RISK-SIGNIFICANT FUNCTIONAL-DEPENDENCIES IN PRESSURIZED WATER-REACTORS

This work provides evidence that functional dependencies among nuclear plant systems, particularly those among frontline safety systems and support systems, are often major contributors to the calculated risks in completed probabilistic risk assessments (PRAs). The study, furthermore, determined how the risk impact of functional dependencies could be reduced in future nuclear power plant designs. The risk reduction insights are summarized by a set of nine generalized design approaches, which we call design principles. These approaches are not new to the nuclear industry nor are the dependencies they address. The contribution made by this study is the use of PRA insights in pointing out the relative importance of the dependencies in terms of their contributions to risk.