Published online by Cambridge University Press: 22 May 2012
The reaction kinetics of depleted uranium under constant hydrogen pressure (1 bar) have been measured as a function of reaction temperatures between 65 and 385 °C for as-polished and vacuum annealed samples. Enhanced hydrogen reactivity was observed on samples that underwent vacuum annealing prior to hydrogen exposure. The enhanced reactivity was found to be the result of enhanced nucleation rates on annealed samples since the specific rate per reacting unit area remained unaffected. X-ray photoelectron spectroscopy demonstrates that the nucleation kinetics were promoted on annealed samples as a result of the dehydration and partial reduction of the UO2+x outer oxide layer and the formation of an oxycarbide (UOxCy) sub-layer.