Tritium and deuterium release behavior of Li₂TiO₃-0.5Li₄SiO₄–Pb ceramic

The neutron multiplier lead (Pb) containing Li₂TiO₃-0.5Li₄SiO₄–Pb was prepared, which aimed at the improvement of the tritium release performance of the lithium ceramic without an increase in lithium density. Li₂TiO₃-0.5Li₄SiO₄–Pb and that without Pb were irradiated at Kyoto University Research Reactor (KUR) with the thermal neutron flux of 5.5 × 10¹² n s⁻¹ cm⁻² and the fast neutron flux of 1.2 × 10¹² n s⁻¹ cm⁻². Fast neutrons can trigger the Pb (n, 2n) reaction. The tritium release experiments were conducted using the tritium thermal desorption spectroscopy (tritium-TDS) system. Compared with Li₂TiO₃-0.5Li₄SiO₄, the tritium release rate at the lower temperature range was higher than that for Li₂TiO₃-0.5Li₄SiO₄–Pb. The tritium-TDS spectrum was also shifted to the lower temperature side. The isothermal heating experimental results confirmed that tritium in the form of gas species (HT) was controlled by the diffusion process, while the trapping and de-trapping process contributed to the total tritium release. Further, 3 keV D₂⁺ implantation with the fluence of 2.0 × 10²² D m⁻² and subsequent TDS measurements were performed. It was shown that the D₂ release at the lower temperature side was increased for Li₂TiO₃-0.5Li₄SiO₄–Pb. Meanwhile, HD and HDO release at higher temperature side was significantly decreased.