OAK RIDGE NATIONAL LABORATORY M

operated by
UNION CARBIDE CORPORATION

for the
U.S. ATOMIC ENERGY COMMISSION
ORNL- TM- 31kk

COPY NO. - f 9!

 

DATE - September 30, 1970

FLUORINE PRODUCTION AND RECOMBINATION IN
FROZEN MSR SALTS AFTER REACTOR OPERATION

P. N. Haubenreich

ABSTRACT

s Exposure of capsules of MSR fuel salts in the MTR between 1961
- and 196L showed that when the salt was chilled below about 80°C, Fyo
was produced by radiolysis at a rate of 0.02 molecules/100 ev, Other
experiments confirmed the radiolysis of frozen salt and provided data

on the effect of temperature on recombination., The data on yield and
recombination have recently been reviewed and used in answering ques-
tions involved in storing and disposing of irradiated salt from the MSRE
and future molten-salt reactors. The energy source in the MSRE salt is
low enough that no fluorine evolution is expected for over a year after
heating to induce recombination. Salt from a high-power MSR can be
stored in bare cans with no fluorine evolution if the surroundings are

kept at about 200°F.
molten-salt reactors, fluorine, fused salts, radiolysis,

Keywords:
storage, waste disposal, afterheat, analysis, experiment, heat transfer,
MSRE, primary salt, reaction rates, recombination.

¥
»

NOTICE This document contains information of a preliminary nature
and was prepared primarily for internal use at the Qak Ridge National

Laboratory. It is subject to revision or correction and therefore does

not represent e final report.

PISTRIBUTION OF THUS DOCUMENT LS UNLIMITED
[~~—-~~~- e e e e oo — LEGAL NOTICE -—— s el s s e
|
i This report was prepared as an account of Government sponsored work. Neither the United States,
. nor the Commission, nor any person acting on behalf of the Cammission:
| A. Makes any warranty or representation, expressed or implied, with respect to the accuracy,
' completeness, or usefulness of the information contained in this report, or that the use of
l any information, apparatus, method, or process disclosed in this report may not infringe
privately owned rights; or
B. Assumes ony ljabifities with raspact to the use of, or for damages resulting from the use of
! any information, apparatys, method, or process disclosed in this report,

As used in the above, *‘person acting on behalf of the Commission’’ includes any employee or

w contractor of the Commission, or employee of such contractor, to the extent that such employee
or contractor of the Commission, or employee of such contractor prepares, disseminates, or
provides access to, any information pursuant to his employment or contract with the Commission,

| or his employment with such contractor.
CONTENTS

Page

ARSTRACT _
INTRODUCTION  « ¢ = o o o o o o v o o v o e e e e e e e e e e o w1
RESULTS OF THE ©°Co EXPERIMENT '+ v & 4 v 2 v o « o o o o v s o o o 2
Description of the Experiment . . . . « « . + + « « &+ o + + 5
Analysis . v ¢ v 4 e s e e s e s e 4 e e s e e e e v s s e

RESULTS OF OTHER EXPERIMENTS . . &+ & ¢ « v o & o o « & = o & « < o 15

In-Pile Experiments . o ¢ ¢ o o s « o« ¢ o o o s 2 o o« o o & = }g
X-Ray Irradiations « o « ¢ « o o o 1 o o o o o s ¢ o o o s & o 18
Fast-Electron Bombardment . .« ¢ « &+ « ¢ 5 5 « « & o s & 5 « = 5
DiscusSsion o « o o e 5 s o = o &+ a4 2+ 6 s 4 s e T e a3 s a2 e+

STORAGE AND DISPOSAL OF MSRE SAIT . + +v ¢« v 4 v & o o o s 1 « + + « 19

* ¥ . * 3 * e 20
Energy Sources . + + + « &+ o s e e e e e e e .
Temperature for Internal Recombination . . . . . . . « + . . .
Tnduction Period and Fluorine Release ., . . v ¢« ¢ 5 « « o + o
DiSCHSSiOn " ° . % - . - - - e - & - . a . o - r - ° € & % o

DEALING WITH SALT FROM LARGE MOLTEN-SALT REACTORS . « + & » « = « « 25

o Mo
£l

o < o » - - 2%
Fnergy Source . .« « o o« « o s s a4 e e e o s = o e 2%
Heat Transfer and Temperatures . . o+ « « « ¢ 5 o o « « &+ o o o -
Fluorine Yield and Induction Period . . ¢ ¢ « ¢ « « & » o « & :
Temperature for Zero Release of Fluorine . . . . . . . . . » . 22
DiSCuSSiOn o . » - » * & . - . * * . 2 . 3 - - - - » L * < " -

e
REFERENCES . . ¢ ¢ & o o « o « s o o s o o + » a

 

LEGAL NOTICE
This report was prepared as an account of work
sponsored by the United States Government. Neither
the United States nor the United States Atomic Energy
Commission, nor any of their employees, nor any of
their contractors, subcontractors, or their employees,
makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, com-
pleteness or usefulness of any information, apparatus,
product or process disclosed, or represents that its use
would not infringe privately owned rights.

 

 

 

 

. T Y T YT
S e ren WS 'S ‘.,Y'.‘ ',i;_‘\z n‘l_,
- sarvy ot . i )
.-.)fr,(.y-q‘\”' P B . Lo L
" Yooa e al
Thay)
INTRODUCTION

The phenomenon with which this report is concerned, that is, the
evolution of fluorine gas from frozen fluoride salts subjected to radi-
ation from included fission products, was first observed in 1962 in cap-
sules that had been exposed in the MTR.' Some capsules (Expt. 47-L4)
when opened several weeks after withdrawal from the reactor were found to
have fluorine pressures as high as 50 atmospheres, It was evident, both
from the lack of metal corrosion and from strength considerations, that
this much Fo could not have been present while the capsules were at high
temperature in the reactor., The next experiment included capsules with
provisions for gas sampling and pressure measurement. These proved that
F, was evolved only when the salt was chilled well below the freezing
point. Monitoring of these capsules after removal from the reactor showed
that at room temperature the rate of fluorine release was proportional to
the fission product decay energy. At slightly higher temperatures, the
F- apparently recombined with the salt, Meanwhile several experiments
had been done in which frozen fluorides were subjected to various kinds
of radiation from external sources.€s> These experiments produced fluorine
with yields comparable to those inferred from the in-pile capsules, In
one experiment, with a ®°Co gamma-ray source, the effect of temperature
on fluorine evolution and recombination was explored during more than
TOOO hours of operation.

