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either the Pu/U cycle or the LEU cycle (about 2.5 times more than the LEU cycle). It must
be noted, however, that the presence of chemically separable fissile material at any point
in a fuel cycle represents a proliferation risk, and thus these points must be subject
to stringent safeguards. Also, the potential spread of enrichment facilities and improve-
ments in enrichment technology (and hence greater ease in obtaining fissile material) may
make such differences between the various fuel cycles less important.
As is evident from Table 7.5-1, the private sector prefers the Pu/U cycle to the
denatured fuel cycle, and a government mandate would probably be required to induce
commercialization of denatured recycle in preference to Pu/U recycle.
have developed recycle technology for mixed-oxide Pu fuels extensively, while putting
little effort into recycle technology for thorium-based fuels.
Private investors
Because reprocessing is inherent in the denatured 233U cycle, implementation of the
cycle is likely to require the development of "fuel service centers," safeguarded facilities
whose purpose would be to protect sensitive fuel cycle activities.
evolve from the safeguarded spent fuel storage facilities required for the once-through
fuel cycles.
cycle facilities to produce denatured 233U fuels from stored 233U-containing spent fuel;
later it would include those reactors that operate on fuel from which the fissile component
could be chemically separated. Under the assumption that no weapons-usable fuel that is
chemically separable can be used in dispersed reactors, a power system utilizing denatured
Z33U fuel has a significant advantage over one based on the Pu/U cycle alone. The Pu/U
cycle would necessitate that all reactors be constrained to the energy center, which will
result in a penalty for electric power transmission since energy centers could not be sited
as conveniently as disperied reactors. With a denatured system, a significant fraction (up
to 85%) of the power could be dispersed since only the Pu-fueled transmuters would be oper-
ated in such centers and thus the system could maintain a relatively high energy-support
ratio (ratio of nuclear capacity installed outside center to nuclear capacity installed
inside center).
Such centers could
For the recycle scenarios, the center would first contain sensitive fuel
Evaluation of the denatured 23% fuel cycle on the basis of economics and/or energy
supply is difficult due to the uncertainties in unit cost factors and potential energy
demand. With the economic and energy demand assumptions employed in the analysis pre-
sented in Chapter 6, however, the economics of the denatured cycle appear to be equivalent
to, or slightly better than, the economics of the classical Pu/U cycle for moderate
growth-rate scenarios (i .e. , those employing combinations of fast and thermal systems).
Although the fuel cycle unit costs of the denatured cycle were assumed to be higher than
those of the Pu/U cycle, power systems utilizing denatured 233U fuel typically allow a
larger fraction of the reactors constructed to be thermal reactors, which have lower
capital costs.
This is possible because the nuclear properties of *33U are such that it
can be used in thermal reactors more efficiently than in fast reactors.