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ORNL-TM-3053.txt
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E uninn
Frrrm
LOCKHEED MARTIN ENERGY RESEARCH LIBRARIES
IERI
4
4
3
{
3 445L 0514237 9
S OO ____ LEGAL MOTICE oo
This report was prepared 0z an’ nccount of Government sponsered work. Maither the United States,
nor the Commission, nof any pe:er)n acting on behell of the Commission:
AL Makms any warranty or répresentution, expressed or implied, with respeu‘lz fa the accuracy,
completennss, or usefulneis of the information contained in this report, or that the use of
any informnrion, appumiufiz, mefhod, or process djisc!ased in this report mny ner infringe
privately owned rigiv‘rs; ar : :
B. Assumes uny lighilities with 1espect 1o the use of, or for damnges resuiting from the use of
cm.'y information, apparaius, method, or process disclesed in this report,
As used in the above, '‘person acting on behuolf of *%é Commission’ includes any employes or
contraptor of the Commission, or emplnyse of such co;ni“racfor, to the extent that suchk 2mployee
or cor}trlx:?or of the Commission, er employee of such ceohinctor prepares, disseminates, or
provides uecess fo, any information pursuant to his employwent or controct wifl".; the Commission,
or his gmployment with such cantrecter,
L da
ORNL-TM-3053
Contract No. W-T4O5-eng-26
CHEMICAL TECHNOLOGY DIVISION
ENGINEERING DEVELOPMENT STUDIES FOR
MOLTEN-SALT BREEDER REACTOR PROCESSING NO. 1
L. E. McNeese
NOVEMBER 1970
OAK RIDGE NATIONAL LABORATORY
Oak Ridge, Tennesgsee
operated by
UNION CARBIDE CORPORATION
for the
U.S. ATOMIC ENERGY COMMISSION
LGCKHEED MARTIN ENERGY RESEARCH LIBRARIES
(AR
3 4456 0514237 9
11
Reports previously issued in this series are as follows:
ORNL ~4094
ORNL~4139
ORNL-4204
ORNL-4234
ORNL-L4235
ORNL-4364
ORNL-4365
ORNL-"3%66
Period
Period
Period
Period
Period
Period
Period
Period
Ending
Ending
Ending
Ending
Ending
Ending
Ending
Ending
December 1966
March 1967
June 1967
September 1967
December 1967
March 1968
June 1968
September 1968
iidi
CONTENTS
Page
SUMMARIES . e o e s . e . . . v
1. INTRODUCTION + ¢ v v o o v v o o o v o o s 0 o o o & o » 1
2. SEMICONTINUQUS ENGINEERING EXPERIMENTS ON REDUCTIVE EXTRACTION 1
2.1 General Operating Procedure . . . . . . . . . 5
2.2 Description of Major Processing Equipment . . . . 3
2.% Extraction Column . . . « .« « .« . . D
2. Jackleg e e e e e e e e e e e e 5
2.5 Feed and Catch Tanks for Salt and Metal . . . . 6
2.6 Treatment Vessel for Salt and Metal . . 6
2.7 Tank Samplers . . . . . . . . . . . o
2.8 Filters, Freeze Valves, and Lines 9
2.9 Instrumentation and Control . .+ ¢« « « « « « + 9
2.10 Gas Purification and Supply Systems 12
%. ELECTROLYTIC CELL DEVELOFENT . . « « ¢« ¢« ¢« ¢ o & o « « « « & 1h
5.1 Experimental Equipment . . . . 15
3.2 Results 16
., SEPARATION OF RARE EARTHS FROM THORIUM BY FRACTIONAL CRYSTALLIZATION
FROM BISMUTH + v ¢ ¢ v o & o o s o o o o o o o s o o 22
4.1 Physical Properties of Materials Considered . . . . . . 27
4.2 Conceptual Design of a ThBi, Precipitator . . . 2k
4.3 Estimation of the Minimum Cross Section for the Precipitator
SECEION + o v v+ « o s 4 2 4 v e e e e e e e e e e e 26
h.4 Estimated Length of Precipitator Section . . . . . 28
L.5 Summary and Conclusions . « « ¢« o « + o o o o &+ o« & 37
5. MATERIAL BALANCE CALCULATIONS FOR AN MSBR . . . 35
5.1 Compilation of MSBR Nuclear Data . . « « « « « « « o 33
5.2 Material Balance Equations . « « « « + « « + & 30
5.3 Computation of Neutron Reaction Rates . . . . b1
iv
CONTENTS (Continued)
Page
5.4 Model for Diffusion of Noble Gases into Graphite . . . Lo
5.5 Model for the Migration of Noble Gases and Noble Metals to