One conclusion from the experiments was that fluorine evclution from
frozen salt would pose no threat to the operation of the MSRE., New ques-
tions were raised, however, when in December 1969 the reactor was shut
down and, for the first time at the MSRE, tanks of fuel salt were allowed
to freeze. During the interim between the end of nuclear operation and
the post-operation examinations (scheduled for the fall of 1970) it was
a simple matter to keep the frozen salt warm enough (>200°C) to positively
preclude any fluorine evolution. During the next phase (Phase III) before
the ultimate disposal of the fissile and radiocactive materials, it would
be convenient to turn off the heaters and let the salts cool to near am-
bient temperature. In anticipation of this phase, then, the data on

fluorine evolution and recombination were reexamined.
RESULTS OF THE °°C0 EXPERIMENT

Of the various experiments, the one that contains the most informa-
tion on temperature effects, which are of paramount importance in the con-

sideration for the shutdown MSRE, is the ®09Co experiment.

Description of the Experiment?®

The equipment for this experiment consisted of a 25-cm” Hastelloy-N
autoclave with provisions for temperature control and measurement and with
two l/8-in. nickel tubes for gas sampling and pressure measurement.
Powdered salt (35 g) of a composition* similar to that proposed for the
MSRE fuel was melted in the autoclave, an array of 24 small graphite
spheres was inserted and the salt was allowed to freeze before the suto-
clave was sealed. All interior surfaces of the equipment were prefluori-
nated before the salt was added.

The assembly was placed in a ®°Co irradiation facility and left there
for 7391 hours between February and December, 1963. During this time the
temperature was held at various levels between 38°C and 150°C, three sam-
ples of gas were taken, the source was removed twice to interrupt the
gamma-ray irradiaticn, and the pressure was observed continuocusly., With
the source in place, the energy absorption rate was 0.45 x 10<° ev/hr—g
salt. The temperature of the salt and the total gas pressure cver the
salt during the experiment are shown in Fig. 1. An atmosphere of pure
helium at 16 to 18 psia was established over the salt initially and after
each sample., Analysis of the samples showed that the pressure changes

were due to changes in the amount of fluorine in the gas phacse.

Analvsis

The original analysis® of the experiment produced the follcwing con-
clusions., It was evidernt that practically pure Fs gas was produced by the

gamma irradiation of solid MSRE salt in the presence of graphite. In the

 

" LiF-BeFo-ZrF ,~ThF4~UF, (69.0 - 23.0 - 5.2 - 1.7 - 1.1 mole %).
ORNL-DWG 84-1995

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

e T
i 2/
=T ES
NG
fi//IL%.niv
T ~/
_.!m,.lll..EELIII.I.I.i ||||||| G+ —— B
< ] !
N
HH94|.|IIL lllllll he—————+——A V
g N
L
1\\._ \,\/
I\
- fl I ———dl—— iAH:l..l-T.llluVl
- N
g /r
3 \
-3
g 8 & R 8 & g @2 ¢
{De) IUNLVYIANIL {13d) JUNSSIud

70 (x10%)

60 6%

55

15 20 25 30 35 40 43

10

TIME {hr)

Pressure and Temperature vs Time in a Fluoride Salt Autoclave

Fig. 1.

Under CQamma Irradiation
abtsence of radiation or at elevated temperatures in the presence of radi-
ation the gas disappeared at a measurable rate, presumably recombining
with the salt. Other points were that following complete recombination,
F- did not reappear in the gas phase until after an "induction pericd,"
that temperature strongly affected the recombination rate, and that Fg
pressure had little if any effect on the release rate or recombination.
The remainder of this section will propose a simple model for the
mechanisms involved and extract from the ®°Co experiment some numbers

that will be useful in calculations for the MSRE and MSBR fuel.

Hypotheses
let us adopt the following hypotheses as a basis for reducing the

®00o data to some quantities that can be applied to other situations.

1. Fluorine molecules (Fz) were produced in the frozen salt at a
rate proportional to the absorption of energy from gamma rays.* The pro-
portionality factor, G, was independent of temperature.

2 Fluorine was evolved into the gas phase only after the average
concentration in the salt reached some limiting value.

3. Fluorine recombined with the salt at a rate proportional to the
concentration of radiolytic fluorine within the salt.** The prcportion-
ality factor was a function only of temperature.

Represent these hypotheses by

P = GE/100
K = k(T)C
R = P-XKg = P - k(T)Cg

 

*In actuality, radiolytic fluorine probably exists within the salt
lattice as single atoms, which form Fo molecules only after they have mi-
grated to a surface., The following description 1s simplified (without
affecting the results) by treating the fluorine within the salt as an

equivalent number of Fs molecules.

*¥
Or the concentration raised to some power n: there is no way tc

tell from this experiment the value of n, but it makes no difference in
the applications we plan to make.
where
C = average concentration of Fp in salt, molecules/g
E = rate of energy absorption in salt, ev/hr - g
G = yleld, molecules/100 ev
K = rate of recombination of Fp with salt, molecules/hr - g
k = recombination factor, hr™?
P = rate of production of Fy in salt, molecules/hr - g
R = rate of release of Fp from salt, molecules/hr - g
T = temperature of salt, °K
sub R = values while release is occurring.

Interpretation of the Data
Iet us first derive values for K during the intervals when the source
was out (making E and P zero). During these intervals the release rate

was negative and equal to the rate of recombination in the salt,
R = =K = -k(T)CR

The release rate can be computed from the rate of pressure change.

Savage, Compere, and Baker® give the formula
_ 4P
G = 0.0073 At

when
E = 0.45 x 10%°

where the units are: G, molecules Fo/100 ev; E, Ev/hr-g; and Ap/At,

psi/l000 hr, From this information, the release rate in molecules

Fo/hr-g is given by

] 20
R = LE O.OO?3%%X—-5——-——~0u X 10 = 0.328x1016é9

100 100 - At

Table 1 gives the observed rate of pressure change and the computed
value of R during intervals with the source out. (These times and pres-

sures were taken from the original data sheets® and the intervals were
Table 1

Fluorine Consumption with the Source Removed

 

 

 

 

 

