Gas-Phase Volume Oxidation of Uranium Mononitride

Gas-phase volume oxidation (voloxidation) of UN in various atmospheres was studied. Oxidation of compact UN samples under the conditions characteristic of the voloxidation of the oxide fuel leads to the formation of uranium oxides. The use of the oxygen-containing atmosphere leads to the predominant formation of U3O8, and the use of water vapor, to the formation of UO2. The major gaseous nitrogen-containing conversion product is, apparently, N2. The use of the alternative oxidizing atmosphere based on NOx gases does not allow the conversion to be performed at a lower temperature. In this case, both UO3 and UO2(NO3)2 hydrates are formed. The maximal degree of the UN conversion to water-soluble compounds, equal to ∼80%, is reached at the process temperature of ∼565 K.