Site-generic approach for performance assessment of HLW disposal system in Japan

This paper presents an overview of the preliminary performance analyses and description of R ampersand D activities designed based upon the results of the analyses, which are to be incorporated in the FY1991 progress report. A preliminary performance analysis for the engineered barriers was made considering wide range of geochemical and hydrological characteristics of geological environment in Japan. The results indicate possibility that adequately designed engineered barrier subsystem with chemical buffer capability reduces release rate to the geosphere to sufficiently small level without counting retardation by natural barriers. Parametric survey of natural barrier performance was also carried out and it shows that two types of rock/groundwater system at different scales can contribute to improving reliability of overall system and are worth further investigation. Major R ampersand D issues were clarified focusing coupled processes in near field and heterogeneity of natural barriers