Security for Long-Term Storage of Used Nuclear Fuel

摘要

Given the uncertain future of the proposed Yucca Mountain Repository for final disposal of used light water reactor fuel, the need to store these fuels past their current regulatory certification periods has become clear. This situation presents possible regulatory and technical issues with regard to both storage safety and security for used nuclear fuel. The U.S Department of Energy (DOE), Office of Nuclear Energy (NE) is engaged in a program to develop the technical bases for extending dry storage and subsequent transportation of used nuclear fuel. The DOE/NE program addressing this issue is divided into four main topical areas: Research and Development (R&D) Opportunities, Security, Transportation, and Concept Evaluations. Previous work focused on a regulatory assessment of security regulations, including those from the U.S. Nuclear Regulatory Commission and the DOE. In addition, it has been determined that the dose rates for commercial used fuel will fall below the current 100 rem/hour self-protection threshold after between 70 and 120 years of storage. Work continues on developing the technical basis for maintaining security for long-term storage of used fuel, including consideration of "barriers" characteristic of used fuel in addition to the radiation hazard that is the basis for the existing self-protection. These additional barriers relate to technical difficulty and detectability of attacks, technical difficulty of separations processes, and thermal/chemicaluclear signatures considered in the National Academy of Sciences spent fuel standard for disposition of excess weapon plutonium. In addition, figures of merit for material attractiveness over the long-term are being evaluated. Security assessments are being performed for orphan storage sites, existing operating storage sites, and possible consolidated storage concepts.