This is the second in a series of three papers documenting two large-scale human reliability analysis (HRA) empirical studies – the International HRA Empirical Study and the US HRA Empirical Study. The goal of the two studies was to develop an empirically-based understanding of the performance, strengths, and weaknesses of HRA methods by comparing HRA method predictions against actual operator performance in simulated accident scenarios on full-scale nuclear power plant (NPP) simulators. The first paper (Paper 1) provides background information for the studies, an overview of their design and methodology, and a description of the simulation scenarios and associated human failure events (HFEs) addressed in the HRA analyses. This paper first discusses the overall simulator data followed by quantitative comparisons of the HRA methods’ predictions with the simulator data. Then, it presents a summary of the results of and knowledge and insights gained from the comparisons between method predictions obtained with the same method.
This is the first in a series of three papers documenting two large-scale human reliability analysis (HRA) empirical studies – the International HRA Empirical Study and the US HRA Empirical Study. The two studies are the first major efforts in recent years to benchmark HRA methods by comparing HRA method predictions against actual operator performance in responding to accidents simulated on nuclear power plant (NPP) full-scale simulators. The studies aimed to gain knowledge and insights concerning the strengths and weaknesses of the studied HRA methods and the factors contributing to inter-analyst (or intra-method) variability. In addition, the studies also compared the results of the same HRA method applied by different analysis teams. This paper provides the background and motivation of the studies, the overall study design, the simulation scenarios and human failure events to be analyzed, and concluding remarks concerning lessons learned on benchmarking HRA methods with crew performance of scenarios on NPP simulators.
This is the second in a series of four papers documenting two large-scale human reliability analysis (HRA) empirical studies – the International HRA Empirical Study and the US HRA Empirical Study. The goal of the two studies was to develop an empirically-based understanding of the performance, strengths, and weaknesses of HRA methods by comparing HRA method predictions against actual operator performance in simulated accident scenarios on nuclear power plant (NPP) simulators. The first paper (Part I), provided background in formation for the studies and an overview of their design and methodology. This paper first briefly describes the scenarios simulated in the studies and the associated human failure events (HFEs) addressed in the HRA analyses. Then, it discusses the overall simulator data followed by observations on the operating crew performance in the scenario simulations. Lastly, it presents some quantitative comparisons of the HRA methods’ predictions with the simulator data.
The Integrated Human Event Analysis System for nuclear power plant internal events at-power application (hereafter "IDHEAS AT-POWER") is a new human reliability analysis (HRA) method developed by the U.S. Nuclear Regulatory Commission (NRC) in collaboration with the Electric Power Research Institute (EPRI). It was developed to provide a structured approach to the qualitative and quantitative analysis of operator actions during internal, at-power nuclear power plant events. The IDHEAS AT-POWER method was tested to evaluate whether its guidance can be practically applied to produce consistent HRA results. This paper presents study findings and final conclusions on the method performance. Lessons learned on study methodology and recommendations for method improvement are also presented.
Human reliability analysis (HRA) is used in the context of probabilistic risk assessment (PRA) to provide risk information regarding human performance to support risk-informed decision-making with respect to high-reliability industries. The IntegrateD Human Event Analysis System (IDHEAS) is a new HRA method developed for internal, at-power nuclear power plant (NPP) events. It was motivated by the intention to reduce unnecessary and inappropriate variability in HRA results and improve the reliability of human error probability (HEP) estimates. The method has a strong foundation in human performance and cognitive psychology theories, and employs a cause-based quantification model. This paper documents a study conducted to pilot test IDHEAS to (1) identify issues that needed to be addressed and (2) provide feedback to refine the method before the method was finalized. An introduction on IDHEAS is provided first. Then sample IDHEAS analysis results are presented for illustration purposes. Next, insights from the testing in terms of method strengths and weaknesses are discussed, which is followed by concluding remarks.
United States nuclear power plant Licensee Event Reports (LERs), submitted to the United States Nuclear Regulatory Commission (NRC) under law as required by 10 CFR 50.72 and 50.73 were evaluated for reliance to the United Kingdom’s Health and Safety Executive – Office for Nuclear Regulation’s (ONR) general design assessment of the Advanced Boiling Water Reactor (ABWR) design. An NRC compendium of LERs, compiled by Idaho National Laboratory over the time period January 1, 2000 through March 31, 2014, were sorted by BWR safety system and sorted into two categories: those events leading to a SCRAM, and those events which constituted a safety system failure. The LERs were then evaluated as to the relevance of the operational experience to the ABWR design.