The Human Factors Engineering Program Review Model (HFE PRM) was developed by the U.S. Nuclear Regulatory Commission (NRC) to support a review process for advanced reactor design certification. The following document was developed to provide additional review guidance to supplement the HFE PRM. It includes general principles and criteria for the review of group-view displays, a prominent design feature in proposed human-system interface designs for advanced nuclear power plants. This document describes group-view displays in terms of their potential functions, relationship to other aspects of the human-system interface, and relationship to capabilities and limitations of plant personnel. General principles and review criteria were drawn from diverse sources including HFE guidelines and research literature from the areas of human system-interface design for complex human-machine systems, situation awareness, team work/crew coordination, and computer-supported cooperative work. This document is intended to be used by NRC reviewers as part of the HFE PRM review process in determining the appropriateness of human-system interface functions and design details for supporting plant safety

Advanced human-system interface (HSI) technology, predominantly based on digital technology, is being integrated into existing nuclear plants as part of modifications and upgrades. The result of this trend is that hybrid HSIs are created, i.e., HSIs containing a mixture of conventional and advanced technology. Since the human factors concerns associated with hybrid HSIs are not well understood, Brookhaven National Laboratory (BNL) is conducting a project for the U.S. Nuclear Regulatory Commission (NRC) to better define their potential effects on personnel performance and plant safety and to develop human factors engineering (HFE) guidance to support the NRC's safety reviews of hybrid HSIs where necessary. In support of this objective, human factors topics associated with hybrid HSIs were identified. A human factors topic is an aspect of hybrid HSIs, such as a design or implementation feature, for which human performance concerns were identified. The topics were identified based on a literature review and a combination of interviews and site visits with organizations and individuals having experience with hybrid systems, both within and outside the nuclear industry. The data collected was used to define the types of technological changes that are being introduced into conventional HSIs and their potential effects on personnel performance in order to identify any human performance concerns.

Plant information systems provide operators with information supporting situation assessment, monitoring and detection of disturbances, response planning, and response implementation. The importance of the design of information systems for human performance and reliability has long been recognized. Recent advances in design goond the 'one sensor one indicator' display systems of conventional plants. Computer-based systems provide a variety of ways to process and present data. These characteristics of design represent a trend toward making displays more immediately meaningful to personnel by mapping display representations to important aspects of plant processes and to underlying cognitive mechanisms, such as perceptual processes and mental models. The objective of this study was to develop guidance for human factors review of advanced information systems based on a technically valid methodology for developing guidance. To support this objective, we developed a characterization framework for describing key design characteristics of information systems. The characterization includes the following major components: information requirements, representation systems, interface management functions, and display devices. Representation systems were further hierarchically divided into display elements (basic building blocks of displays, such as axes, alphanumeric elements, and icons), display formats (such as mimic displays, configural displays, and novel graphics), display pages (a defined set of information that is intended to be displayed as a single unit), and display networks (the organization of display pages). Then, we examined research in the following areas: (1) generic cognitive tasks that an information system must support, (2) information requirements analysis, (3) information representation, and (4) information organization. This research was used to provide the technical basis on which guidelines for review of design were developed. These guidelines address both the design process and the implementation of advanced information systems. However, there were aspects of information systems for which the technical basis was insufficient to support the development of guidance. These were identified as issues to be addressed in future research.

Plant procedures are instructions to guide operators in monitoring, decision making, and controlling nuclear power plants. While plant procedures historically have been paper-based, computer-based procedures (CBPs) are being developed to support procedure use. CBPs have a range of capabilities that may support operators and reduce demands associated with paper procedures. The objective of this study was to establish human factors review guidance for CBP systems based on a technically valid methodology. While the study mainly addressed emergency operating procedures, much of the guidance developed applies to other types of procedures. First, a CBP characterization was developed for describing their key design features including both procedure representation and functionality. Then, the research on CBPs and related areas was reviewed. This information provided the technical basis on which the guidelines for design review were developed. The review guidelines address both the design process and the implementation of CBP systems. For some aspects of CBPs the technical basis was insufficient to develop guidance; these aspects were identified as issues to be addressed in future research.