Circulating Helium Bubbles . . . ¢« + « « « « o « « o & L5
5.6 Assumed Chemical Behavior of Fission Products . . . . . L6
5.7 Material Balance Calculations for a 1000 Mw(electrical)
Sil’lgle"’F].Uid MSBR . . . . . . . . . . . . . . . . . . . )4'7
6. REFERENCES L9
APPENDIX A. LIBRARY OF NUCLEAR DATA FOR MSBR APPLICATIONS . . . 51
APPENDIX B. TYPICAL MATADOR OUTPUT FOR A 2250-Mw(thermal) SINCLE -
FLUID MSBR + « = v v o e v e e e e e e e e e e e 67
SUMMARIES
SEMICONTINTOUS ENGINEERING EXPERIMENTS
ON REDUCTIVE EXTRACTICN
Equipment has been installed in Bldg. 5592 to permit engineering
studies on reductive extracticn in countercurrent centactcecrs. The
system will allow the countercurrent contact of up to 15 liters each of
molten salt and bismuth at flow rates of 0.0% to 0.5 liter/minfi Almost
all of the componentg that contact sgalt or bismuth are fabricated of
carben steel. The contactor presently being studied is a 0.82«in. ~ID,
2-ft-long column (excluding end sections) that is packed with solid
1/4~in. right circular cylinders of molybdenum.
The salt and bismuth can be purified by contact with H,-HF mixtures
7
‘J.,J
o
followed by filtration thrvough porcus melybdenum filters. The two phases
can be gampled at varicus poicts in the sgystem.
ELECTROLYTIC CELL DEVELGPMENT
The flowsheet under consgideration for processing fuel from the
proposed MSBR uses an electrelytic cell. Fluorides of thoriuvm or
lithium in a molten-salt stream are rveduced at the bismuth cathode,
while metals that are extracted into bismuth are coxidized at the
bismuth anode. Preliminary experiments made in static cells con-
structed of quartz show that the current variss linearly with the
applied potential. This indicates the absence of a limiting current in
the range of the experiments for which the highest average current
_— 2
density was 4.35 amp/cm .
SEPARATION OF RARE EARTHES FROM THORIUM BY
FRACTIONAL CRYSTALLIZATION FROM BISMUTH
The feasibility of separating rare earths from thorium in a bismuth
golution by fractional crystallization of ThBi, was sxamined. A possible
2
Vi
equipment configuration was considered, and an analysis was made of
factors affecting the fraction of ThBi, that could be potentially re-
2
covered. It was concluded that operation in the envisioned manner might
be difficult because of the need for close control of nucleation rates.
MATERTIAL BALANCE CALCULATIONS FOR AN MSBR
We have developed a computer code, MATADOR, to perform steady-state
material-balance calculations that describe the nuclear, chemical, and
physical processes occurring in the fuel stream of an MSBR. This code
allows us to investigate the effects of chemical processing on the
nuclear performance of an MSBR, to determine fission-product inventories
and heat-generation rates, and to specify flow rates of streams in the
chemical processing plant. The buildup of transuranium isotopes, the
production of activation products by neutron capture in the carrier salt,
and chain~branching in the decay fission products are considered.
The MATADOR code has been used to compute inventories and heat-
generation rates in the fuel stream of a 1000-Mw (electrical) single-
fluid MSBR; this information is summarized for the reference reactor.
e
1. TINTRCDUCTION
A molten-salt breeder reactor {MSBR) will be fueled with a molten
fluoride mixture that will circulate continuously through the blanket
and core regions of the reactor and through the primary heat exchanger.
We are developing methods for use in a close-coupled processing facility
for removing fission products, corrosion products, and fissile materials
from the molten fluoride mixture.
Several operations associated with MSBR precessing are under study.
