Permeation behavior of tritium through F82H stainless steel; Permeation from tritiated water vapor in purge gas for breeder to coolant

Oyaizu, Makoto; Hayashi, Takumi; Yamanishi, Toshihiko

For the safety issue of fusion reactors, several studies have been performed to reveal the tritium permeation behavior in F82H, one of low-activation ferritic steels, as a potential structural material of blanket. These studies were performed with the use of pure hydrogen isotope gas for inlet side and vacuum for outlet side, although these in the blanket system are different. Therefore in the present study, it is subjected to reveal the tritium permeation from feed gas composed from tritiated water vapor diluted by helium to purge gas composed from helium, as a simulation of HCSB blanket. The temperature dependence and tritiated water vapor partial pressure dependence experiments were performed. As the results, tritium permeation looked limited by diffusion, it is implied that one or some of the surface reactions could be different, and suggested that the existence of water could result in the formation of oxide layer which have a possibility to work as tritium permeation barrier.