Ageing Impact on Reliability and Components Importance of an NPP’s Emergency Power Supply Model

This paper deals with the ageing impact assessment on the reliability as well as on the components importance in an Emergency Power Supply System (EPSS) of a Nuclear Power Plant (NPP). The fault tree analysis (FTA) method of the EPSS failure is developed using RiskSpectrum PSA software considering the ageing model of electrical components. The quantitative reliability assessment of FTA is performed by calculating the EPSS failure probability and the components’ importance factors. Three widely used importance factors are considered in this paper namely: Fussel Vesley (FV) factor, Risk Increased factor (RIF) and Risk Decreased Factor (RDF). The obtained results show, clearly, that the age of components has a remarkable impact on their reliability and importance.