Ap /At -1071®R

Interval (hr) Temp ., Pressure (psi) psi molecules

From To At (°C) Start End Ap (lOOO hr) ( hr-g )
5542,5 5590,0 47.5 110 20.21 20.1k -0.07 - 1.h47 0.48
5593,0 5618.5 25.5 150 20.99 20.43 -0.56 -22.0 T.22
5637.0 5708.7 T7l.7 110 19.79 19.58 -0.21 - 2.93 0.96
T7075.5 T221.0 1k45,5 110 21.04 20.78 -0.26 - 1.79 0.59
7221.,8 7291.5 69.7 130 21,05 20.63 -0.k2 - 6.03 1.98
7293,0 7381.1 88.1 150 20.89 19.02 -1.87 -21.2 6.95

 

chosen to eliminate transient periods associlated with changing tempera-
tures.) Since a functional relationship of k and T of the form

k = a e-b/T
is a good possibility, let us try a plot of 1n R ys 1/T. (In attempting
such a representation, one implies that K, which is the product of k and
Cr, 1s a function of temperature having the above form. This is a con-
venient approximation, as will be seen later.) Figure 2 shows that indeed
data do seem to show the anticipated dependence on temperature, The line
in the figure was fitted to the data, taking into account that some points
are more reliable because they were measured over greater intervals, The

equation of the line is

-9710/T molecules

K = 6.65 x 10°° e
hr-g
(x 10‘*’)‘

)

MOLECULES Fq
HR - GRAM SALTY

FLUORINE CONSUMPTION RATE (

Fig. 2

0

T MPERATURL  (°C)
140 1

2.4 2.5
000 for. -t
P2 (k™)

120

ORNL-DWG. 70-12905

1o

 

2.6

Fluorine Consumption in Autoclave bty Recombination with

Simulated MSEE Fuel Salt
Iet us turn now to the observed rates of pressure change while the
salt was being irradiated. During three intervals the release rate was
zero because the concentration of Fy in the salt was below the threshold,
Co. The first was the initial interval at ambient temperature (about 50°C),
when the salt was irradiated for more than 600 hr before any pressure in-
crease occurred. Another was the interval of similar length at 110°C
after Sample 3. (The significance of such "induction periods" will be
discussed later,) The other interval was the 150 hr at 150°C just before
Sample 3. The pressure had decreased rapidly just before this until all
the Fs was out of the gas (verified by Sample 3), indicating that recombi-
nation was exceeding production. Thus, after the pressure became constant
the F, concentration in the salt presumably continued to decrease.

The rates of pressure change during all the intervals when the source
was in and there was significant Fs pressure in the gas are listed in
Table 2 and in Fig. 3 they are plotted against temperature. These pressure
changes are, of course, proportional to the difference between production
and recombination, and the effect of increasing recombination rate at
higher temperatures causes the pressure change to be negative even though
fluorine is still being produced in the salt. The production rate can
be computed by adding the recombination rate calculated from Fig. 2 to
the rate of F- release indicated by the observed pressure change., (In
doing this we must assume that the recombination rate during an interval
of pressure increase was the same as during an interval of pressure de-
crease with the source out at the same temperature, which is to say that
Cr is about the same when there was an outward flow of fluorine from the
salt as when there was an inward flow.) Figure 4 shows the results of
this computation.

Some of the differences between the points in Fig., 4 are no doubt
due to error inherent in the measurements, but there 1s also a suggestion
of some remaining temperature effect, One suspects the effects of limited
diffusion rates in the salt and variation of the same with temperature,
but no firm conclusion is justified. The band from 3 to & psi/1000 hr,
which includes most of the points, corresponds to values of G from C.02

to 0.06 molecules/lOO ev, based on the energy absorption rate of
Fluorine Evolution from Salt Exposed to €°Co Source

Table 2

 

 

 

 

Ap /At
Interval (hr) Temp Pressure (psi) psi
From To At (°C) Start End CAp (7000 nr
T6L 88k 120 65 17.00 17.28 .28 2.23
1008 1343 331 58 17.28 18.7h 1.46 Lohl
1364 172k 360 38 18.35 2044 2.09 5.81
17Tk 1871 97 66 22.36 22,97 0.61 6.29
1893 2182 289 67 16.38 17.L0 1,02 3.53
2713 2852 139 61 16,78 17.28 0.50 3.60
2948 3190 242 85 18.28 20,1k 1.86 T.69
3217 3357 140 95 20.9k4 22,09 1.15 8.21
3hok 3619 215 110 22,78 23.78 1.00 h.65
3741 L029 288 110 16,67 19.08 .41 8.37
4033 4156 123 150 21 . 4h 18.06 -3.38 -27.5
4156 4268 112 150 18.06 16.09 -1.97 ~17.5
5084 5301 217 110 18.1k 19.07 0.93 4.29
5301 5541 240 110 19.07 20,28 1.21 5.04
5878 6142 264 110 19.94 20,84 0.90 3.4
6217 6380 163 110 21.20 22.18 0.98 6.01
6387 6596 209 130 22.75 22.7h -0.01 - 0.05
6603 6645 Lo 150 23.16 22 bk ~0.72 -17.1
6740 6979 239 130 21,7k 21.39 -0.35 - 1.46

 
0

ORNL DWG. 70-12906

 

20 40 ¢o 3 160
T‘E'—M PERAT  KE. (o(. )

f‘\J

'l

:?-L
T
)
0

T : e e L O
Fig. 3. Observe Drespure Increase 1 Sait Txposed to ©9Co
Jource and Calculated Raze of Preegsure Change Due to Recombination
11

ORNL DWG. 70~12907
/5o

 

Fig. 4. Rates of Pressure Increase in Salt Exposed to ®°Co Source That
Would Have Resulted if There had been nc Recombination
12

0.45 x 10%° ev/hr-g. If we exclude the 150°C points, which are very
sensitive to temperature reproducibility, the average of the data in
Fig. 4 corresponds to G = 0.045 molecules/100 ev.

Now let us turn again to "induction periods." We would like to be
able to predict for various kinds of salt under various conditions how
much energy can be absorbed before fluorine evolution begins., This is
not a constant, the most obvious variables affecting it being temperature
and the rate of energy absorption. If the temperature were high encugh
or E low encugh, recombination would maintain an Fy concentration in the
salt below that at which any significant Fs is released into the gas.

