PWR EFFECT ON CRACK INITIATION UNDER EQUI-BIAXIAL LOADING DEVELOPMENT OF THE EXPERIMENT

Fatigue lifetime assessment is essential in the design of structures. Under-estimated lifetime predictions may generate overly conservative usage factor values and hence result in unnecessary in-service inspections. In the framework of upgrading the fatigue design rules (RCC-M, RCC-MRx), the uniaxial reference fatigue curve was altered by taking into account effects like: Multiaxiality, Mean stress or strain, Surface roughness (polished or ground), Scale effect, Loading History... In addition to this effect, Environmentally Assisted Fatigue is also receiving nowadays an increased level of attention. To formally integrate these effects, some international codes have already proposed and suggested a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which has to be multiplied by the usual fatigue usage factor. The aim of this paper is to present a new device "FABIME2E" developed in the LISN in collaboration with EDF and AREVA. These new tests allow quantifying accurately the effect of PWR environment on semi-structure specimen. This new device combines the structural effect like equibiaxiality and mean strain and the environmental penalty effect with the use of PWR environment during the fatigue tests.