Out-of-pile tritium release of LiAlO₂ pebble

It is important to understand the tritium properties of tritium breeding materials from the viewpoints of a fusion reactor blanket, the tritium fuel cycle and tritium safety. Out-of-pile tritium release experiments were performed to investigate the effects of heating rate, purge gas composition and platinum catalytic metal on the tritium release behaviors of the lithium aluminate (LiAlO₂) ceramic pebbles after neutron-irradiation, and the ESR measuring technique was applied to analyzing the paramagnetic characteristics of irradiation defects. The experimental results show that the bred tritium requires a high temperature region of 750-1000 K to be liberated from LiAlO₂ ceramic pebbles corresponding to the slow diffusivity and high desorption activity energy. Catalytic metals and hydrogen in the purge gas can enhance the hydrogen isotope exchange reaction between the tritium on the solid surface and the hydrogen in the purge gas, and accelerate the recovery rate of the molecular tritium (HT). Neutron irradiation can induce F⁺-center, O^--center and O₂- center in LiAlO₂, and there is a certain relationship between the annihilation behavior of the irradiation defects and the tritium release process. (authors)