This secticn describes: (1) a recently completed facility fer semi-
continuous engineering experiments on reductive extraction, (2) exper-
iments related to the development of electrolytic cells for use with
molten salt and bismuth, (3) consideration of selective crystallization
of thorium bismuthide from bismuth-thorium-vare earth solutions as a
means for separating thorium from the rare earths, and (I} a computer
code that calculates the nuclear, chemical, and physical processes
occurring in the fuel stream of an MSBR. This work was carried out ia
the Chemical Technology Division during the periced October through
December 1368.
2. SEMICONTINUQUS ENGINEERING EXPERIMENTS
ON REDUCTIVE EXTRACTION
L. E. McNeese B. A. Hannaford
H. D. Cochran, Jr.
The proposed MSBR processing method is based on reductive sxtraction,
uging countercurrent contact of molten salt and bismuth in multistage
contactors. Equipment has been fabricated and installed in Bldg. %592
for enginzering studies of reductive extraction in countercurrent con-
tactors. These studies will be made using molten salt {72-16-12 mole %
LiF-BeF2~ThFA) and 1liquid bismuth metal. Uranium {about ©¢.3 mole % UF4
in the salt) will be transferred between the salt and the metal, using
thorium as the reductant in the bismuth. 7The salt and the metal will be
contacted countercurrently at 600°C.
One planned objective of these experiments is the investigation of
mass transfer between the salt and bismuth under different flow condi-
tions in various contacting devices. The effective overall mass-transfer
coefficient (or, equivalently, the height equivalent to a theoretical
stage) will be determined in several experiments with various contactors
which include packed and baffled columns. The mass-transfer performance
is determined, in part, by the hydrodynamic conditions in the contactor;
information on hydrodynamic conditions in packed columns will be inferred
from measurements of the pressure drop through the column by analogy
to a water-mercury system being studied by WatSOn.l The experiments
should answer the following questions: (1) What is the limiting flow
rate beyond which the column will flood? (2) Is the bismuth well
dispersed, or does channel type flow occur? (%) How much interfacial
area exists for mass transfer? (&) Is disengagement of the phases
complete in the end sections, or does entrainment present a problem?
(5) How severe a problem will be caused by axial backmixing, particularly
in the salt phase at high metal rates?
A second objective is the evaluation of the performance of aux-
iliary equipment necessary to perform experiments of this type. Such
information will be used in designing subseqQuent experimental facil-
ities. The following components will be included in the evaluation:
freeze valves, filters, instrumentation, and supply systems for argon,
hydrogen, and hydrogen fluoride.
We plan to determine the probable lifetime for freeze valves
subjected to repeated freeze-thaw cycles since we expect them to fail
eventually under such stress; in addition, we will study the perform-
ance of freeze valves containing two fluid phases. The performance of
filters with the possible entrainment of a second fluid is also of
interest. As a part of these studies, we wish to determine whether
carbon steel is a suitable structural material for short-term use in
experiments of this kind, and whether graphite is a suitable material
in which to hydrofluorinate the salt and metal mixture.
In carrying out the experiments outlined above, we will gain oper-
ating experience and confidence in handling the process fluids. We will
also uncover areas of unforeseen difficulty, where further dzvelopmental
work may be needed.
2.1 General Cperating Procedure
Prior to an experiment, slightly more than 15 liters of salt and
15 liters of bismuth will be present in the treatment vessel. This
material will be hydrofluorinated to return lithium, thovium, uranium,
etc. to the salt phase, and to remove oxides from the salt. After
suitable sparging with argon to remove HF and H., salt (15 liters) will
be transferred to the salt feed tank, leaving amheel about 1/2 in. deep
in the treatment vessel. Then bismuth {15 liters) will be transfarred
to the bismuth feed tank, leaving an additicnal heel of abeout 1 in.
Finally, reductant will be added to the bismuth in the metal feed
tank. Samples of galt and metal feed will be withdrawn.
During an experiment, salt and metal may be transferred through the
column at controlled flow rates from 0.05 to 0.5 liter/min. During this
transfer, the pressure drop acreoss the column can be monitored, and
samples can be taken from the salt and the metal streams exiting from
the column. After an experiment, the salt and the metal may be sampled
in the catch tanks before being transferred back to the treatment veszsel.
