Structural material properties and dimensional stability of components in first wall components of a breeding blanket module

A full-scale first wall structure for a breeding blanket has been developed using processes that are practical for industrial production. This paper summarizes the processes used to fabricate this first wall component and describes the material properties and dimensional stability of the structural material. Cover plates and square tubes were fabricated from the reduced activation ferritic/martensitic steel F82H. The tubes were assembled between plates and they were joined by welding and hot isostatic pressing (HIP). Dimensional stability of the components was maintained during this process. The steel showed a fine-grained martensitic structure with the grains extending across the HIP interface. Although no defects were detected by ultrasonic inspection, some oxides were found at the interface. Therefore, oxidation of components must be strictly controlled during the fabrication process.