Corrosion Resistance of (Th,U)O2 Fuel in Water

Abstract

Dissolution and corrosion of (Th,U)O₂ fuel was investigated in near neutral and slightly acidic water (pH 3) at room temperature and near 100°C. X-ray photoelectron spectroscopy and X-ray diffraction were used to study oxidation of (Th,U)O₂ fuel during corrosion experiments. The uranium in the surface of (Th,U)O₂ fuel undergoes oxidation similar to that observed in UO₂ fuel under similar conditions. Nevertheless, the dissolution rate of uranium from (Th,U)O₂ fuel in aerated solutions is much lower than that from UO₂ fuel under similar conditions. These studies suggest that used (Th,U)O₂ fuel should be an acceptable waste form for direct geological disposal.