Development of radionuclide migration model considering pore properties in clay barriers for geological disposal

Tachi, Yukio  ; Yotsuji, Kenji*; Fukatsu, Yuta  ; Sugiura, Yuki  ; Okubo, Takahiro*

Understanding the radionuclide migration in clay minerals contained in the buffer material bentonite and rocks is important for the safety assessment of geological disposal of radioactive waste. The pore structures and the electrostatic interactions at the surface, formed by the clay mineral with a layered structure, are key components for developing the radionuclide migration model in clay minerals. In this study, in order to evaluate the influence of alteration from Na- to Ca-montmorillonite on radionuclide migration, the diffusion and sorption model was developed by considering the effects of both pore structures and electrostatic interactions in the compacted montmorillonite.