Cause-Defense Approach to the Understanding and Analysis of Common Cause Failures.

摘要

The report presents the results of research to develop a new methodology for common cause failure analysis and prevention. Common cause failures are defined as those caused by single events that can make redundant components unavailable, thus compromising the reliability of redundant trains of equipment. Probabilistic risk assessments (PRAs) and nuclear power plant (NPP) operations have demonstrated that CCF events are often major contributors to the potential risk posed at such plants. Over the years, qualitative and quantitative analysis methods have been developed to improve CCF analysis. However, these methodologies have not explicitly accounted for the impact of plant-specific defenses, such as design features and operational and maintenance policies, in reducing the likelihood of failures at NPPs. The research documented in the report describes a cause-defense methodology for CCF analysis and prevention to help correct this deficiency. The report discusses the development of (1) procedures for identifying the potential for CCF events at individual NPPs and (2) cause-defense matrices for analyzing CCF events. New concepts and more precise definitions are introduced to enhance CCF terminology and interpretation of historical event data.