The status of the Japanese material properties handbook and the challenge to facilitate structural design criteria for DEMO in-vessel components

Abstract

The paper summarizes the current status of the materials property handbook for a structural design using Japanese reduced activation ferritic/martensitic steel F82H. Specifically, the key structural parameters, e.g., time-independent/dependent design stresses and fatigue design curves, were determined following the French structural design code RCC-MRx. Besides, under the Japan-U.S. collaboration, tensile data were newly added to the benchmark heavy irradiation data up to 80 dpa, as critical input information in the intermediate check and review in Japan. Furthermore, the status of structural material data and the near-term and long-term issues were clarified by the evaluation using the attribute guides. In parallel, the structural design approaches which were newly introduced and extended to cope with the structural design issues under the complex environmental conditions peculiar to the DEMO reactor were noted with the initial R&D results. Of many design issues, the multi-axial loading condition due to the complexity of the DEMO reactor as well as the coolant compatibility and the irradiation effect is mentioned. For example in the paper, the multi-axial fatigue-creep testing and evaluation using the modified universal slope method and the brittle/ductile fracture testing and evaluation by the local approach are explained toward DEMO.