AbstractAlthough lithium ceramic materials such as Li2O, LiAlO2, Li2ZrO3 and Li4SiO4 are considered as breeding materials in the blanket of a D-T fusion reactor, the release behavior of the bred tritium in these solid breeder materials is not yet fully understood. Most results of in situ tritium release experiments are analyzed assuming that the overall release process of tritium is mainly controlled with tritium diffusion in the crystal grain of a solid breeder material. However, the diffusivities by various authors for solid breeder materials do not agree with each other. An insufficient estimation of the surface reactions, the effect due to irradiation defects or the system effect may be the reason. Effects of diffusion of tritium in the grain, absorption of water in the bulk of grain, and adsorption of water on the surface of grain, together with two types of isotope exchange reaction on the tritium inventory in the steady-state condition, are discussed in this study. Comparisons of tritium inventory estimated in this study with data obtained in several in-situ experiments are also performed, and good agreement is obtained when the existence of some water vapor is assumed in the purge gas.
リチウムセラミックス材料、例えばLi2O、LiAlO2、Li2ZrO3およびLi4SiO4は、D-T核融合炉のブランケットにおける増殖材として考えられているが、これらの固体増殖材における生成トリチウムの放出挙動はまだ完全には理解されていない。その場トリチウム放出実験の結果の多くは、トリチウムの全放出過程が主に固体増殖材の結晶粒内におけるトリチウム拡散によって支配されることを仮定して解析されている。しかしながら、固体増殖材について種々の研究者によって報告された拡散係数は互いに一致していない。その理由は、表面反応の評価不足、照射欠陥による影響、またはシステム効果である可能性がある。本研