The influence of adsorption properties on radionuclides transport in porous medium

The repository design for disposing of radioactive wastes is intended to ensure adequate long-term isolation of the radionuclides. The system consists of natural and engineered barriers to prevent or retard the release of the wastes from the package to the biosphere. An analytical solution covering the entire range of sorption properties between solid phase and liquid phase has been derived for the migration of radionuclides in a porous medium. The analysis takes into account the advective transport, hydrodynamic dispersion, adsorption between solid phase and liquid phase, and the radioactive decay. Three kinds of sorption properties of no sorption, linear nonequilibrium sorption, and linear equilibrium sorption are integrated into the generic transient analytical solution. The results indicate that the assumption of equilibrium sorption results in underestimation of the concentration profile in the early stages of migration. It is worth noting that the concentration profile of the nonequilibrium sorption case is slightly smaller than that of the equilibrium sorption case after a certain time. However, the profiles eventually approach the same value. And the case of nonequilibrium sorption has a plateau in its profile