Scenario development for mineral alternations in granite by high pH solution

Shimoda, Satoko*; Saito, Hironori*; Takase, Toshio*; Yamaguchi, Kohei; Oda, Chie  ; Honda, Akira

The unstable primary mineral is dissolved and the precipitation of a steadier secondary mineral happens thermodynamically when a high alkaline groundwater of the cement system material origin is infiltrated from the radioactive waste geological disposal facilities to a peripheral bedrock. Therefore, the pore structure of the hostrock changes by the precipitation and dissolution, and the material transportation characteristic of the bedrock changes. It is necessary to decide the chemical reaction scheme for the analysis. However, the combination of the secondary minerals exists innumerably. Therefore, granite was assumed to be an example by summarizing the chemical reaction scheme in the mineral alteration scenario, and the mineral alteration scenario concerning the reaction with a high pH groundwater was presented. It dealt with the uncertainty concerning the mineral alteration by preparing two or more scenarios with a different alteration route.