In this paper the relevance of environmental fatigue for real components of a PWR is discussed based on the ANL procedure according to NUREG/CR-6909 using the penalty factor Fen. Monitoring data of several German PWRs for the surge lines and spray lines have been evaluated and assessed for five years of operation each. Monitored loads are compared to specified loads and lab loads and the fatigue evaluation is assessed comparing traditional fatigue evaluation to the ANL approach. Taking into account environmental fatigue the calculated life time of a component in LWR environments can be reduced by a factor of 10 or even more compared to common fatigue evaluation. These tremendous reductions are based on lab results whereas experience from existent nuclear power plants has not yet shown any relevance of this influence. The conclusions of evaluations and assessments are summarized in a concept for long term operation (LTO). This concept contains procedures how to manage environmental fatigue. In the design phase conservatism in specified loads, especially numbers of load cycles, can be reduced based on the duty to monitor real loads and assess fatigue during operation. In the operating phase monitoring data should be used to record loads, evaluate and assess fatigue and subsequently reduce fatigue by optimizing operational modes.
- Pressure Vessels and Piping Division
Managing Environmental Fatigue of the Real Components in a PWR
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Rothenho¨fer, H, & Ko¨nig, G. "Managing Environmental Fatigue of the Real Components in a PWR." Proceedings of the ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASME 2010 Pressure Vessels and Piping Conference: Volume 7. Bellevue, Washington, USA. July 18–22, 2010. pp. 247-254. ASME. https://doi.org/10.1115/PVP2010-25979
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