An improved model for the corrosion of used nuclear fuel inside a failed waste container under permanent disposal conditions

Highlights: • The corrosion of spent nuclear fuel in a failed waste container is modelled. • Alpha-radiolysis process is simulated using a full reaction set. • Corrosion of UO2 is largely influenced by steel corrosion products, Fe2+ and H2. • H2 concentrations required to completely suppress fuel corrosion are calculated. • Influences of burnup and fuel age are examined. - Abstract: An improved model for nuclear fuel corrosion inside a failed waste container has been developed. The model considers the influence of the α-radiolysis products using a full radiolytic reaction set, and demonstrates that H2O2 is the dominant oxidant. Corrosion of the fuel is modelled considering both the direct oxidation of UO2 by H2O2 and the galvanically-coupled oxidation by H2O2 reduction on noble metal (ε) particles. Corrosion has been found to be very sensitive to the corrosion products of steel container, Fe2+ and H2. The surface coverage of ε-particles can significantly influence the dissolution rate