An Equivalent Kd-based Radionuclide Transport Model Implemented in COMSOL Multiphysics® Software

O. Silva [1], E. Abarca [1], J. Molinero [1], U. Kautsky [2]
[1] Amphos 21 Consulting, Barcelona, Spain
[2] Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden
Published in 2015

Radionuclide sorption is often simulated using a lumped approach where retention processes are represented by the distribution coefficient (Kd), which relates the radionuclide mass retained in the solid phase to its aqueous concentration. Classical Kd-based simulations rely on two strong assumptions: Kd depends on soil properties and is constant in time. However, sorption processes depend also on the fluid characteristics, which can vary in space and time. In this work, we implement in COMSOL Multiphysics® software two equivalent Kd-based radionuclides transport models that can reproduce the hydro-geochemical evolution of the soils at the site for spent nuclear fuel (Forsmark, Sweden).