Common cause failure analysis of PWR containment spray system by GO-FLOW methodology

•Identification of particular causes of failure for common cause failure analysis.•Evaluation of dynamic reliability of PWR containment sprays system (standard case).•Selection of important parameters by sensitivity analysis for CCF analysis.•Calculated dynamic reliability has significantly worsened than that of standard case.•GO-FLOW with it advance function can be used alternatively to FAT and ET tree. Common cause failure (CCF) is the simultaneous failure of multiple components due to some particular cause of failure and has long been recognized as an important issue in the probabilistic safety assessment (PSA). Sometimes CCFs have an important contribution to system unreliability. In this study, Common Cause Failure has been considered in the reliability analysis and procedure of CCF analysis is treated by GO-FLOW methodology. As the sample system, PWR containment spray system has been taken. It is shown that dynamic reliability of the containment spray system has been significantly decreased by common cause failures.