Oxyhydroxides on Aluminum Spent Nuclear Fuel: Formation Studies and Removal Practices to Prevent Radiolytic Gas Production

Aluminum-clad Spent Nuclear Fuel (ASNF) forms hydrated oxides or (oxy)hydroxides on the cladding due to water exposure during irradiation and storage. This poses challenges to sealed (road-ready) dry storage due to risks of release of bound water and decomposition releasing hydrogen and or oxygens. To assess the risks, it is necessary to understand the (oxy)hydroxides' growth/formation and morphology as the precursor state for drying and their gas generation from radiolysis. This will help determine safe (oxy)hydroxide loadings on dry-stored fuel as well as methods of removal. In this work, (oxy)hydroxides were grown on aluminum alloy substrates and the resulting layers studied for morphology and thickness; radiolysis studies were performed on powders to correlate morphology and particle size to gas generation, and drying studies were performed on powders and adherent oxide films. These experiments will be used to guide development of drying strategies for safe dry storage.