lower
liquidusttemperaturesL The ThF,-containing end member has the maximum
liquidus temperature for all the joins, while the UF,-containing end
member has the minimum liquidus temperature for three of the four joins.
The solid solution 7LiF+6(U,Th)F, is the primary phase for all the com-
positions on the joins listed above. The interchangeability of UF, and
ThF, implies that a breeder blanket selected from the quatérnary.system
or its limiting systems will contain the maximum concentration of ThF,
for a given temperature only if no UF, is present. 1In other'words; if
UF, is added an approximately equal amount of ThF, must be removed to
maintain the same liquidus temperature. '

Mixtures containing a maximum amount of ThF, for a given temperature
are found in the system LiF-BeF,-ThF, (Figs. 9%-11) up to 568°C. Above
568° the mixtures must contain no BeF,; thus they will be binary mixtures
of LiF and ThF,. : - |

The members.of a second series contain a small total mole percentage
of UF, and ThF, (Table 11). They represent the breeder fuels, such as
C-134, BULT 4-0.5U, and BULT 4-1U. Cdmpositions containing up to 5 mole -
% UF, + ThF, in the range 30-38 mole % BeF, have 1iquidus values close to
those. of the system LiF-BeF,. These compositions differ from the LiF- =
‘Bng binary mixtures in that their liquidus values are slightly lower

and solid solutions containing UF,; and ThF, precipitate as primary or
Table 11. Thermal Gradient Quench Data for the System LiF-BeF,-UF,-ThF,

Composition a
(mole %) : Tem?fg?ture Phasesb Above Temperature Phasesb Below Temperature
LiF BeF's UF4 ThF4
55 35 3 7 427 + 3 LS and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
2LiF -BeF,
56 35 2 7 432 *+ 3 L and 7LiF-6(U,Th)F,ss L, 7LiF+6(U,Th)F,;ss, and
2LiF -BeF,
57 35 3 5 488 + L L and LiF-2ThF,ss
57 35 3 5 480 * L and LiF-2ThF,ss L and 7LiF.6(U,Th)F,ss
57 35 3 5 433 L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
| 2LiF -BeF,
58 35 2 5 498 + 3 L L and LiF-2ThF,ss (15 mole
| % UF,)
58 35 2 5 460 + 2 L and LiF.2ThF.ss 'L and 7LiF-6(U,Th)Fsss (11
' mole % UF,)
58 35 2 5 433 £ 3 L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
2LiF-BeF2
59 35 3 3 479 + 2 L L and 7LiF.6(U,Th)F,ss (22
mole % UF.)
59 35 3. 3 434 £ 2 L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
2LiF-BeF2
60 35 2 3 449 + 2 L L and 7LiF.6(U,Th)F,ss
60 35 2. 3 440 * L and 7LiF.6(U,Th)F,ss L, 7LiF-6{U,Th)F,ss, and
2LiF-BeF,
60 35 2 3 ~425 L, 7LiF-6(U,Th)F;ss, and 2LiF.BeF, and
2LiF-BeF, 7LiF-6(U,Th)F,ss (20 mole

% UF,)

17
Table 11 .(continued)

Composition

a . ) . .
(mole %) Tem%igjfiure A Phasesb Above Temperature ‘Phasesb-Bele Temperature
LiF  BeF, UF;  ThF,
60 36 3 1 449 + L . L and 7LiF.6(U,Th)F,ss
60 36 3 1 432 * L and 7LiF+6(U,Th)F,ss L, 2LiF-BeF,, and
o ‘ _ - 7LiF-6(U,Th)F,
60 37 2 1 - 434 * L L and 7LiF+6(U,Th)F;ss - -
60 37 - 2 1 431 * L and 7LiF+6(U,Th)F,ss L, 7LiF+6(U,Th)F,;ss, and
" , - : S 2LiF.BeF,
60 38 442+ L . | L and 2LiF.BeF,
60 38 1 1 433 %2 I and 2LiF-BeF, L, 2LiF+BeF,, and
| : . : 7LiF+6(U,Th)F,ss (20 mole
| | b UF,)
61 36 2 1 437 2 L - L and 2LiF-BeF,
61 36 2 1 434 + 2 L and 2LiF-BeF, L, 2LiF-BeF,, and
‘ ' ' - 7LiF-6(U,Th)F,ss (23 mole
. : % UF,) |
61 37.5 0.5 1 439 + 3 L I and 2LiF-BeF,
62 34 3 1 446 * 2 . . L and 7LiF.6(U,Th)F,ss
62. 34 -3 1 443 % L and 7LiF-6(U,Th)F,ss L, 7LiF+6(U,Th)F,ss, and
. . . 2LiF°BeF2 '
62 36 . 1. 1 446 + 2 L L and 2LiF<BeF,
62 36 1 1 438 = 2 L and 2LiF-BeF, - L, 2LiF-BeF,, and
- : | | ) 7LiF-6(U,Th)F,ss
62 36 1 1 ~420 I, 2LiF-BeF,, and 2LiF+BeF, and
. : - 7LiF-6(U,Th)F,ss 7LiF+6(U,Th)F,ss

c7
Table 11 (continued}

Composition 5
(mole %) Temp?figure Phasesb Above Temperature Phasesb Below Temperature

LiF BeF, UFy ThF,,

62 36.5 0.5 1 452 + L L and 2LiF-EeF,

62 36.5 0.5 1 448 * L and 2LiF-BeF, L, 2LiF-BeF,, and
7LiF.6(U,Th)F,ss

62 36.5 0.5 1 ~433 L, 2LiF-BeF,, and 2LiF.BeF, and

7LiF+6(U,Th)F;ss 7LiF+6(U,Th)F,ss .

