Chemical partitioning technologies for an ATW system

A roadmap for the development of the technology of an Accelerator Transmutation of Waste (ATW) system was recently submitted to the U.S. Congress by the U.S. Department of Energy. One element of this roadmap was a development plan for the separations technologies that would be required to support an ATW system operating with a sustained feed of 1,450 tonnes of commercial light water reactor spent fuel per year. A Technical Working Group was constituted to identify appropriate separations processes and prepare a plan for their development. The baseline process selected combines aqueous and pyrochemical processes to enable efficient separation of uranium, technetium, iodine, and the transuranic elements from LWR spent fuel in the head-end step. For the recycle of unburned transuranics and newly-generated technetium and iodine from irradiated ATW transmuter assemblies, which were given to be metallic in form, a second and quite different pyrochemical process was identified. The diversity of processing methods was chosen for both technical and economic factors; aqueous methods are deemed to be better suited to large tonnages of commercial oxide spent fuel, while it is considered that pyrochemical processes can be exploited effectively in smaller-scale operations, particularly when the application is to metallic fuels or targets. A six-year technology evaluation and development program is foreseen, by the end of which an informed decision can be made on proceeding with demonstration of the ATW system.