Status of Assessment Techniques for Long-Term Stability of Buffer Material

Shibata, Masahiro ; Sasamoto, Hiroshi   ; Jintoku, Takashi; Yui, Mikazu

This report presents the assessment for long-term stability of buffer material considering the possible alteration scenarios under repository conditions based on the recent research results (i.e., H12) about bentonite alteration. In the assessment, the following three effects have a priority in view points of performance assessment: 1) temperature effect, 2) interaction effect with overpack as a engineered barrier material, 3) interaction effect with cement as support materials of the dritf in soft rock. Four cases were selected in combination with geological environment in the assessment considering the temperature effect and effects with near-field components.