Coordination-behavior patterns of control crews in digital nuclear power plants during emergencies from a network perspective: An exploratory study

This study aims to investigate the coordination-behavior patterns of control crews in digital nuclear power plants (NPPs) during emergencies from a network perspective. We observed and coded 12 coordination processes (each from one crew) of handling simulated emergencies on a full-scope dynamic simulator in Tianwan NPP of China. By calculating the proportion of coordination breakdowns and referring to the subjective evaluation of instructors, these control crews (all male) were classified into two performance levels (high and low). To compare the coordination-behavior patterns between high- and low-performing crews, we conducted social network analysis based on the number and direction of coordination behaviors. By examining intracrew relations in team coordination, this study indicated that high-performing crews exhibited higher cohesion and more balanced behavioral patterns in team coordination than low-performing ones. By investigating coordination-behavior patterns from the hierarchical structure of relations in the team, this study revealed that high-performing crews exhibited higher degree of team autonomy and self-management among junior operators, as well as reactor operator (RO)-centered pattern, whereas the low-performing crews exhibited senior reactor operator-centered pattern. For researchers, the results advance the understanding of the team coordination mechanism in NPP control rooms during emergencies and enrich team coordination theory in process control industries from the network perspective. In practice, this study suggested that the team coordination training of NPP control crews might be centered around junior operators (especially RO), with focuses on facilitating information sharing and mutual assistance between junior operators and enhancing the awareness of active cooperation of crew members. The results of the study provide nuclear instructors with practical reference to team coordination training and processes optimization.     

Comparison between conventional and digital nuclear power plant main control rooms: A task complexity perspective,part I: Overall results and analysis

Digitalization is a trend in safety-critical complex systems. It changes the way human interacts with systems. We have less empirical knowledge about its potential negative effects on human. In our study, we compared conventional and digital main control rooms (MCRs) in nuclear power plants (NPPs) from a task complexity perspective. Complexity factors in MCRs were quantified in terms of three aspects, frequency of occurrence, complexity induced by their being, and impact caused by them. A total of 69 licensed operators participated in the study. The study consists of two parts. In Part I, overall results and analysis were reported. Generally, operators in digital MCRs perceived higher frequency and higher impact of complexity factors than those in conventional MCRs, no matter in abnormal/emergency or normal situations. Operators in digital MCRs perceived higher complexity than those in conventional MCRs in abnormal/emergency situations. These findings suggest that operators in digital MCRs experience higher complexity and workload which may reduce their reliability. These findings imply that we should caution the side-effects of ubiquitous digitalization in complex industrial systems.Relevance to industryDigital technologies are widely deployed in the nuclear industry. They change the working environments in which operators interact with NPP systems. There is insufficient research on operator experience on the changes brought by technological developments in NPP control rooms. Our findings imply that we should take care of the potential negative effect of digitalization on operator working environments.     

Development and validation of a behavioural video coding scheme for detecting mental workload in manual assembly

Abstract

Manual assembly in the future Industry 4.0 workplace will put high demands on operators’ cognitive processing. The development of mental workload (MWL) measures therefore looms large. Physiological gauges such as electroencephalography (EEG) show promising possibilities, but still lack sufficient reliability when applied in the field. This study presents an alternative measure with a substantial ecological validity. First, we developed a behavioural video coding scheme identifying 11 assembly behaviours potentially revealing MWL being too high. Subsequently, we explored its validity by analysing videos of 24 participants performing a high and a low complexity assembly. Results showed that five of the behaviours identified, such as freezing and the amount of part rotations, significantly differed in occurrence and/or duration between the two conditions. The study hereby proposes a novel and naturalistic method that could help practitioners to map and redesign critical assembly phases, and researchers to enrich validation of MWL-measures through measurement triangulation.

Practitioner summary: Current physiological mental workload (MWL) measures still lack sufficient reliability when applied in the field. Therefore, we identified several observable assembly behaviours that could reveal MWL being too high. The results propose a method to map MWL by observing specific assembly behaviours such as freezing and rotating parts.

