Human Reliability Analysis for a Passive NPP and Application in Plant Operating Procedure Optimization

Abstract Human Reliability Analysis (HRA) is an important element in probabilistic safety assessment (PSA) for nuclear power plants (NPPs). Usually three types of human interactions (HIs) are defined in HRA for NPPs, i.e., pre-initiating event HIs, initiating event-related HIs, and post-initiating event HIs. In this paper, a brief introduction of the HRA methodology for a passive NPP is first presented. Then based on the HRA/PSA results and insights, design improvements and PSA applications could be performed. The optimization of plant operating procedures is one of the PSA applications in plant design phase. The risk-important human actions are obtained from the PSA importance analysis. Next, two risk-important human actions related to SGTR accident are studied in detail with the human error probability versus the design of plant operating procedures. Based on the sensitivity analysis, the operator response time for these two events, which varies with the steps of plant operating procedures, has certain influence on the plant core damage frequency (CDF) and rather high impact on the ratio of CDF variation of SGTR accident. Finally some proposals for optimization of the SGTR event analysis and relevant procedure steps are discussed. The plant operating procedures of the passive NPP are still under developing and optimization, and the study provides a useful way for plant operating procedure optimization.