There is more to monitoring a nuclear power plant than meets the eye

A fundamental challenge in studying cognitive systems in context is how to move from the specific work setting studied to a more general understanding of distributed cognitive work and how to support it. We present a series of cognitive field studies that illustrate one response to this challenge. Our focus was on how nuclear power plant (NPP) operators monitor plant state during normal operating conditions. We studied operators at two NPPs with different control room interfaces. We identified strong consistencies with respect to factors that made monitoring difficult and the strategies that operators have developed to facilitate monitoring. We found that what makes monitoring difficult is not the need to identify subtle abnormal indications against a quiescent background, but rather the need to identify and pursue relevant findings against a noisy background. Operators devised proactive strategies to make important information more salient or reduce meaningless change, create new information, and off-load some cognitive processing onto the interface. These findings emphasize the active problem-solving nature of monitoring, and highlight the use of strategies for knowledge-driven monitoring and the proactive adaptation of the interface to support monitoring. Potential applications of this research include control room design for process control and alarm systems and user interfaces for complex systems.     

Human processes of control: tracing the goals and strategies of control room teams

This study utilized a process tracing methodology to analyse the goals and strategies of control room teams in dealing with an unpredicted plant disturbance. The human processes of control used by operators and their supervisors, and interactions between them, were analysed during phases of detection, diagnosis, and control of a small plant leak. Five control room teams were videotaped tackling this simulated scenario on a full-scale simulator. The results found substantial differences both within and between teams in how the goals of monitoring and implementing procedures during the detection phase, and problem-solving and plant control during the diagnosis phase were achieved. The temporal patterning of the activities associated with these goals revealed that the teams used different strategies. The training implications of these findings are discussed, in particular with respect to the control room supervisor who had a pivotal role.     

The impact of computer-based procedures on team performance,communication, and situation awareness

In nuclear power plants, operating procedures are adopted to aid the operators in performing their tasks. With the evolution of computer hardware and software, the analog human-machine systems of the main control room in the nuclear power plant have been replaced with digital systems. Moreover, automated operations now outnumber manual operations. The purpose of this study was to evaluate the impact of computer-based procedures on the team performance, communication, and situation awareness of operators in the main control room. To achieve the purpose, a within-subjects experiment was designed and then a survey was conducted. The results showed that the teams had better objective performance and higher situation awareness when using computer-based procedures. In addition, the teams also had lower human error and lower communication rates when using computer-based procedures. This study proposes that computer-based procedures are advantageous to the operation of the systems of the main control rooms in nuclear power plants.Relevance to industryComputerized procedures system is one of the specific features for advanced nuclear power plant. This study explores and analyzes the team performance, communication, and situation awareness difference between paper-based, electronic, and computer-based procedures in detail. It may provide practical information for how to apply computer-based procedures to perform the tasks in the main control room of the advanced nuclear power plant.     

I spy with my AI: The effects of AI-based visual cueing on human operators’ performance and cognitive load in CCTV control rooms

The increased number of security cameras in modern cities has elevated the video-feed monitoring demands of closed-circuit television (CCTV) operators. As a result, new AI-driven support systems that leverage the power of computer vision algorithms have been deployed to facilitate the operators' work. However, to effectively design intuitive, AI-driven interfaces and validate their impact on the operators' performance, extensive user testing is required. To address this, we previously developed and tested a virtual reality (VR) control room that can be used to iteratively evaluate intelligent computer assistants and interfaces while operators are subjected to different cognitive load. In the present study, we use this VR environment and physiological markers (e.g., eye tracking measures) to investigate how AI-based visual cueing (i.e., pushing forward video streams on which detections are highlighted by rectangles drawn around targets) affects operator performance and cognitive load. Results suggest that support systems using such technology in a control room improve operators’ performance and decrease their cognitive load, as reflected by changes in pupil dilation and subjective reports irrespective of induced cognitive load.     

