XPS and XRD studies of corrosion of uranium nitride by water

Corrosion of UN in water was investigated as a function of pH and temperature using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and by measuring the amount of ammonia formed due to its corrosion. The XPS results indicate that a freshly fractured surface of UN is quickly converted to UO2 on exposure to liquid water or water vapours at ambient temperatures. These results show that UN is unstable in contact with water. The corrosion rate of UN is estimated to be ≥40 μmol m-2 h-1 in deaerated water at approximately 92oC. There was no significant difference in corrosion rates measured in water at initial pHs of approximately 6 and 10.3. These results contradict the literature reports stating that UN is stable in contact with boiling water. (author)