At the other extreme, at temperatures so low that recombination is neg-
ligible, all the production would go into raising the concentration. At
some intermediate temperature, C would increase more slowly because of
partial recombination, but the limiting concentration, Cg, could con-
ceivably be lower so the induction time would not necessarily be longer
than at low temperature. In the ©0Cco experiments we observed two in-
duction periods, one at 50°C where recombination was practically negligible
and the other at 110°C where the recombination rate during the induction
period probably ranged up to roughly half the production rate (see Fig. 3).
Examination of the detailed plot of the experimental data? shows that the
50°C induction period was close to 700 hours (3.1 x 10%% ev/g) and the
110°C period was about 630 hours (2.8 x 10%% ev/g). The Fy concentration
in the salt at the start of the latter period was not guite zero but was
probably practically so., Thus the fact that, despite greater recombi-
nation, the induction period at 110°C was about the same as at 50°C indi-
cates that Cg was indeed substantially lower at the highgr temperature,
Further support for a lower (g at higher temperature are the pressure
transients accompanying some of the steps in temperature, which seemed to
indicate rapid release of fluorine when the temperature was raised.

From the foregoing, it is apparent that there is indeed a dependence
of Cg with temperature that is included in the exponential approximation
for kCp w8 T that we derived., The probable difference in the form of the
temperature dependence of k and of Cp should not affect the fit of the

empirical relation too much, however, because Cg prcbably varies by a
13

factor of several while k is varying by a couple of decades, It is not
essential that we separate the relations for k and Cgr; in most applica-
tions what we want to know is whether or not the temperature is high
enough so that there will be no fluorine release (that the product kCg
is less than P).

Although the point has no significance for future applications where
no fluorine pressure is allowed to develop, it may be noted that the data
of the ®°Co experiment do not indicate any clear dependence of recombi-

nation rate on fluorine pressure in the gas,

Summary
Yield (production in the salt) in the simulated MSRE fuel salt was

0.045 + 0.02 molecules F5/100 ev, with little or no dependence on tem-
perature. TIn salt initially free of Fp, a considerable amount of energy
was absorbed before any fluorine appeared in the gas over the salt:
induction periods of 3.1 x 1052 and 2.8 x 10%% ev/g were observed at
55°C and 110°C respectively. Rates of recombination in "saturated salt"
(when there was fluorine in the gas) depended strongly on temperature;

practically not at all on fluorine overpressure. An empirical relation

-(9%%9) molecules

K = kCR = 6.65x 107® e g

Fo

fit the data within + 50%.

In applying these results to other situations, different units may
be convenient. In particular, the induction period and recombination
rates should probably be related to moles of salt rather than weight of

salt. Table 3 expresses the &0 experiment results in various units.
14

Table 3

Results of ®9Co Irradiation of Simulated MSRE Fuel®

 

molecules Fyo

Yield 0.0k ————— ~ = or 0.38 EELfiEElEg
100 ev watt - hr
Induction ev _ _
Period 3,0x10%% g or 1.3 watt-hr or 62 —ngigggf
g mole salt
Recombination molecules Fo cc(STP)Fy cc(STP)F
Coefficient 6.65x10%° ~ pr-g or 2.47x107 ~ hr-g  or 1.15x10° ——=—J/2

hr-mole salt

 

“Composition: LiF-BeFo-ZrF4-ThF 4-UF4(69.0-23.0-5.2-1.7-1.1 mole %).
Molecular weight = L6.5.
15

RESULTS OF OTHER EXPERIMENTS

In-Pile Experiments?

The series of in-pile experiments which first drew attention to the
matter of fluorine evolution and later proved it to be a low-temperature
phenomenon also produced quantitative information on yields and tempera-
ture effects on recombination.

There were clues in experiments L7-1, L7-2, and L7-3 that were later
recognized as effects of fluorine evolution, but about the only guanti-
tative information on this subject was that CF, yields were much lower in
capsules in which the salt had cooled and frozen more slowly.

When the capsules from experiment 47-4 were punctured after exposure
and cooling, fluorine was identified and the equipment was revised to
allow measurement of the amounts in the capsules. Pressures observed in
the capsules ranged as high as 50 atmospheres of Fs and a tenth as much
CFs. On the assumption that half of the decay energy released during the
95-day cooling period was absorbed in the salt, it was calculated that a
G value of 0.035 molecules/100 ev would have produced the fluorine observed
in the maximum case. Other capsules showed less Fo, with extremely wide
variations both in the amounts of Fp and the ratio CF./F5, indicating the
presence of unidentified factors affeCting the net yield of fluorine.

Experiment 47-5, designed after the observation of CF, in the L47-3
capsules, included two capsules with provisions for gas sampling and
pressure measurement., During intervals when the MIR was shut down, the
capsules were cooled to about L40°C, and, after variable induction periods,
an accumulation of gas in the capsules was noted by pressure measurements.
The accumulating gas was found to be F- and to be released from the frozen
fuel at Gpg values (molecules of Fy per 100 ev of absorbed energy) from
about 0.005 to 0.031, although on occasion the induction period persisted
throughout the shutdown. No correlation between capsule power density

just before shutdown and either G, values or duration of induction pericds

J =
was observed., There were geven shutdowng of sufficient duration for the

effects to be noted. Short (4-hr) periods at low power in which fissioning
16

continued at some rate with the salt at temperatures between 85 and 325°C
produced no detectable accumulation of gas.

The six capsules of experiment 47-5 were moved quickly from the MTR
to an ORNL hot cell where pressures were monitored to determine fluorine
evolution in the two vented capsules, Results for these two capsules,
one of which had operated at 65 watts/cm® and the other at 35 watts/cm3,
are shown in Fig. 5. Analysis of the data brought out the following
points.>® The evolution rates calculated from pressure derivatives between
11 and 31 days at 36°C and 50°C were proportional to the power density in
the capsules and correspond to a yield of 0.020 molecules F5/100 ev., Ex-
periments at various temperatures showed that evolution was suppressed
when the salt was either very cold (-70°C) or moderately warm (80°C).
Bursts of Fs occurred immediately after the temperature was stepped up.
These data suggest that the rate of evolution of Fz is controlled at low
temperatures by rates of diffusion of radiolytic species within the solid,
and at higher temperatures by a back reaction whose rate is strongly tem-
perature dependent. Later (after day 113) the effect of Fs pressure was
explored by adding F-s to the capsules. Above 50°C there were pronounced
decreases in evolution at higher pressures, but some extraneous effects,
presumed to be changing condition of the salt surface, did not permit
derivation of a quantitative pressure relation.

Also exposed in L7-5 were L sealed capsules of 3 different geometries.
The gas spaces in these capsules, after 5 months cooling, ylelded very
different quantities of Fo and CF,; one gave 39 cm” of Fp and 70 em” of
CF,, another gave 2.5 cm”® of Fs and 0.6 cm” of CF,, and two smaller cap-
sules yielded none of either gas. The most plausible reason for the dif-
ferences seemed to be the large differences in cooling rates among the
capsules and consequent differences in crystallite sizes and degrees of
stress introduced into the crystallite, with slower cooling resulting in
less gas evolution.

