Integrated experiment of blanket in-pile mockup with Li2TiO3 pebbles

Lithium titanate (Li2TiO3) is one of the candidate tritium breeding materials for breeding blanket of the fusion reactor. Therefore, tritium release experiments from Li2TiO3 packing region were carried out to evaluate the effects of various parameters, i.e. sweep gas flow rate, irradiation temperature, and hydrogen content in sweep gas, etc. on tritium release. As for the shape of the Li2TiO3, a small spherical form (pebbles) is preferred to reduce the induced thermal stress in the breeding material. The diameter and total weight of Li2TiO3 pebbles were 1 mm and ∼135 g, respectively. And the integrated experiment of blanket in-pile mockup with Li2TiO3 pebble bed was carried out at the Japan Materials Testing Reactor (JMTR). The tritium released from Li2TiO3 pebble bed was swept by the helium gas with hydrogen. The total tritium concentration (HT+HTO) and gaseous tritium concentration (HT) of tritium released from Li2TiO3 pebbles were measured, and HT/(HT+HTO) ratio was evaluated under various conditions.