Evaluation of effective thermal diffusivity of Li2TiO3 pebble bed under neutron irradiation

Li2TiO3 is a candidate material for the tritium breeder blanket in the fusion reactor. The knowledge of Li2TiO3 pebble bed properties is necessary to design the fusion blanket. In this study, the effective thermal diffusivity of Li2TiO3 pebble bed under the neutron irradiation was evaluated. According to the irradiation test conducted in the Japan Materials Testing Reactor (JMTR), the effective thermal diffusivity of Li2TiO3 pebble bed decreased with increasing the irradiation temperature and the thermal neutron fluence. However, horizontal temperature difference (DT) was almost constant at 400 °C under neutron irradiation up to 1×1024 n/m2. Therefore, we can conclude that the effective thermal conductivity of Li2TiO3 pebble bed is constant for thermal neutron fluence up to 1×1024 n/m2 at least.