A Semi-analytical Solution for Advection-dispersion Migration of Radionuclides through Two-layered Geologic Media

Abstract

A semi-analytical solution was obtained for a one-dimensional migration of radionuclides in four (or less) member-decay chains with dispersion through a two-layered sorbing medium. The Preferential-release model is applied, in which each element can take a different and time-depending release rate from the waste form. The two types of geologic media concerned were characterized by different retardation factors for each element, the dispersion coefficients, and the ground-water velocities between the two layers. In connection with a long-term safety assessment of geologic disposal of high-level radioactive wastes (HLW), the concentration profiles of radionuclides predicted by the solution can be applied to heterogeneous geologic formations, in which radionuclides migrate through e. g. granite of a host rock followed by subsoil bounded by a surface water body.