Advanced Main Control Room Research Articles

Human Reliability Analysis of Soft Control Operations in Nuclear Power Plants: Issues and Perspectives

Objective: The aim of this study is to describe several issues which should be considered in the human reliability analysis of soft control operations in nuclear power plants. Background: The operational environment of advanced main control rooms is totally different from that of conventional control rooms. The soft control is one of the major distinguishable features of the advanced main control rooms. The soft control operations should be analyzed to estimate the effects on human reliability. Method: The literatures, about task analysis, simulation data analysis, and a human reliability analysis method for the soft control, were reviewed. From the review, important issues for the human reliability analysis of the soft control were raised. Results: The results of task and simulation data analysis showed that the soft control characteristics could have large effect on human reliability and they should be considered in the human reliability analysis of the soft control operations. Conclusion: The soft control may affect human error and performance of operators. The issues described in this paper should be considered in the human reliability method for the advanced main control rooms. Application: The results of the soft control operation analysis might help to design more efficient interface and education/training program for preventing human errors. The described issues might help to develop a human reliability analysis method for soft control operations.

Human Factors Evaluations of Alarm Displays in Main Control Rooms

Objective: This study proposes an alarm display and compares it with the one(alarm tile display) widely used in main control rooms(MCRs) of nuclear power plants. Background: Catching up with the rapid development of computer technologies, advanced MCRs has been required. Using modern technologies of computers and visual displays, we have a lot of potential to improve user performance and satisfaction as well as safety in MCRs. Method: The alarm bar display has been proposed to reduce some potential problems of the alarm tile display in this study. Human factors evaluations were conducted to compare both types of displays. Two interfaces of bar alarm and tile alarm were simulated on the desktop computer for the user-involved experiment. Eight students participated in the experiment with the within-subject design. Results: The alarm bar was slightly better in terms of situation awareness, and preferred to understand alarm dynamics. The alarm tile was slightly or significantly better in other measures. Conclusion: Both alarm displays have their own advantages and disadvantages. Therefore, combining benefits of both displays can be used to optimize the design of alarm displays. Application: The proposed display is expected to compensate the existing displays for certain purposes.

Human Error Identification based on EEG Analysis for the Introduction of Digital Devices in Nuclear Power Plants

Objective: This paper describes an analysis of electroencephalography(EEG) signals to identify human errors during using digital devices in nuclear power plants(NPPs). Background: The application of an advanced main control room(MCR) has accompanied with lots of changes in different forms and features by virtue of new digital technologies. The characteristics of these digital technologies and devices provide several opportunities for the use of interface management. It can integrate into a compact single workstation in an advanced MCR, allowing workers to operate the plant with minimum physical burden under any operating condition. However these devices may introduce new types of human errors, and thus we need a means to assess and prevent such errors especially those related to digital devices. Method/Conclusion: The EEG data are relatively objective, and thus we introduce several measures to EEG analysis for obtaining the feasibility of human error identification. Application: This study may support to ensure the safety when applying digital devices in NPPs.

Empirical investigation of communication characteristics under a computer-based procedure in an advanced control room

With the development of computer-based control rooms including a computer-based procedure (CBP), shift supervisors (SSs) can directly access plant information through a CBP or personal displays instead of depending on other board operators (BOs) to obtain plant information. In relation to this change, we examined the characteristics of SS inquiry patterns in the computer-based control rooms of nuclear power plants during emergency situations. Operator behaviors and speech patterns were observed and analyzed through several experiments on simulated accident scenarios in a full-scope simulator for an advanced computer-based main control room. We found that the SS inquiry in the advanced control room had less dependency on the BOs, and that the inquiry patterns varied according to the operators and operating dates. From these findings, the necessity to establish communication standards under computer-based control rooms was discussed with some recommendations. Another requirement to reduce the cognitive workload of SSs was also discussed.

Development and validation of a heuristic model for evaluation of the team performance of operators in nuclear power plants

