Uranium + water reaction. Part 1.—Kinetics, products and mechanism

Abstract

The effects of temperature, relative humidity and pH on the rate of the uranium + water reaction have been studied. Linear rates of corrosion and hydrogen evolution are obtained at different temperatures and the derived activation energies vary from 12 to 17 kcal mole^–1 depending on the batch of uranium. Hydrogen has no effect on the reaction. The products of the reaction have been investigated under varying conditions of temperature and relative humidity. Parallel studies have been made of the uranium hydride + water system. The data are consistent with an oxide product UO_2.06±0.02, containing 2–9% uranium hydride in a protected form. A reaction mechanism is proposed, involving OH^– ion diffusion and formation of uranium hydride as a partial intermediate. It is suggested that the rate-controlling step is diffusion of water through fine capillaries to the oxide surface.