Hydrogen capacity evaluation of the ZrCo hydrogen isotope storage bed in fusion power plant and verification of its repeated recovery effect

ZrCo used in a tritium storage bed in Fusion Power Plant showed decrease in tritium storage capacity as a result of material degradation over long-term operation. Therefore, it is necessary to demonstrate the recovery of tritium storage capacity of ZrCo through a regeneration process. In this paper, an experimental procedure was established with well-defined conditions based on the Fusion Power Plant operation to eliminate the influence of temperature and pressure history in ZrCo. By repeating the experimental procedure, the storage capacity of ZrCo corresponding to 3–4 months operation in Fusion Power Plant was assessed through long-term laboratory-scale testing. After carrying out the recovery process under these experimental conditions, a 30 % decrease in storage capacity was observed compared to the initial status. In addition, changes in composition of ZrCo investigated by X-ray Diffraction (XRD) patterns showed that ZrCo after each process has different chemical bonds. The changes in XRD peaks are consistent with the reactions expected to occur during interaction between ZrCo and hydrogen in tritium storage bed operations which implies the experimental sequence demonstrated in this study followed the reported chemical reactions. Also, the experimental results suggested that capacity could be improved by performing the recovery process at a higher vacuum level. Considering that tritium storage systems in Fusion Power Plant will be operated as a storage bed component integrated in parallel, the observed 30 % performance degradation together with the results from long-term scale operation assessment determined the viability of ZrCo as tritium storage material in future Fusion Power Plant.