Large-scale molecular dynamics simulations of cesium diffusion in systems with clay particles and water molecules

Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita ; Yamaguchi, Akiko  ; Itakura, Mitsuhiro  ; Machida, Masahiko  ; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko   

Understanding the radionuclide diffusion phenomena is crucial for the safe geological disposal of high-level radioactive waste. The diffusion in clay-water systems is particularly important for the performance of the artificial barrier made of bentonite. Numerical simulation is one of the best research methods for understanding the phenomenon at the microscopic level. Recently, large-scale molecular dynamics (MD) simulations of the systems with clay particles and water molecules were realized. In this presentation, we will show numerical simulation results of diffusion of cesium in the large system with MD. Our recent results suggest that cesium is less diffuse than sodium.