Abbreviations: MWL: mental workload; EEG: electroencephalography; fNIRS: functional near infrared spectroscopy; AOI: area of interest; SMI: SensoMotoric Instruments, ETG: Eye-Tracking Glasses; FPS: frames per second; BORIS: Behavioral Observation Research Interactive Software; IRR: inter-rater reliability; SWAT: Subjective Workload Assessment Technique; NASA-TLX: National Aeronautics and Space Administration Task Load Index; EL: emotional load; DSSQ: Dundee Stress State Questionnaire; PHL: physical load; SBO: Strategisch Basis Onderzoek     

Validation of an Adaptive Alarm Interface Design for Digital Control Panels

ABSTRACT

This study proposes an adaptive alarm interface, which is supposed to have the good features of both alarm–tile interfaces that are typical in nuclear power plants (NPPs), and alarm–bar interfaces that use changing bars to indicate the current condition of an NPP and its abnormalities. Depending on the situation, the alarm management system will decide whether the alarm–tile or the alarm–bar interface should be presented to operators. To validate the usability of the adaptive alarm interface, it was compared against both the alarm–tile and alarm–bar interfaces through laboratory experiments with 45 participants. The results demonstrated that the adaptive alarm interface not only allowed the understanding of parameter trending, which was a distinguishing feature of the alarm–bar interface, but also improved the alarm detection, which was one advantage of the alarm–tile interface. However, the situation awareness level of the adaptive alarm interface was insufficient compared to the alarm–tile and bar interfaces possibly due to distraction from interface swapping.     

The Design of Human–Machine Interface for Accident Support in Nuclear Power Plants

As feedback from Three Mile Island No. 2, a large amount of human–machine interface (HMI) design has been proposed to support operators during accidents by presenting information on plant status, some of which is implemented in commercial nuclear power plants (NPPs). However, it has not yet been discussed what role HMI should play under conditions where operators must take action as instructed under emergency operating procedure. Regarding this principal issue, an HMI design is proposed together with specific screen images. The advantage of this design is based on the involvement of an ex-operator in NPP in this paper. The participation of users in the design of HMI has been rare. Accordingly the proposed HMI is comprehensive for average operators and is expected to be acceptable for future implementation in commercial NPPs. The effectiveness of the proposed HMI has been examined in a small experiment.     

From cockpit to operating theatre to drilling rig floor: five principles for improving safety using simulator-based exercises to enhance team cognition

For over 30 years, aviation has conducted training courses to enhance team performance and improve safety involving simulation with observation and directed feedback. Participants’ performance is observed by trained and experienced observers who then provide feedback using behaviour-based evidence noted during the simulator exercise. More recently, in healthcare, operating theatre personnel have adopted simulator-based training (SBT), observation and feedback for learning and practice to reduce the potential for human errors and improve safety. Maritime and nuclear power also incorporate high-fidelity simulators and feedback in team training interventions including technical and non-technical skills. The design and development of drilling rig simulators means that drill crews can now practise and test out their decision-making and receive feedback from observers, with the aim of improving team non-technical skills and consequently reducing the potential for errors. This paper presents five principles gleaned from research and the experiences of both aviation and healthcare to be applied to the development of simulator-based exercising for drilling teams. The principles include: (a) developing learning objectives and expected performance standards; (b) training the team as a whole; (c) using a structured observation tool; (d) providing feedback during a structured debrief; (e) repeat the SBT regularly to enhance expertise and retain performance standards. It is anticipated that these principles can be generalised for simulator-based exercising to benefit team social and cognitive competences in other high-hazard or process industries.

     

Training for Vigilance: Repeated Sessions with Knowledge of Results

Abstract

Two groups of subjects were run in a visual monitoring test, one with knowledge of results (KR) providing instant feedback of correct responses, commissive errors, and missed signals, and the other with no knowledge of results (NKR). The groups were run for five 48-minute sessions on consecutive days, with a follow-up transfer session five weeks later. Results showed significant differences in detection rates between the groups on all five training sessions, but not on the transfer session. Detection rates increased significantly during the five training sessions for both groups, and at approximately the same rate. Commissive errors were significantly different only in the first two training sessions, with the KR subjects showing more false alarms. Commissive errors did not increase or decrease over time within sessions, or over the five training sessions.     

A study on assigning performance shaping factors of the SPAR-H method for adequacy human reliability analysis of nuclear power plants

The performance shaping factors (PSFs) of the standardized plant analysis of risk-human reliability analysis (SPAR-H) method are unclearly defined, which contributes to the uncertainty of human reliability analysis (HRA) in nuclear power plants (NPPs). This work proposes an expert-based modification approach for redefining the PSFs based on four criteria in terms of less overlap, hierarchy, flexibility, and digitalization.For demonstration, the proposed approach is used to assign PSFs to three specific human failure events in NPPs. Three tests (Kendall's W Test, Jonckheere-Terpstra Test, and Paired Samples Test) are applied to analyze the assignments. Compared to the PSF assignment of SPAR-H, the results show that the redefined PSFs meet the four criteria and reduce the overestimation of human error probabilities (HEPs).     

