Thorium fuel cycles for LWRs: fuel diversion assessments and recycle requirements

A number of fuel cycles have been proposed for evaluation in the nonproliferation alternative systems assessment program. Among these systems are light water reactors (LWR) operating on the thorium-uranium cycle or the plutonium-thorium cycle either inside or outside energy centers. These proposals support the President's nuclear power policy of accelerating research into alternative fuel cycles that do not permit direct access to materials usable for nuclear weapons but still retain the benefits of nuclear power. Reprocessing and refabrication (often referred to as the ''back cycle'') constitute a portion of the overall fuel cycle and represent potential access points to fissionable materials, which, in many cases, may be in a rather attractive form for diversion. These operations for LWR thorium-uranium and plutonium-thorium fuels were analyzed to assess and rate the diversion or proliferation potential of each major operation. Reprocessing and refabrication evaluations per se constitute insufficient data for rating the acceptability of an entire fuel cycle and must be considered along with reactor analysis, environmental data, resource utilization, and political factors. Each back cycle operation has been evaluated according to needed development, material location, material description, convertibility and radiation hazard. Needed development relates to the state of the art of the operation and identifies the stage to which the development has progressed