Neutron irradiation effect on the mechanical properties of type 316L SS welded joints

In the International Thermonuclear Experimental Reactor design activity, the vacuum vessel (VV) is designed as a double walled structure so that some parts are not qualified by the conventional design standards. JAERI has executed the preparation activity of the new design standards and obtained the technical data to support them. In this study, neutron irradiation effects on the mechanical properties of 316L SS welded joints were investigated. The tensile and Charpy-impact specimens were irradiated at 473 K. The results of post irradiation experiments indicate that sufficient ductility is still maintained for tungsten inert gas (TIG) and electron beam (EB) welded joints; whereas, the impact properties of metal inert gas (MAG) weld metal are extremely poor. Consequently, the soundness of the 316L SS base metal and its TIG and EB welded joints are retained after 0.2-0.5 dpa neutron irradiation. However, it is rather difficult to adopt MAG welding for the fabrication of the VV