Analysis of information exchange activities to actualize and validate situation awareness during shift changeovers in nuclear power plants

Shift work situations occur in almost all safety‐critical organizations, and the investigations of some catastrophes like Chernobyl, Exxon Valdez, and the Gol/Legacy mid‐air collision indicated that shift work information exchange played an important role during the evolution of the situation before the accidents. Inadequate communications during shift changeovers challenged operators' work in the moments that preceded these accidents, because they got inadequate information about the current situation. Our research focuses on the information exchange activities (verbal, written, and nonverbal) of nuclear power plant control operators during shift changeovers. Our aim is to investigate how verbal exchanges and other representations enable operator crews to share information regarding the events that occurred in the previous shift to achieve adequate situation awareness. Our findings indicated the importance and richness of the information exchange during the shift changeover process to update and validate individual and collective situation awareness, showing that information adequately shared enables the ad hoc configurations of regulation loops and a safer use of simplified strategies that can be understood and be validated by other operators, reducing the occurrence of cognitive overloads and contributing to the construction of a common cognitive ground that enhances system resilience. © 2010 Wiley Periodicals, Inc.     

Reasoning and knowledge of nuclear power plant operators in case of accidents

This paper presents the results of an ergonomics analysis of the work activities of nuclear power plant operators. It focuses on cognitive activity during simulated accidents. Qualitative aspects of this activity are described, which include operators' knowledge, diagnoses, goals, situation ranking and procedure management. The results show that successful emergency operation depends on a combination of adherence to procedures and specific operator competence.     

Ergonomic design of a railway traffic control room: A Serbian experience

The aim of the research presented in this paper is to perform an ergonomic evaluation of compatibility between control desk, display panel, and their control devices with operators’ capabilities in the process of railway traffic control. This paper covers the application of ergonomic criteria for designing the control room and its main elements, functional characteristics of operators, and the influence of illumination on operator’s work efficiency. The paper also introduces methodologies for anthropometric and kinesiological analysis of operators, ergonomic analysis of control desk and display panel, and analysis of illumination in the Railway Traffic Control Room in Nis, Serbia. The research also includes basic statistical parameters for body measures of operators, configuration, and dimension of control desk as a unit, ergonomic analysis of control desk buttons, ergonomic analysis of display panel and its elements, parameters for illumination level of control room, control desk and display panel, and uniformity of illumination and brightness. To establish a link between these research and cognitive demands, methods of cognitive analysis of control and management activities in control room and decision making in abnormal situation by using an operator’s stress model are presented. The importance of this approach is that ergonomic assessment of current condition will determine the inadequate design and the ergonomic approach to be used in the implementation of the analysed control room. The results given in this paper enable the beginning of reconstruction and design of new elements in the control room, which will lead to abettor optimized control of railway traffic.     

The development of critical criteria to improve the alarm system in the process industry

The process industry handles most of the flammable and toxic materials within the industrial sector. Hence, safety issues are of prime importance as any possible accident can have severe consequences for both humans and the environment. For the safe and efficient operation of a plant while preventing mishaps in the process, a good alarm system is very important. Ultimate plant safety relies not only on the efficiency of the alarm system but also on the ability of the operators. In this study the authors develop the specifications required for a critical alarm system appropriate for most of the process industries; the specifications are based on optimal information flow between the operating system, guidance system, and the operator, ultimately to make the job less stressful and easier for the operators. The aim is to reduce the risk involved in control room operations that are associated with human factors. © 2006 Wiley Periodicals, Inc. Hum Factors Man 16: 321–337, 2006.     

