AREVA’s Fatigue Concept – An Integrated and Multidisciplinary Approach to the Fatigue Assessment of NPP Components
Jürgen Rudolph, Steffen Bergholz, Benedikt Heinz,
and Nikolaus Wirtz
Department PEEA-G, AREVA NP GmbH, Henri-Dunant-Strasse 50, 91058 Erlangen, Germany
Preventing fatigue damage is crucial in changing boundary conditions such as code modification, lifetime extension, new plants with operating periods of 60 years. The AREVA fatigue concept (AFC) provides for a multiple-step multidisciplinary process – process engineering, fatigue monitoring, fatigue analysis, etc. – against fatigue before and during the entire nuclear power plant (NPP) operation. Fatigue analysis is based on real operational loads measured continuously on site in plants via fatigue monitoring, enabling qualified fatigue usage factors to be determined. Potential fatigue failure sites are reliably identified, reducing expensive inspection costs. Direct processing of measured temperatures is immediately used for a first automated fast fatigue estimation. In the periodic safety inspection (PSI) framework, detailed fatigue check conforming to code rules and based on real loads is recommended. The additional check against progressive plastic deformation (ratcheting) is unique. In the elastic plastic approach, much care must be taken in applying appropriate material law and extrapolation emanating from a low number of analyzed cycles.
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