Study of oxidation mechanisms of plutonium alloys by photoemission spectroscopy

In order to study the plutonium corrosion, a study of its oxidation mechanisms has been carried out by photoemission spectroscopy (XPS). Preliminary oxygen exposure experiments have been led in situ to obtain surfaces of PuO2 and Pu2O3 stable in time. Exposures at increasing durations have been carried out at O2 pressures of 2.5*10-8 mbar to the atmospheric pressure. The oxidation of Pu into Pu2O3 and those of Pu2O3 into PuO2 have been observed but have not been able to be completely carried out on all the thickness analyzed, in the used conditions. Two oxidation conditions, parabolic and linear, have been observed. Under ultra-high vacuum, the reduction of PuO2 into Pu2O3 have been established. As for the inverse oxidation reaction, it seems to be produced by two conditions and be controlled by the diffusion of the oxygen to the metal. (O.M.)