In conventional control rooms, the predominant means for providing control input is via hard-wired, spatially dedicated control devices that have fixed functions. However, in human-system interfaces featuring computer-based technologies, the operator may interact via “soft” controls – devices having connections with control and display systems that are mediated by software rather than direct physical connections. Soft controls can have functions that are variable and context dependent rather than statically defined. For example, a particular action may produce different results based on the currently active mode of the control device. Also, device locations may be virtual rather than spatially dedicated. That is, personnel may be able to access a particular soft control from multiple locations within a display system. These characteristics provide new opportunities for operator errors and may affect operator response during time-critical tasks. The objective of this study was to develop human factors review guidance for soft control systems. A methodology for developing technically valid guidance was used. To support this objective, we developed a characterization framework for describing key design characteristics of soft control systems including: display devices, input devices, and methods of interaction. Then, we examined research in the following, areas (1) human error in soft control use, (2) general design approaches for error tolerance, and (3)human performance considerations associated with specific control actions. This research provided the technical basis upon which design review guidelines were developed for the following: display devices, input devices, information displays, and interaction methods. There were aspects of soft controls for which the technical basis was insufficient to support development of the guidance. These were identified as issues to be addressed in future research.

There is currently a trend in nuclear power plants (NPPs) toward introducing digital technology into safety and non-safety systems. However, this equipment has characteristics different from older analog equipment and is susceptible to additional failure modes. Inadequate integration of digital systems into operating and maintenance practices, and inadequate understanding of the intricacies of software-based digital systems on the part of technicians and operators, can result in failures that render systems inoperable. Digital systems impose new demands on personnel for the testing, troubleshooting, servicing, and repair of hardware and software. This may become increasingly important as licensees, using the on-line maintenance capabilities of digital systems, perform more maintenance while the plant is at-power. The objective of this study was to establish human factors review guidance for the maintainability of digital systems based on a technically valid methodology. To support this objective, a characterization was developed for describing design features and practices important to maintaining digital systems. Then, technical information related to human performance in maintenance was reviewed. Information was drawn from nuclear power, process control, and aerospace domains and included reviews of maintenance practices and digital system failures. This information provided the technical basis on which guidelines were developed for reviewing design features that support maintenance. For some aspects the technical basis was insufficient to develop guidance; these were identified as issues to be addressed in future research.

Hybrid human-system interfaces (HSIs) result from the combination of new (e.g., digital) and traditional technologies. New demands may be imposed on personnel in operating and maintaining these systems. These demands may result from many factors including the characteristics of the new technologies, the characteristics of the mixture of new and traditional technologies, the process by which the hybrid HSI is developed and used, and the way in which personnel are prepared to use the hybrid HSI. The objective of this study was to develop human factors review guidance on the processes by which hybrid HSIs are developed, implemented, and integrated into plant operations. A characterization framework was developed for describing the key characteristics of hybrid HSIs that are important to human factors engineering (HFE) reviews. Then, the research studies, HFE processes, and guidance related to system development and modernization were reviewed. This information was used as the technical basis upon which we developed the design review guidelines. This guidance applies to general work that should be undertaken and factors that should be considered in designing and implementing hybrid HSIs, particularly in upgrading existing HSIs. The establishment and analysis of design requirements, interface design, and the evaluation of the final system are addressed. Issues for further research were identified for process consideration for which the technical basis was insufficient to support guidance development.

The primary tasks performed by nuclear power plant operators are process monitoring and control. To perform these tasks in a computer-based system, operators must perform secondary tasks such as retrieving information and configuring workstation displays. These are called "interface management tasks." Demands associated with interface management tasks may be excessive under some circumstances and potentially affect plant safety. The objective of this research was to evaluate the effects of interface management tasks on crew performance and safety using published literature, discussions with subject-matter experts, site visits, and simulator studies. We found evidence of two forms of negative effects: (1) primary task performance declines because operator attention is directed toward the interface management task, and (2) under high workload, operators minimize their performance of interface management tasks, thus failing to retrieve potentially important information for their primary tasks. Further, these effects were found to have potential negative effect on safety. The results of this study are reported in two volumes. Volume 1 provides an overview of the major findings. Volume 2 describes the detailed analyses that were performed. The results form the technical basis for human factors engineering guidelines for the review the interface management aspects of human-system interface designs, to help ensure that they do not compromise safety.

