Integrated experiment of blanket in-pile mockup with Li 2TiO 3 pebbles

Abstract

Lithium titanate (Li 2TiO 3) is one of the candidate tritium breeding materials for breeding blanket of the fusion reactor. Therefore, tritium release experiments from Li 2TiO 3 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 Li 2TiO 3, a small spherical form (pebbles) is preferred to reduce the induced thermal stress in the breeding material. The diameter and total weight of Li 2TiO 3 pebbles were 1 mm and ∼135 g, respectively. And the integrated experiment of blanket in-pile mockup with Li 2TiO 3 pebble bed was carried out at the Japan Materials Testing Reactor (JMTR). The tritium released from Li 2TiO 3 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 Li 2TiO 3 pebbles were measured, and HT/(HT+HTO) ratio was evaluated under various conditions.