The oxidation of uranium-cerium mononitride microspheres

The reaction of oxygen with UN and (U,Ce)N microspheres containing 15 and 30 mole % of cerium was studied in 6.6 kPa pressure of oxygen, under non-isothermal heating conditions, using a thermobalance coupled to a gas chromatograph for evolved gas analysis. For uranium mononitride the final product was U3O8 with UO2 and U2N3 as intermediate products. However, for (U,Ce)N containing 15 mole% of cerium, the final product of oxidation was MO2+x with sesqui-nitride as the intermediate product. The (U,Ce)N microspheres with 30 mole % of cerium ignited during the reaction forming a mixture of M3O8 and MO2+x. The kinetic parameters were evaluated and the mechanism of the reaction was suggested to explain the catalytic action of cerium on the oxidation of nitride. (orig.)