Study on T production using high-temperature gas-cooled reactor for DEMO fusion reactor − H absorption properties of Zr sphere with Ni coating

We have proposed tritium (T) production using a high-temperature gas-cooled reactor (HTGR) and explored its application for initial T possession in a demonstration (DEMO) fusion reactor. To maintain T containment within the Li-loading rod throughout the HTGR operation period, Ni-coated Zr spheres are considered as T absorption materials, designed to prevent an increase in internal T partial pressure and secure T retention in the Li-loading rod. This study evaluates the performance of Zr spheres by examining their hydrogen absorption properties within the HTGR environment, where oxides coexist. In addition, the apparent diffusivities and solubilities of hydrogen in Zr are studied at pressures ranging from 80 to 8000 Pa. It is shown that the coexisting oxides cause a reduction in diffusivity but has minimal impact on solubility, the pressure has no significant impact on the hydrogen absorption performance in HTGR environment at 900 °C.