Break Exclusion in French EPR: A Step by Step Analysis

After a lot of analysis in USA, USNRC has accepted a leak before break procedure developed in NUREG 1061 [4]. An updated version is under preparation in particular for operating plant to include field experience, but also for future plants. In France, EDF and AREVA have developed a new “break exclusion” methodology in 2 steps: - the safety consideration and defense in depth principle, - a modernized procedure to justify applications of break exclusion on a given system. Finally, large piping double-ended guillotine break are not considered in EPR-FA3 as a design transient. The Large Break Loss of Coolant Accident (LB-LOCA) is not considered as a design transient, only safety analysis with realistic data and methods are performed. For EPR-FA3, the larger break considered is the double end guillotine break of the surge line (16^″ instead of 28 or 32^″). The paper will present the details of these 2 step procedure and will discuss possible extension to other piping systems.