In-situ observation of hydrogen hot trapping from molten lithium with yttrium

Hydrogen permeation window is candidate not only for tritium recovery system from molten lithium, but also for hydrogen monitor for molten lithium because hydrogen permeation rate is dominated by hydrogen concentration. In this study, in-situ observation of deuterium hot trapping by yttrium in molten lithium was performed, measuring HD and D2 permeation through an iron wall at 773, 823 and 873 K. Deuterium permeation showed good agreement with deuterium concentration in lithium and iron permeation wall was found to be reliable for deuterium monitoring for liquid lithium around a hundred wppm. As a result of in-situ observation, gettering rate for deuterium was 6 × 10−5 mol/m2/sec at 773 K, 5 × 10−4 mol/m2/sec at 823 K and 4 × 10−4 mol/m2/sec at 873 K. Oxidation or nitridation at the surface of yttrium may suppress gettering rate at 873 K.