In-Situ Tritium Release Experiment from Solid Breeder γ-LiAlO₂ in SWINPC

The first Chinese in-situ tritium release experiment is being carried out in the fission reactor SPRR-300 in the Southwest Institute of Nuclear Physics and Chemistry (SWINPC). Several runs of the experiment were conducted to study tritium generation and release behaviors from China-made γ-LiAlO₂ pellets. The effects of some key operational factors (temperature, sweep gas composition and flow rate) upon tritium release were studied. The results show that the equilibrium tritium release rate at different temperatures approached the tritium generation rate obtained from neutron calculations. The tritium concentration in the sweep gas decreased with increasing the flow rate. Addition of a small quantity of hydrogen greatly enhanced the release of tritium. It was also found that the tritium released in the sweep gas was mostly in the form of HT. However, when the generated tritium was not purged in time, the HTO fraction increased gradually. By using the inventory difference method, through the special run which lasted 72 hours, we determined the diffusion coefficient for tritium in γ-LiAlO₂. The obtained diffusivity and its activation energy were compared with those from other experiments. It was found that the value of Q was close to those from LILA and TTTEx experiments, but the value of D₀ was smaller.