63 35 450 = L L and 2LiF.BeF,

63 35 438 + L and 2LiF-BeF, L, 2LiF+BeF.;, and
7LiF.6(U,Th)F,ss

63 35 1 1 416 * L, 2LiF+BeF,, and 2LiF+BeF, and

7LiF.6(U,Th)F ss 7LiF+6(U,Th)F,ss

63 35 2 442 + L L and 2LiF-BeF,

63 35 438 = L and 2LiF-BeF, L, 2LiF+BeF.;, and
7LiF-6(U,Th)F,ss (23 mole
% UF,)

63 35.5 0.5 456 * L L and 2LiF-BeF,

63 35.5 0.5 448 * L and 2LiF-BeF, L, 2LiF+BeF;, and
7LiF.6(U,Th)F,ss

64 32 3 1 446 + L L and 2LiF-BeF,

64 32 3 1 443 & L and 2LiF-BeF; L, 2LiF-BeF;, and
7LiF.6(U,Th)Fss

64 33 2 1 442 + L L and 2LiF.BeF,

v
Table 11 (continued)

Composition

a : .
(mole %) Tempifggure Phasesb Above Temperature Phaseéb Below Temperature
IiF - BeF, UF,  ThF, o -
64 33 2 1 440 * 2 L and 2LiF-BeF, L, 2LiF-BeF,, and |
| ' 7LiF+6(U,Th)F ss (22 mole
| % UF,)
65 25 3 7 477 £ L L and 7LiF-6(U,Th)F,ss
65 25 3 7 437 + L and 7LiF+6(U,Th)F,ss L, 7LiF- -6(U,Th)F,ss, and
65 25 5 5 447 + 3 L L and 7LiF+6(U,Th)F;ss (22 |
. mole % UF,)
65 25 5 5 437 + 3 L and 7LiF-6(U,Th)F,ss I, 2LiF-BeF,, and - N
: , 7LiF-6(U,Th)F,ss '
65 25 5 5 430 + 3 L, 2LiF+BeF,, and 7LiF+6(U,Th)F;ss and
7LiF+6(U,Th)F,ss 2LiF+BeF,
65 25 8 2 442 £ 3 L | ) | L and 7L1Fo6(U,Th)F4ss
65 25 8 2 432 * L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss (36 mole
' % UF,), and 2LiF-BeF,
65 - 25 8 2 424 + 2 L, 7LiF+6(U, Th)F4ss, and  LiF, 7LiF.6(U,Th)F,ss, and
2LiF -BeF, 2LiF-BeF,
65 30 1 4 448 + 2 L L, 2LiF.BeFp, and
' : . ' 3LiF+ThF,ss
65 30 1 A 423 + 2 L, 2LiF.BeF,, and L, 2LiF.BeF,, and o
: 3LiF.ThF,ss 7LiF-6(U,Th)Fsss (9 mole
- : % UF,)
65 30.5 0.5 4 453 = 1 L , L and 3LiF-ThFyss
65 30.5 0.5 4 448 + L and 3LiF.ThF,ss . L, 3LiF-ThF,ss, and

2LiF-BeF,
Table 11 (continued)

Composition a
(mole %) Temp?fggure Phasesb Above Temperature Phasesb Below Temperature
LiF Bel', UF, ThF,
65 31 449 £ 2 L L and 2LiF.BeF,
65 31 3 443 + 2 L and 2LiF-BeF, L, 2LiF.BeF,, and
7LiF+6(U,Th)F,ss
65 33 465 = 1 L L and 2LiF-BeF,
65 33 446 = 2 L and 2LiF-+BeF, L, 2LiF.BeF,, and
7LiF-6(U,Ta)F,ss (22 mole
. % UF,)
65 33 1 1 408 + 2 L, 2LiF+BeF,, and 2LiF-BeF, and
7LiF-6(U,Th)F,ss 7LiF-6(U,Th)F,ss
66.4 24.9 5.4 3.3 446 + 2 L L and 7LiF+6(U,Th)F,ss (21
mole % UF.)
67 18. 0.5 14 499 + L L and 3LiF-ThF,ss )
67.5 17.5 12 490 + L L and 7LiF.6(U,Th)F,ss
67.5 17.5 12 480 = L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F,;ss, and
3LiF-ThF ,ss
67.5 17.5 3 12 429 * 2 L, 7LiF-6(U,Th)F,ss, and L and 3LiF+ThF,ss
3LiF-ThF,ss
67.5 17.5 490 + L L and 7LiF+€(U,Th)F,ss
67.5 17.5 462 + L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
3LiF.ThF,ss
67.5 17.5 6 9 429 £ 2 L, 7LiF-6(U,Th)F,;ss, and L, 7LiF-6(U,Th)F,ss, and