The primary tasks performed by nuclear power plant operators are process monitoring and control. To perform these tasks in a computer-based system, operators must perform secondary tasks such as retrieving information and configuring workstation displays. These are called "interface management tasks." Demands associated with interface management tasks may be excessive under some circumstances and potentially affect plant safety. The objective of this research was to evaluate the effects of interface management tasks on crew performance and safety using published literature, discussions with subject-matter experts, site visits, and simulator studies. We found evidence of two forms of negative effects: (1) primary task performance declines because operator attention is directed toward the interface management task, and (2) under high workload, operators minimize their performance of interface management tasks, thus failing to retrieve potentially important information for their primary tasks. Further, these effects were found to have potential negative effect on safety. The results of this study are reported in two volumes. Volume 1 provides an overview of the major findings. Volume 2 describes the detailed analyses that were performed. The results form the technical basis for human factors engineering guidelines for the review the interface management aspects of human-system interface designs, to help ensure that they do not compromise safety.

This study examined the impact of introducing advanced human-system interfaces (HSI) into a conventional nuclear power plant control room. The advanced HSIs include a computer-based procedure system, an advanced alarm system, and a graphic-based plant information display system. The impact of the new systems on the cognitive functioning of individual crew members and on the structure and functioning of the crew as a team was examined. Information on crew performance was obtained by observing crews during full-scope training simulations of plant disturbances. In addition, interviews were conducted with operators and other utility and vendor personnel. The general findings were that the new HSIs provided positive support for crew performance, reduced workload, and were well accepted by the crews. One of the more interesting and significant effects introduced by the advanced HSI systems was on crew structure and communication. The computer-based procedure system enabled the shift supervisor to access plant state information directly, reducing the need to ask board operators for plant parameter values. In turn, the board operators had access to a richer source of plant state information via the advanced alarm system and graphic-based plant information system than previously was available, enabling them to monitor plant state more broadly. These changes have potential implications for human performance and reliability. The fact that crews use multiple independent sources of information and multiple independent perspectives may increase the crew reliability by increasing the probability of detecting and correcting errors in situation assessment, thus reducing the potential for errors of intention. However, the improvement in human performance and reliability depends on the crew's ability to effectively communicate and maintain a shared situation awareness. The study provides illustrative cases where successful performance is dependent on effective communication among crew members. While this study began exploring these issues, further research is required to establish how new HSIs affect crew structure, communication, decision-making and reliability. The lessons learned from this investigation will be used to support human factors guidance development addressing these topics.

The NRC Human Factors Engineering Program Review Model (HFE PRM, NUREG-071 1) was developed to support a design process review for advanced reactor design certification under IOCFR52. The HFE PRM defines ten fundamental elements of a human factors engineering program. An Operating Experience Review (OER) is one of these elements. The main purpose of an OER is to identify potential safety issues from operating plant experience and ensure that they are addressed in a new design. Broad-based experience reviews have typically been performed in the past by reactor designers. For the HFE PRM the intent is to have a more focussed OER that concentrates on HFE issues or experience that would be relevant to the human-system interface (HSI) design process for new advanced reactors. This document provides a detailed list of HFE-relevant operating experience pertinent to the HSI design process for advanced nuclear power plants. This document is intended to be used by NRC reviewers as part of the HFE PRM review process in determining the completeness of an OER performed by an applicant for advanced reactor design certification.

This report provides guidance to support the review of the human factors aspects of advanced alarm system designs in nuclear power plants. The report is organized into three major sections. The first section describes the methodology and criteria that were used to develop the design review guidelines. Also included is a description of the scope, organization, and format of the guidelines. The second section provides a systematic review procedure in which important characteristics of the alarm system are identified, described, and evaluated. The third section provides the detailed review guidelines. The review guidelines are organized according to important characteristics of the alarm system including: alarm definition; alarm processing and reduction; alarm prioritization and availability; display; control; automated, dynamic, and modifiable characteristics; reliability, test, maintenance, and failure indication; alarm response procedures; and control-display integration and layout.

