Comparison of tritium release behavior in Li2TiO3 and promising core-shell Li2TiO3–Li4SiO4 biphasic ceramic pebbles

Abstract

In a D-T fusion reactor, self-sufficiency of tritium is one of the critical issues to maintain steady-state operation of the reactor. Li2TiO3 and core-shell Li2TiO3–Li4SiO4 biphasic pebbles have been irradiated by thermal neutrons in Kyoto University. T-TDS (Tritium - Thermal Desorption Spectroscopy) was performed in Shizuoka University. There is one main tritium trapping site in neutron irradiated Li2TiO3. However, three tritium trapping sites are introduced in neutron irradiated core-shell Li2TiO3– Li4SiO4. The two peaks at lower temperature agree with that of Li2TiO3 which can be attributed to tritium release from Li2TiO3 including shell and core. The peak at higher temperature is mainly considered as tritium release from Li4SiO4. The amount of tritium released from core-shell Li2TiO3–Li4SiO4 is slight higher than that of Li2TiO3. The kinetic parameters of tritium diffusion in Li2TiO3 have been obtained. In the case of Li2TiO3 and core-shell Li2TiO3–Li4SiO4, almost all the tritium is released as HTO observed from T-TDS. Purge gas has little effect on tritium release, indicating tritium release from Li2TiO3 was mainly controlled by tritium diffusion in Li2TiO3 grain.