Thermal diffusivity measurement on neutron irradiated tungsten materials in PHENIX project

Thermal diffusivity is extremely important in fusion reactor materials, especially in divertor materials that receive a high heat load, and it is known that the thermal diffusivity is greatly reduced by neutron irradiation. In tungsten, which is one of the candidate materials, both the contribution of the introduction of lattice defects and the contribution of the introduction of nuclear transmutation elements must be considered. In the PHENIX project, extremely unique studies, where gadolinium shield is used to reduce the thermal neutron flux to suppress the nuclear transmutation, have been conducted, and some of them are introduced here. (A.O.)