3LiF-ThHF,

2LiF +BeF,

GY
Table 11 (continued)

Composition

-,

a .
(mole %) Tempifggure Phasesb Above Temperature 'Phasesb Below Temperature
LiF _Bng UF, ThF, |
S 67.5 17.5 9 484 + | o L and 7LiF+6(U,Th)F,ss
67.5 ~17.5 438 + L and 7LiF+6(U,Th)F,ss L, 7LiF-6(U,Th)F;ss, and
S . ' 2L1F -BeF,
87.5  17.5 12 484 % L L and 7IiF- 6(U,Th)F4ss
67.5 17.5 12 433 % L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and
- ' : 2LiF-BeF, - |
68 18.7 10.8 2.5 446 + L L and 7LiF-6(U,Th)F,;ss (34
| mole % UF,)
. 69.7 12.4 16.2 1.7 461 * L L, LiF, and 7LiF:6(U,Th)F,ss
‘ | (38 mole % UF,)
70 18 540 * L L and 7LiF-6(U,Th)F,ss
70 18 531 + L and 7LiF-6(U,Th)F,ss L, 7LiF.6(U,Th)F;ss, and
A . 3LiF°ThF4SS '
70 6 12 12 516 * L L and 7LiF-6(U,Th)F,ss (16
| | mole % UF,)
70 6 12 12 ' 503 * L and 7LiF.6(U,Th)F,ss L, TLAF- 6(U, Th)F4ss, and
' ‘ » 3LiF+ThF,ss |
70 6 .18 6 494 + L L and 7LiF. 6(U Th)F4ss (30
- . | | : mole % UF,) . .
70 .18 6 476 % L and 7LiF-6(U,Th)F,ss L, 7LiF-6(U,Th)F,ss, and LiF
70 24 od 480 % L | L and 7LiF-6UF,
70 - 24 o4 462 t L and 7LiF-6UF, L, 7LiF.6UF,, and LiF

9%
Table 11 (continued)

Composition a
(mole %) Tempfiiggure Phasesb Above Temperature Phasesb Below Temperature
LiF Bel', U-Fg'_ ThF4
70 10 5 15 512 + 3 L L and 7LiF+6(U,Th)F;ss (6
mole % UF,)
70 10 5 15 510 + 3 L and 7LiF-6(U,Th)Fyss (6 L, 7LiF-6(U,Th)F;ss, and
mole % UF,) 3LiF-ThF,ss
70 10 5 15 485 + 3 L, 7LiF+6(U,Th)F,ss, and L and 3LiF.ThF;ss
3LiFThF,ss
70 10 10 10 493 = L L and 7LiF.€(U,Th)F;ss
70 10 10 10 489 + L and 7LiF.6(U,Th)F,ss L, 7LiF.5(U,Th)F;ss, and
3LiF-ThF,ss
70 10 10 10 455 + 3 L, 7LiF-6(U,Th)F,ss, and L, 7LiF+6(U,Th)F,ss, and
3LiF+ThF,ss LiF
70 10 15 5 475 £ 3 L L and 7LiF+6(U,Th)F,;ss (28
mole % UF,) |
70 10 1= 5 471 + 3 L and 7LiF+6(U,Th)7,ss L, 7LiF.6(U,Th)F,ss (28
mole % UF,), and LiF
71 16 1 12 513 = L L and 3LiF.ThF,ss
71.4 6.2 21.6 0.8 483 + L L and 7LiF+5(U,Th)F.ss (13
mole % UF,)
71.4 6.2 21.6 0.8 480 * 2 L and 7LiF+6(U,Th)F,ss L, LiF, and 7LiF.6(U,Th)F,ss

aThe uncertainty indicates the temperature difference between the quenched samples.

bOnly phases -found in major quantity are given.

Minor quantities of other phases resulting from

lack of comp_ete reaction between solids or from trace amouats of oxide impurities are not noted.
Glasses or poorly formed crystals assumed to have been produced during rapid cooling of liquid were
found in those samples for which the observed phase is indicated as "liquid."

C

L = liquid.

dThis ternary mixture is included here because its liquidus temperature, as measured at ORNL, dif-
fers somewha® from that found on the Mound Laboratory diagram for the system LiF-UF,;-BeF, (Fig. 7).

L7
48

UNCLASSIFIED
ORNL-LR-DWG 39287R

600
\</ LIQUIDUS :
£ 500 ——
&J ' .\
oD l\-_—.
g
a
w
s
& 400 , .
7LiF-6ThF,— 7LiF-6UF, ss PRIMARY PHASE
300
0 5 10 15 20

ug, (mole %)

‘Fig. 30. The Join LiF-BeF,-
ThF, (70-10-20)-LiF-BeF,-UF, (70-10-
20) in the Quaternary System LiF-
BeF,-ThF,-UF,.

