Study on sudden loss of cryogenic coolant accident happened in the hydrogen isotope separation system for fusion reactor

Sudden loss of cryogenic helium coolant accident (ISS-LOCA) in the cryogenic distillation columns for the hydrogen isotope separation system (ISS) is one of the worst situations because it leads the evaporation of liquid hydrogen in the column. From this background, an intended ISS-LOCA test was conducted with an actual ITER-scale cryogenic distillation column. Sudden increase of internal pressure was not observed and enough time is found to recover the hydrogen isotope into a storage system if vacuum insulation is maintained and reboiler heaters are turned off immediately. In off-normal conditions, the rapid recovery of hydrogen in the column by an empty hydrogen storage bed is a reasonable hydrogen recovery scenario. Validity of the hydrogen recovery scenario was proved by a demonstration test.