ORNL-5388 - the Molten Salt Energy Technologies Web Site

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Enerqy-Center-Constrained Fuels
Reference Fuel
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F. LEU, recycle of uranium and self-generated plutonium, 235U makeup.
6. PU/~~~U, recycle of plutonium, plutonium makeup.
H. P~/~32Th, recycle of plutonium, plutonium makeup.
I. P~/~32Th, one-pass pl uto-ni um, pl utoni um. makeup.
J. HEU/Th (i.e., highly enriched uranium, 93.15 w/o 235U in 238U , mixed with 232Th),
recycle of uranium (235U + 233U), 235U makeup.
Case A represents the current mode of LWR operation in the absence of reprocessing.
Case B involves the use of MEU/Th fuel in which the initial uranium enrichment is limited
to 20% 235U/238U.
With reprocessing again disallowed, Case B reflects a "stowaway" option
in which the 233U bred in the fuel and the unburned 235U are reserved for future utilization.
Case C represents one logical extension of Case A for the cases where the recycle
of certain materiels is allowed.
ground rule, only the uranium component is recycled back into the dispersed reactors. Case D
similarly reflects the extension of Case B to the recycle scenario. In this case, the bred
plutonium is assumed to be separated from the spent fuel but is not recycled. MEU(2O% 235U/U)/Th
fuel is used as makeup material and is assumed to be fabricated in separate assemblies from
the recycle material. Thus, only the assemblies containing recycle material require remote
fabrication due to the presence of 232U. (It i s assumed that the presence of the 232U pre-
cludes the recovered uranium being reenriched by isotopic separation. ) The recovered uranium
from both the recycle and the makeup fuel fractions are mixed together prior to the next
recycle. This addition of a relatively high quality fissile material (uranium recovered from
the makeup fuel) to the recycle fuel stream slows the decrease in the fissile content of
the recycle uranium. As in the LEU cycle, the fissile component of the recycle fuel in
this fuel cycle scheme is diluted with 23eU which provides a potential safeguards advantage
over the conventional concept of plutonium recycle in LWRs with about the same U3O8
uti1 ization.
However, consistent with the reduced proliferation risk
Case E is the denatured 233U'fuel. It utilizes an exogenous source of 233U for both
the initial core fissile requirements and the fissile makeup requirements.
Cases F - I represent possible fissile/fertile fuel cycle systems allowable for use
in secure energy centers. Case F represents an extension of Case C in which all the fissile
material present in the spent fuel, including the plutonium, is recycled. Under equilibrium
conditions, about 1/3 of each reload fuel batch consists of mixed oxide IM02) fuel assemblies
which contain the recycled plutonium in a uranium diluent. The remaining 2/3 of each reload
consists of fresh or recycled uranium (235U) oxide fuel.