The global concerns about safety in the digital technology of the main control room (MCR) are growing as domestic and foreign nuclear power plants are developed with computerized control facilities and human–system interfaces. In a narrow space, the digital technology contributes to a control room environment, which can facilitate the acquisition of all the information needed for operation. Thus, although an individual performance of the advanced MCR can be further improved; there is a limit in expecting an improvement in team performance. The team performance depends on organic coherence as a whole team rather than on the knowledge and skill of an individual operator. Moreover, a good team performance improves communication between and within teams in an efficient manner, and then it can be conducive to addressing unsafe conditions. Respecting this, it is important and necessary to develop methodological technology for the evaluation of operators’ teamwork or collaboration, thus enhancing operational performance in nuclear power plant at the MCR. The objectives of this research are twofold: to develop a systematic methodology for evaluation of the team performance of MCR operators in consideration of advanced MCR characteristics, and to validate that the methodology is adaptable to the advanced MCR of nuclear power plants. In order to achieve these two objectives, first, team performance factors were extracted through literature reviews and methodological study concerning team performance theories. Second, the team performance factors were identified and behavior markers were deducted based on the factors. Lastly, an estimation model for the evaluation of team performance was developed, and the model thereon was validated. The estimation model consists of an evaluation of task characteristics, identification of team performance factors, evaluation of team performance, calculation of team performance, and analysis of team performance. The detailed contents and validations of the model are also presented in this paper.

Human Error Mode Identification for NPP Main Control Room Operations Using Soft Controls

The operation environment of main control rooms (MCRs) in modern nuclear power plants (NPPs) has considerably changed over the years. Advanced MCRs, which have been designed by adapting digital and computer technologies, have simplerinterfaces using large display panels, computerized displays, soft controls, computerized procedure systems, and so on. The actions for the NPP operations are performed using soft controls in advanced MCRs. Soft controls have different features from conventional controls. Operators need to navigate the screens to find indicators and controls and manipulate controls using a mouse, touch screens, and so on. Due to these different interfaces, different human errors should be considered in the human reliability analysis (HRA) for advanced MCRs. In this work, human errors that could occur during operation executions using soft controls were analyzed. This work classified the human errors in soft controls into six types, and the reasons that affect the occurrence of the human errors were also analyzed.

Development of a qualitative evaluation framework for performance shaping factors (PSFs) in advanced MCR HRA

Human reliability analysis (HRA) is performed as part of the probabilistic risk assessment to identify and quantify human actions and the associated impacts on structures, systems, and components of complex facilities. In performing HRA, conditions that influence human performance have been analyzed in terms of several context factors. These context factors, which are called performance shaping factors (PSFs) are used to adjust the basic human error probability (BHEP), and PSFs have been derived in various ways depending on the HRA methods used. As the design of instrumentation and control (I&C) systems for nuclear power plants (NPPs) is rapidly moving toward fully digital I&C, and modern computer techniques have been gradually introduced into the design of advanced main control room (MCR), computer-based human–system interfaces (HSIs), such as CRT-based displays, large display panels (LDPs), advanced information systems, soft control, and computerized procedure system (CPS) will be applied in advanced MCR. Environmental changes in MCR have some implications for PSFs, and they have an influence on when PSFs should be applied in HRA because different situations might induce different internal or external factors which can lead to human errors. In this study, PSFs for advanced MCR HRA are derived, and a new qualitative evaluation framework for these PSFs is suggested. First, PSFs from various HRA methods are collected, and these PSFs are further grouped into PSFs categories to be used in advanced MCR HRA. Second, human factor (HF) issues in advanced MCR are analyzed and derived to be used as an evaluation framework for PSFs.

Investigation of automation deployment in the main control room of nuclear power plants by using adaptive automation

AbstractRecently, with the progress of computer technology, the digitalization of human–system interface (HSI) in the main control room (MCR) of advanced nuclear power plants (NPPs) has become an important issue. A higher level of automation means that the computers execute the greater part of the task. The frequency, however, of automation‐induced system failures, including human errors, prompts us to more closely investigate the influences of automation. The objective of this study is to measure the effects of adaptive automation on the primary task performance, operator situation awareness (SA), and workload in an advanced MCR of an advanced NPP to reduce the number of failures and improve human performance. This study selects automatic mode and semi‐automatic mode to compose five different types of automation allocations. The experiment scenario is a reactor shutdown task. A personal computer transient analyzer (PCTran) is used to simulate the HSI of an MCR. Twelve participants are required to perform the experiment scenario on the automation allocation types. The dependent variables were the primary task performance; the subjective workload was measured using an NASA‐Task Load Index (NASA‐TLX) questionnaire; and three levels of SA were estimated by SA queries. Experimental results revealed that the automation allocations made up of higher ratio automatic modes led to superior primary task performance, lower operator workload, and lower frequency of human errors. In the high ratio automatic mode allocation, the operators have the lowest SA queries score. This study provides additional information for future digital HSI design in the MCRs of advanced NPPs. © 2011 Wiley Periodicals, Inc.

