3D random walk simulation of migration behavior of radionuclide in a granite core

A 3D random walk simulation (RWS) of a heterogeneous intact rock system was performed to examine the influences of heterogeneity of the rock, such as spatial distribution of minerals and/or sorption sites and migration path, on its retardation behavior for diffusants. A cube based 3D granite model with heterogeneous mineral distribution was constructed based on the mineral composition and distribution of the Inada granite of Japan. Impulse responses of the 3D granite model for both sorptive and non-sorptive walker particles were obtained by the RWS and were evaluated in comparison with the breakthrough patterns of a simple 1D diffusion model in a homogeneous system with various retardation parameters.