Long-term stability and function as a natural barrier of various geological environments in Japan from the perspective of uranium deposits

Sasao, Eiji   

This study utilizes information on the uranium deposit as an analogue of the long-term stability and function as the natural barrier system of the geological environments in Japanese island. Information on distribution and mode of occurrence of uranium deposit was compiled from the published data. Distribution of uranium deposit suggests that geological environments suitable for geological isolation are widely distributed in the Japanese Islands, despite their location in a geologically active area. The mode of occurrence of the uranium deposits indicates that formation of uranium-bearing mineral as well as sorption is expected in both sedimentary and crystalline rocks. The functioning of the natural barrier would be expected in various geological environments in the Japanese Islands, because mineralization and sorption are regarded as a barrier function to retard the migration of radionuclides in HLW, and because of the uranium deposits in the various rock types.