Hydrofluorination would be repeated to return lithium, thorium, and
uranium to the salt phase prior to the next run. Thus, there will be a
constant amount of each comperent in the system {notably uranium),
except for a known amount of thorium which will be added to the system
in each run. Material-balance determinations will be greatly facilitated
by this fact.
2.2 Description of Major Processing Equipment
All componentg that contact molten salt or bismuth are fabricated of
carbon steel, except as noted. The major components in the gystem
for handling salt and metal are described below and are shown schematically
in Fig. 1.
ORNL-DWG 68-14347 A
FV_1L,{T1~/ FILTER
Fv-2 U
j
-
-
T
v
i3
FILTER
e
1
V_
p_—————
i
-
1
2
mTT T
1
FV-4
————
!
I
1
|
SALT AND METAL
TREATMENT VESSEL
SALT FEED AND
COLLECTION TANK
METAL FEED AND
COLLECTIOM TANK
£ and Metal Filowsheet.
-~
ied Sal
Simplif
1.
Fig.
T
2.% Extraction Column
The four contactors that have been fabricated have the same physical
dimensions: 0.82 in. ID x 2 ft long, excluding end sections. In each,
bismuth is introduced through a tube (0.259 in. ID, 0.058-in. wall
thickness) that projects at right angles into the end section about 7/16
in. above a slotted grid. The grid acts as a distributor and restrainer
for the packing. Salt is withdrawn through an overflow line 1-11/16 in.
above the bismuth feed port. 1In the bottem end section, salt is intro-
duced through a 0.259~in. tube at right angles to the columo 7/16 in.
below a slotted restraining grid similar to that at the top. Bismuth
flows from the bottom of the end section threough a tube 1-11/16 in.
below the salt feed port.
Internally, the four columns contain one of the following: (1) 1/h-
in. right circular cylinders of molybdenum (void fraction, about 40%);
(2) 1/8-in. right circular cylinders of molybdenum {void fraction, about
Lo%Y; (3) segmental baffles covering 96% of the column cross section at
1/2-in. spacing; or (&) open column area that could be packed later or
could be used as a spray column. On the basis of studies with the water-
mercury system, the 1/lL-in. packing looks most promising. Therefore,
it will be studied first.
2.4 Jackleg
The pressurs drop across the column will be measured with a jackleg
by using the following procedure. The salt level in the jackleg will be
measured using an argon bubbler. The sum of the pregsure resulting from
this head of salt and the difference in the pressures in the gas spaces
above the fluids in the jackleg and the column will be equal to the salt
pressure at the bottom of the column. The pressure at the bottom of the
column will, in turn, equal the pressure drop across the columm. The
gsalt head in the column, the bismuth held up in the column, and the
vigscous drag in the column will contribute to thig pressure drop.
The jackleg can accommodate a head of approximately 4 ft of salt.
Preliminary estimates indicate that the pressure drop across the column
may be 3 to 6 ft of salt under conditions of maximum flow. The jackleg
will be pressurized in order to operate under conditions where the
pressure drop is greater than 4 ft of salt.
2.5 Feed and Catch Tanks for Salt and Metal
The duplex feed and catch tanks for salt and bismuth are identical
in construction. The feed tank, an inner cylinder of 8-in. sched 80
pipe, is designed to operate at pressures up to 50 psig at 600°C. Both
the inner feed tank and the outer catch tank will hold about 20 liters
of fluid. We plan to use only about 15 liters of salt and 15 liters of
bismuth.
The top of each feed tank contains seven ports: (1) an inlet port
(1/2~in. pipe with a fitting for %/8-in. tubing), which does not extend
into the tank; (2) an outlet line (1/2-in. pipe with a fitting for 3/8-
in. tubing), which extends to within 1/2 in. of the bottom of the tank;
(3) a sparge and pressurization port (with a fitting for 3/8-in. tubing),
which extends to within 1/2 in. of the bottom of the tank; (4) a 1/2-in.
pipe (with a fitting for %/8-in. tubing) used as a thermocouple well,
which extends to within 1/2 in. of the bottom of the tank; (5) a 1/2-in.
pipe with a fitting for a 1/2~in. ball valve and sampler and a {itting
for 1/4-in. tubing below the valve; (6) a 1-in. pipe with a l-in. ball
valve as an addition port; and (7) a 1/2-in. capped pipe as a spare port.
