ORNL-1816 - the Molten Salt Energy Technologies Web Site

portionation of UF, occurred at a lower tempera-
ture than would have been expected in the absence
of KF. Further experimentation is planned to
determine the stability of UF, in KF and other
solvents as a function of temperature and of con-
tainer material. Preliminary experiments indicate
that UF, may be more stable when dissolved in
KF in a platinum container than in a nickel con-
tainer.
Differential Thermal Analysis
C. J. Barton
Materials Chemistry Division
D. L. Stockton
Merck and Company, Inc.
As a result of the high frequency of failures ex-
perienced with nickel capsules containing NaF-UF,
samples, a new system was designed for containing
samples during differential thermal analysis.
Graphite containers constructed so that the thermo-
couple junctions can be immersed directly in the
melt are now being used. The new system is
designed to permit evacuation before introduction
of helium as the inert atmosphere.
A cylindrical graphite block (3% in. in diameter
and 6 in. high) serves as a heat sink inside a
nickel reaction vessel (4 in. in diameter and 7 in.
deep) with a flanged head. Six graphite thimbles,
'/2 in. ID, $ in. OD, and 3 in. deep, are spaced
on a hexagonal array inside the upper half of the
graphite block. Each thimble is filled to a depth
of about 1 in. with either sample (about 6 g) or
reference material, AI,O,; the sample depth is
reduced by about 50% upon melting.
A g-in.-dia nickel tube which contains two
Chromel-Alumel thermocouples contained in a
each sample thimble.
..
PERIOD ENDING DECEMBER 70, 7954
sensitivity as compared with the nickel capsule
technique and may be very useful if the oxidation
difficulty can be overcome. Further experimen-
tation with this apparatus and with simplified
equipment that will permit the use of smaller
samples is in progress.
CHEMICAL REACTIONS IN MOLTEN SALTS
F. F. Blankenship L. G. Overhol!jer
W. R. Grimes
Materials Chemistry Division
Reduction of FeF, by H, in NaF-ZrF, Systems
C. M. Blood
Materials Chemistry Division
The reduction of FeF, with hydrogen is of particular
significance in considering the time necessary
for purification of NaZrF5 mixtures, as
discussed previously, l6 and has therefore been
studied in considerable detail. The reaction
FeF, + H 2 e FeO + 2HF
was previously explored by a dynamic method and
by an equilibration method that actually determined
equilibrium conditions of the system. During the
past quarter the dynamic method was employed
further.
Measurements of the equilibrium HF pressures
from the reduction of FeF, in NaZrF5 by hydrogen
gave, as a preliminary result, an equilibrium
constant, K, of 0.2 at 600°C as compared with the
value of 2.0 at 8OOOC previously reported.16 The
equilibrium constant is calculated from the equation
where P is expressed in atmospheres and C in
mole fractions.
, to UF, in Fluoride Melts
ditions on the extent of reduction of UF, to UF,
in fluori ued by the use of a
Dreviouslv described Drocedure.' To dlstermine
to obtain a sufficiently vacuum-tight assembly to
17C. M. Bled et al., ANP Quar. Prog. Rep. Sept. 10,
avoid oxidation of UF,. It has shown very high 1954, ORNL-1771, p 77.
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