Effects of water adsorption on tritium release behavior of Li4TiO4 and Li4TiO4-Li2TiO3 core-shell structure breeding ceramics

Li4TiO4 and Li4TiO4-Li2TiO3 core-shell breeding ceramics were considered as promising tritium breeding ma-terials in fusion reactor blanket, and the effect of adsorbed water on the tritium release behavior of these two types of materials was investigated and compared in this study. All samples were first irradiated by thermal neutrons at Kyoto University, followed by out-of-pile tritium release experiments at Kyushu University. It was found that both Li4TiO4 and Li4TiO4-Li2TiO3 core-shell breeding ceramics have two tritium trapping sites, mainly due to the overlapping of the tritium release temperature of Li2TiO3 with the second tritium release site of Li4TiO4. Besides, it was observed that the adsorbed water can slightly reduce the tritium release temperature of the two types of tritium breeding materials. More importantly, the effect of adsorbed water on tritium release form (HT/HTO ratio) was quantitatively studied. The results demonstrate that water adsorption has a significant effect on the tritium release form of the breeding ceramics, and the core-shell structure can inhibit the hygro-scopicity of Li4TiO4 to increase the fraction of tritium release in the HT form.