Development of diffusion database of buffer materials and rocks; Expansion and application method of foreign buffer materials

Tochigi, Yoshikatsu; Tachi, Yukio  

Japan Atomic Energy Agency (JAEA) has been developing database of diffusion parameters in buffer material (bentonite) and rock, which are key parameters for safety assessment of the geological disposal. JAEA is continuing development and updating such as parameter estimation, finding data trend, examining related information concerning reliability have been carried on to apply the database in parameter setting for safety assessment. As the result of data addition, total data count of effective diffusion coefficient is 2,020 (599 for measured value) and that of apparent diffusion coefficient is 1,747 (measured value). As an example of practical use of the improved database, the example of evaluation for the plot of a diffusion coefficient vs. dry and partial smectite density was discussed. As a result of introducing partial smectite density for database update, domestic and foreign bentonites are normalized on same index and compared each other on the same plot of measured data.