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ANP QUARTERLY PROGRESS REPORT
whether a greater percentage of UF, could be
reduced to UF, in NaF-LiF-KF (1 1.5-46.5-42.0
mole %) at a lower temperature than previously
used, a trial was made in nickel at 5OOOC. After
2 hr of equilibration of the alkali fluoride with
sufficient UF, to equal 25 wt % uranium as UF,
and 100% excess uranium metal, the mixture could
not be filtered, and no quadrivalent uranium was
detectable by petrographic or x-ray analyses, Thus
complete reduction of UF, to UF, was indicated.
A similar experiment involved equilibrating the
NaF-LiF eutectic (40-60 mole %) in nickel for 2 hr
5OC with added UF, and an excess of ura-
nium metal. Chemical analysis revealed that
all the uranium present after the test (25 wt %)
was in the trivalent form. When the same type of
experiment was carried out with the LiF-KF
eutectic (50-50 mole %) at 6OO0C, only 60% of
uranium was found to have been reduced. Thus
KF appears to differ from NaF and LiF as a
solvent for UF, and UF,.
A trace of volatilized alkali metal was the only
evidence of reduction when purified KF was heated
at 9OOOC for 2 hr with finely divided uranium metal.
A similar result was noted when NaF-KF-LiF
(1 1.5-42.0-46.5 mole %) was heated to 7OOOC with
uranium metal for 4 hr with gas stirring. Dispro-
portionation of UF, is therefore seen as a reason-
able explanation for the quadrivalent uranium found
in UF,-KF mixtures. P
Heating of high-purity UF, with the NaF-KF-LiF
mixture at 8OOOC yielded material which, when
filtered, was found to have 73% of the uranium in
the filtrate, as well as all the uranium in the
residue, present as U3+. Evidence of slight vola-
tilization of the alkali metal precludes a definite
conclusion as to whether reduction of KF or dispro-
portionation of UF, was responsible for the de-
tected UF,; however, the presence of uranium
metal also in the residue indicates strongly that
some disproportionation took place.
Electrochemistry of Fused Salts
L. E. Topol
Materia Is Chemistry D ivi sion
Decomposition potential measurements of molten
KCI and of chromous and chromic chlorides dis-
solved in KCI have been continued. These elec-
trolyses, reported in Table 5.1, conclude, for the
present, the decomposition study in fused KCI.
TABLE 5.1. DECOMPOSITION POTENTIALS OF VARIOUS CHLORIDES IN KCI AT'85O0C
Anode: Carbon
Salt in KCI*
Salt Container Cathode Atmosphere E (observed) (v)
(mole %)
KCI** 100 Platinum Crucible He 3.25 to 3.30
100 Platinum Crucible He 2.90 to 2.75
CrCI, 3.0 Morganite A1203 Platinum He
33.3 Morganite A1203 Nickel He
0.55 to 0.65, 0.30 to 0.36, 0.90 to
1-05, 1.65 to 1.80, 0
1.60, 0.70 to 0.80, 1.25 to 1.35
33.3 Morganite A1203 Platinum He 0.45 to 0.50, 1.04 to 1.15, 1.25,
1.45, 1.57, 0
33.3 Morganite Al2O3 Platinum
H2
0.98 to 1.03, 1.22
3.0 Morganite A1203 Nickel
H2
1.06, 1.45 to 1.50, 1.75
Morganite A1203 Nickel
H2
1.70 to 1.80, 1.15 to 1.25
Morganite Al2O3 Nickel He 1.20 to 1.45
Morganite A1203 Nickel He 1.16, 1.67 to 1.75, 1.35 to 1.65
0.90 to 0.98
P -
These concentrations were made by mixing together the appropriate weights of the salts.
ade with a slotted Morganite crucible inserted between the two electrodes as a diaphragm.
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