PHOTOEMISSION AND SECONDARY ION MASS SPECTROMETRY STUDY OF URANIUM PASSIVATION BY C+ IMPLANTATION

Preventing the corrosion and oxidation of uranium is important to the continued development of advanced nuclear fuel technologies. Knowledge of the surface reactions of uranium metal with various environmental and atmospheric agents, and the subsequent degradation processes, are vitally important in 21st century nuclear technology. A review of the oxidation of actinide elements and their use in catalysis summarizes the present understanding of the kinetics and mechanisms of the reaction in dry and humid air. Researchers have recently used N{sub 2}{sup +} and C{sup +} ion implantation to modify the near surface region chemistry and structure of U to affect the nucleation and growth kinetics of corrosion and to passivate the surface. These researchers used Auger electron spectroscopy (AES) in conjunction with sputter depth profiling to show that the implanted surfaces had compositional gradients containing nitrides and carbides. In addition to chemical modification, ion implantation can create special reactive surface species that include defect structures that affect the initial absorption and dissociation of molecules on the surface, thus providing mechanical stability and protection against further air corrosion