T production using a high-temperature gas-cooled reactor for the DEMO fusion reactor: Li rod structure for the initial irradiation test

This work proposes tritium (T) production using a high-temperature gas-cooled reactor (HTGR) and studies it for the initial T inventory in a demonstration fusion reactor and a prior engineering test with T handling. At this stage, the aim is to investigate the compatibility between electricity and T production, which makes the stable confinement of T in the Li-loading rods during the HTGR operation period a crucial issue. The total T outflow into the helium gas during the reactor operation period was attempted to be reduced using Zr spheres with Ni coating as a T absorption material to avoid an increase in the inner T pressure. The basic hydrogen absorption properties of the Zr spheres with Ni coating, which coexist in an environment with Al₂O₃ and/or LiAlO₂ oxides, were measured. The structures of the Li-loading rod for a typical commercial HTGR and irradiation test were studied using the obtained data. In addition, an outline of the irradiation test is reported.