UNCLASSIFIED
ORNL-LR=-DWG 50420

575 I T | 1 . T 1
7LiF'6Th|Z—7LiF'6UfZ ss PRIMARY PHASE
550 =g
- 5.\
S .
- &£ 525 .
wl
e L—1_IQUIDUS
g \<\ .
g 500 \.,\ .
li" \\
E 475
’—
450
425
400 -
0 5 10 i5 20 24
UF, (mole %)

Fig. 32. The Join LiF-BeFj,-
. Th¥F, " (70-6-24)-LiF-BeF,-UF, (70-6-
24) in the Quaternary System LiF-
BeF2-UF 4~ThE .

TEMPERATURE (°C)

UNCLASSIFIED
ORNL-LR~DWG 39286R

550
7LiF-6ThE,~7LiF - 6UF, ss PRIMARY PHASE
2
- _
%- .
& 500 '
EJ . . -fo-/__~__'__ ‘ '
E . . .fifi‘l .
i .
450 L — :
0 5 10 15

UF:‘ (mole %)

Fig. 31. The Join LiF-BeF,-
ThF, (67.5-17.5-15)~LiF-BeF,-UF,
(67.5-17.5-15) in the Quaternary
System LiF-BeF,-UF,-ThF,.

UNCLASSIFIED

ORNL-LR-DWG 50119

500 T T T Y T T

|| 7LIF-6THE ~7LiF-6UF, 55 PRIMARY PHASE
|
475 - \\ | :
: Nt~ Liavious 7
450 ' | A
e g
425
400
0 2 . a4 6 8

UF, (mole %)

Fig. 33. The Join LiF-BeF,-

 ThF, (65-25-10)-LiF-BeF,-UF, (65-

25-10) in the Quaternary System

'LiF Ber-UF4-ThF4.

'secondary phases. qunldns values rise sharply as the UF4 + ThF, concen—

tratlon is increased beyond 5 mole %.

The . compos1t10ns referred to in the ORNL lltera ture by code comprise

avthlrd series, which overlaps the group gbove. Their equilibrinm'be-

havior is, described in Table 11 and Appendix C.

Melts which have been cooled slowly, rather than annealed and

quenched frequently contaln nonequlllbrlum comblnatlons of stable phases,

A
o2

49

metastable phases, and glass. Consequently the phase analysis of slowly

cooled melts cannot be relied upon to yield subsolidus equilibrium data.

Supercooling is also observed and so affects the thermal analysis that
this technique for studying heterogeneous equilibria cannot be used for
the system LiF-UF,-ThF,-BeF,.

It has been suggested that the uranium concentration in a molten
salt reactor might be increased by adding the eutectic mixture of LiF
and UF4.69 Consequently, phase relationships in the quaternary section
between 73 LiF-27 UF, and 64.75 LiF—4.15 ThF,-31.1 BeF, have bheen inves-
tigated. This join contains the fuel mixture 65 LiF-30 BeF,—4 ThF;—1
UF,; (BULT 4-1U), and all the compositions which may be produced by mix-
ing 73 LiF-27 UF, and 64.75 LiF-4.15 ThF,—31.1 BeF,. The results of
thermal gradient quenching experiments may be found in Table 1l. The
liquidus values are shown as a function of composition in Fig. 34.

Throughout the investigated
UNCLASSIFIED
ORNL-LR-DWG 50424
600 portions of the quaternary sys-

tem, the compositions of the solid

550 solutions precipitating as pri-

mary phases indicate that the

an
o
o

_ U/Th ratio is less in the solid
uoumus-7:=,,~"°

T
s in the liquid phase. However,

which first appears than it is

H
(523
O
o
]

TEMPERATURE (°C)

the concentration of uranium in

400 | +r--- these precipitates is frequently

much higher than in the liquid

0 10 20 27 phase.

UF, {(mote %)
a . .
Quaternar Y mixtures such as

Fig. 34. The Join LiF-UF, (73- : :
27)—LiF-BeF,-ThF, (64.75-31.1-4.15) 62 LiF-36.5 BeF2—0.5 UF4—1 ThF,
in the Quaternary System LiF-BeF,- (mole %) (C-134) are hygroscopic
UF,~ThF,, . ' and are prone to hydrolyze.7©
Purified samples of this material were exposed to water-saturated air

at room temperature, vacuum-dried at 135°C, and melted under vacuum

6%F. F. Blankenship, ORNL, personal communication.
'OMSR Quar. Prog. Rep. Oct. 31, 1959, ORNL-2890, p 63.

