Impact of calcium ions on the oxidative dissolution of UO2-based surrogats for spent nuclear fuel

This study investigates the impact of calcium ions on the dissolution behavior of UO2 based surrogates for spent nuclear fuel (SNF) in granite-type repositories. The prevalence of calcium ions as one of the main components in groundwater raises questions about their influence on the stability of SNF. Leaching experiments were conducted using pure UO2 and UO2 containing fission product noble metal particles under various conditions. Electrochemical analysis and surface characterization complemented the experiments. The results indicate that Ca2+ accelerates the oxidative dissolution process of the UO2 matrix in simulated groundwater. Additionally, the establishment of a micro corrosion cell between the UO2 matrix and simulated fission product alloy particles further enhances the oxidative dissolution of UO2 in groundwater with or without presence of Ca2+. This research contributes to a better understanding of SNF environmental behavior.