Assessment of austenitic stainless steels

An assessment of stainless steels is performed in order to recommend the most suitable structural material for ITER, to identify areas where additional research and development work is needed for full qualification and licensing of the recommended material, and to estimate the cost of such a research and development programme to be completed within a five year time schedule.After a brief assessment of different stainless steel categories, the choice is narrowed down to austenitic stainless steels, and more precisely to the type 316LN. The available database is presented for the selected steel using the boundary conditions extracted from the most recent report by the Joint Central Team on ITER Outline Design, but also incorporating possible changes that may be made in these conditions either for the initial basic performance phase or for the future extended performance phase.For each evaluated property, whether physical, mechanical or environmental, reference values and their corresponding trend curves are presented and, when applicable, lower bound or upper bound design curves are proposed. Using end-of-life properties of unirradiated materials as the reference design critierion, effects of irradiation are evaluated. If the observed changes remain within the safety margins incorporated in design they are considered acceptable. This is shown to be the case for materials irradiated to doses up to 10dpa at temperatures either less than 200 C or around 400 C. (orig.)