In the final experiment, 47-6, the salt in the capsules was kept
molten during exposure and no fluorine evolution was detected. After re-
moval, the capsules were quickly disassembled for inspection so no fluorine

evolution rate was measured.
L7

ORNL—-DWG 63-598R

 

   
 

 

 

 

 

 

 

 

 

 

 

 

 

 

14 T I l I 1 |
e b \\ |
10 I~ \ CALCULATED YIELD FOR HIGH-POWER -
\ CAPSULE WITH Gy =0.02
= 2
2 8 | _
[,
QO
Q
LLN
S & 65 w/cm3 ]
E CAPSULE
4
| ~ e ]
W \\\ \\
35 whm®
CAPSULE
2 |- ]
\
\
\
. ~
N
o
| 3ecc| s0° | 8e°|sa|-ro0| 30| 470 | 290 | eo [s79 28
S L
0 10 20 30 40 50 60 70 80 90 100

COOLING TIME (days)

Fig. 5. Postirradiation Fluorine Release in MIR-47-5 Capsules
18

X-Rayv Irradiations?

Soft x-ray irradiation of a solid mixture similar to the MSRE fuel
gave evidence of radioclytic decomposition with yields of volatile fluorine
compounds equivalent to Gp, (moles of Fo per 100 ev absorbed) values
ranging from 0.0006 to 0.0L., In some cases elemental fluorine was identi-
fied, but, generally, the products were carbon tetrafluoride and carbonyl
fluoride. Prefluorination of the salt removed carbon-containing impurities
and encouraged liberation of elemental fluorine. ZFine particles liberated
volatile fluorine-containing products at about ten times the rate from
coarse particles, The compound 6LiF+BeFo+ZrF,, one of the complex com-
pounds which crystallize from the MSRE fuel, decomposed with an equivalent
Gp, of about 0.02. Prefluorinated thorium fluoride liberated elemental
fluorine at rates of about 0.005 molecule per 100 ev. Neither lithium nor

zirconium fluorides gave any evidence of radiolysis.

Fast Electron Bombardment®

A Van de Graaf machine was used to bombard salt at 25 - 30°C, under a
He~Fo atmosphere, in an irradiation cell equipped for gas analysis. Yields
from simulated MSEE fuel salt varied with dose rate and total dose, ex-
hibiting maxima about 0.02 molecules F5/100 ev. Bombardment of ILiF showed

ne evolution of fluorine, but an uptake that was induced by the irradiation.

Discussion

The in-pile capsules were notable for the wide variations in fluorine
yields, with some capsules yielding no fluorine (the small capsules in
47-5) and others producing up to 0.035 molecules/lOO ev, The evidence
seems to be that slow freezing can greatly reduce subsequent fluorine evo-
lution even to zero,

There is some suggestion in a comparison of all the different experi-
ments that electrons or fission-product beta particles produce less fluorine
than do gamma rays per unit of absorbed energy (perhaps because of dif-
ferences in density of dislocations along the particle tracks). Whereas

the ®9Co gamma rays produced Fs with an average G value of 0.0L5
19

molecules/10C ev, the best value of yield from irradiation by included
fission products (measured in the rapidly cooled Lr-5 capsules) is about
0,020 molecules/100.

Recombination (suppression of evolution) was significant in the 47-5
capsules at temperatures from 69 to 87°C, a range in which the recombi-
nation factor derived from the ®°Co experiment would be quite low.

In calculations for MSRE or MSBR salt, frozen slowly in relatively
large tanks, and irradiated by contained fission products, it seems
reasonable to use the G value of 0.02 molecules/100 ev observed in the
47-5 capsules., This is probably conservative because the salt in the
larger vessels will cool and freeze even more slowly than the slowest
cooled capsules, which showed no fluorine evolution, There may be some
tendency toward a higher G because a greater fraction of the gamma rays
will be absorbed in the large bodies of salt, but this is probably not
as important as the cooling rate effect. TIn any case the value of 0.02
is probably within a factor of two.

Use of the recowbination factor from the ®°Co experiment is probably

also conservative, based on the results of the L7-5 experiment.

STORAGE AND DISPOSAL OF MSRE SALT

Shortly after the nuclear operation of the MSRE was concluded on
December 12, 1969, the fuel salt was divided between the two L9-inch ID
drain tanks and the heat was turned off.” In the insulated tanks the
salt cooled very slowly, and it was 22 days before thermocouples at the
centers of the tanks Indicated that the salt there had reached the sclidus
temperature (662°F). A few days later, the tank heaters were turned on
at low settings to hold the salt temperatures between 450 and 650°F. The
same was done with the flush salt.

In planning for the ultimate disposal of the MSRE salts and the interim
surveillance, it is necessary to consider radiolytic production of fluorine
and the measures needed to control fluorine evolution from the salt., There
would be some advantage in being able to turn off the heaters on the salt

tanks.,
20

Energy Sources

During operation of the MSRE, gaseous fission products (Xe, Kr) were
stripped from the fuel on a short cycle, noble metals (Nb, Mo, Ru, Te)
soon deposited on surfaces, and the other fission products remained in the
fuel salt, Each time the fuel loop was flushed, about 0.4% of the fission
products in the fuel salt became mixed into the flush salt. This was done
only 9 times during the L4 years of power cperation, so the activity in the
fuel salt was not diminished significantly by this effect.

The inventories of fission products and actinides in the MSRE salt
were computed by M, J. Bell, using the ORIGEN code and taking into account
gas stripping and the operating history of the reactor.® Figure 6 shows
the curies of fission products remaining as a function of time after the
end of nuclear operation on December 12, 1969. The calculated activity
of the actinides (mainly the chain descending from 232U) amounts to
2.5 x 10° Ci at 384 d, decreasing very slowly to 2.3 x 102 Ci at 1845 4,
The energy sources represented by the fission products and heavy nuclides
in the MSRE salt are shown in Fig. 7. In the 49-inch ID salt tanks
practically all of this energy will be absorbed. There is L4647 kg (1.06 x
10° moles) of fuel salt, so the energy source per mole is 0.94 x 107° times
the total source shown in Fig. 7. As of January 1, 1971 (when it would be
convenient to be able to turn off the heat on the tanks) the source in-
tensity would be 0.0069 watts/mole. On January 1, 1975, which is perhaps
as soon as the permanent disposal might be made, the source would amount

to 0.00195 watts/mole.

