New insights on the radiation-microstructural evolution of the ferritic/martensitic stainless steel and its consequences on dimensional and mechanical evolution

Full text: Ferritic/martensitic (F/M) steels are drawing increasing attention as candidates for advanced reactor concepts, such as those proposed for Generation 4, fusion and accelerator-driven spallation neutron devices. In a recent series of published studies it appears that ferritic/martensitic steels may not be quite as resistant to the deleterious effects of radiation as previously perceived. It is shown the perception of superiority of F/M steels over their austenitic rivals should be treated with great caution, especially when extrapolating limited high exposure data from high-flux, relatively low-temperature environments to lower-flux, and significantly higher gas generation environments. A number of studies being conducted in Russia are now providing extensive high exposure data on Russian F/M steels developed either for sodium compatibility or compatibility with Pb-Bi coolant. These data are being used in an attempt to extend the data base upon which data from Western steels might reasonably be extrapolated. The effort on Russian steel is part of a larger coordinated effort to provide a wider data base on the response to radiation of both Western and Russian steels. Other efforts in progress or active planning involve previously unexamined steels at high fluence from the U.S. LMFBR program examination of F/M structural components from BN-350 (INP-Kazakhstan) and the influence of high generation rates of helium and hydrogen (KIPT-Ukraine)