Basic Relation between RAW and RRW and Some of Its Implications on Risk Reduction Strategies

In using risk-informed approaches for ensuring safety of operating nuclear power plants (NPPs), risk importance measures obtained from probabilistic assessments (PSAs) the are integral elements consideration in many cases. PSA models and applications associated with NPPs a particular feature (e.g. function, system, component, failure mode or operator action) can be, most generally, divided into two categories: respect to increase potential decrease potential. The representative first category, as used practical purposes, is Risk Achievement Worth (RAW). Representative second mentioned importance, Reduction (RRW). It be shown that measures, RAW RRW, dependent on each other. only parameter this mutual dependency probability considered feature. paper discusses relation between RRW some its implications, including those general strategies reduction imposed operation facility. Two which discussion are: a) by decreasing feature; b) while keeping at same level. Simple examples provided illustrate differences point main issues conclusions.