Analysis Patterns: A Taxonomy and its Implications

Abstract

With the accumulation of problem-solving experience, practitioners document recurring problems and standard solutions in what are commonly referred to as patterns. This study develops a six-cell taxonomy of analysis patterns used for specifying system requirements, based on the dimensions of granularity and abstraction. A categorization of analysis patterns currently used in practice yields some managerial guidelines about lifetime pattern benefits, analyst training, and the allocation of resources for pattern harvesting.     

Procedure and information displays in advanced nuclear control rooms: experimental evaluation of an integrated design

Abstract

In the main control rooms of nuclear power plants, operators frequently have to switch between procedure displays and system information displays. In this study, we proposed an operation-unit-based integrated design, which combines the two displays to facilitate the synthesis of information. We grouped actions that complete a single goal into operation units and showed these operation units on the displays of system states. In addition, we used different levels of visual salience to highlight the current unit and provided a list of execution history records. A laboratory experiment, with 42 students performing a simulated procedure to deal with unexpected high pressuriser level, was conducted to compare this design against an action-based integrated design and the existing separated-displays design. The results indicate that our operation-unit-based integrated design yields the best performance in terms of time and completion rate and helped more participants to detect unexpected system failures.

Practitioner Summary: In current nuclear control rooms, operators frequently have to switch between procedure and system information displays. We developed an integrated design that incorporates procedure information into system displays. A laboratory study showed that the proposed design significantly improved participants’ performance and increased the probability of detecting unexpected system failures.     

Distributed cognition in Search and Rescue: loosely coupled tasks and tightly coupled roles

The perceptual cycle model (PCM) underpins much Ergonomics research, particularly in a team context, for example in its theoretical underpinning of distributed situation awareness. Despite this, the PCM framework it has not been explicitly applied to explore team processes, which is surprising given the prevalence of teamwork in safety critical systems. This paper explores team processes in the context of search and rescue (SAR) by applying the PCM and an association classification scheme with a network analysis approach utilising the event analysis of systemic teamwork (EAST) method. Data were collected via observations and communication recordings during training flights with SAR crews and were amalgamated into a representative case study. The analysis demonstrates how the SAR team function within a distributed perceptual cycle whereby the actions of one team member become world information for another team member. Advancements to the EAST method are proposed and the implications of the research are discussed.

Practitioner Summary: This paper explores the perceptual cycle interactions of SAR crews using a novel EAST approach. The analysis demonstrates how the crew function as a distributed cognitive unit and applications in terms of training and design are discussed.     

Training Effective Human Performance in the Management of Stressful Emergencies

Emergency situations in industry occur suddenly and often unexpectedly; operators must make critical decisions under stress, and the consequences of errors can be immediate and catastrophic. Training effective performance under stress becomes an important aspect in the management of emergencies. This article proposes a taxonomy of cognitive strategies that enable operators to regulate their thinking and adapt decisions to changes in the demands of the situation. Cognitive strategies, such as, tolerating uncertainty, managing workload, planning for contingencies, and self-monitoring, provide the content of training emergency response. Stress, however, interferes with the learning of strategies, which presents a challenge to the design of training methods. Exposure to stress during training, degree of task decomposition, guidance, contextual variety and feedback are some of the training methods explored to facilitate the acquisition and transfer of cognitive strategies. Diversions from the traditional systems approach to training are pointed out and areas for further training research are identified.     

Learning while multitasking: short and long-term benefits of brain stimulation

Abstract

We employed a simulated production task that mimics the real-world skill acquisition required of operators working in control rooms of power plants to assess short and long-term effects of transcranial random noise stimulation (tRNS). tRNS has shown potential for enhancing learning and performance of cognitive skills. Forty subjects (24 female) learned how to execute the simulated production task during the training phase and were required to perform a secondary task during the skill acquisition phase while they received active (12?min) or sham tRNS on DLPFC. After 2 weeks they had to recall the task again without any stimulation. The results demonstrate that tRNS promoted better multitasking as reflected by better performance in a secondary task during and immediately after tRNS. However, 2 weeks later, beneficial effect of tRNS on retention was moderated by general mental ability. Particularly, tRNS benefited those with lower general mental ability.

Practitioner summary: By using a simulated production task, we assessed the effects of tRNS on learning and skill retention. The study indicates that neurostimulation can enhance the learning of multiple complex tasks. Moreover, it shows that retention of those tasks can be supported by neurostimulation, especially for those with lower general mental ability.     

