Progress in the knowledge of the mechanism of tritium release from lithium ceramics

Abstract Tritium extraction experiments have been performed in various experimental conditions, most of the time out-of-pile, with a sweep gas containing 1000 vpm H 2 and at fixed temperatures. They were performed on pure or doped lithium aluminates or orthosilicates. The fine material texture, the type of defects created by dopant insertion, and Li + mobility were known by various techniques. Analysis of the tritium release has shown the presence of several types of sites for tritium and has allowed the study of the mechanisms' respective role as a function of experimental conditions, such as sample texture. In the particular case of large diameter single crystals, a combined contribution of diffusion and internal sites seems to explain the results obtained; in the case of sintered materials, the limiting step could be a desorption from discrete activation energies sites.