Modeling of Surface Reactions in Tritium Release from Solid Breeding Materials

Modeling of the tritium reaction at the surface of Li₂O was performed using data obtained in in-situ and out-of-pile tritium release experiments. In this model the effects of H₂O and H₂ in the sweep gas were considered. On the surface, recombination of -OT and dissociatively adsorbed -OH was considered to produce HTO. In addition to this, HT was considered to be produced by the reaction of surface tritium with dissociated hydrogen on the surface. On the surfaces of tubes and the solid breeder itself, conversion reactions of HTO to HT by H₂ were also considered. Tritium inventory on the solid breeder surface and the released chemical form were calculated. They agreed fairly well with those of TTTEx in-situ tritium release experiments. It was found that H₂O as well as H₂ in the sweep gas affects tritium release behavior.