Automatic Fatigue Monitoring Based on Real Loads - Calculation Example of a Flange

Abstract

The ageing management of power plants is nowadays a main issue for all nuclear industry actors: states, regulatory agencies, operators, designers or suppliers. Consequently, lots of operators have to deal with demanding security requirements to ensure the operation of power plants. Regarding with fatigue assessment of nuclear components, stringent safety standards are synonymous of new parameters to take into account in the fatigue analysis process, for instance: new design of fatigue curves, consideration of environmental parameters or stratification effects. In this context AREVA developed within the integral approach AREVA Fatigue Concept (AFC) new tools and methods to live up to operators’ expectations. Based on measured thermal loads, the Fast Fatigue Evaluation (FFE) process allows for highly-automated and reliable data processing to evaluate time-dependant cumulative usage factors of mechanical components. Calculation and management of results are performed with the software FAMOSi, thus impact of operating cycles on components in terms of stress but also with regard of fatigue can be taken into account to plan an optimized decision related to the plant operation or maintenance activities. The FFE process was exemplary applied in 2012 in the EnBW Power Plant of Neckarwestheim (GKN II) to perform an informative fatigue diagnose of a spray line flange for different operating cycles. This paper describes the calculation methodology but also some relevant results to point out the benefits of this method to the ageing management of mechanical parts.