Isotope exchange capacity of solid breeder materials

Abstract

Though lithium ceramic materials such as Li 2O, LiAlO 2, Li 2ZrO 3 and Li 4SiO 4 are considered as the candidates of tritium 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. It is observed in this study that LiAlO 2 or Li 4SiO 4 has an additional capacity for tritium uptake on the surface through isotope exchange reactions, the isotope exchange capacity, other than the adsorption capacity. It is considered that some -OH bases attributed to the strongly bound chemically adsorbed water or the crystal water formed on the grain surface act as tritium trap, when the isotope exchange reaction are active. It is also observed in this study that Li 2ZrO 3 has no isotope exchange capacity. Effects of the isotope exchange capacity on the tritium inventory in the breeding blanket is discussed based on the data observed in this study where 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 isotope exchange reactions are considered.