Information theoretic approach to man-machine interface complexityevaluation

We analyze the interactions between human operators and control room equipment and find that several factors affect the information-gathering and decision-making processes of operators: contents of the provided information, the way information is provided, and knowledge of the operators. These factors contribute to the perceived cognitive complexity by human operators in plant operation. Based on the information theory concept, we propose an integrated framework for evaluating this complexity. The proposed framework is designed to be applied to various types of control room equipment which have different types of man-machine interface and contain different types of information. An experimental verification for the proposed framework is performed and its result shows that the framework successfully integrates various aspects of man-machine interface systems and estimates the mental workload of human operators     

Operators’ orientations to procedure guidance in NPP process control

Resilience in nuclear power plant (NPP) process control depends, among other things, on balance between operators’ autonomy in online decisions and pre-defined guidance for operations. Striking balance between these inherent demands of process control belongs to the strategic decisions by the management, but finally balancing takes place at the sharp end, by the operating personnel. We studied operators’ basic assumptions about the role of operating procedures in action. Conceptions of 62 control room operators at two Finnish NPPs were queried. Answers were classified into theory-based categories, i.e., interpretative, confirmative or reactive orientations. Orientation is an epistemic attitude to work that influences the process and content of sense making in situations that require action. In both NPPs, the confirmative orientation, emphasising the importance of acting according to rules, prevails, which corresponds to the expectations set by the organisations. It was also found that orientations reflect the operator roles and their demands: Among turbine operators, the interpretative orientation is significantly more prevalent than among the reactor operators as regards control of action. All operators consider interpretative orientation as a characteristic of a “good operator”. It is concluded that interpretative orientation represents an epistemic attitude to NPP operator work, in which autonomy based on operators’ professional competence and procedure usage is not seen opposite to each other, but intertwined into a practice. Identification interpretativeness as an epistemic attitude relevant in action extends the notion of “intelligent use of procedures” proposed earlier, by elaborating the inherent logic and ethos of operators’ procedure usage. It is recommended that appropriation of interpretative orientation should be actively supported as a means to facilitate resilience in NPP activity.     

Nuclear power plant communications in normative and actual practice: A field study of control room operators' communications

The safety and availability of sociotechnical critical systems still relies on human operators, both through human reliability and human ability to handle adequately unexpected events. In this article, the authors focus on ergonomic field studies of nuclear power plant control room operator activities, and more specifically on the analysis of communications within control room crews. They show how operators use vague and porous verbal exchanges to produce continuous, redundant, and diverse interactions to successfully construct and maintain individual and mutual awareness, which is paramount to achieve system stability and safety. Such continuous interactions enable the operators to prevent, detect, and reverse system errors or flaws by anticipation or regulation. This study helps in providing cues for the design of more workable systems for human cooperation in nuclear power plant operation. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 43–78, 2007.     

Human factors approach for evaluation and redesign of human–system interfaces of a nuclear power plant simulator

Nuclear power production is a safety-critical process where ultimate execution of process change decisions lie with the operators. Thus it is important to provide the best possible decision support through effective supervisory control operator interfaces. This requires a human factors/ergonomics approach in the modernization of analog instrumentation and control systems of the existing nuclear power plants. In this article, we describe how this approach is being used for modernization of the ANGRA I power plant. Using a cognitive task analysis (CTA) approach, we observed operators working on an advanced control room of a nuclear power plant digital simulator and noted several opportunities for improvement in the human/system interfaces related to the graphics design, alarm systems and procedure integration. A redesigned prototype was constructed as an alternative to the current simulator and hardcopy procedure manuals. The design improves upon the graphical layout of system information and provides better integration of procedures, automation and alarm systems. The design was validated by expert opinion and a scenario-based comparison.

Relevance to industry

Human factors/ergonomics are not playing the role they deserve in the design of process control systems making them less controllable than they could be if human factors were adequately incorporated. The use of human factors approach in the design of process control systems throughout the industry presents many opportunities for improvements with regard to system effectiveness, efficiency, reliability and safety.     

