The kinetics of oxidation of uranium between 300 and 625° C

Abstract Studies of the isothermal oxidation of uranium in the 300 to 625° C temperature range have been carried out in a metal “heat sink” reaction cell designed to minimize self-heating. Data with two sources of pure uranium as well as 1 at % copper and 1 at % aluminum alloys of uranium showed substantially identical selfaccelerating reaction rates up to 400° C. Oxidation with pure uranium and the copper alloy underwent a transition to a slower reaction in which the oxide was somewhat protective above 500° C, with the copper alloy considerably more protective than the pure metal. The self-accelerating reaction continued to higher temepratures for the aluminum alloy. The results of isothermal oxidation studies for the β -quenched pure uranium metal have been expressed in the form of empirical equations. From 300 to 450° C the oxidation rate was found to be proportional to (time) 5 4 while above 450° C a decelerating rate proportional to (time) 5 6 holds. There is evidence linking this change in the reaction kinetics at 450° C with a changed character of the oxide.