Temperature for Internal Recombination

The production of Fo within the MSRE salt is proportional to the
absorbed energy. It would appear reasonable to estimate the yield on the
basis of values observed in the inpile capsules, where the salt composition

*
was very similar to that of the final MSRE fuel and the irradiation was

 

*The composition of the MSRE fuel at the final shutdown, based on
on averages of fuel samples was LiF-BeFo-ZrF,~UF, (64.2-30.7-5.0-0,1k
mole %). The molecular weight is U3,7.
(CURIES)

RADIOACTIVITY

10,

WViln

Fig. 6.

21

ORNL DWG. 70-12908
1hf12 11 /13 Wi/14 11 /75

   

_ N
tritrr e

f

Fission Product Inventories in MSRE Salt

1
{
!

ke -

 

 
o 8

ENERQY SOURCE (WATTS)
o

i/\/ T

W/1/712

Fner

o

S

ORNL DWG. 70-12909
N/T3 11/ 74 \/1/75

 

Sources in MSEE Salt
23

similarly from included fission products. The most precisely measured
value was 0,020 molecules/loo ev, obtained by tracking the flucrine evo-
lution from the two vented capsules in experiment L7-5. The MSRE fuel
froze very much more slowly than did the salt in these capsules and the
evidence seems to indicate lower yields from slower-cooled salt, so use
of G = 0.020 probably is a conservatively high value for the yield in the
MSRE. (This is not certain, however, because of the unknown effects of
tank size, degree of salt cracking, etc., on escape of fluorine,) Assuming
a yield of 0.020 molecules/lOO ev, the production within the salt would
amount to 0.17 S cc(STP)/hr-mole where S is the energy absorpticon rate in
watts/mole,

The recombination of fluorine in the salt can be estimated by the
relation derived from the ®°Co experiment. When the production is equated
to the expression for the recombination rate as & function of temperature,

the result is

g - 1,15 x 10° o 91%9 watts
- 0.17 mole

This is the relation between S and the tempeféture at which all the
fluorine would just be recombined,

If one takes S for the MSRE fuel from Fig. 7 and uses the foregoing
relation between S and T to compute temperature, one finds that the re-
quired temperature decreases very slowly from 173°F in January, 1971 ©o
145°F in January, 1975. The required temperatures would be higher by only
15°F if one were arbitrarily to assume twice the fluorine yield (G = 0.0k

instead of 0.02 molecules/100 ev).

Tnduction Period and Fluorine Release

Tf the MSRE salt were somehow cooled below the point of complete in-
ternal recombination of the Fy, it would probably still be a very long
time before any Fs was released. If the induction period were 62 watt-hr/
mole (as in the ©9Co experiment), this would amount to 6.6 x 10° watt-hr

in the MSRE fuel salt, If the salt were chilled on January 1, 1971, it
2k

would be over 30 months before this much energy was absorbed., If the
induction pericd began on January 1, 1975, it would be at least 45 months
before the absorbed energy amounted to 62 watt-hr/mole.

The Fo production in the MSRE fuel salt on Januvary 1, 1971 (assuming
G = 0.02 molecules/100 ev) will be 0.17 x 737 = 125 cc(STP)/hr. If there
were no recombination and all the Fs accumulated in the gas space in the
fuel drain tanks, the rate of pressure Increase would be 0.12 psi/week,
(The volume of the two tanks is 160 ft2, of which 66 ft> is filled with
salt.) By January 1, 1975 the production rate would be down to 35 cc(STP)/hr.
If the salt were put in cans with 10% free volume and all the Fs produced
accumulated in the gas space, the rate of pressure rise at that time would

be 0.42 psi/week.

Discussion

The figures generated above provide a basis for planning the sur-
veillance and disposal of the MSRE fuel salt, This planning, which takes
into account many considerations besides fluorine evolution, is currently
underway and will be reported separately. One simple mode of operation
during the surveillance period, that appears feasible from the standpoint
of Fyp production and recombination, would be to heat the drain tanks only
once a year (at the time of the annual system tests) to a temperature
(say 300°F) at which all the Fy would certainly be recombined. There are
some data which indicate the tanks might not cool below the threshold
temperature in one year without external heat. But even if it did, the
estimated induction period is much longer than a year, so probably no Fo

would be released in the interval between heating.
25

DEALING WITH SALT FROM LARGE MOLTEN-SALT REACTORS

In one scheme of operation of molten-salt converter reactors, the
fuel salt would be discarded periodically (after the uranium had been
stripped from it). After being held for a while in large tanks with
internal cooling capabilities, the salt would be put into simple cans
and allowed to freeze, Internal heating by the fission products would,
of course, keep the salt above the ambient temperature and the salt could
not be canned too socon after operation without creating a problem of
keeping the cans from overheating. ILater, after the heat source had di-
minished, the problem would change to one of keeping the salt warm enough

to prevent fluorine evolution due to radiolysis of the frozen salt.

Energy Source

Typical MSR power densities during operation fall in the range from
about 1.0 to 1.5 Mw(t)/ft> of salt. A few minutes after shutdown of the
fission chain reaction, the energy from decay of fission products in the
salt is on the order of 10 kw/ft”?, By the time the salt could be pro-
cessed and ready to put into storage cans (say 6 weeks after shutdown),
the energy source would be down to around 500 watts/ft3. This then will
be taken as the high end of the range to be considered. The low end de-
pends on detailed plans for salt storage and disposal., If the cans of
fluoride salt are to be disposed of by burial in a salt mine, an economic
analysis of the relation between heat source and allowable spacing in the
mine would probably dictate a cooling time of at least a year, At one
year the heat source in MSR salt would be down to about 60 watts/ft3.

