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and recycle modes, is better defined and as advanced converter designs are optimized for
denatured systems, the analysis will become more useful for R,D&D planning. Also, system
interaction studies for the dispersed denatured reactors and centralized transmuters
require refinement based on improved reactor designs and updated mass balances. Finally,
the question of implementing the energy-center concept, together with the use of specially
designed transmuters as a source of denatured fuel, deserves more detailed study. The
Monprol iferation Alternative Systems Assessment Program (NASAP) is currently developing
characterizations of improved fast transmuters, improved LWRs, and reoptimized advanced
converters and LMFBRs. Light Water Breeder Reactors (LWBRs) will also be included in
these characterization studies.
7.5.3. Overall Conclusions and Recommendations
The denatured 233U cycle emerges from this assessment as a potential alternative
to the conventional Pu/U cycle. Its advantages may be characterized as follows:
0 The denatured 233U cycle offers proliferation-resistance advantages relative
to the Pu/U cycle in that the "fresh" denatured fuel has an isotopic barrier;
that is, it does not contain chemically separable Pu or highly enriched uranium.
By contrast, the Pu/U cycle together with fast breeder reactors tends toward
an equilibrium with all reactors using Pu fuels. Also, fresh denatured fuel
has a much more intense radioactive barrier than does the fresh fuel of the
classical Pu/U cycle.
For moderate growth rate scenarios, deployment of power systems that include
reactors operating on denatured 233U fuel would allow a larger fraction of
the reactors in a power system to be thermal reactors. This would tend to
minimize the overall capital costs of the system compared to fast/thermal
power systems based on the Pu/U cycle.
0 If in addition to LWRs, the denatured thermal reactors of the power system
were to include denatured advanced converters, the dependence of the power
system on a fast reactor component (i.e., fast transmuters) could be further
minimized due to the improved resource utilization of denatured advanced
converters compared to denatured LWRs. A1 though the advanced converters
would have higher capital costs than the LWRs, this might be offset by
reduced requirements for FBRs.
The disadvantages of the cycle are the following:
0 The denatured 23% fuel cycle is more complex than the Pu/U cycle, and since
z3% must be produced in transmuter reactors, the rate at which denatured 233U
reactors can be introduced will be inherently limited. Because the Pu/U cycle
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