Evaluation of distribution coefficients for radionuclides sorption on bentonite colloid

Ishidera, Takamitsu ; Kurosawa, Seiichi*; Hayashi, Masanori*; Suzuki, Yasuyuki*

In the geological disposal of high-level radioactive waste (HLW) in Japan, potential impact of bentonite colloid on the migration of radionuclides needs to be evaluated in the performance assessment of geological disposal. Japan Atomic Energy Agency (JAEA) has been investigating sorption behavior of radionuclides on bentonite colloid and developing the evaluation model for the radionuclide sorption behavior on bentonite colloid. In our previous studies, the sorption behavior of Cs and Am on bentonite colloid was well interpreted by the evaluation model based on a previously reported sorption model for non-colloidal bentonite. In the presentation, the evaluation model for distribution coefficient of radionuclides sorption on bentonite colloid will be introduced in detail and the application result of evaluation model to the sorption behavior of Np on bentonite colloid will be shown.