Each catch tank has the same ports as the feed tanks except that no
addition port is provided. The outer surfaces of the feed and catch
tanks are coated with nickel aluminide to retard oxidation.
2.6 Treatment Vessel for Salt and Metal
The treatment vessel consists of a 304L stainless steel pressure
vessel that holds a graphite crucible. The cylindrical portion of the
pressure vessel is 26.5 in. long (1/4-in. wall thickness) and has a
standard pipe cap on ecach end. It is designed to withstand H, -HF at
600°C at a pressure of 50 psig. -
The inner crucible, machined of graphitej% has an outer diameter of
16.75 in. and is 26.7% in. (overall) high. The wall thickness tapers
from 1.75 in. at the bottom to 0.75 ia. at 16.75 in. from the bottom, and
is uniform from there to the top. The bottom of the crucible is 1.75
in. thick. The crucible has a 16.75~-in.-diam 1id, whose thickness
varies from 1 in. at the rim to 0.5 in. at the center. The graphite
crucible rests on a support plate inside the pressure vessel, and the
1id is held loosely in position by three gtuds projecting from inside
the top of the pressure vessel. The vesgel has 15 nozzles, which are
described in Table 1.
2.7 Tank Samplers
The treatment vessal and the feed and catch tanks are each pro-
vided with a 1/2~-in. sched 40 pipe nozzle fitted with a ball valve and
sampler. These tank samplers hold four fritted filter sticks that
extend through a Teflon plug in the top and can be lowered (while the
gystem is under argon pressure) through the ball wvalve into the tank
below. Samples can be drawn into the filter sticks by vacuum. Four
samples can be taken during one run.
In addition to the five samplers on the vessels, there are two
flowing-stream samplers, which operate in a manner similar to that of
the tank samplers. These flowing-stream samplers allow seven samples
to be taken from each of two flowing streams during column operation.
One sampler is located on the salt return line (between the column
and the salt catch tank), and one is located on the metal return line
(between the column and the metal catch tank).
¥
No. 8735, Speer Carbon Co., a Division of Air Reduction Co., St. Marys,
Pa.
Table 1. Description of Nozzles on Treatment Vessel
Nozzle
No. Used For Description
1 Bismuth charging Z2-in. sched 40 pipe, flanged at the top to accom-
modate a chute for loading bismuth. The graphite
1id below this nozzle has a 1.625-in.-diam hole
with a removable plug.
2 Bismuth sampling; salt 0.5-in. sched "0 pipe with ball valve and sampler.
sampling; gas-phase pres- The lid is fitted with a l-in.-ID graphite pipe
sure connection. into which the C.%-in. pipe slips. The graphite
pipe extends through the graphite lid and into the
crucible for a distance of 1 in.
= Returning salt from the 0.5-in. sched 40 pipe nozzle containing a sleeved
salt receiver 0.379=in.-0D tube. Below the carbon-steel-to-~
molybdenum transition, the 0.375-in.-0D molybdenum
tubing extends 4 in. below the graphite 1id.
ly Returning bismuth from the Identical to nozzle No. 3.
bismuth receiver
5 Transferring bismuth to 0.5-in. sched 40 pipe nozzle containing a sleeved
bismuth feed tank 0.375-in.-0D tube that extends to within 0.5 in.
of the bottom of the crucible. The tubing that
extends inte the crucible is made of molyhdenum.
6 Transferring salt to the Similar to nozzle No. 5; set so that 1% liters of
salt feed tank salt can be transferred rto the salt feed tank,
leaving a 0.5-in. heel of salt on top of the
bismuath.
T Monitoring liquid level® Similar to nozzle No. 5.
& Sparging with H,-HF Similar to nozzle No. 5.
9 Adding salt Similar to nozzle No. 3.
10 Spare Similatr to nozzle No. 3.
11 Thermocouple well 0.5-in. sched %0 pipe with fittings for 0.375-in.-
0D tubing
12 Making miscellaneous ad- l-in. sched 4C pipe, with ball valve.
ditions, or vessel venting
13 Draining vessel 0.5-in. sched 4C pipe extending from the bottom of
the pressure vessel; this line is capped.
“Acts as a bubbler type of liquid-level monitor.