Use of portable ladders – field observations and self-reported safety performance in the cable TV industry

Abstract

Portable ladders incidents remain a major cause of falls from heights. This study reported field observations of environments, work conditions and safety behaviour involving portable ladders and their correlations with self-reported safety performance. Seventy-five professional installers of a company in the cable and other pay TV industry were observed for 320 ladder usages at their worksites. The participants also filled out a questionnaire to measure self-reported safety performance. Proper setup on slippery surfaces, correct method for ladder inclination setup and ladder secured at the bottom had the lowest compliance with best practices and training guidelines. The observation compliance score was found to have significant correlation with straight ladder inclined angle (Pearson’s r = 0.23, p < 0.0002) and employees’ self-reported safety participation (r = 0.29, p < 0.01). The results provide a broad perspective on employees’ safety compliance and identify areas for improving safety behaviours.

Practitioner Summary: A checklist was used while observing professional installers of a cable company for portable ladder usage at their worksites. Items that had the lowest compliance with best practices and training guidelines were identified. The results provide a broad perspective on employees’ safety compliance and identify areas for improving safety behaviours.     

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.     

A Comparison of Three Types of Manual Controls on a Third-Order Tracking Task

Abstract

Three types of control levers— the spring-centrod-displaccment control, the on-off control and the pressure control— were compared on a third-order compensatory tracking task. Based on an analysis of the control transfer functions, the predicted ranking of the three controls is: (1) pressure, (2) displacement and (3) on-off. The results of a study in which five subjects tracked six trials with each control for 18 sessions were as follows. The data at the beginning of training indicated rankings of (1) pressure, (2) on-off and (3) displacement. However, the data taken during the latter sessions ranked the controls as predicted, although the difference between displacement and on-off was not statistically significant. Differences in results between, early and late training, and comparisons of these results with other studies, are discussed.     

A decision ladder analysis of eco-driving: the first step towards fuel-efficient driving behaviour

This paper provides a decision ladder analysis of eco-driving, and a discussion of the resultant models in terms of the skills, rules and knowledge taxonomy of human behaviour and how this can inform the design of an in-vehicle, eco-driving support system. In order to understand the types of behaviours that characterise fuel-efficient driving, a review was conducted of the academic literature and of more publicly available resources, such as governmental, car manufacturers' and specific eco-driving organisations' websites. The review identified four largely distinct driving activities that play a central role in the use of fuel in the private road vehicle. A focus group involving four researchers in the transport ergonomics field, followed by a series of five interviews with eco-driving experts, served to validate, supplement and further specify the models.

Practitioner Summary: This paper presents a decision ladder analysis of eco-driving. A four-member focus group and five interviews with eco-driving experts were conducted; the resultant models are discussed in terms of supporting fuel-efficient driving behaviours in the novice eco-driver through their potential to inform the design of an in-vehicle eco-driving support system.     

Multidisciplinary fault diagnosis of complex engineering systems: A case study of nuclear power plants

Fault diagnosis is a key process in ensuring complex engineering system safety. It often requires collaborative and multidisciplinary efforts. This study seeks to understand the process of multidisciplinary fault diagnosis in complex engineering systems and the key human factors issues that impair this process. Data were collected from multidisciplinary diagnostic activities conducted in the commissioning phase of nuclear power plants (NPPs). In the first phase, we proposed a process model based on a combination of literature review, specialist interviews, and field observations. In phase two, the influencing issues identified in the first phase were assessed through a survey with 117 NPP commissioning specialists. Five factors influencing multidisciplinary fault diagnosis were identified: cognitive artifacts, diagnosis biases, preparation for multidisciplinary diagnosis, information sharing and collaborative reasoning, and collaborative decision-making. The significances of each factor were compared. The results provide guidance for the development of improvement measures to enhance the performance of multidisciplinary fault diagnosis.Practitioner summaryThe processes and influencing issues of multidisciplinary fault diagnosis during the commissioning phase of nuclear power plants were studied with field observations, interviews of 28 specialists, and a survey of 117 specialists. Five major influencing factors were identified, and their influences were compared.     

A Review of Alarm System Design for Advanced Control Rooms of Nuclear Power Plants

Alarm systems are designed to provide cues to make operators aware of an operational problem, so that mitigation actions can be taken. New technologies are enabling innovative designs of alarm systems for safety-critical systems. To help better design alarm systems in advanced control rooms of nuclear power plants (NPPs), recent researches on alarm system design in the NPP domain are reviewed from the following aspects: (1) functions of an alarm system and opportunities and challenges of new technologies; (2) effects of alarm floods and different alarm management methods; (3) visual presentation of alarm information; (4) evaluation criteria for alarm systems. Through the comprehensive literature review, this article proposes research topics related to human factors and ergonomics that are worth studying in advanced alarm systems of NPPs.