Solid surface evolution model to predict uranium release from unirradiated UO2 and nuclear spent fuel dissolution under oxidizing conditions

The dissolution of UO2 under oxidizing conditions has been studied in the last years in different waste disposal conditions. These studies have indicated the importance of the solid surface evolution during leaching experiments. In this work, a mathematical model based on X-ray photoelectron spectroscopy determinations or. the solid surface was developed. This model allows the uranium release under oxidizing conditions at acidic pH or in carbonate medium to be predicted. At alkaline pH without carbonate, the formation of a UO2.33 surface layer and irs equilibrium with the uranium concentration in solution could be responsible for the disagreement observed between the model and the experimental data, This model has been also applied to uranium release from spent nuclear fuel dissolution experiments carried out in granitic groundwater.