The Role of Clays for Safe Storage of Nuclear Waste

Nuclear power production creates hazardous radioactive waste and spent fuel. Safe storage of such waste is of major concern for countries that produce nuclear power, particularly after Fukushima. A period of up to 1 Ma became widely accepted as the relevant time horizon. The chapter gives an overview about the scientific challenges of disposal concepts which rely on the isolation of conditioned radioactive waste from the environment. Clay-rich sedimentary formations are studied as host rocks, whereas bentonites are candidate materials for engineered barriers in all host rock concepts; both fulfil the requirements for a multi-barrier system. The desired and required properties of bentonites are discussed to evaluate the performance of bentonite buffers. The chapter ends with a case study of the Swedish program for final disposal of spent nuclear fuel explaining the safety functions of the barriers.