Because of their excellent corrosion resistance in pure liquid sodium at high temperature, austenitic stainless steels are foreseen to be used for the structure of the primary circuit as well as for the heat exchanger units such as the steam generator (316LN, A800?), as well as for the core materials such as the fuel cladding (15-15Ti, Advanced Austenitic steels?) for sodium cooled generation IV reactor. Despite of its past extensive studies, numerous issues are still to be elucidated before any definitive answers, from the corrosion viewpoint, could be given for the limits of use of new grade of austenitic steels or for the 60 years service lifetime guarantee function of reactor operating conditions. It is then proposed to study the austenitic steels interactions with the liquid sodium in order to determine the elementary mechanisms at stake in the overall damaging process of the material, function of representative reactor operating conditions (temperature, oxidation, dissolution) and function of the composition and microstructure of the alloy. Then, a first modeling will be proposed based on the limiting mechanisms identified and compared to the available experimental results.

Methodology: liquid metal corrosion testing, characterization at the finest scale possible (FEG-SEM, TEM, GD-AES, XPS, WDS), and modeling.