FRACTURE MECHANIC AT DESIGN LEVEL FOR NEW REACTORS

For new plants in particular, or for some replaced components a new failure mode has to be considered: flaw tolerance and rupture. Different cracks have to be considered at the early stage in design in different locations with different crack sizes and crack locations, in particular for components in the brittle or transition temperature range. In addition, for some location thermal ageing or radiation ageing have to be considered. Potential fatigue or corrosion crack growth has to be also considered. Another aspect that needs to consider fracture mechanic is the Leak Before Break justification or the Break Exclusion justification of some components or piping systems. This paper will summarize how these requirements are considered in French Codes RCC-M, RCC-MRx and RSE-M for normal, upset, emergency, faulted, severe accident and test conditions. On-going developments, like Appendix G modernization, will be presented to conclude the paper.