Suppression mechanism of radiation defects of tungsten alloys and searching for alloying elements using computational science

Suzudo, Tomoaki   ; Tsuru, Tomohito   ; Hasegawa, Akira*

Tungsten is a promising candidate for plasma-facing materials for the first wall and the divertor of future fusion reactors due to its high melting point, high sputtering resistance and low hydrogen retention. However, under irradiation, several problems have been pointed out. First, ruthenium and osmium produced by nuclear transformation form irradiated induced precipitation, and the ductility of the material is decreased. In addition, irradiation defects in tungsten serve as trapping sites for hydrogen isotopes, increasing the retention amount. However, it has also been pointed out experimentally that residual irradiation defects decrease due to the presence of rhenium, and the retention problem may be alleviated. In this presentation, we analyze the interaction of rhenium and osmium with irradiation defects by using computational method and irradiation experiment result, and we discuss the elements to be added for irradiation resistant tungsten materials.