Modeling and Measuring Common Cause Failures in Measurement of Reliability of Nuclear Power Plant Systems

Abstract

Much attention has been given to measure the reliability of safety critical systems (SCSs), assuming that components fail independently. However, in practice, dependent failures of components due to come common cause play a significant role in determining system reliabilities and hence can measure the risk more accurately. In this article, we propose a method to measure such dependent failures systematically, known as common cause failures (CCFs). We propose a framework to model and quantify CCF that contains two phases: screening analysis and detailed analysis. Screening analysis involves qualitative and quantitative screening; detailed analysis involves estimation of common cause basic event probabilities by developing a probability model. The proposed approach is applied on a case study of nuclear power plant (NPP). The result proves that risk is highly sensitive to the probability of a CCF.