The objective of this study was to update and revise the Nuclear Regulatory Commission's (NRC) guidance for reviewing alarm system designs. The revisions were based on recent NRC research on the effects of alarm system design characteristics on operator performance and on a study examining the introduction of new computer-based human-system interface systems into conventional nuclear power plants (NPPs). In addition this present study examined research on alarm systems published since the NRC's previous development of guidance for alarm systems, Human Factors Engineering Guidance for the Review of Advanced Alarm Systems (NUREG/CR-6105). Specifically, where supported by the technical bases, changes were made to the alarm system characterization, HFE guidelines, and the previously identified human performance issues. While the characterization of alarm systems in NUREG/CR-6105 did a reasonable job of representing their functional characteristics, it did not sufficiently address all aspects of alarm systems that are important to a design review. Thus, the characterization was expanded to better illustrate the relationship of the alarm system to the NPP processes and systems. In general, the research reviewed provided confirmatory data that was used to clarify the guidelines. In addition, several new guidelines were developed and the criteria of some existing guidelines were modified or supplemented based on this recent research. Several human performance issues were identified in recent literature. In most cases, they reflect those previously identified in earlier phases of this project. This information was used to revise issues, where appropriate. The changes to the characterization and HFE guidelines discussed in this document were independently peer reviewed and will be incorporated into the Human-System Interface Design Review Guideline, NUREG-0700, Revision 2.

The impact of alarm system design characteristics on crew performance was evaluated to contribute to the understanding of potential safety issues and to provide data to support the development of design review guidance. The research served two purposes. First, to provide the information upon which to develop guidance on alarm design review. Second, to confirm that a selected set of previously developed guidelines were acceptable. The characteristics of alarm system design that we investigated were display (a dedicated tile format, a mixed tile and message list format, and a format in which alarm information is integrated into the process displays), processing (degree of alarm reduction), and availability (dynamic prioritization and suppression). These characteristics were combined into eight separate experimental conditions. Six, two-person crews of nuclear power plant operators completed sixteen test trials consisting of two trials in each of the eight experimental conditions (one with a low-complexity scenario and one with a high-complexity scenario). Measures of plant performance, operator task performance, and cognitive performance (situation awareness and workload) were obtained. In addition, operator ratings and evaluations of the alarm characteristics were collected. The results indicated all the crews were able to detect the disturbances and handle them effectively. There were not many significant effects on the plant, task performance, and cognitive measures. The most notable tendency was for the alarm effects to come in the form of interactions with scenario complexity. We concluded that the performance effects were modest because the alarm systems were generally well designed, integrated into an information-rich environment, and the operators were able to shift their information-gathering strategies to compensate for the differences in designs. The operators' ratings and evaluations were more sensitive to differences in alarm design. These data provided many insights on the strengths and weaknesses of the various alarm design features. Confirmatory evidence was found for the alarm guidance evaluated. The results of this study were used to extend and improve human factors guidance for the review of alarm systems.

This report describes a research program sponsored by the U.S. Nuclear Regulatory Commission (NRC) to address the human factors engineering (HFE) deficiencies associated with nuclear power plant alarm systems. The objective of the study was develop HFE review guidance for alarm systems based on HFE guidance and research available in the literature. The primary focus was advanced , computer-based alarm processing and display systems. In addition, an objective of the study was to identify priority areas where guidance was insufficient to support NRC alarm design reviews and to develop an approach to addressing these topics. These objectives were accomplished through the conduct of several tasks, including: (1) the development of a characterization framework for advanced alarm systems, (2) a review of human performance research related to alarm systems, (3) the development of HFE review guidance for alarm systems, and (4) the identification of research priorities and a test plan to address priority issues. This report constitutes the final report of the project and documents the results of the entire program. The detailed HFE alarm review guidance and the test plan are reported separately.

This technical report (TR) has been prepared by Brookhaven National Laboratory for the Human Factors Assessment Branch of the U.S. Nuclear Regulatory Commission's (NRC's) Office of Nuclear Reactor Regulation. This report is submitted under the Advanced Reactor Human Factors Review Project (FIN E-2090) as part of Task 4, "HFE Program Review Model." The NRC Project Manager is Karen Pulsipher and the Project Engineer is Garmon West. The BNL Principal Investigator is John O'Hara

