Simulation of radionuclides Tc-99 and Am-243 migration in compacted bentonite

摘要

The distribution coefficients of radionuclides derived from batch experiments are used to evaluate the migration behavior of radionuclides Tc-99 and Am-243 in compacted bentonite after different times. The effects of times, dispersion coefficient, distribution coefficient and pore water velocity on the concentration distribution of Tc-99 and Am-243 in the environment are also calculated from the theoretical migration equation. Tc-99 is poorly sorbed to bentonite and moves quickly into the environment. Migration of radionuclide increases with increasing dispersion coefficient and decreasing distribution coefficient. The effects of water velocity on the migration of Tc and Am are obvious. Most Am-243 is retained in the first several meters, and 20 m of the backfill-compacted bentonites are sufficient to prevent the migration of radionuclide Am from the repository to the environment. (c) 2004 Elsevier Ltd. All rights reserved.