50

(Fig. 35). The cooled melts contained appreciable amounts of UO,, which
was detected by polarized light microscopy.®3"7® These results indicate
that a simple drying operation

UNCLASSIFIED

RNL-LR-DWG 50422 . .
75 oRNLL o cannot be used with such mixtures

and that to prevent hydrolysis

|
_/,//f’ | these reactor fuels must be pro-
16.5 _ 1 . ) '
7 tected from water vapor even at
— 160 = | SAMPLE PLACED IN :
K= VACUUM DRY BOX, ;
= o R O / | room temperature.
5 ) TWO HOURS, FUSED , : S ) )
Y 55 /// > Several investigations of
|
<
S y A _ ) the interaction of molten mix-

tures of LiF, BeF,, UF,, and ThF4

found in the ORNL literature.

|
|
. ! . .
. /' . ! with other substances may be
12.0 ‘ ' i
|

B 5 w0 1’ 25 30 35 40 45 The. solubility of CeF3’' in
o LiF-BeF,-UF,-ThF, liquids and the

. Fig. 35. Hydration—Vacuum-Dehy- reactions of Be07? and steam on
dration Cycle for LiF-BeF,-~ThF,-UF,

(62-36.5-1-0.5). these solvents have been reported.

_ The exchange of CeF; (dissolved
in a quaternary solvent) and LaFs; (solid) has been studied.’® The segre-

60

gation effect of thermal cycling,®® graphite compatibility,®? and the

1eaching of chromium from INOR-872 have been investigated.

4. ACKNOWLEDGMENTS

It is a pleasure to acknowledge the assistance of G. M. Hebert, who
prepared a number of the quenched samples. We are especially grateful
to J. H. Burns, F. F. Blankenship, H. G. MacPherson, and J. E. Ricci for

" suggestions and advice concerning many phases of the investigation.

7!R. A. Strehlow et al., Reactor Chem. Ann. Prog. Rep: Jan. 31,
1960 ORNL-2931, p 79.
72J. H. Shaffer, G. M. Watson, and W. R. Grlmes, Reactor Chem. Ann.
Prog. Rep. Jan. 31, 1960, ORNL-2931, p 86.

_ 735, E. Eorgan et al., Reactor Chem. Ann. Prog. Rep. Jan. 31 1960,
ORNL-2931, p 67.. .

N
Appendix A

51

OPTICAL AND CRYSTALLOGRAPHIC PROPERTIES

The optical and crystallographic properties of the compounds which

occur in the system LiF-UF,-ThF,-BeF, are summarized in Tables A-1 and

A-2 respectively.

No. ternary or quaternary compounds have been observed.

The refractive indices of the LiF-UF,-ThF, and UF,-Th¥, solid solutions

may be found in Figs.

Table A-1.

A-1 through A-5.

Optical Properties of the Components and Binary

Compounds in the System LiF-UF,-1hF,-BeF,

Optiéal Optic Optic Refractive Indices
Compound Character Angle, Sign : Color
2V Nw or Na N€ or Ny
LiF Isotropic 1.3915 Colorless
BeF> Uniaxial + 1.325 Colorless
UF,° Biaxial ~60° —~ 1.552 1.598 Green
ThF4b Biaxial ~60° — 1.500 1.534 Colorless
2LiF-BeF,’ Uniaxial + 1.312 1.319 Colorless
LiF-BeF; Biaxial Large 1.35 (average) Colorless
4LiF-UF4b Biaxial ~10° — 1.560 1.472 Green
7LiF-6UF,° Uniaxial — 1.554 1.551 Green
LiFoAUF4b Biaxial ~10° — 1.584 1.600 Green
3LiF°ThF4d’e Biaxial ~10° — 1.480 1.488 Colorless
’7LiF'6'I‘hF4d Uniaxial + 1.502 1.508 Colorless
L1F-2ThF4d Ufiiaxial - 1.554 1.548 Colorless
LlF-4ThF4d’e Biaxial ~10° - 1.528 1.538 Colorless
“Am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 4-0857.

bH. Insley et al.,

Optical Properties and X-Ray Diffraction Data for Some

Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct. 23, 1956).

°W. W. Harris and R. A. Wolters, Optical Properties of UF,, MDDC-1662 (Nov.
5, 1947); USAEC, Abstracts of Declassified Documents, vol 2, p 103 Techni-
cal Information Div., Oak Ridge,

dR. E. Thoma EE al.,

J. Phys.

Tenn., 1948.
Chem. 63, 1266 (1959).

©This routinely observed biaxialifiy appears to be a function of strain,
since the crystal type is tetragonal as determined by x-ray diffraction

measurements (see Table A-2).
Table A-2. (Crystallographic Properties of the Components and the Binary Compounds
Which Occur in the System LiF-UF,-ThF,-BeF;

Lattice Parameters X-Ray

Compound g;zizzl Space Group Density
ag (A)  bo (A) co (A) B (g/cc)
LiF®  ©  Cubic (face-  4.0270 0’-Fm3m 2.638
o centered) ’ '
BeFéb S Hexagonal 4.72 5.18 : D¢ = C6,2,
' DI = C6,2
ThrF,° Monoclinic  13.1  11.0L 8.6 126° 5, -c2/ec - 5.71
U’Fg,c’d Monoclinic 12.82 - 10.74 8.41 126°10" Cgh-C2/c _ 6.70
7LiF-6UF,°  Tetragonal 10.48 | | 5.98 T4y /a
3LiF-’I‘hF4f Tetragonal 6.206 6.470 P4/nmm or P4/n 5.143
'7LiF-6ThF4f Tetragonal 15.10 6.60 | T4, /a | 5.387
LiF'ZThF4f Tetragonal 11.307 6.399 Body-centered(?)
LiF-4ThF4f - Tetragonal 12.984 . 11.46
- 2LiF-BeF,®  Hexagonal 13.23 8.87 )

