Development of a systematic approach for the analysis of system-level dependent failures

A framework for a systematic treatment of common cause failures in safety and reliability studies was developed in a recent project. The project was jointly sponsored by the EPRI and the USNRC and received a broad scope of input from the nuclear industry and research community in the U.S. and in Europe. The framework that was developed sets forth principles that should be followed in the treatment of common cause failures in PRA-type systems reliability evaluations. It provides step-by-step procedures for the performance of each task of the analysis and allows the flexibility of choice among alternative acceptable models and analytical techniques. The major aspects of the analysis considered in this work include logic model development, screening of common cause events, common cause modeling, data analysis, system quantification, and interpretation of results. In contrast with previous work on this subject, a major emphasis was placed on the extraction of information from event report data to support the qualitative as well as quantitative aspects of the analysis. (orig./HSCH)