Study on evaluation method of colloidal migration of radionuclides; Models on colloid transport in porous media

Mukai, Masayuki ; Tanaka, Tadao ; Yukawa, Kazuhiko; Suryantoro*

To evaluate radionuclides migration through geologic media coexistent with colloids in groundwater, a model has been coded. To evaluate an applicability of four models to colloid transport through porous media, breakthrough curves (BTCs) from column experiments using sand and reddish soil have been analyzed. Instantaneous equilibrium model could not explain both timings of breakthrough and reach to C/C=1 concurrenyly, however 1st order kinetic reaction model successfully simulate them well. BTCs from the reddish soil column have a particular feature that shows step-wise rising pattern in response to alternately inflow of colloid. Both the instantaneous equilibrium, the 1st order kinetic reaction and filtration models could not simulate this feature, however a 1st order kinetic reaction with filtration capacity model reasonably simulates the feature. The model for colloid transport, given an important role as a part of colloidal migration model of radionuclide, has been validated on the basis of the laboratory experiments.