Integration of task networks and cognitive user models using coloured Petri nets and its application to job design for safety and productivity

Changes of task demands due to unforeseen events and technological changes can cause variations in job design such as modifications to job procedures and task allocation. Failure to adapt to job design variations can lead to human errors that may have severe consequences for system safety. Existing techniques for task modelling cannot adequately model how task networks can be adapted to changing work conditions and task demands. Therefore, there is a need to integrate task networks with cognitive user models that indicate how operators process information, make decisions, or cope with suspended tasks and errors. The work described here presents a tool for integrating task and cognitive models using coloured Petri nets. The cognitive user model comprises two modules of attention management (selective and divided attention), a module of memory management of suspended tasks and a module of work organization. Performance Shaping Factors (e.g., workload, fatigue and mental-tracking load) are calculated at any point in time to take into account the context of work (e.g., competing activities, errors and suspended tasks). Different types of human error can be modelled for rule-based behaviours required in proceduralized work environments. Simulation analysis and formal analysis techniques can be applied to process control tasks to verify job procedures, workload management strategies and task allocation schemes in response to technological changes and unfamiliar events.     

Exploring the Openness of Cognitive Artifacts in Cooperative Process Management

This paper presents a field study at a Stockholm underground control room, with particular focus on the different interactional affordances of the artifacts, used by the operators. The analysis is based on the notion that the design of cognitive artifacts affords different degrees of openness, i.e. to what extent they render the interaction of a task performer with the artifact open to others in the vicinity. A comparison between the dayshift and nightshift demonstrates how the various levels of openness are manifested during work. Some tentative design comments are made with regard to computer support systems for the underground line control.     

What can possibly go wrong? Anticipatory work in space operations

This paper explores how different forms of anticipatory work contribute to reliability in high-risk space operations. It is based on ethnographic field work, participant observation and interviews supplemented with video recordings from a control room responsible for operating a microgravity greenhouse at the International Space Station (ISS). Drawing on examples from different stages of a biological experiment on the ISS, we demonstrate how engineers, researchers and technicians work to anticipate and proactively mitigate possible problems. Space research is expensive and risky. The experiments are planned over the course of many years by a globally distributed network of organizations. Owing to the inaccessibility of the ISS, every trivial detail that could possibly cause a problem is subject to scrutiny. We discuss what we label anticipatory work: practices constituted of an entanglement of cognitive, social and technical elements involved in anticipating and proactively mitigating everything that might go wrong. We show how the nature of anticipatory work changes between planning and the operational phases of an experiment. In the planning phase, operators inscribe their anticipation into technology and procedures. In the operational phase, we show how troubleshooting involves the ability to look ahead in the evolving temporal trajectory of the ISS operations and to juggle pre-planned fixes along these trajectories. A key objective of this paper is to illustrate how anticipation is shared between humans and different forms of technology. Moreover, it illustrates the importance of including considerations of temporality in safety and reliability research.     

Failure to adapt or adaptations that fail: contrasting models on procedures and safety

This paper introduces two models on procedures and safety and assesses the practical consequences these have for organizations trying to make progress on safety through procedures. The application of procedures is contrasted as rote rule following versus substantive cognitive activity. It reveals a fundamental double bind: operators can fail to adapt procedures when adapting proved necessary, or attempt procedural adaptations that may fail. Rather than simply increasing pressure to comply, organizations should invest in their understanding of the gap between procedures and practice, and help develop operators' skill at adapting.     

All at sea: An ergonomic analysis of oil production platform control rooms

Control rooms on offshore production platforms are the focal point for their safe and efficient operation. Following the Piper Alpha disaster in 1988 a sizeable body of safety literature was generated covering the Ergonomic/Human Factors issues then in play. More than twenty years have passed since that time and significant changes have occurred to how control rooms are manned and the technology now in use. As the North Sea oil industry in the UK enters a new phase in its life cycle, and becomes subject to unprecedented production and cost pressures, it is time to revisit these issues. This paper reports on a high-level ergonomic survey covering approximately a third of all North Sea control rooms. The focus is on the adaptive capacity of the highly experienced control room operators and the current challenges to that capacity. Areas of concern include the support provided for dealing with non-routine events, the persistent issue of ‘alarm overload’, the flexibility and control of current SCADA systems, the use of control rooms for non-related tasks, and the possible role of non-technical skills training.