ORNL-5388 - the Molten Salt Energy Technologies Web Site

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7-43
7.5.1. No-Recycle Options
Since commercial-scale reprocessing is not envisioned for some time, the currently
employed once-through low-enriched uranium cycle (LEU) represents the only significant
commercial possibility in the near term. At current ore and separative work prices,
power generated via the once-through LEU cycle in LWRs is economically competitive with
other energy sources. The once-through fuel cycle also has favorable proliferation-
resistant characteristics:
while its spent fuel contains plutonium, the fuel is contaminated with highly radioactive
fission products and thus has a radiation barrier.
its fresh fuel contains an inherent isotopic barrier; and
advantages (see Case A i n Table 7.5-l), the continued near-term use of the once-through
LEU fuel cycle for nuclear-based electrical generation is desirable.
On the basis of these and other
The principal drawback of the once-through fuel cycle lies in the fact that it is
tied to resources that will become increasingly more expensive. Satisfying the nuclear
demand postulated in this study to year 2050 would require the consumption of 5.6 to 7.1
million tons u@8. An equally important consideration is that it would also require an
annual U& production capacity of 90,000 to 130,000 tons of U$I8 by the year 2030. As
the price of uranium increases, there will be incentives to reduce both these requirements
by using uranium more efficiently. For example, improved LWR technology could potentially
reduce U308 consumption levels up to about 25% in the year 2030. A reduction in enrichment
tails assay could result in an additional reduction in the uranium requirements of about
16%; however, this would require about 80% additional SWU capacity to maintain a constant
production level of enriched uranium. But even with these gains the viability of the once-
through cycle would be limited by the availability and producibility of U308 from uncertain
resources in the next century.
A second once-through option (Case B in Table 7.5-1) would involve the addition of
advanced converters to the power system either on the LEU cycle or on the MEU(235)/Th cycle.
The implementation of the MEU(235)/Th once-through cycle in LWRs is uneconomic relative to
the LEU cycle primarily because it would require higher fissile loadings and hence higher
U308 commitments. And even if incentives were provided, the use of thorium-based fuels in
LWRs would necessitate additional fuel R,D&D. To use either the LEU cycle or the MEU/Th
cycle in other reactor types would entail significant expenditures to commercialize the
reactors in the U.S. Moreover, the generic drawback of once-through cycles - that is, the
uncertainty in the size of the economically recoverable resource base - woula remain. On
the other hand, as costs for extracting the resource base increase (to above $100/lb u&y
for example), comnercialization of the alternate reactors will become more attractive.
If continued reliance on once-through fuel cycles is to be a long-term policy, it
would be desirable to make provisions for restricting the spread of enrichment facilities.
Also, safeguarding the spent fuel elements is necessary since the plutonium bred in the
spent fuel represents a potential source of weapons-usable material which becomes i ncreas-
ingly accessible as its radioactivity decays with time. Near-term resolution of the storage
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