Development of evaluation methodology for effects of cementitious grouting materials on groundwater and rock in fractured media

Sasamoto, Hiroshi   ; Yui, Mikazu; Takase, Hiroyasu*

Leachates from cementitious grouting materials used for reducing water-inflow are hyperalkaline and chemically reactive with the engineered barriers and host rock of deep repository of high level radioactive waste. Evaluation methods for long-term alteration of host rock have been developing since the extent of chemical modification may influence the transport and retardation properties of radionuclides in the far-field. Not only conventional Ordinary Portland Cement (OPC) but also low-pH (alkaline) cement (LoAC) has been considered as the grouting material in order to reduce the extent of alteration of host rock. Comparative simulations for long-term alteration of host rock considering both OPC and LoAC grouts are conducted to propose an idea for evaluation of applicability of cementitious grouting materials from view points of reducing uncertainty and conservatism of safety assessment.