SOME PRACTICAL CONSIDERATIONS IN TREATING DEPENDENCIES IN PRAS

This paper reviews the integrated framework for doing common cause failure analysis developed by the US Nuclear Regulatory Commission (USNRC) and the Electric Power Research Institute (EPRI). The important insights that have been gained from this concentrated effort are highlighted. They include a balance between the qualitative and quantitative analysis, the importance of having plant-specific data, and the explicit delineation of the assumptions underlying the various models. The paper also provides some insights into quantifying common cause failures and some approximations that can be used in the quantification process. Data collection needs for common cause failure events are briefly discussed.