The U.S. Nuclear Regulatory Commission (NRC) is addressing the human performance aspects of changes to operator actions that are credited for safety, especially those involving changes in the licensing basis of the plant; e.g., using of human actions (HA) in place of an automatic action for safety system operations. The objective of this project was to assist the NRC in developing proposed risk-informed review guidance and acceptance criteria for the NRC's review of licensee proposals addressing such modifications. This report addresses the development and evaluation of the proposed guidance and review method. The guidance was based on: (1) a review of past cases of changes in credited operator actions, (2) a review of NRC guidance for conducting risk-informed regulatory reviews, and (3) a review of NRC methodologies used for reviewing human factors engineering (HFE) topics. Using these sources of information, draft review guidance was developed. The review method uses a graded, risk-informed approach and provides guidance for reviewing the human performance aspects of changes to plant systems and operations. Risk insights are used to determine the level of regulatory review needed. The evaluation method uses a two-step approach. The first step is a screening analysis of the plant modification and the affected HAs to determination their risk importance. They are categorized into high, medium, and low risk regions. In the second step, HAs are reviewed using human factors engineering criteria. The purpose of the HFE review is to provide adequate assurance that the proposed HA can be reliably performed when called upon in the plant. HAs in the high-risk region receive a detailed review and those in the medium-risk region receive a less detailed review that is commensurate with their risk. In the lower-risk region, no human factors review is performed. The risk screening method was evaluated in several ways using data from individual plant examinations. The HFE review methodology was evaluated using existing NRC case files involving changes to credited operator actions. The risk screening and HFE review methods was revised based on the results of the evaluation. The final review guidance is described in a report entitled Proposed Approach for Reviewing Plant Modifications Involving Risk-Important Human Actions (Higgins and O'Hara, 2000).

This document is used by the staff of the Nuclear Regulatory Commission to review the human factors engineering (HFE) programs of applicants for construction permits, operating licenses, standard design certifications, combined operating licenses, and for license amendments. The purpose of these reviews is to verify that accepted HFE practices and guidelines are incorporated into the applicant’s HFE program. The review methodology provides a basis for performing reviews that address the twelve elements of an HFE program: HFE Program Management, Operating Experience Review; Functional Requirements Analysis and Function Allocation, Task Analysis, Staffing, Human Reliability Analysis, Human-System Interface Design, Procedure Development, Training Program Development, Human Factors Verification and Validation, Design Implementation, and Human Performance Monitoring. Each review element is divided into four sections: Background, Objective, Applicant Submittals, and Review Criteria. References to sources of additional information are also provided for each element.

This technical evaluation report has been prepared by Brookhaven National Laboratory for the Human Factors Assessment Branch of the U.S. Nuclear Regulatory Commission's (NRC's) Office of Nuclear Reactor Regulation. This report is submitted under the Advanced Reactor Human Factors Review Project (FIN E-2090) as part of Task 2 - "System 80+ Human Factors Program Review." The NRC Project Manager is Karen Pulsipher and the Project Engineer is Garmon West. The BNL Principal Investigator is John O'Hara.

Advanced control rooms will use advanced human-system interface (HSI) technologies that may have significant implications for plant safety in that they will affect the operator's overall role in the system, the method of information presentation, and the ways in which operators interact with the system. The U.S. Nuclear Regulatory Commission (NRC) reviews the HSI aspects of control rooms to ensure that they are designed to good human factors engineering principles and that operator performance and reliability are appropriately supported to protect public health and safety. The principal guidance available to the NRC, however, was developed more than ten years ago, well before these technological changes. Accordingly, the human factors guidance needs to be updated to serve as the basis for NRC review of these advanced designs. The purpose of this project was to develop a general approach to advanced HSI review and the human factors guidelines to support NRC safety reviews of advanced systems. This two-volume report provides the results of the project. Volume 1 describes the development of the Advanced HSI Design Review Guideline (DRG) including (1) its theoretical and technical foundation, (2) a general model for the review of advanced HSIs, (3) guideline development in both hard-copy and computer-based versions, and (4) the tests and evaluations performed to develop and validate the DRG. Volume 1 also includes a discussion of the gaps in available guidance and a methodology for addressing them. Volume 2 provides the guidelines to be used for advanced HSI review and the procedures for their use.

The U.S. Nuclear Regulatory Commission (NRC) staff reviews the human factors engineering (HFE) aspects of nuclear power plants in accordance with the Standard Review Plan (NUREG-0800). Detailed design review procedures are provided in the HFE Program Review Model (NUREG-0711). As part of the review process, the interfaces between plant personnel and plant's systems and components are evaluated for conformance with HFE guidelines. This document, Human-System Interface Design Review Guidelines (NUREG-0700, Revision 2), provides the guidelines necessary to perform this evaluation. The review guidelines address the physical and functional characteristics of human-system interfaces (HSIs). Since these guidelines only address the HFE aspects of design and not other related considerations, such as instrumentation and control and structural design, they are referred to as HFE guidelines. In addition to the review of actual HSIs, the NRC staff can use the NUREG-0700 guidelines to evaluate a designspecific HFE guidelines document or style guide. The HFE guidelines are organized into four basic parts, which are divided into sections. Part I contains guidelines for the basic HSI elements: displays, user-interface interaction and management, and controls. These elements are used as building blocks to develop HSI systems to serve specific functions. Part II contains the guidelines for reviewing six such systems: alarm system, group-view display system, soft control system, computer-based procedure system, computerized operator support system, and communication system. Part III provides guidelines for the review of workstations and workplaces. Part IV provides guidelines for the review of HSI support, i.e., maintainability of digital systems.

