Fatigue is identified as a significant degradation mode that affects nuclear power plants world-wide. The various international codes and standards (ASME, RCC-M, JSME, etc...) offer rules to predict its damaging effect on the locations of the various components of an NPP. These rules, which ensure conservatism and safe operation, have grown in complexity over the years because they have integrated R&D results showing aggravating effects (such as PWR environment degradation) that were not explicitly included in the original analyses (such as Environmental Assisted Fatigue [1] [2]) but also because an economically viable design of components has required optimization and refinement of mechanical assessment methods.

EDF has been developing since 1989 its own in-house FEA code baptised code_aster that is included in the Salome-Meca mechanical package. Salome-Meca is open-access and can be used freely by international users. It is continuously improved with a release at a rate of one new software version per year and it integrates the most recent results obtained by the EDF R&D, in fields as broad as fracture mechanics, XFEM and fatigue.

The fatigue post-processing in code_aster offers a span of criteria (Dang Van, Stress Intensity, etc...) to pick and choose from and even offers the possibility to make up owns one fatigue criteria. It also offers the possibility to post-process fatigue according to the RCC-M rules: this is implemented in code_aster through the so-called POST_RCCM operator.

Recent developments have enabled EDF to update the POST_RCCM operator in order to bridge the gap with modern fatigue industrial codes. The update effort has included in particular the development of a new option to evaluate fatigue for nozzles according to the RCC-M Annex ZE-200 as well as the clarification of the methodologies used for combining time points and transients. In addition, POST_RCCM includes the possibility to perform calculations with integration of environmental effects, with significant freedom to design one’s own corrections. The option is even left open to integrate a correction per the methodology proposed in [2]. The overall work scope and progress as of early 2016 was reported in [3] and is now in its validation phase.

The validation of a fatigue computer code is not an easy task as the full validation using hand calculations would be a highly tedious effort, given the technicality and the multiple choices to make along the various steps of the fatigue analysis. As a result, an accepted way of validating the results obtained with a given code is to perform a benchmark analysis against another industrial fatigue code. This strategy was adopted for the validation of the new POST_RCCM functionalities and this paper presents the work performed and the results obtained.

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