John M. O'Hara

The Effect of Pressure Suit Gloves on Hand Performance

The effects of pressure gloves on human hand capabilities is a major concern in the performance of extravehicular activity (EVA) for space maintenance and construction missions. The effects of EVA gloves on six hand performance domains was investigated in this NASA sponsored research. They were range of motion, strength, tactile perception, dexterity, fatigue, and comfort. All tests were designed to be performed in a glove box using the barehand as well as the glove at 0 and 4.3 pressure differentials. Ten subjects participated in the test in a repeated measures design. The results of the experiments are summarized in this paper.

Human Factors Challenges for Advanced Process Control

New human-system interface technologies provide opportunities for improving operator and plant performance. However, if these technologies are not properly implemented, they may introduce new challenges to performance and safety. This paper reports the results from a survey of human factors considerations that arise in the implementation of advanced human-system interface technologies in process control and other complex systems. General trends were identified for several areas based on a review of technical literature and a combination of interviews and site visits with process control organizations. Human factors considerations are discussed for two of these areas, automation and controls.

Guidance for Human-system Interfaces to Automatic Systems

Automation is ubiquitous in modern complex systems, and commercial nuclear- power plants are no exception. Automation is applied to a wide range of functions, including monitoring and detection, situation assessment, response planning, and response implementation. Automation has become a “team player” supporting personnel in nearly all aspects of system operation. In light of its increasing use and importance in new- and future-plants, guidance is needed to conduct safety reviews of the operators interface with automation. The objective of this research was to develop such guidance. We first characterized the important HFE aspects of automation, including six dimensions: Levels, functions, processes, modes, flexibility, and reliability. Next, we reviewed literature on the effects of all of these aspects of automation on human performance, and on the design of human-system interfaces (HSIs). Then, we used this technical basis established from the literature to identify general principles for human-automation interaction and to develop review guidelines. The guidelines consist of the following seven topics: Automation displays, interaction and control, automation modes, automation levels, adaptive automation, error tolerance and failure management, and HSI integration.

COMPUTERIZATION OF NUCLEAR POWER PLANT EMERGENCY OPERATING PROCEDURES.

Emergency operating procedures (EOPs) in nuclear plants guide operators in handling significant process disturbances. Historically these procedures have been paper-based. More recently, computer-based procedure (CBP) systems have been developed to improve the usability of EOPs. The objective of this study was to establish human factors review guidance for CBP systems based on a technically valid methodology. First, a characterization of CBPs 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 were developed. 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.

The development and evaluation of human factors guidelines for the review of advanced human-system interfaces

Advanced control rooms for future nuclear power plants are being designed utilizing computer-based technologies. The US Nuclear Regulatory Commission (NRC) reviews the human engineering aspects of such control rooms to ensure that they are designed to good human factors engineering principles and that operator performance and reliability are appropriately supported in order to protect public health and safety. The rationale, general approach, and initial development of an NRC Advanced Control Room Design Review Guidelines are reviewed.<<ETX>>

Decision-centered design as the basis of defining the human role in systems

In the last decade, controls research has focused on the interaction between the controlled plant and a computer controller, but in many situations a human operator is an integral part of the system. The operator interface to the system must support operators to maintain situational awareness and vigilance, and alert them when their intervention is required. The interface must be designed to allow operators to act/react effectively when human control intervention is needed. This requires the operator to make critical decisions about the state of the system and choose the optimal response. This paper describes a decision-centered design process which results in interfaces that support these monitoring and decisionmaking roles. The process begins by identifying the critical decisions that operators must make. With this understanding, the information presentation and interaction modes to support the operator to optimize decisions can be focused appropriately.