“Am. Soc. Testing Materials, X-Ray lefractlon Data Cards, card No. 4-0857; H. E. Swanson and E.
Tatge, J C Fel Reports, NBS 1949. A

bThlS is the B-quartz form of BeF, routinely observed in the systems described in this report.

. The B- quartz and three other forms of BeF, are.described by A. V. Novoselova, Uspekhi Khim 27, 33 (1959).

w H. Zacharlasen, Acta Cryst. 2, 388 (1949).
Am Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 8-428.

L A. Harris, The Crystal Structures of 7:6 Type Compounds of Alkali Fluorldes with Uranium
Tetrafluoride, ORNL CF-58-3-15 (Mar. 6, 1958).

fL, A. Harris, G. D. White, and R. E. Thoma, J. Phys. Chem. 63, 1974 (1959)

€am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No. 6-0557; E. Thilo and H. A.
Lehmann, Z. anorg: Chem. 258, 332 (1949).

(4
UNCLASSIFIED
ORNL—LR—DWG 27944R

1.62
1.60 ——
= // ‘
3 1.58 "
= L
Q /
E 1.56 /,
w |
(¢4 | "]
% 154 — / ;’/
x ,/
‘é 152 P
= / ’/‘
150 "]
148
THE, 20 40 60 80 UF,
UR, (mole %)
Fig. A-1. Refractive Indices

of the UF,-ThF, Solid Solutions.

53

UNCLASSIFIED
ORNL-LR-DWG 27916R

1.62
1.60
b4
2 A
O 1.58
I
R T
T 156 >
w ' (T
© —"SCd INDEX OF
& ,//‘,o’/‘ T REFRACTION
2 1.54 o
Z v
[
1.52.
1.50
0 0 20 30 40 S0 60 70 80
UF, (mole %)
Fig. A-2. Refractive Indices

of the LiFo4UF4-LiF-4ThF4 Solid So-
lutions.

UNCLASSIFIED
ORNL-LR-DWG 35507R

1.57

N, =ORDINARY INDEX OF REFRACTION

1.56

//(

"

Q |
|

/‘1

O
~

INDEX OF REFRACTION
%)
o

N =EXTRAORDINARY INDEX OF REFRACTION

PROBABLE LIMIT
OF EXISTENCE
FOR 1iF- 2ThFg ss

)
IS

1.53

15 20 29 a0 -

UF; (mole %)

Fig. A-3. Refractive Indices of the LiF-2Th(U)F, Solid Solutions.
54

UNCLASSIFIED UNCLASSIFIED

-l R~ ORNL-LR-DWG 312t7R2
1.62 - ORN.L LR-DWG 279{8R2 1.540
1.60
2 1.530
=
S 1.58
x - . N, =ORDINARY INDEX OF REFRACTION<' z
wi N, =EXTRAORDINARY [NDEX OF REFRACTION\ Q 1.520 MAXIMUM EXTENT OF
x 1.56 3 5 3LiF- ThF,
o
S = p SOLID sownon—-l
x w !
w 1,54 ‘ & 1.510 f
8 T A i
- A ) .—0'/¢ © /
1.52 /‘,//I - 5 1.500 c‘(\ON / |
) < RS cFRM *
" . = % of RET : /0
1501 | y WoE _— |
0 "5 10 .15 20 25 30, 35 40 45 490 - Efauc“°§*“ !
o ' P R |
UF4 (mO'e o) ) . ] \NDE‘L Offi/ |
Fig. A-4. Refractive Indices 1-480¢ 5 5 é
Of the 7L1F 6IJF4"7L1F 6ThF4 SOlld UF4 CONTENT {mole %)
Solutions.

Fig. A-5. Refractive Indices
of the 3LiF.Th(U)F, Solid Solu-
tions.

Appendix.B

X-RAY DIFFRACTION DATA FOR THE SOLID PHASES OBSERVED IN- THE- QUATERNARY
SYSTEM LiF-BeF,-UF,~ThF, .

