Tritium Release Behavior of Biphasic Lithium Ceramic with Low Li₄SiO₄ Content

Abstract

Nuclear fusion is one of the promising options for the global energy supply. In a fusion reactor, tritium (T) is produced by the Li(n, α)T reaction. Lithium ceramics, e.g., Li₂TiO₃, Li₄SiO₄, are regarded as candidate materials for tritium breeding. In this study, the tritium release behavior of Li₂TiO₃-Li₄SiO₄ biphasic ceramic was investigated. Especially, the content of Li₄SiO₄ was controlled at 12.5% and 25%. The Li₂TiO₃-xLi₄SiO₄ (x = 0.125, 0.25) ceramic powders were prepared by the solution combustion synthesis. The neutron irradiation was conducted using Kyoto University Research Reactor (KUR) with a neutron flux of 5.5 × 10¹² n cm⁻² s⁻¹. The tritium thermal desorption spectroscopy (Tritium-TDS) device at Shizuoka University was upgraded to recover tritium under various conditions. It was found that the tritium desorption rate at higher temperatures was increased with increasing Li₄SiO₄ content and the amount of tritium was also increased. The tritium recovery process was significantly improved using the purge gas with water vapor. The tritium-TDS spectra were shifted to the lower temperature side with a higher desorption rate. Besides, the tritiated water (HTO) and tritium gas (HT) were separated successfully. The desorption rate of HTO was increased and the HT desorption was shifted to the high temperature for the ceramic irradiated under higher neutron fluence.