Geological Storage of High Level Nuclear Waste

The quantity of radioactive waste will grow significantly with an increasing interest and use of nuclear-generated energy. There will always be inevitable radioactive waste residues that require disposal, even using an advanced nuclear fuel cycle in the future. Deep geological disposal, one of the most promising final disposal methods, should be validated for its long-term performance and safety assessment. Geotechnical issues related to the deep geological disposal are critical for the sustainable development of nuclear energy. They play challenging roles especially under extreme circumstances that result from deep geological conditions of a repository, extremely long containment time, and the characteristics of nuclear waste itself such as high decay heat, which may primarily affect thermo-hydro-mechanical and geochemical-coupled behavior of a repository for geologic time scales. This paper introduces an overview of deep geological disposal concepts based on Finnish, Korean, Spanish, and Swedish disposal programs, discusses the outstanding research issues in disposal from the aspect of geological and geotechnical engineering, such as Excavation-Damaged Zone (EDZ), cementitious material, long-term gas migration, and self-sealing/healing of fractured rocks with a focus on the state of the art in-situ validation experiments, and additionally presents a numerical modeling of the coupled THMG process in the repository near field, which is one of the major factors concerning the fuel canisters.