Mechanistic interpretations of UO2 oxidation

The literature dealing with experiments and modeling of UO2 oxidation at temperatures > similar to 600 degrees C is reviewed and a detailed model is proposed. Mechanistic modeling is subjected to the principle of detailed balancing, which provides a framework for the elementary reactions contained in the reaction scheme. This principle interrelates the rate constants of the model, provides a link to gas-solid thermochemistry, and constrains the forms of the rate laws applied to the elementary steps of the model. Previous mechanistic models are analyzed in these terms and the rate constants deduced from them are assessed. A more general oxidation mechanism is proposed and compared to typical data. The types of new experiments needed to elucidate the mechanism are suggested. (C) 1998 Elsevier Science B.V.