Experimental investigation on tritium release from lithium titanate pebble under high temperature of 1073 K

Abstract

The temperature of Li2TiO3 pebble breeder in a fusion DEMO blanket is assumed to be more than 1000K. For the investigation of tritium release from a Li2TiO3 pebble breeder blanket at such a high temperature, we have carried out a tritium release experiment with the DT neutron source at the JAEA-FNS. The Li2TiO3 pebble (1.0–1.2mm in diameter) of 70g was put into a stainless steel container and installed into an assembly stratified with beryllium and Li2TiO3 layers. During the DT neutron irradiation, the temperature was kept at 1073K with wire heaters in the blanket container. Helium gas including 1% hydrogen gas (H2/He) mainly flowed inside the container as the purge gas. Two chemical forms, HT and HTO, of extracted tritium were separately collected during the DT neutron irradiation by using water bubblers and CuO bed. The tritium activity in the water bubbler was measured by a liquid scintillation counter. To investigate the effect of moisture in the purge gas, we also performed the same experiments with H2O/He gas (H2O content: 1%) or pure helium gas. From our experiment at 1073K, in the case of the purge gas includes H2, it is indicated that the increasing tendency of HT release is similar to that of the dry H2/He.