ABSTRACT
A handbook was published to document methods and guidance that NRC staff should use to achieve more consistent results when performing risk assessments of operational events by the U.S. NRC. Korea Atomic Energy Research Institute (KAERI) launched a research project to develop a regulatory purpose Level 1 PSA (Probabilistic Safety Assessment) model and framework for use in risk-informed regulation. To this end, we designed a regulatory risk model reflected regulatory purposes based on the real conditions and developed a regulatory software called RYAN (Risk Analysis for ASP/SDP of NPP) that enables the regulatory body to perform the overall safety assessment such as ASP/SDP (Accident Sequence Precursor/Significance Determination Process). In order to verify and validate the RYAN software, we investigated operational events occurred in domestic NPPs from databases such as OPIS (Operational Performance Information System for Nuclear Power Plant) and KRDB (Korean Integrated Reliability Database). From those nuclear event databases, we selected some component failures and IEs for the software verification and validation. We performed a sensitivity analysis for the various cases with the selected operational events. Based on the framework, it is expected that the regulatory staff can identify a nuclear power plant or SSC (Structure, System, and Component) for which safety performance has been decreased. For a further study, we are confirming the applicability of RYAN by performing a sensitivity analysis with more event data. In addition, we are to analyze the significance of each case with the AIMS-PSA to compare the results from RYAN and AIMS-PSA for ensuring the accuracy of the analysis results with RYAN.
