Transuranium Elements in the Nuclear Fuel Cycle

Abstract

Transuranium elements, neptunium, plutonium, americium, and curium, are formed via neutron capture processes of actinides, and are mainly by-products of fuel irradiation during the operation of a nuclear reactor. Their properties significantly impact the nuclear fuel cycle, affecting and often determining requirements and procedures related to handling, storage, reprocessing, and disposal of fuels and high-level waste. It is still debated if, in particular, plutonium is an unwanted waste or, possibly, a resource for the production of energy. A standard universally agreed route for the treatment of transuranium elements is not yet established. This chapter provides an overview of past and ongoing experience and perspectives related to studies on transuranic recovery and incorporation in fuels and targets for advanced nuclear fuel cycles and their disposal as the main component of high-level nuclear waste. In particular, the chapter describes the main properties of transuranium fuels, the specific requirements for their fabrication, their irradiation behavior, and their impact on the back-end of the fuel cycle. For the latter, a major issue is the development of options for reprocessing and separation of transuranium elements from spent fuel to make them available for further treatment. The effects caused by their presence in irradiated fuel and high-level nuclear waste on long-term storage and final disposal are also discussed.