Tritium Release Behavior of Biphasic Lithium Ceramic with Low Li4SiO4 Content

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.