9
2.8 Filters, Freeze Valves, and Lines
The experimental facility has two filters, one of which is located
on each of the lines between the treatment vessel and the salt and metal
feed tanks. These filters, made of fritted molybdenum. have.a nominal
pore size of 25 py. The permeability of each filter was measured before
and after fabrication, and was found to be about 40O cm’ (sTP) em™>
(cm Hg)_l at a pressure differential of 1.5 c¢m Hg. Both filters can be
bypassed if necessary.
Salt and metal flows through the facility are directed by 10 freeze
valves in the transfer lines, located as indicated in Fig. 1. These
valves are simply dips (in the carbon steel tubing), which are fitted
with air cooling linesn Those freeze valves that must be closed before
any salt or metal can be transferred from the Creatment vessel were
equipped with small reservoirs {about 50 cmB) of bismuth prior to being
welded into the lines. The facility, which is of welded construction,
contains approximately 200 ft of salt and metal transfer lines (3/8-in.
and 1/2-in. pressure tubing).
2.9 Instrumentation and Control
The principal cbjective of the instrumentation and control system
is to provide closely~regulated flows of bismuth and molten salt to the
extraction column. The range of flow rates provided for both bismuth
and molten salt is nominally 40 to 500 ml/min, corresponding to experi-
ment durations of about 5 to 0.5 hr. Pressures and liquid levels in
the six vessels (treatment vessel, feed and catch tanks, and jackleg)
of the facility are sensed by Foxboro differential-pressure transmitters,
which send signals to miniature pneumatic recorders or controllers.
Liquid level is inferred from the pressure of the argon that is supplied
to a dip-leg bubbler in each tank. Flow rates of bismuth and salt to
the column are controlled by regulating the rate of change of liquid
level in the twe feed tanks. The locations of galt-argon and salt-
LO
bismuth interfaces in the column are not directly measured, but can be
determined from pressure measurements. The feed and catch tanks and the
treatment vessel are maintained at the desired temperatures by automatic
controllers; transf-r-line temperatures and temperatures of small com-
ponents are controlled by manually regulating the appropriate voltage
transformers that supply power to Calrod tubular heaters.
Figure 2 is a schematic diagram of the control system that reg-
ulates the flow of bismuth or salt to the extraction column. It is
designed to circumvent the flow-control problems that sometimes occur
when gas pressure is used to maintain a constant flow of liquid from a
heated feed tank. An adjustable ramp generator and an electric-to-
pneumatic converter are used to linearly decrease the set point of a
controller that senses liquid level in the feed tank and controls the
level by controlling the flow rate of pressurizing argon to the gas
space of the feed tank. The result should be a uniformly decreasing
bismuth level and, hence, a uniform discharge rate of bismuth or salt
from the tank. This control system should be unaffected by small
increases in back pressure caused by changing column hydraulics, par-
tial plugging of transfer lines, decreasing feed tank level, etc., or
leakage of pressurizing argon (a small argon bleed is provided to
improve pressure control). Small gas pressure oscillations caused by
the temperature cycling of a conventional temperature controller will
be minimized by the time-~-proportioning controller. Rates of transfer
of salt and metal between the collection tanks and the treatment
vessel need not be closely regulated; therefore, manual control of
pressurization is used.
Heating circuits are manually controlled for 11 transfer lines,
5 flowing-stream samplers, the salt jackleg, and the extraction column.
On the transfer lines, the Calrodsrated at 230 v are run at 1h0 v or
less, and provide up to 185 w per foot of line. Typically, temperatures
at three points on each line are recorded. Approximately 100 points
are recorded for the system.
For obvious reasons the gas bubbler method for measuring static
head cannot be used directly in the small-diameter extraction column.
11
ORNL DWG 7O-4574R4
FOXBORO
ADJUSTAR RAMP
? STABLE RAMP ! cONVERTER E/P ot RECORDER
GENERATOR (E vst) CONTROLLER
A
7
A
’
d / P ?{l Ily r.l'( ?.{I t’i’ '_’f’ 7# In{/ )7” 3
CELL
ARGON
PURGE ] —D<G—= ARGON BLEED
BISMUTH OUT ey
50-500 m!/min.
