This paper describes the most recent version of a human reliability analysis (HRA) method called ``A Technique for Human Event Analysis'' (ATHEANA). The new version is documented in NUREG-1624, Rev. 1 [1] and reflects improvements to the method based on comments received from a peer review that was held in 1998 (see [2] for a detailed discussion of the peer review comments) and on the results of an initial trial application of the method conducted at a nuclear power plant in 1997 (see Appendix A in [3]). A summary of the more important recommendations resulting from the peer review and trial application is provided and critical and unique aspects of the revised method are discussed.

This paper summarizes the current status of the treatment of human reliability in fire risk analyses for nuclear power plants and identifies areas that need to be addressed. A new approach is suggested to improve the modeling.

ATHEANA, a second-generation Human Reliability Analysis (HRA) method integrates advances in psychology with engineering, human factors, and Probabilistic Risk Analysis (PRA) disciplines to provide an HRA quantification process and PRA modeling interface that can accommodate and represent human performance in real nuclear power plant events. The method uses the characteristics of serious accidents identified through retrospective analysis of serious operational events to set priorities in a search process for significant human failure events, unsafe acts, and error-forcing context (unfavorable plant conditions combined with negative performance-shaping factors). ATHEANA has been tested in a demonstration project at an operating pressurized water reactor.

In May of 1998, a technical basis and implementation guidelines document for A Technique for Human Event Analysis (ATHEANA) was issued as a draft report for public comment (NUREG-1624). In conjunction with the release of the draft NUREG, a paper review of the method, its documentation, and the results of an initial test of the method was held over a two-day period in Seattle, Washington, in June of 1998. Four internationally-known and respected experts in human reliability analysis (HRA) were selected to serve as the peer reviewers and were paid for their services. In addition, approximately 20 other individuals with an interest in HRA and ATHEANA also attended the peer review meeting and were invited to provide comments. The peer review team was asked to comment on any aspect of the method or the report in which improvements could be made and to discuss its strengths and weaknesses. All of the reviewers thought the ATEANA method had made significant contributions to the field of PRA/HRA, in particular by addressing the most important open questions and issues in HRA, by attempting to develop an integrated approach, and by developing a framework capable of identifying types of unsafe actions that generally have not been considered using existing methods. The reviewers had many concerns about specific aspects of the methodology and made many recommendations for ways to improve and extend the method, and to make its application more cost effective and useful to PRA in general. Details of the reviewers` comments and the ATHEANA team`s responses to specific criticisms will be discussed.

Over the past several years, the US Nuclear Regulatory Commission (NRC) has sponsored the development of a new method for performing human reliability analyses (HRAs). A major impetus for the program was the recognized need for a method that would not only address errors of omission (EOOs), but also errors of commission (EOCs). Although several documents have been issued describing the basis and development of the new method referred to as ``A Technique for Human Event Analysis`` (ATHEANA), two documents were drafted to initially provide the necessary documentation for applying the method: the frame of reference (FOR) manual, which served as the technical basis document for the method and the implementation guideline (IG), which provided step by step guidance for applying the method. Upon the completion of the draft FOR manual and the draft IG in April 1997, along with several step-throughs of the process by the development team, the method was ready for a third-party test. The method was demonstrated at Seabrook Station in July 1997. The main goals of the demonstration were to (1) test the ATHENA process as described in the FOR manual and the IG, (2) test a training package developed for the method, (3) test the hypothesis that plant operators and trainers have significant insight into the EFCs that can make UAs more likely, and (4) identify ways to improve the method and its documentation. The results of the Seabrook demonstration are evaluated against the success criteria, and important findings and recommendations regarding ATHENA that were obtained from the demonstration are presented here.

This paper summarizes recent efforts addressing management and organization factors in probabilistic risk assessment (PRA). This work will produce tools to support risk-informed regulation. It focuses on the technical basis for including management and organization factors as part of the risk management process. Technical gaps in the current understanding of management and organization factors, review of current state of the art in HRA modeling, and needs for-future research are discussed and summarized.

This paper summarizes an analytical process for performing an HRA in the context of a Probabilistic Risk Assessment (PRA), that addresses the major deficiencies of current HRA methods. This analytical process is being developed using the concepts captured in a multidisciplinary HRA framework [1], and is supplemented with the experience obtained from the analysis of historical nuclear power plant (NPP) events [2]. Both the framework and its application to the analysis of NPP events are earlier products of the HRA development project initiated by NRC in response to the recognized need for an improved, more realistic, approach to the modeling of human-system interactions. The analytical process is the application phase of a new approach to human reliability analysis called ATHEANA (A Technique for Human Error Analysis), which is based on an understanding of why human-system interaction failures occur, rather than on a behavioral, phenomenological description of operator responses, and represents a fundamental change in the approach to human reliability analysis.

Since the early 1970s, human reliability analysis (HRA) has been considered to be an integral part of probabilistic risk assessments (PRAs). Nuclear power plant (NPP) events, from Three Mile Island through the mid-1980s, showed the importance of human performance to NPP risk. Recent events demonstrate that human performance continues to be a dominant source of risk. In light of these observations, the current limitations of existing HRA approaches become apparent when the role of humans is examined explicitly in the context of real NPP events. The development of new or improved HRA methodologies to more realistically represent human performance is recognized by the Nuclear Regulatory Commission (NRC) as a necessary means to increase the utility of PRAS. To accomplish this objective, an Improved HRA Project, sponsored by the NRC`s Office of Nuclear Regulatory Research (RES), was initiated in late February, 1992, at Brookhaven National Laboratory (BNL) to develop an improved method for HRA that more realistically assesses the human contribution to plant risk and can be fully integrated with PRA. This report describes the research efforts including the development of a multidisciplinary HRA framework, the characterization and representation of errors of commission, and an approach for addressing human dependencies. The implications of the research and necessary requirements for further development also are discussed.

results with those accidents initiated during full power operation as assessed in NUREG-1150. The objective of this report is to document the approach utilized in the Surry plant and discuss the results obtained. A parallel report for the Grand Gulf plant is prepared by SNL. This study shows that the core-damage frequency during mid-loop operation at the Surry plant is comparable to that of power operation. The authors recognize that there is very large uncertainty in the human error probabilities in this study. This study identified that only a few procedures are available for mitigating accidents that may occur during shutdown. Procedures written specifically for shutdown accidents would be useful.

The Human Performance Investigation Process (HPIP) is a standard investigation process being developed through the Human Factors Branch, Nuclear Regulatory Research, for use by US Nuclear Regulatory Commission (HNRC) personnel when investigating human-performance-related events at nuclear power plants. The process was developed to meet the special needs of NRC personnel, especially NRC senior resident and resident inspectors. The HPIP melds current procedures and field practices, expert experience, NRC human performance research, and the best applicable investigation techniques into a procedure with stand-alone investigation modules for use by investigators in the field. The intent of the system is to be intuitive and easy to learn and use. The HPIP is designed to help NRC personnel perform better field investigations, resulting in a better understanding of human performance problems at nuclear power plants. The HPIP is now being tested on a limited number of nuclear plant events by trained NRC field personnel with assistance from the HPIP development team. The goal of the testing is to strengthen the system by providing the opportunity for additional user feedback. This feedback will make the system even more attuned to the user's needs, assuring that the implemented version of the HPIP is readily accepted inmore » the field. This paper outlines the HPIP and the six techniques built into the process.« less