Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Okumura, Masahiko; Kerisit, S.*; Bourg, I. C.*; Lammers, L. N.*; Ikeda, Takashi*; Sassi, M.*; Rosso, K. M.*; Machida, Masahiko
Journal of Environmental Radioactivity, 189, p.135 - 145, 2018/09
Times Cited Count：63 Percentile：87.43(Environmental Sciences)no abstracts in English
Lammers, L.*; Bourg, I. C.*; Okumura, Masahiko; Kolluri, K.*; Sposito, G.*; Machida, Masahiko
Journal of Colloid and Interface Science, 490, p.608 - 620, 2017/03
Times Cited Count：130 Percentile：93.64(Chemistry, Physical)no abstracts in English
Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko
no journal, ,
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.
Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko
no journal, ,
In order to evaluate the long-term safety of geological disposal of high-level radioactive waste, it is necessary to clarify and model the migration behavior of radionuclides in clay minerals used as buffer material on a molecular scale. In this study, we perform classical molecular dynamics simulations in clay minerals-water systems and evaluate free-energy profiles of clay minerals to clarify and model the diffusion behavior of cesium on a molecular scale.
Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko
no journal, ,
The migration behavior of radionuclides in clay minerals used as buffer material must be clarified for the long-term safety of geological disposal of high-level radioactive waste. The recent development of supercomputers enables us to perform large-scale classical molecular dynamics (MD) simulations to evaluate the adsorption properties of cation to clay minerals. We evaluated the free-energy profiles of cesium adsorption from mesopore to the interlayer of Na-montmorillonite by classical MD on a supercomputer. We found that the free-energy profiles of cesium adsorption depend on the interlayer distance of the Na-montmorillonite and mesopore salinity in the water system. In the presentation, we also discuss the distribution and diffusion coefficients of cesium ions.
Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko
no journal, ,
In order to evaluate the long-term safety of geological disposal of high-level radioactive waste, it is necessary to understand the migration behavior of radionuclides in clay minerals used as buffer materials. In this study, the difference in the diffusion behavior of cesium and sodium ions in Na-montmorillonite is analyzed by evaluating the free energy using classical molecular dynamics simulations.
Hiraguchi, Atsuki; Zheng, X.*; Underwood, T. R.*; Kobayashi, Keita; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Rosso, K. M.*; Bourg, I. C.*; Okumura, Masahiko
no journal, ,
The migration behavior of radionuclides in clay minerals used as buffer material must be clarified for the long-term safety of geological disposal of high-level radioactive waste. We can investigate diffusion/adsorption behavior of cesium ion and sodium ion in clay minerals and water systems at molecular scale using molecular dynamics simulation on a supercomputing system. In this study, we evaluated the free energy profiles of cesium and sodium ions adsorption to the interlayer of Na-montmorillonite from bulk water in mesopore. As a result, we found that the minimum of free energy profiles of these cations locates in the interlayer of Na-montmorillonite, and the minimum of free energy profile of cesium is lower than that of sodium. This result shows that the affinity of cesium ion to Na-montmorillonite is stronger than that of sodium ion. Moreover, we confirmed that the affinities of both cations to Na-montmorillonite decrease with salinity increase, and these cations maintain their adsorption mechanism. In the presentation, we discuss layer charge and layer size dependence on the free energy profiles of these cations.
