ORNL-TM-7207 - the Molten Salt Energy Technologies Web Site

such contamination. For a demonstration reactor, this relatively sinple
equipment probably should be sized to pernit treatment of the fuel on a
300-d cycle; if it were pessimistically assmed that 3.3 d would be re-
quired to ~ P Q C ~ a ~ batch, S the equipment should be sized to assomodate
1% of the fuel charge (-1 m3)0
Some fission products would be affected by this treatment; iodine,
in particular, would be evolved and would have to be managed in the off-
gas.
~elenim and tellurium (if they are soluble as ~e2- and ~ e in ~ the -
molten fuel) might also evolve.
kidation of pa49 to pas+ could be
avoided by inelusion of a few percent of H2 with the HF.
However, oxidation of a large fraction of the UF3 to UF4 would re-
sult unless the IIF-H2 mixture contained so large a fraction of M2 that it
would be relatively inefficient at oxide removal. Accordingly9 to allow
for additional (beryllium or uranium) reduction of this UF4 would be nec-
essary to maintain the desired ~ J F ~ / Uratio. P ~
For example, in the unlikely event that the fuel must be treated
for oxide removal each 1000 full-power clays, the inventory would require
treatment 8.2 times during the reactor lifetime. The inventory of ura-
nium isotopes (see Table 9) increases regu%arly during the reactor life-
time and may average 1.07 x 105 moles during the 30 years.
not true) all the UF~ were oxidized each time and if 5% of the uranium
inventory were to be reduced, some 2.2 x IO4 moles of BeQ would be re-
quired during the reactor lifetime. nis, when added to the 2.9 x 104
moles of beryllium estimated previoulsy to be required to overcome the
oxidative effect of uranium fission, would total some 5.1 x 104 moles of
BeF2 generated or near 5.4% of the BeF2 3n the original feed.
BeF2, though added at a slowly increasing rate during reactor life, is a
good match for the 6.8% of 7 ~ needed i ~ to add the uranium as ~ i 3 ~ ~ A 7 .
perfect match of LiF and BeFz additions is certainly not requ-ired; the
maintenance processes briefly indicated above might provide a sufficiently
good addition rate for LiF and BeF2.
~f (as is
This added
Possible addition of thorium. If making a few additions of thorim
to the reactor fuel during its lifetime is necessary, then adding it as
a liquid containing %iF and TRF4 should be possible.
A possibility would
be a melt containing about 70 nole % LiF and 30 mole X ThF4 melting wear