International Concepts for the Assessment of Deep Geological Disposal of Radioactive Waste

More than 50 countries worldwide are currently exploring options for radioactive waste (RW) disposal, considering the link between geoscience fundamentals and the safety of RW disposal sites. The presentation will focus on the lessons learned from representative RW disposal projects worldwide (such as those conducted in Sweden, Finland, France, Spain, Switzerland, Japan, and the USA), summarizing the existing deep geological repository (DGR) concepts, including potential DGR site selection and characterization, as well as long-time modeling predictions. A comparative assessment of models of coupled thermo-hydro-mechanical-chemical (THMC) processes has been performed within the scope of the international project DECOVALEX, which has helped advance the understanding of THMC processes in geological systems. The experimental and modeling studies of the DGR concepts are ultimately linked to assessing the safety of RW disposal. The presentation will provide critical references and case studies related to the representative national disposal programs, which would interest geoscientists, engineers, and decision-makers working on national RW disposal programs. We will summarize and compare challenging geological problems and experiences in siting nuclear waste repositories in different host rocks, such as hard rock (crystalline and sediments), clayey, and salt formations. The availability of rock in a country limits the choice of rock type for the DGR. The interplay of geological conditions with technical feasibility, an engineering design for different rock types and operational and post-closure safety is critical in technical evaluating potential sites. We will also present summaries of the progress in international cooperation studies and testing of the design of buffer and backfill materials, the development of the concept of RW disposal in deep boreholes, the RD research in Underground Research Laboratories (URL), and multi-national RW repository initiatives. Acknowledgments: LBNL work was supported under Contract Number DE-AC02-05CH11231 with the US DOE. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.