Effect of ambient humidity on deuterium release behavior in Li4SiO4 solid breeder

Abstract In order to discuss the effect of ambient humidity on deuterium release, the release behaviors of Li4SiO4 breeders under different storage conditions and different pretreatments with varied hydrous concentrations were investigated. It was concluded that the local humidity was a vital factor, which would affect the process of deuterium release-chemical constitution and release temperature. For the former, an increase of the humidity would result in a remarkable increment of the deuterated water (D2O and HDO) fraction but a reduction of the gaseous deuterium (D2 and HD) fraction. For the latter, the main release temperature of deuterium decreased noticeably from nearly 600 °C under the anhydrous condition to 145 °C and 460 °C in air storage condition. In addition, detailed release curves of different hydrous Li4SiO4 breeders were achieved. The released deuterated water was divided into three parts, including generation with Li4SiO4 during D2 injection process, isotopic exchange with surface water absorption and water formation reaction at high temperature during the release experiment. Thereinto, the surface absorbed water showed four desorption peaks, which were considered as physisorbed water, chemisorbed water through H-bridges, Li-OH and Si-OH of Li4SiO4. It is believed that this gains useful information for tritium recovery of Li4SiO4 breeder in the D-T fuel cycle.