Behavior of different austenitic stainless steels, conventional, reduced activation (RA) and ODS chromium-rich ferritic-martensitic steels under neutron irradiation at 325°C in PWR environment

The main objective of this paper is to summarize CEA data recently obtained on different kinds of steels irradiated at 325 degreesC in the Osiris experimental reactor in a typical PWR environment, that is, pressurized water - P=155 bars - with controlled PWR type chemistry. The different steels studied can be classified in four groups: 304/316 type austenitic stainless steels, conventional 9-12%Cr(Mo,V,Nb) and reduced activation 7.5-11%Cr(W,V,Ta) martensitic steels, and two ferritic-martensitic alloys strengthened by oxide dispersion (ODS). Some of those steels have been included with different initial metallurgical conditions, that is, (1) for austenitic steels : solution annealed and cold-worked structures; (2) for martensitic steels : tempered, cold-worked and as-quenched martensitic structures. This experimental irradiation, named "Alexandre", has been carried out in the Osiris experimental reactor (under a mixed fast/thermal neutron flux) for different neutron fluence levels with a maximum irradiation damage of similar to 9dpa. The main results obtained are discussed, with a special emphasis on the chemical composition and initial metallurgical condition effects on the tensile and uniform corrosion properties of both conventional and reduced activation chromium-rich martensitic steels.