Effect of colloids on radionuclide migration assessment for radioactive waste geological disposal

It is necessary to evaluate the effect of colloids on radionuclide transport in geologic environments relevant to safety assessment of radioactive waste geological disposal. This report summarizes the recent researches from the viewpoint of colloids generation in radioactive waste disposal system, effect of the colloids on the radionuclide transport, and transport model development. (1) The colloid of radionuclide could be generated by the waste dissolution. It is possible to be filtered by the engineered barrier system. (2) The effect of humic substance and biological colloids on radionuclide migration should be estimated, thus the researches on the interaction of organic matter, microbe and radionuclide are required. (3) Colloid generation from bentonite and cement material has been investigated, however the data in due consideration of the alteration are not sufficient, especially for discussion on the effect of these colloids on radionuclide transport. (4) To simulate the radionuclide migration behavior under existence of colloids, the modeling of the interaction among three phases (radionuclide-colloid-rock) is important. (author)