ORNL-5388 - the Molten Salt Energy Technologies Web Site

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routinely in LWRs and small-scale fabrication of MEU(235)/Th fuels for LWRs might be attain-
able within 2 - 3 years. However, it is pointed out that the once-through cyc~c has two
variants - throwaway and stowaway - and in certain systems (for example, the PWR, as noted
below). the MEU(235)/Th cycle might be economic only from a stowaway standpoint - that is,
only if a reprocessing capability is eventually envisioned.
Table 7.2-1 sumnarizes the U308 and separative work requirements estimated for PWRS
HWRs, HTGRs, PBRs, and SSCRs operating as once-through systems on both the LEU and the
MEU(235)/Th cycles. Several interesting points are evident from these data. The LEU-HWR
requires the smallest resource comnitment (as well as the smallest SWU requirement). The
conventional PWR requires a significantly greater resource comnitment and larger SWU
requirements for the MEU/Th once-through cycle than for the LEU once-through cycle and
hence no incentive exists for the MEU/Th cycle on PWRs if only the throwaway option is
considered. Significantly, however, both of the gas-cooled graphi te-moderated reactors, the
HTGR and the PBR, require smaller U308 commitments for the MEU/Th once-through cycle than
for the LEU case. Moreover, for both of these reactors, the SWU requirements for the MEU/Th
cycle are not significantly different from those for the LEU cycle; in fact, for the PBR,
the MEU/Th cycle is slightly less demanding than the LEU cycle. These effects are pri-
marily due to the high burnup design of both the HTGR and the PBR.
levels of the gas-cooled reactors, most of the 233U produced in the MEU/Th cycle is burned in
situ and contributes significantly to both the power and the conversion ratio. It is also
interesting to note that, while not considered in Table 7.2-1, the unique design of the
PBR would permit recycle of the fertile elements without intervening reprocessing and thus
would further reduce both the ore and SWU requirements for the MEU/Th cycle. [Note: The
data given in Table 7.2-1 for PWRs considers only current comnercially deployed designs.
Studies now underway in the WE-sponsored Nonproliferation Alternative Systems Assessment
Program (NASAP) indicate that LWR modifications to reduce uranium requirements are feasible.
Similarly, much of the other reactor data are subject to design refinement and uncertain-
ties, as well as to future optimization for specific roles.]
Table 7.2-1. 30-Year Uranium and Separative Kork Requirgments for
Once-Through LEU and MEU(235)/Th Fuel Cycles*'
Uranium Requirement Separative Work Requirement
(ST U308/GWe) (MT SWU/GWe)
Reactor LEU MEU/Th LEU MEU/Th
PWR 5989 8360 3555 7595
HWR 3563 8281 666 7521
HTGR 4860 451 5 3781 4143
PBR 4289 4184' 3891 3669
SSCR 5320 7920 301 0 71 60
At the higher burnup
a
-75% capacity factor; no credit for end-of-1 ife core inventories;
,0.2% tails.
"The data presented in this table are consistent with the data subm tted
by the U.S. to INFCE (International Nuclear Fuel Cycle Evaluation) for
the cases in which corresponding reactors are considered.
C
Does not include recycle of fertile elements without intervening r -
processing.