Fatigue Assessment of NPP Piping and Components Using Realistic Thermal-Mechanical Load Histories

Abstract

Modern state-of-the-art fatigue monitoring approaches gain in importance as part of the ageing management of conventional and nuclear power plant components (NPP) and particularly in the context of lifetime extension projects and new plants. A key feature of qualified fatigue monitoring is the measurement of realistic loads based on plant instrumentation and/or local temperature measurement. The major prerequisites for any subsequent fatigue assessment are the accurate component stress analysis and the identification of relevant cycles, using highly qualified and efficient cycle counting methods. component). Conventional and more advanced methodologies are subsequently applied for comparison purpose. The influence of the cycle counting method applied on the resulting partial fatigue usage factors are elaborated based on the given realistic plant data.