Alan M Krichinsky

Safeguards Considerations for Thorium Fuel Cycles

Abstract By around 2025, thorium-based fuel cycles are likely to be deployed internationally. States such as China and India are pursuing research, development, and deployment pathways toward a number of commercial-scale thorium fuel cycles, and they are already building test reactors and the associated fuel cycle infrastructure. In the future, the potential exists for these emerging programs to sell, export, and deploy thorium fuel cycle technology in other states. Without technically adequate international safeguards protocols and measures in place, any future potential clandestine misuse of these fuel cycles could go undetected, compromising the deterrent value of these protocols and measures. The development of safeguards approaches for thorium-based fuel cycles is therefore a matter of some urgency. Yet, the focus of the international safeguards community remains mainly on safeguarding conventional 235U- and 239Pu-based fuel cycles while the safeguards challenges of thorium-uranium fuel cycles remain largely uninvestigated. This raises the following question: Is the International Atomic Energy Agency and international safeguards system ready for thorium fuel cycles? Furthermore, is the safeguards technology of today sufficiently mature to meet the verification challenges posed by thorium-based fuel cycles? In defining these and other related research questions, the objectives of this paper are to identify key safeguards considerations for thorium-based fuel cycles and to call for an early dialogue between the international safeguards and the nuclear fuel cycle communities to prepare for the potential safeguards challenges associated with these fuel cycles. In this paper, it is concluded that directed research and development programs are required to meet the identified safeguards challenges and to take timely action in preparation for the international deployment of thorium fuel cycles.

ORNL experience and perspectives related to processing of thorium and 233U for nuclear fuel

Abstract Thorium-based nuclear fuel cycles have received renewed attention in both research and public circles since about the year 2000. Much of the attention has been focused on nuclear fission energy production that utilizes thorium as a fertile element for producing fissionable 233U for recycle in thermal reactors, fast reactors, or externally driven systems. Lesser attention has been paid to other fuel cycle operations that are necessary for implementation of a sustainable thorium-based fuel cycle such as reprocessing and fabrication of recycle fuels containing 233U. This paper first identifies recent literature that has resulted from the renewed interest in thorium-based fuel cycles. Next, differences in the radiation characteristics of nuclear materials associated with thorium-based and uranium-based fuels are discussed, and the generic implications of the differences to nuclear material processing are identified. Then, experience at Oak Ridge National Laboratory concerning processing of thorium and 233U is described in terms of the processing projects and campaigns undertaken and the facilities in which the processing was implemented. This experience then provides the basis for a generalized discussion of processing nuclear materials associated with thorium-based fuel cycles as compared to uranium-based fuel cycles. This comparative discussion focuses on key out-of-reactor fuel cycle operations: reprocessing of metal-clad oxide and graphite-matrix oxide used nuclear fuels (UNFs) including head-end processing (shearing and dissolution), solvent extraction, product conversion, fuel fabrication, and waste management. It is concluded that the recycle of thorium-based UNF constituents (233U and thorium) is more technically challenging than the recycle of uranium-based UNF constituents (plutonium and uranium) based on the radiation, chemical, and physical characteristics of nuclear materials in thorium-based fuel cycles as compared to uranium-based fuel cycles.