Verification of the HPR1000 Safety Classification in a Probabilistic Way

Abstract Probabilistic Safety Assessment (PSA) insights according to nuclear power plant (NPP) risk importance distribution profiles are used as a complementary way of deterministic safety analysis in verifying the adequacy of the safety classification. Fractional Contribution (FC) importance measure and Risk Achievement Worth (RAW) importance measure are chosen as two key indexes to show the full scope of NPPs risk profiles. It is expected that the equipment ranked with high safety class would be in the risk importance distribution areas with high FC importance or high RAW importance, while the equipment ranked with low safety class would be in the risk importance distribution areas with low FC importance and low RAW importance. The equipment whose safety classification do not match with the risk importance distribution are identified for further assessment to understand the reasons for it. Some case studies are performed on HPR1000 to show the process of this safety classification verification method, and to show whether the HPR1000 safety classification match with its PSA results or not. The result shows that the majority of the HPR1000 equipment safety classification matches with its risk importance distribution, which provides the confidence that the HPR1000 safety classification is mainly correct and adequate. There are still some exceptions, so two typical systems are selected for further discussion to provide detail insights about the reasons for it, and some recommendations for the safety classification are then given.