It is necessary to consider much lower energy sources, however, because
for some reason it might be desirable to store the salt for much longer

than a year,

Heat Transfer and Tempersatures

The temperature of the canned salt will depend on the heat source,
the dimensions of the can, and the ambient conditions., The size can

tentatively considered is 2-ft dia by 10-ft long. When first loaded,
26

the cans might be left bare, radiating to relatively cool surfaces in
some kind of storage vault., Later, if necessary to prevent fluorine evo-
lution, the cans presumably could be set into insulated or heated en-

closures,

Internal Distribution
The radial temperature distribution within a long cylinder in which
heat transfer is only by conduction (as it would be if the salt were

frozen) is

RZS
T-Tg = 5 [1- (3

For molten MSER salt, k is about 0.7 Btu/hr-ft-°F., The conductivity of
frozen salt increases rapidly as the temperature is lowered.® For sim-
plicity, let us use a constant value of X = 0,7. Then for R = 1 ft, the

centerline temperature, T is given by

e

T, = Tg + 1.22 5

where the temperatures are in °F and 8 is in watts/ft3. If the salt were
molten, convective currents would reduce the temperature gradient within

the salt.

surface cof Bare Cylinder

Consider the case where the can is exposed to the air. A convective
film coefficient can be estimated from a convenient alignment chart for
natural convection from vertical surfaces, given by McAdams (Ref. 10,
p. 175.) Assuming air at 1 atmosphere and 100°F, the estimated heat flux
due to convection varies with surface temperature as indicated in Table L,
Heat loss by radiation will be quite important if the can sees cool sur-
faces. If there are 'black" surfaces at To °R in all directions the heat

transferred by radiation is given by (Ref. 10, p. 65).

Ty . Te
- 4
lOO) ( lOO) ]

 

 

q __ = 0.7l e, A [(

Assuming g = 0.5 (about right for oxidized nickel-alloy surfaces) and

T_ = 560°R (100°F), the heat flux due to radiation is as shown in Table k,
2T

Table 4

Heat Loss from Vertical Surface Exposed to
Air and Cool Surfaces at 100°F

 

 

 

Surface T Heat Flux (Btu/hr-ft=)

(°F) Convection Radiation Total
150 36 3k 70
200 90 80 170
300 230 200 130
400 400 380 780
500 560 640 1200

 

For a long 2-ft diameter cylinder, the heat flux at the surface is

related to the internal heat source by

a4 _
4 o= L1 s

where q/A is in Btu/hr-£t% and S is in watts/ft®, This relation, the
numbers in Table 1 and the relation given above for centerline tempera-
ture combine to give salt temperatures in a bare, radiating can as a

function of S as shown in Fig. 8.

Surface of Insulated Cylinder

When measures have to be taken to keep the cans of salt warm, there
are several things that might be done. It is evident from Table L that
simply cutting off the radiant heat loss would almost double the AT be-
tween the can and the air., (Actually a layer of reflective material
would probably also cut down on convection,) Iater, as more efficient
insulation became necessary, 1t would be simple to set several cans to-
gether in a insulated box, To get a feel for the amount of insulation

required, consider a single can, with a non-radiating layer of insulation
28

 

Fig. 8. Temperatures in a 2-ft Diemeter Can of Salt Exposed to 100°F
Surroundings and the Temperature Required to Prevent Fluorine Release
29

immediately around it. For any thickness, x, less than the radius of the
can, R, the AT between the can surface and the outside surface of the

insulation is closely approximated by
_ 9y —B X
AT = @r G2

let us make calculations for a long, 2-ft diameter can, closely surrounded
by insulation with k = 0.03 Btu/hr-ft-°F, which does not radiate, but
gives up heat by thermal convection to air at 100°F. With the convective
film coefficient evaluated as indicated in the preceding section and the
AT through the insulation given by the above relation, one calculates the

temperatures as a function of S shown in Fig. 9.

Can Imbedded in a Salt Mine

If the cans of MSR salt are disposed of in the proposed national
disposal facility,ll they would be put into holes bored in rock salt (NaCl)
and covered with crushed salt. After burial, the NaCl will flow and seal
in the cans. The temperature of the salt bed initially will be about T70°F,
so if there is good thermal contact, the temperature in the canned fluo-
ride salt would be pulled so low that fluorine would not be recombined
effectively, at least not for a while. Some gquestions that arise then
are "How fast and how far will the salt bed temperature rise?' and "Can
insulation around each can be used effectively?”

The answer to the first question depends on the intensity of the heat
source, the spacing between cans and the extent of the buried array,
Current planning for the disposal facility anticipates allowable salt
temperatures up to 200°C, but in typical layouts the temperature takes
about 3 years to rise above 100°C (Ref. 12). So there would probably be
considerable fluorine evolution from MSR salt in bare cans for the first
few years at least. _

The question of insulation may be wroth investigating. One factor
to be considered is the effect of the brine inclusions in the salt that
will migrate up the thermal gradient to the heat source.

Probably more practical would be to anticipate fluorine generation
and possible escape from the cans. The rates of release would not be

great in any case, and probably would not create a hazard.
30

e el
f

1
+
G ks

 

- oy e mn o Fal g
+ Diarester Canrs o
¢

Fig. 9.
+0 Prevent Fluorine Keleasge

Suit in 100°F Air
31

Fluorine Yield and Induction Period

The fluorine production in the salt will be proportional to the
energy source, S, As discussed in preceding chapters a reascnable value
for the fluorine yield is 0.020 molecules Fg/lOO ev of absorbed energy.
This is equivalent to 0.17 ce/(B8TP) /watt/hr.
| Tt is interesting to consider the rate of pressure increase that
might occur in a can of salt if the temperature were such that there was
no recombination so that all fluorine was going into the gas phase.
Assume an energy source of 100 watts/ft>. (With more intense sources
even a bare can of salt would probably be warm enough to recombine some
of the Fp.) Assume also that the gas space in the can is 0.1 as large

as the salt volume. Then

vatts 17 ce(STP)Fo x 1h.7 psi

 

po 199 53 satt | watt-hr cc(STP) /cc psi
At = 0.09 7%
4 _Cc¢ cc_gas
2.83 x 10 P 0.1 ~aalt

Obviously the foregoing situation could be tolerated only temporarily,
so the question of the induction period arises. The amount of energy that
might be absorbed before fluorine begins to be evolved is around 62
wat-hr/mole salt (based on the ®°Co experiments). MSBR salt molar density
is about 1500 moles/ft. If the energy source in the salt were 100 watts/
ft° (0.067 watts/mole), then following a reduction in salt temperature
from the range of complete recombination, the interval before fluorine

evoluation began would be roughly 5 to 6 weeks.

6o watt-hr

mole
At = o opr ¥att T 930 hr
L0067 mole
32

Temperature for Zero Release of Fluorine

The rate of fluorine recombination in MSR salt can be calculated
from the results of the ©9Co experiment., The rate of recombination when
the concentration of fluorine in the salt is at the threshold of evolu-

tion is

_ 9710
K = 1.15 x 10° x 1500 e 1 SS(SIP)

- hr-f+3

where T is in degrees Kelvin. The production in the salt (corresponding

to G = 0.02) is

P - 0.17 § cc(STP)

hr-ft°

where S is in watts/ft>. Equating P and K gives a relation between T
and the maximum value of S at which all the fluorine would be recombined
internally.