Since issuing NUREG-0700, Revision 1, "Human System Interface Design Review Guideline," in June 1996, the U. S. Nuclear Regulatory Commission (NRC) has been committed to the periodic update and improvement to this document to ensure that it will remain a state-of-the-art design review tool. The technical content of the guidelines in Revision 0 and 1 were reviewed to determine whether updating may be needed as a result of new, validated guidance that may have been developed since their publication, and to modify the guidelines accordingly. NUREG/CR-5680 presents the results of a comprehensive review of the technical literature on the impact of environmental conditions on human performance in nuclear power plant settings. Although that report was not intended to provide design review guidelines for environmental conditions, it was recognized that the information developed in this effort might provide a basis for updating and/or augmenting the existing review guidance. This report summarizes the results of comparing the guidance in NUREG-0700, Rev.1 for environmental conditions against the information in NUREG/CR-5680. It contains summaries of the scope and content of NUREG/CR-5680, and the information for each of the environmental factors considered in NUREG/CR-5680 that pertain to the guidance in NUREG-0700. Proposed modifications to NUREG-0700, which are based on the information in NUREG/CR-5680, are contained in the appendices.

Recent nuclear power plant events (e.g., Chernobyl, Diablo Canyon, and Vogtle) and U.S. Nuclear Regulatory Commission (NRC) reports (e.g., NUREG-1449) have led to concerns regarding human reliability during low power and shutdown (LPS) conditions and limitations of human reliability analysis (HRA) methodologies in adequately representing the LPS environment. As a result of these concerns, the NRC initiated two parallel research projects to assess the influence of LPS conditions on human reliability through an analysis of operational experience at pressurized water reactors (PWRs) and boiling water reactors (BWRs). These research projects, performed by Brookhaven National Laboratory for PWRs, and Sandia National Laboratories for BWRs, identified unique aspects of human performance during LPS conditions and provided a program plan for research and development necessary to improve existing HRA methodologies. This report documents the results of the analysis of LPS operating experience and describes the improved HRA program plan.

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.

A human factors analysis was performed to assess how identified upgrades to local control stations (LCSs) in nuclear power plants affect both human performance and plant risk. Upgrades in the design of individual control panels and overall improvement of functional centralization were considered. The analysis methodology was accomplished in four stages. First, a list of LCS human engineering design deficiencies was developed using data collected from a variety of sources including visits to nuclear power plants. From these data, a set of potential upgrades were defined to correct the deficiencies. Second, the effects of the upgrades on human error probabilities (HEPs) were determined using a computer-based methodology for soliciting expert judgement. Third, the HEPs were propagated through a plant probabilistic risk assessment (PRA), and new core melt frequencies were established. A preliminary, scoping value-impact assessment was performed to evaluate the regulatory need for further review of possible action to improve the human factors engineering aspects of local control stations. The results indicated that implementation of both types of upgrades would improve human performance and lower risk, but that only the panel design improvements would be cost beneficial.

The objective of this research project was to evaluate current human engineering at local control stations (LCSs) in nuclear power plants, and to identify good human engineering practices relevant to the design of these operator interfaces. General literature and reports of operating experience were reviewed to determine the extent and type of human engineering deficiencies at LCSs in nuclear power plants. In-plant assessments were made of human engineering at single-function as well as multifunction LCSs. Besides confirming the existence of human engineering deficiencies at LCSs, the in-plant assessments provided information about the human engineering upgrades that have been made at nuclear power plants. Upgrades were typically the result of any of three influences -regulatory activity, broad industry initiatives such as INPO, and specific in-plant programs (e.g., activities related to training). It is concluded that the quality of LCSs is quite variable and might be improved if there were greater awareness of good practices and existing human engineering guidance relevant to these operator interfaces, which is available from a variety of sources. To make such human engineering guidance more readily accessible, guidelines were compiled from such sources and included in the report as an appendix.

