Application of solubility and transport limited radionuclide release in performance assessment of a spent fuel repository in Boom Clay

This report focuses on the modelling assumptions of radionuclide release from a spent fuel (SF) repository from performance assessment (PA) point of view. Radionuclides dissolved in the crystalline UO2 grains of the spent fuel matrix constitute the vast majority of the radionuclide source term and their release will be governed by the matrix dissolution rate. In previous PA studies, fuel matrix dissolution is modelled as a predefined constant-rate process, i.e, all the radionuclides (RNs) are released from the matrix at the same constant rate as the fuel matrix dissolution rate, followed by an independent transport process of RNs which can be solubility limited.