Predicting Radionuclide Release Rates from Spent Nuclear Fuel Inside a Failed Waste Disposal Container Using a Finite Element Model

Models for the corrosion of spent nuclear fuel (fission and actinide-doped uranium dioxide) provide the essential source term for the release of radionuclides from within a failed nuclear waste container in a deep geologic repository. Although redox conditions within a repository are expected to be anoxic, exposure of the fuel to groundwater will cause the generation of oxidants at the fuel surface, leading to its corrosion and the release of radionuclides. The influence of these oxidants will be partially mitigated by the anoxic corrosion of the inner walls of the steel container to produce the oxidant scavengers, Fe2+ and H-2. This review summarizes the development of a finite element model developed to determine the influence of the various redox-controlling species (H2O2, Fe2+, H-2). Both one-dimensional and two-dimensional models are described, with the latter required to take into account the fractured geometry of the fuel.