This is the first of a two-volume report (Volume II to be published at a later date) that presents the results of a research project conducted by Brookhaven National Laboratory for the United States Nuclear Regulatory Commission, Office of Nuclear Regulatory Research. The purpose of the project was to develop a general methodology to be used in the assessment of the organizational factors which affect performance reliability (safety) in a nuclear power plant. The research described in this report includes the development of the Nuclear Organization and Management Analysis Concept (NOMAC). This concept characterizes the organizational factors that impact safety performance in a nuclear power plant and identifies some methods for systematically measuring and analyzing the influence of these factors on safety performance. This report is divided into two parts. Part I presents an overview of the development of the methodology, while Part II provides more details and a technical analysis of the methodological development. Specifically, the results of two demonstration studies, the feasibility of the methodology, and a specific application for which the methodology was developed are presented. Volume II presents the procedures for implementing the NOMAC methodology and applying the results to probabilistic risk assessment.

The probability of detecting residual contamination in the field using portable radiological survey instruments depends not only on the sensitivity of the instrumentation used in scanning, but also on the surveyor's performance. This report provides a basis for taking human performance into account in determining of the minimum level of activity detectable by scanning. A theoretical framework was developed (based on signal detection theory) which allows influences on surveyors to be anticipated and understood, and supports a quantitative assessment of performance. The performance of surveyors under controlled yet realistic field conditions was examined to gain insight into the task and to develop means of quantifying performance. Then, their performance was assessed under laboratory conditions to quantify more precisely their ability to make the required discriminations. The information was used to characterize surveyors' performance in the scanning task and to provide a basis for predicting levels of radioactivity that are likely to be detectable under various conditions by surveyors using portable survey instruments.

This report describes and quantitatively evaluates the effects of various factors on the detection sensitivity of commercially available portable field instruments being used to conduct radiological surveys in support of decommissioning. The U.S. Nuclear Regulatory Commission (NRC) is currently involved in a rulemaking effort to establish residual contamination criteria for release of facilities for restricted or unrestricted use. In support of that rulemaking, the Commission has prepared a draft Generic Environmental Impact Statement (GEIS), consistent with the National Environmental Policy Act (NEPA). The effects of this new rulemaking on the overall cost of decommissioning are among the many factors considered in the GEIS. The overall cost includes the costs of decontamination, waste disposal, and radiological surveys to demonstrate compliance with the applicable guidelines. An important factor affecting the costs of such radiological surveys is the minimum detectable concentrations (MDCs) of field survey instruments in relation to the residual contamination guidelines. The purpose of this study was two-fold. First, the data were used to determine the validity of the theoretical MDCs used in the NRC draft GEIS. Second, the results of the study, published herein, provide guidance to licensees for (a) selection and proper use of portable survey instruments and (b) understanding the field conditions and the extent to which the capabilities of those instruments can be limited. The types of instruments commonly used in field radiological surveys were evaluated, such as gas proportional, Geiger-Mueller (GM), zinc sulfide (ZnS), and sodium iodide (NaI) detectors.

This report describes and applies a process for validating a model for a risk-based performance indicator. The purpose of the risk-based indicator evaluated, Safety System Function Trend (SSFT), is to monitor the unavailability of selected safety systems. Interim validation of this indicator is based on three aspects: a theoretical basis, an empirical basis relying on statistical correlations, and case studies employing 25 plant years of histor-ical data collected from five plants for a number of safety systems. Results using the SSFT model are encouraging. Application of the model through case studies dealing with the performance of important safety systems shows that statistically significant trends in, and levels of, system performance can be discerned which thereby can provide leading indications of degrading and/or improving performances.

Methods for developing system performance tolerance bounds are discussed and applied to aid in the interpretation of the trends in this risk-based in-dicator.

Some additional characteristics of the SSFT indicator, learned through the data-collection efforts and subsequent data analyses performed, are also discussed. The usefulness and practicality of other data sources for validation purposes are explored. Further validation of this indicator is noted. Also, additional research is underway in developing a more detailed estimator of system unavailability.

A sensitivity evaluation was conducted to assess the impact of human errors on the internal event risk parameters in the LaSalle plant. The results provide the variation in the risk parameters, namely, core melt frequency and accident sequence frequencies, due to hypothetical changes in human error probabilities. Also provided are insights derived from the results, which highlight important areas for concentration of risk limitation efforts associated with human performance.