ORNL-1816 - the Molten Salt Energy Technologies Web Site

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ANP QUARTERLY PROGRESS REPORT
The program of MTR irradiations of lnconel
capsules containing fluoride fuels has continued,
and the capsules examined thus far have revealed
no evidence of radiation damage. The horizontal
type of fuel-circulating loop designed for irradiation
in the LlTR has been operated out-of-pile with a
non-uranium-bearing salt and is now being inserted
in the HB-2 facility of the LITR. A small loop suit-
able for vertical operation in the LITR lattice has
also been successfully bench tested, and a second
model for in-pile operation is being constructed.
The creep test apparatus for testing lnconel at
high temperatures in the MTR is being bench
tested. The stress-corrosion apparatus for LlTR
operation has been successfully bench tested, and
an in-pile apparatus is being constructed.
Remote metallographic studies of solid fuel
elements were continued, and additional information
on the relationship between UO, particle size and
radiation damage was obtained.
MTR STATIC CORROSION TESTS
W. E. Browning G. W. Keilholtz
Solid State Division
H. L. Hemphill
Analytical Chemistry Division
The program of MTR irradiations of lnconel
capsules containing fused fluoride fuels has been
continued. Additional irradiations were carried out
on capsules containing NaF-ZrF,-UF, (48.9-49.3-
1.79 mole %) and on capsules containing NaF-
ZrF,-UF, (50.1-48.2-1.74 mole %). These fuels
generate 1100 w/cm3 in the A-38 position in the
MTR. To date, five capsules in this series, three
with UF, and two with UF, fuels, have been
successfully irradiated for a two-week period with
metal-liquid interface temperatures of 1500 +5OoF.
The capsules have been examined metal lographi-
cally, and the fuels have been chemically analyzed.
One out-of-pile electrically heated control capsule
containing UF, and one containing UF, have also
been examined, and the fuel batches have been
chemically analyzed.
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9. RADIATION DAMAGE
J. B. Trice
Solid State Division
A. J, Miller
ANP Project
The irradiated UF3-bearing capsules and one of
the irradiated UF, capsules showed practically no
corrosion - that is, they were similar to the control
capsules - while one irradiated UF4-bearing cap-
sule, previously reported, ’ had subsurface voids
to a depth of 2 mils. There were no significant dif-
ferences in the iron, chromium, or nickel contents
of the irradiated fuels, as compared with the starting
fuel batches, and there was no evidence of segrega-
tion of either uranium or impurities. The chemical
analyses of the two out-of-pile controls that have
been examined to date were accidentally spoiled.
The uranium in the UF3-bearing fuel analyzed not
less than 96% UF,, and the UF4-bearing fuel
showed no trivalent uranium. In an attempt to de-
tect any minute radiotion effects which might be
occurring, the irradiation period is being extended
to six weeks for the other capsules in this series.
Additional examinations were made of capsules
containing NaF-ZrF,-UF, (50-46-4 mole %) that
had been irradiated at a nominal temperature of
162OOF and had generated 2700 w/cm3. In this
series of irradiations, the in-pi le temperature
history was quite complex. No evidence of chemi-
cal damage could be found in the fuel, and there
were no high concentrations of lnconel components.
There was some corrosion evident, and therefore
out-of-pile control tests will be made in which the
in-pi le temperature patterns will be duplicated
insofar as possible. New experiments with this
fuel are to be made in which more closely controlled
temperatures and planned temperature excursions
will be used.
The chemical analyses of samples of fuel taken
from irradiated lnconel capsules have at times
shown increases in iron such that the iron-to-
chromium ratio was greater than that found in the
Inconel, and therefore a series of radioactivation
analyses of the iron content in the irradiated fuel
was made; these analyses demonstrated that the
high -values were due to contamination of the fuel
‘W. E. Browning and G. W. Keiiholtz, ANP Quat.
Ptog. Rep. Sept. 10, 1954, ORNL-1771, p 134.
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