ORNL-4191 - the Molten Salt Energy Technologies Web Site

f 243uUF,-7biF Fuel
for the
J. M. Chandler
Plans are nosv being made for refueling and op-
erating the MSXE with 233U fuel early in 1968;
approximately 40 kg of 233U as 233UF4-7LiF (27
and 73 mole %) eutectic salt will be required.
This material must be prepared in a shielded fa-
cility because of the high 232U content (240 ppm)
of the 233U. The following sections describe the
process, equipment, and status of the fuel prep-
aration process.
PROCESS
'The process for preparing eutectic- UF4-T,iF (27
and 73 mole %) salt for the original MSRE charge
started with UF4 and LiF.' Since 233U is avail-
able only as the oxide, the process was modified.
The UO, is charged to a nickel-lined vessel, and
LiF is added on top of it. 'The charge is heated,
under helium, to 9QOOC to melt the LiF, which
wets the oxide and thermally decomposes the UO,
to an average composition of U02.6. 'The charge
is treated with H, to reduce the U02,6 to U02 and
then hydrofluorinated with H,-HF (approximately
1O:l mole ratio) to convert the UO, to UF4. The
progress of the reaction of 1J02 to form UF4 is
followed by the changes in the liquidus tempera-
ture of the binary mixture as the melting point of
the charge decreases from the initial melting point
of 845OC for the LiF to 49OOC for the UF4-LiF
(27 and 73 mole %) eutectic product. Hydrogen
fluoride utilization and water production are also
indicative of the progress of the reaction. After
MSR Program Semiann. Progr. Hept. Feb. 28, 1965,
OHNL-3812, pp. 149-50.
252
E. L. Nicholson
a final H, sparge to reduce impurities, such as
iron and nickel fluorides, to metals and to sweep
out dissolved HF, the salt is sampled, filtered,
and stored in a product container. This process
has been satisfactorily tested on a small scale,
and the results indicate that the processing time
will be about 15 days/batch.
'Tentative plans are to make three 12-kg 233U
batches of salt, which will be used for the major
additions to the barren salt in the MSRE, and one
7-kg 233U batch, which will be loaded into 60 en-
riching capsules.
EQUIPMENT AND OPERATIONS
The scheiiiatic equipment flowsheet for salt
preparation is shown in Fig. 26.1. The cans of
U03, each containing about 500 g of uranium, will
be transported in a shielded cask from the 233U
storage Bcility in Building 3019 to the TURF
building (7930) and introduced into cell G. All
operations in cell G will be done remotely. k?y the
use of manipulators, the cans will be loaded into
the alpha-sealed can opener and the dunipei box,
which discharges the oxide into the heated nickellined
8-in.-diarn by 3-ft-high reaction vessel and
routes the empty cans to storage for subsequent
removal from the cell. The 'LiF is charged to
the reaction vessel via the dumper. Process
gases are supplied from outside the cell, and
instrumentation is provided to control gas flows
and processing temperatures. Waste gases are
filtered to remove entrained 233U and scrubbed
with KOH to remove unreacted WF before disposal
to the radioactive off-gas system. After
sampling, the product is transferred via a heated