The kinetics and mechanism of the uranium hydride - water vapour system under ambient conditions

This work investigated the reaction of uranium hydride powder with saturated water vapour at 25 °C. Two corrosion experiments were conducted one with deionised water (H2O) and one with deuterated water (D2O). The kinetics of the reaction were measured through gas generation method while concurrent residual gas analysis (RGA) allowed better understanding of the oxidation mechanism governing the system. From the analysis, it was found that the kinetics of the reaction are robust initially, followed by quasi-linear decelerating regime indicative of a 'shrinking core' type oxidation behaviour. The extent of the reaction (conversion to UO2) was lower in comparison to other works. The reaction remained incomplete bolstering the case of UH3 persistence in legacy wastes. Through interpretation of the gas analysis data, a mechanism for the uranium hydride water reaction was suggested.