LiF> | ThF,, ThF, (continued)
Bngb a (A) I/11 a4 (a) I/Iy
a (a) I/13 7.63 10 2.528 12
. 5.24 10 2.495 12
4 .09 - 70 4.75 20 | 2.361 5
3.21 100 4 46 12 2.350 10
2.367 100 4.29 20 | 2.338 10
2.189 - 100 - 4.02 60 2.259 5
2.154 100 © 3.80 100 2.242 5
1.905 70 3.72 5 2.196 5
1.748 50 3,63 - 50 2.156 15
1.606 35 3.43 ' 15 2.132 35
1.591 20 3.35 50 2.113 - 35
1.550 30 3.04 5 2.067 5

1.484 30 2.848 5 2.040 20
1.320 30 2.796 5 2.023 20
1.233 15 2.747 15 . 1.985 . 35
1.208 15 2.723 .5 1.965 15
- ' 2.629 5 | 1.937 .15
UF, o 1.922 25

(s
¥

55

Appendix B (continued)

ThF, (continued) 3LiF-UF4b - 7LiF-6UF4b
(metastable) (continued)

a (a) 1/1,

a (A) I/I,1 a (A) I/I,
1.881 10
1.859 - 5. 4 .98 20 3.33 90
1.771 10 4% .80 15 3.15 70
1.737 10 4 41 100 3.07 10
1.683 20 4 .34 100 2.99 95

- 1.666 10 3.98 15 2.771 30
1.640 10 3.91 8 2.707 30
1.612 10 3.60 80 2 .542 25
1.588 5 3.40 10 2.350 13
1.575 10 3.14 25 2.286 25
.1.520 20 3.07 50 2.264 13
1.484 5 2.84 80 2.184 10
1.455 20 2.771 30 2.097 30
1.431 10 2.529 35 2.060 30
1. 404 5 2.169 15 2.047 75
1.373 10 2.083 75 1.993 25
_ o 2.055 35 1.972 20
4LIiF-UF, 1.943 50 1.947 25

1.913 - 25 1.924 15
a (a) 1/1, 1.861 30 1.909 30

1.751 25 1.854 45
5.67 20 1.723 25 1.825 20
5.46 25 1.685 25 1.773 20
5.13 70 1.662 8 1.757 25
4.93 100 1.646 20 1.709 15
4 .55 45 1.599 8 1.680 15
A 100 1.625 15
4 .23 7 7LiF-6UF,, 1.579 25
3.82 40 : 1.562 8
3.55 30 a (A) 1/1, =
3.03 50 LiF-4UF,
2.89 25 6.61 6
2.866 30 5.97 20 a (a) I/1,
2.747 50 5.82 15
2.468 40 5.24 90 7.02 8
2.398 20 5.15 10 6.33 12
2.221 40 4.65 10 6.07 5
2.107 75 4 .37 13 5.73 25
2.07% 20 3,95 55 4.98 8
2.025 20 3.85 13 4.70 25
1.872 20 3.68 20 .25 90
1.836 25 3.49 75 3.88 20
56

Appendix B (continued)

LiF-4UF4b4 3LiF-ThF4d
‘(continued) (continued)
da (A) I/1, da (a) I/I1
3.78 100 1.701 35
3.52 90 1.661 10
3.16 8 1.618 10
3.13 8 1.547 35
3.06 12 1.520 35
2.84 40
g:zzg 52 7LiF‘6ThF4d
2.350 10
2.310 10° a (a) 1/1,
2.226 8
2.000 10 6.07 15
2.088 35 5.91 20
2.016 60 5.36 90
1.991 50 5.25 15
1.888 20 4 .95 30
1.819 8 .85 . 20
1.767 25 475 100
- T 4.01 85
3LiF-ThF, 3.92 15
—— ‘ 3.74 15
a (a) I/1, 3.55 65
' - . 3.44 10
6.42 100 3.39 70
4.6 100 3.29 60
4,37 100 3.03 100
3.62 85 2.814 25
3.09 55 2.747 25
2.866 70 2.578 20
2.788 30 2.430 10
2.542 25 2.392 10
2.327 10 2.302 20
2.189 20 2.137 20
2.104 65 2.018 5
1 2.071 25 2.001 15
2.036 40 1.892 55
1.959 30 1.859 15
1.933 .- .60 1.804 15
1.877 .25 1.680 15
1.771 25 1.653 20
1.743 30 1.600 20

LiF°2ThF4d
da (A) 1/1,
7.97 5
6.37 10
3.96 100
3.57 65
3.25 5
3.21 5
2.97 20
2.822 25
2.675 7
2-.528 10
2.388 5
2.123 85
2.053 "~ 30
2.001 65
1.787 7
1.701 10
1.689 5
1.603 5
1.519 5
LiF°4ThF4d
a (A) I1/1,
8.34 3
7.76 3
6.51 5
5.80 25
4 .62 5
4.33 70
3.88 100
3.60 60
3.25 10
2.92 25
2.822 25
2.603 10
2.398 10
2.137 25
2.053 35
2.040 10
2.018 10
2.005 30

y—
_Appendix B (continued)

LiF-4Thr, LiF.BeF,T LiF-BeF,~

(continued) (continued)
a () - 1n - h ¢ (0 I/12
1.937 .20 4.353 20 2.040 20
1.820 20 3 .;1.80 50 1.829 10
1.778 3 3.084 30 1.691 10
1.725 5 2.926 20 1.558 - 5
1.719 5 2.836 5 1.488 2
1.666 5 2.780 50 1.439 2
1.605 5 2.739 10 1.324 10
1.595 5 2.455 40 1.303 1
1.563 5 2.259 50 1.244 2
2.201 100 - 1.233 1
2LiF . Bng € 2 .074 80 . 1. 216 2

“Am. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No.
4"0857 . :

bH. Insley et al., Optical Properties and X-Ray Diffraction Data. for
Some Inorganic Fluoride and Chloride Compounds, ORNL-2192 (Oct. 23, 1956).

cAm.ASoc. Testing Materials, X-Ray Diffraction Data Cards, card No.
8-428.

