Status of assessment for the long-term stability of buffer material; Evaluation of the effect by iron-bentonite interactions

Ueno, Kenichi; Sasamoto, Hiroshi   ; Suyama, Tadahiro

The iron-bentonite interaction was assessed no significant effect for long term stability of buffer material. But recently, smectite alteration for non-swelling mineral such as berthierin at iron-rich environment was reported. This report wraps up the recent study and assess for the effect of iron-bentonite interaction for long term stability of buffer materials. In this report processes for candidate under repository condition were considered following three phenomena, ion-type changing from Na-type bentonite to Fe-type, mineralogical alteration for non-swelling minerals and cementation caused by corrosion products.