ORNL-5388 - the Molten Salt Energy Technologies Web Site

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The isotopic composition of the spent fuel inventories is also of interest from a
proliferation standpoint.
For both the LEU and the MEU/Th once-through fuel cycles, the
fissile uranium content of the spent fuel is denatured (diluted with 238U) and hence is
protected by the inherent isotopic barrier.
fissile material most subject to diversion.
Thus the plutonium in the fuel would be the
The use of the MEU/Th cycle in place of the
LEU cycle sharply reduces the amount of plutonium produced (by 60-80%, depending on reactor
type), and for both cycles the quantity of plutonium produced in the gas-cooled reactors is
substantially less than that produced in the other reactor types.
Recycle Systems
If recyling of the fissile material in the thermal reactors is permitted, then 233U
(and plutonium) produced in the MEU(235)/Th is recoverable on a schedule dictated by the
production rate of the system.
and production of various fissile materials for the MEU(235)/Th fuel cycle under the as-
sumption that the capability for uranium recycle is available.
ated does not reflect the 235U lost to the enrichment tailings.)
the MEU(233)/Th fuel cycle estimates are also provided. The most striking aspect of
Table 7.2-3 is the apparent 30% reduction of fissile consumption achieved with the 233U system,
indicating the higher value of 233U as a thermal reactor fuel.
this effect is masked somewhat since a large fraction of the recycled fuel for the 235U makeup
case is in fact 233U. It should also be noted that the MEU(233)/Th cycle generally results in
a smaller net plutonium production, even though the degree of denaturing is less (i.e., the
238U fraction of uranium charged is higher).
Table 7.2-3 gives estimates of the net lifetime consumption
Table 7.2-3. Estimated Net 30-Year Fissile Consumption and
Production for MEU/Th Cycles with Uranium Recyclea
MT/GWe
(The 235U consumption tabul-
For comparison purposes,
In fact, the true extent of
With 235U loading and Makeup With 233U Loading and Makeup
Fissile Pu Fissile Pu
Reactor 235U Consumption Production 233U Consumption Production
PWR 12.5 2.85 9.1 1.89
HWR 4.5 0.90 3.1 0.96
HTGR 10.4 1.13 7.7 1.09
PBR - - - -
SSCR 8.7 2.56 5.9 2.44
a At 75% capacity factor.