_ 9710

S - 1.00x 103 e p |datt

£t2

This relationship is represented by the dashed curve superimposed on the
calculated salt temperatures in Figs. 8 and 9. Any combination of tem-
perature and absorbed energy source below and to the right of the curve
would result in fluorine release from the salt, At any point on the
other side of the curve, the fluorine would all be recombined within the

salt,
Discussion

The purpose of the foregoing calculations is to provide a basis for
considering ways of storing irradiated MSR salt, For example, from Fig. &
one could conclude that salt could be put into a 2-ft diameter can one
month after reactor shutdown and, with no cooling other than natural con-

vection to 100°air and radiation to 100°F surroundings, it would not
33

overheat. For these storage conditions, fluorine evolution might begin
when the heat source had decayed to about 150 watts/ft~, which would be
about 3 months after shutdown., A reflective layer around the can would
keep the temperature high enough out to about a year. Then, as indicated
in Fig. 9, an inch or so of insulation would keep the can warm enough for
several more years. Of course, rather than changing the insulation, 1t
might be simpler to store the cans in a controlled-temperature enclosure,
In this case the control range would not need to be wide: 100°F sur-
roundings would keep the cans cool enough at the beginning and 200°F
would keep the cans warm enough at the end,

If the cans were to be hauled to a disposal site say a year after
shutdown, the radiation shielding around the can would probably keep the
salt warm enough to prevent fluorine evolution., But even if the salt
were chilled at this time, it would probably be a few weeks before
fluorine began to be evolved.

It must be recognized that there are considerable uncertainties in
the data on fluorine evolution and the extrapolation from the capsule
experiments to the MSR salt storage conditions., Further research would
be valuable. Nevertheless it is clear that prevention of fluorine evo-

lution from stored MSR salt will not be very difficult or expensive.
10.

11.

12,

3k

REFERENCES

MSR Program Semiann., Progr. Rept. July 31, 1964, ORNL-3708,
pp. 252 - 287.

H. C. Savage, E, L. Compere, and J. M. Baker, Gamma Irradiatlon of
a Simulated MSRE Fuel Salt in the Solid Phase, Reactor Chem. Div,
Ann. Progr. Rept., Jan. 31, 1964, ORNL-3591, pp. 16 - 37.

MSR Program Semiann, Progr. Rept., Jan. 31, 1964, ORNI-3626,
pp. 101 - 105.

E. L. Compere, private communication, September 1970.

F, F. Blankenship, 8. S. Kirslis, and J. E., Savolainen, In-Pile Tests
of MSR Materials, Reactor Chem., Div. Ann. Progr. Rept., Jan. 31, 196k,
ORNL-3591, pp. 21 - 23.

J. E. Baker and G. H. Jenks, Fluorine Evolution from Solid Fluoride
Salts Under Irradiations by Van de Graaf Electrons, Reactor Chem,

Div. Ann. Progr. Rept., Jan., 31, 1964, ORNL-3591, pp. 31 - 3k,

MSR Program Semiann. Progr. Rept., Feb. 28, 1970, ORNL-4548, p. 3.

M, J. Bell, Calculated Radiocactivity of MSRE Fuel Salt, USAEC Report
ORNL-TM-2970, (May 1970).

MSR Program Semiann. Progr. Rept., Aug. 31, 1969, ORNIL-LLLQ,
pp. 89 - 93.

W. H. McAdams, Heat Transmission, 3d ed., McGraw-Hill, New York, 195k,

Siting of Fuel Reprocessing Plants and Waste Management Facilities,
ORNL-L4L451 (July 1970) pp. 4 - 55 — 4 - 67.

R. L. Bradshaw, private communication, September 1970.
-

W OO O\ Fw o

H M~ P e
Nt w RO
*® & e = 2 @

16.

o » © - - - ® *

- ®

- &

. e ® o - ® . . - ® s © e - °

.LIZCD"Uflm*dbdbiiiic—ifbt“tjtli:m%*figEHEUSUBUQOBJQ@UHZUJO"—I‘;U

B G

- . * * < - . . . ° .

SHHY @D EsEnQOodROddaHdd Y9 Y W EHuuRE QY NpndEE

Affel
Anderson
Baes
Beall

ender

Bettis
Billington
Blankenship
Blomeke

. Bohlmann

Borkowski
Boyd
Bradshaw
Briggs
Chapman
Compere
Cottrell
Culler
Distefano
Ditto
Eatherly

., Engel

Ferguson
Ferris

., Fraas

Frye
Furlong
Grimes
Grindell
Guymon
Haubenreich
Hoffman
Jordan
Kasten
Kaplan
Kelley
Keyes

81-82.
830
8L-86.
87.
88.

35

INTERNAL
DISTRIBUTION

Lo,
L3,
Ly,
Ls,
L6,
L.
Lg,
k9.
50,
51,
52-53.
54,
55
56.
57,
58.
59.
60.
61-63.
6,
65.
66.
67
68.
69.
T70.
T1l.
2.
T3.
Th.
5.
6.
7.
78.
79.
80.

S. S.

ORNL-TM-314L

Kirslis

Kermit Laughon, AEC-CSR

B.

o > L] * - - * . * - - .
. - e - ® e * . * - - o

»

:D.:q.zngqub?bemmswmmzw
EI§:=E:§ biWit*Cagutfl FToHOHQZEH

Lindauver
Lundin
Lyon
MacPherson
MacPherson
McClain

. McCoy

McCurdy
McIntosh, AEC-Washington
McNeese

Meyer

Miller

Moore

Nichols
Nicholson
Perry
Rosenthal
Roth, AEC-CRO
Savolainen

Dunlap Scott
. Shaw, AEC-Washington

. Jo
* L.

- * o

godHd =2 HHE>

M
M
W
I. Spiewak
D
R
D

Skinner
Smalley, AEC-ORO

Sundberg
Thoma
Trauger
Watson
Weinberg
Weir
Whatley
White
Whitman

ale Young

Central Research Library

Y-12 Document Reference Section
Ieboratory Records Department
Leboratory Records Department (RC)
ORNL Patent Office
36

ORNL-TM-31h4L

EXTERNAL
DISTRIBUTION

89-103. Division of Technical Information Extension (DTIE)
104, ILaboratory and University Division, ORO