Your Design Probably Needs More VDU'S

The most frequent complaint of operators in modern computer-based control rooms is that there just are not enough video display units (VDUs). In this paper we examine the basis for this concern and try to understand the technical and historical reasons for this complaint, and its implications for the design of complex human- machine systems, including the number of VDUs in the control room. The overall aim of our work is to develop human factors guidance for the review of computer-based and modernized control rooms in nuclear power plants. As part of these efforts we have conducted literature reviews and studies using both simulators and actual systems in a broad range of industries, including process control, aerospace, medical, and others. Our findings reflect the general complaint of operators across all these industries: there just are not enough VDUs in the control room. We conclude that there are three primary reasons for this complaint. First, as part of a workload management strategy, operators frequently avoid interface management tasks and do not access all the information available, preferring instead to use a fixed set of familiar displays that provide much (but not all) of the information needed. Performance thereby becomes data limited and operators complain that they do not have a sufficient number of VDUs to set up in the early phases of a high-workload period so they can get all the information they need. Second, display designs are typically not designed with operator tasks in mind. The most common method of representing information is by functions and systems. Since tasks typically cut across many systems, operators need many displays. Thus, to make task performance easier operators need additional VDUs. Finally, there is a differing “concept of operations” between designers and operators. Modern computer-based control rooms are designed with vast amounts of data, available through hundreds of displays, viewed by the operator through a limited number of display devices. Designers expect that operators will use the flexibility of the computer-based interfaces to configure them in such a way that they are ideally tailored to the unique demands of the current situation. However, operators usually do not do that and instead configure the interfaces in a spatially dedicated way. Thus, while the number of VDUs may seem reasonable to the designer, it is not to the operator who is attempting to minimize the interface management aspects of workload. The implications of these findings for design are discussed in terms of the need for a method for determining the number of displays, task-relevant displays, data-dense displays, and enhanced interface management design and training.

Human factors considerations in control room modernization: trends and personnel performance issues

Advanced human-system interface (HSI) technology is being integrated into existing nuclear plants as part of plant modifications and upgrades. The result of this trend is that hybrid HSIs are created, i.e., HSIs containing a mixture of conventional (analog) and advanced (digital) technology. The purpose of the present research is to define the potential effects of hybrid HSIs on personnel performance and plant safety and to develop human factors guidance for safety reviews of them where necessary. In support of this objective, human factors issues associated with hybrid HSIs were identified. The issues were evaluated for their potential significance to plant safety, i.e., their human performance concerns have the potential to compromise plant safety. The issues were then prioritized and a subset was selected for design review guidance development.

Comprehensive Guidance for the Evaluation of Human-Systems Interfaces in Complex Systems

Advanced human-system interface (HSI) technologies are being developed in the commercial nuclear power industry. These HSIs may have significant implications for plant safety in that they will affect the ways in which the operator interacts with and supervises an increasingly complex system. The U.S. Nuclear Regulatory Commission (NRC) reviews the HSI aspects of nuclear plants to ensure that operator performance and reliability are supported. The NRC is developing guidance to support its review of these advanced designs. The guidance consists of an evaluation methodology and an extensive set of human factors guidelines which are used in one aspect of the evaluation. The paper describes the guidance development of the evaluation methodology and the guidelines. While originally developed for nuclear plant evaluation, the methodology is applicable to other types of complex human-machine systems as well.

Improving control room design and operations based on human factors analyses or how much human factors upgrade is enough

The Jose Cabrera nuclear power plant is a one loop Westinghouse pressurized water reactor. In the control room, the displays and controls used by operators for the emergency operating procedures are distributed on front and back panels. This configuration contributed to risk in the probabilistic safety assessment where important operator actions are required. This study was undertaken to evaluate the impact of the design on crew performance and plant safety and to develop design improvements. Five potential effects were identified. Then NUREG-0711, programmatic, human factors, analyses were conducted to systematically evaluate the CR-layout to determine if there was evidence of the potential effects. These analyses included operating experience review, PSA review, task analyses, and walkthrough simulations. Based on the results of these analyses, a variety of control room modifications were identified. From the alternatives, a selection was made that provided a reasonable balance between performance, risk and economics, and modifications were made to the plant.