Modelling of diffusion behaviour of humic acid and Nd in the presence of humic acid in compacted bentonite

Iijima, Kazuki  ; Kurosawa, Seiichi*; Kibe, Satoshi*; Tobita, Minoru*; Ouchi, Yuji*

Diffusion behavior of humic acid and Nd in the presence of humic acid was investigated and modeled. Breakthrough of humic acid is observed in 0.1 and 1M NaCl with 1.2-1.6 Mg/m dry density of compacted bentonite. The presence of humic acid facilitates the migration of Nd. Diffusion Parameters were evaluated from experimental results using the one dimensional diffusion model in which migration of several Nd species with different diffusion behaviors keeping equilibrium in parallel was taken into account. Obtained diffusion parameters for humic acid and Nd will be used for prediction of diffusion behavior of radionuclides in the presence of humic acid under various conditions.