Effects of hydrogen mixture into helium gas on deuterium removal from lithium titanate

Tsuchiya, Akihito*; Hino, Tomoaki*; Yamauchi, Yuji*; Nobuta, Yuji*; Akiba, Masato; Enoeda, Mikio

Lithium titanate (LiTiO) pebbles were irradiated with deuterium ions with energy of 1.7 keV and then exposed to helium or helium and hydrogen mixed gas at various temperatures, in order to evaluate the effects of gas exposure on deuterium removal from the pebbles. The amounts of residual deuterium in the pebbles were measured by thermal desorption spectroscopy. The mixing of hydrogen gas into helium gas enhanced the removal amount of deuterium. In addition, we also evaluated the pebbles exposed to the helium gas with different hydrogen mixture ratio from 0% to 1%, at 573 K. Although the amount of residual deuteriumin the pebbles after the exposure decreased with increasing the hydrogen mixture ratio, the implanted deuterium partly remained after the exposure. These results suggest that the tritium inventory may occur at low temperature region in the blanket during the operation.