. E. Thoma et al., J. Phys. Chem. 63, 1266 (1959).

'eAm. Soc. Testing Materials, X-Ray Diffraction Data Cards, card No.
6-0557.

fg. Thilo and H. A. Lehmann, Z. anorg. Chem. 258, 332-55 (1949).

~ Appendix C

58

; LIQUIDUS TEMPERATURES AND PRIMARY PHASES FOR SPECIFIC COMPOSITIONS

 FULL 73

73

27

Composition Liquidus
(mole %) TquLed Primary Phase
Code Temperature
. . (°C) or Phases
LiF BeF2 U-Fz, ThF4
C-9 .. 100 548 BeF,
c-10 100 845 LiF
C-74 69 31 530 LiF
C-75 67 30.5 2.5 464 LiF
C-111 71 16 1 12 505 3LiF+ThF,ss
c-112 50 50 370 2LiF «BeF,
C-126 53 46 1 400 2LiF-BeFs
c-127 58 35 7 460 LiF.2ThF,
c-128 71 29 568% 3LiF <ThF, and
| ‘ .7LiF +6ThF;
'C-130 62 37 1 440 2LiF-BeF,
- C-131 60 36 b 450 7LiF+6UF,
C-132 57 43 420 2LiF-BeF,.
C-133 (11ll-a) 71 16 v 13 505 3LiF+«ThF;ss.
C-134 62  36.5 0.5 1 44,5 2LiF-BeF,
C-136 70 10 20 500 7LiF -6UF,,
BeLT-15 67 18 15 500 - 7LiF-6ThF, and
. - - ~ 3LiF.ThF,ss
BULT 4-0.5U 65  30.5 0.5 4 453  3LiF.ThF,ss
BULT 4-<1U 65 30 4. 448 2LiF+BeF, and
= ' : 3LiF°ThF4SS'
BULT 14-0.5U 67 18.5 0.5 14 500 7LiF-6(Th,U)F ss
and 3LiF-ThF,ss .
490% LLAF-UF, and

7LiF -6UF,,

sitions.

*The solidus and liquidus coincide, since these are eutectic compo-

oL

-
59

_ ORNL-2896
UC-4 — Chemistry-General
TID-4500 (15th ed.)

INTERNAL DISTRIBUTION

o

[ I

- L ]

Voe~JovunmPhwie -

C. E. Center 43. M. A, Bredig

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A. H. Snell 51. H. F. McDuffie
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S. C. Lind 56. C. J. Barton

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W. R. Grimes 67. W. L. Marshall
A. Hollaender 68. R. E. Moore

A. S. Householder 69. A. D, Callihan
M., T. Kelley 70. R. F. Newton

T. A. Lincoln 71. L. G. Overholser
R. S. Livingston 72. W. T. Rainey

K. Z. Morgan 73. J. H. Shaffer

M. L. Nelson 74. M. D. Silverman
H. E. Seagren 75. B. A. Soldano

E. D. Shipley 76. R. A, Strehlow
E. H. Taylor 77-87. R. E. Thoma

C. P. Keim 88. (G. M. Hebert

R. S. Cockreham 89, J. H. Burns

P. M. Reyling 90. C. F. Weaver

M. J. Skinner 91. H. A. Friedman
G, C. Williams 92. G. M. Watson

A. L. Boch 93, P. H. Emmett (consultant)
E. G. Bohlmann 9., H. Eyring (consultant)
95.

%.

97.
98.

2.
100.
101.
102.
103.
104,

132,

137-

133.

134.
135.
136.
693.

60

105.

G. Hill (consultant)

E. Larson (consultant) 106.
0. Milligan (consultant) 107-108.
E. Riceci (consultant) 109-128.
T. Seaborg (consultant)

P. Wigner (consultant) 129.
T. Gucker (consultant)-

Daniels (consultant) 130.
T, Miles (consultant) 131.

N. McVay (consultant)

Biology Library

Health Physics Library v
Central Research Library
Laboratory Records

Department : S

.Laboratory Records,

ORNL R.C. R
Reactor D1V151on-L1brany

ORNL Y-12 Technical

Library

EXTERNAL DISTRIBUTION

Division of Research and Development
Division of Research and Development,
Division of Reactor Development AEC,
Division of Reactor Development, AEC
L. Brewer, University of California

,” AEC, Washington

AEC, ORO
Washington : '
ORO - L

Given distribution as shown in TID-4500 (lSth ed.) under

Chemistry-General category (75 copies

— 0TS)

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