LEN
TEMPERATURE
RECORDER
CONTROLLER
{(TIME
PROPORTIONING)
Fig. 2. Schematic Diagram of Control System for Metering Bismuth
from the Pressurized Feed Tank, T-l.
12
However, the bubbler that terminates near the bottom of the jackleg can
be used to determine the pressure at the base of the columm. This liquid
level measurement, in conjunction with the measurement of gas phase pres-
sure in the jackleg, will accommodate a bismuth holdup in the column
approaching 100% of the open column volume.
2.10 Gas Purification and Supply Systems
Three gases are required for the experimental facility: HF, hy-
drogen, and argon. Because of the highly deleterious effect of small
amounts of oxygen, the nominally pure bottled hydrogen and argon are
further purified to remove traces of oxygen or water. The anhydrous
HF is given no additional purification; it, along with hydrogen, is
used only in the treatment vessel for hydrofluorination of the metal
and the salt. A schematic diagram for each of the three supply systems
is shown in Fig. 3.
Highly purified argon is used for all applications requiring an
inert gas: pressurization of tanks for trangferring bismuth and molten
salt, dip-leg bubblers for liquid-level measurements, purging of appa-
ratus for sampling bismuth and salt, etc. Cylinder argon with a mini-
mum purity of 99.995% is fed, first, to a bed of molecular sieves [Fig.
%2(a)), which reduces the water content to about 2 ppm (-100°F dew point).
The argon thenflows through a bed of uranium metal turnings, where the
remaining oxygen and water are removed. A porous stainless steel filter
removes any uranivm oxide dust that might be carried from the uranium
bed by the gas stream. The maximum argon flow rate, based on the ca-
pacity of the molecular sieve bed, is about & scfm.
The hydrogen purification system is a commercially avilable device*
that purifies hydrogen by the selective diffusion of hydrogen across a
palladium alloy barrier. Impurities, along with a small flow of hydrogen,
are continuously bled from the upstream side of the barrier. The capacity
of the unit is 15 scfh. Controls for the purifier are self-contained.
*
Serfass Hydrogen Purifier, product of Milton Roy Co., St. Petersburg, Fla.
15
ORNL DWG 702801
(a)
MOISTURE
- MONITOR. s
X ) X
?—] MOLECULAR SiEVE BED LS URANIUM CHIP BED ~380
X { WATER REMOVAL.) w (OXYGEN REMOVAL) FILTER e sccth
~28080 ~65O°AC { max.)
ARGON
CYLINDERS (4) ARGON PURIFICATION SYSTEM
IMPURITIES BLEED
(b} t
i l SERFASS ~{5
A} - HYDROGEN » scfh
PURIFIER {max.)
HYDROGEN
CYLINDERS (2}
" HYDROGEN PURIFICATION SYSTEM o
(c)
! WEIGH
CELL
7 o ~Glb/hr
b {mox.)
pp
HOT WATER SUPPLY HOT AIR BATH
e FOR CAPILLARIES
TANK
HOT WATER BATH PRESSURE
RECORDER
CONTROLLER
HF SUPPLY SYSTEM .
Fig. 3. Simplified Diagram of the Gas Supply Systems.
14
The anhydrous HF supply system utilizes small capillaries for
metering; a pneumatic controller maintains a specified pressure drop
across a capillary by controlling the HF gas supply pressure. This is
achieved by regulating the temperature of the water bath in which the
HF supply tank is suspended. Accidental overheating of the HF supply
tank is prevented by a switch that releases cold water into the bathifl
the temperature exceeds 60°C. The minimum flow range for the HF supply is
nominally O to 0.25 1b of HF per hour; the maximum range is O Lo “ 1b
per hour. A calibrated weigh cell provides a means of checking the
rate of HI delivery and the HF inventory.
5. ELECTROLYTIC CELL DEVELOPMENT
M. S. Lin L. E. McNeese
In the proposed MSBR fuel flowsheet2 using reductive extraction, an
oxidizer-reducer is required (1) to convert extracted materials to their
fluorides in the presence of a salt stream, and (2) to reduce the fluorides
of lithium and thorium at a bismuth cathode. Electrolytic cells for
simultaneously carrying out these operations are being developed.
The advantages of using an electrolytic cell are as follows:
1. The oxidizer and reducer are coupled together; thus the amounts
of the oxidized and reduced products are always in the correct