Feasibility of recycling yttrium-based hydrogen traps for the IFMIF-DONES lithium loop: a numerical study and experimental design

Yttrium will be used in the IFMIF-DONES lithium loop as a getter material for trapping hydrogen isotopes from the liquid metal. The presence of tritium, together with the radiological limit on its allowable inventory, constrains the hydrogen-trap lifetime to about one month of full operation. The temperature sensitivity of hydrogen isotopes in the yttrium matrix represents both a safety concern and a potential opportunity for recycling the getter material by thermal desorption. Since up to 20 kg of yttrium may be used in the hydrogen traps, regeneration of the getter material by heat treatment could be of considerable practical interest. In this work, the feasibility of yttrium recycling for the IFMIF-DONES hydrogen trap is assessed by combining thermal desorption experiments, numerical simulations, and conceptual engineering design. The experimental and numerical results show that significant hydrogen desorption starts above about 400 °C, whereas efficient regeneration of the DONES traps requires prolonged treatment at higher temperatures, typically above 600 °C depending on the initial trap loading state. Based on these findings, a conceptual recycling system is proposed, including inert transfer, external thermal treatment, and verification steps prior to reuse. The results support the feasibility of yttrium recycling, while also showing that practical implementation would require a technically demanding external regeneration system and further engineering development.