Human Error Mode Identification for NPP Main Control Room Operations Using Soft Controls

The operation environment of main control rooms (MCRs) in modern nuclear power plants (NPPs) has considerably changed over the years. Advanced MCRs, which have been designed by adapting digital and computer technologies, have simplerinterfaces using large display panels, computerized displays, soft controls, computerized procedure systems, and so on. The actions for the NPP operations are performed using soft controls in advanced MCRs. Soft controls have different features from conventional controls. Operators need to navigate the screens to find indicators and controls and manipulate controls using a mouse, touch screens, and so on. Due to these different interfaces, different human errors should be considered in the human reliability analysis (HRA) for advanced MCRs. In this work, human errors that could occur during operation executions using soft controls were analyzed. This work classified the human errors in soft controls into six types, and the reasons that affect the occurrence of the human errors were also analyzed.

Modeling of a Dependence between Human Operators in Advanced Main Control Rooms

For the human reliability analysis of main control room (MCR) operations, not only parameters such as the given situation and capability of the operators but also the dependence between the actions of the operators should be considered because MCR operations are team operations. The dependence between operators might be more prevalent in an advanced MCR in which operators share the same information using a computerized monitoring system or a computerized procedure system. Therefore, this work focused on the computerized operation environment of advanced MCRs and proposed a model to consider the dependence representing the recovery possibility of an operator error by another operator. The proposed model estimates human error probability values by considering adjustment values for a situation and dependence values for operators during the same operation using independent event trees. This work can be used to quantitatively calculate a more reliable operation failure probability for an advanced MCR.

Modeling of a Dependence between Human Operators in Advanced Main Control Rooms

Modeling of a Dependence between Human Operators in Advanced Main Control Rooms

A model-based framework for the analysis of team communication in nuclear power plants

Advanced human–machine interfaces are rapidly changing the interaction between humans and systems, with the level of abstraction of the presented information, the human task characteristics, and the modes of communication all affected. To accommodate the changes in the human/system co-working environment, an extended communication analysis framework is needed that can describe and relate the tasks, verbal exchanges, and information interface. This paper proposes an extended analytic framework, referred to as the H–H–S (human–human–system) communication analysis framework, which can model the changes in team communication that are emerging in these new working environments. The stage-specific decision-making model and analysis tool of the proposed framework make the analysis of team communication easier by providing visual clues. The usefulness of the proposed framework is demonstrated with an in-depth comparison of the characteristics of communication in the conventional and advanced main control rooms of nuclear power plants.

국내 원자력발전소 첨단 주제어실 운전원의 팀 효율성 측정 방법에 관한 연구

An increased use of teams of actors within complex systems has led to the emergence of various approaches for the assessment of different features associated with team performance. Over the last two decades, the performance of teams in complex systems has received considerable attention from the human factors community, and a number of methods have been developed in order to assess and evaluate team performance. The purpose of this paper is to propose a methodology for measuring team efficiency of operators in the advanced main control room of Korean nuclear power plant. Team efficiency is an index which is estimated of gabs between individual performances and team performance. The index was developed to compare among teams through past all performance measurements.

DEVELOPMENT OF AN INTEGRATED DECISION SUPPORT SYSTEM TO AID COGNITIVE ACTIVITIES OF OPERATORS

As digital and computer technologies have grown, human-machine interfaces (HMIs) have evolved. In safety-critical systems, especially in nuclear power plants (NPPs), HMIs are important for reducing operational costs, the number of necessary operators, and the probability of accident occurrence. Efforts have been made to improve main control room (MCR) interface design and to develop automated or decision support systems to ensure convenient operation and maintenance. In this paper, an integrated decision support system to aid operator cognitive processes is proposed for advanced MCRs of future NPPs. This work suggests the design concept of a decision support system which accounts for an operator's cognitive processes. The proposed system supports not only a particular task, but also the entire operation process based on a human cognitive process model. In this paper, the operator's operation processes are analyzed according to a human cognitive process model and appropriate support systems that support each cognitive process activity are suggested.

Development of Human Performance Measures for Human Factors Validation in the Advanced MCR of APR-1400

Main control room (MCR) man-machine interface (MMI) design of advanced nuclear power plants (NPPs) such as APR (advanced power reactor)-1400 can be validated through performance-based tests to determine whether it acceptably supports safe operation of the plant. In this paper, plant performance, personnel task performance, situation awareness, workload, teamwork, and anthropometric/physiological factor are considered for the human performance evaluation. For the development of human performance measures, attention is paid to considerations and constraints such as the changed environment in an advanced MCR, needs for a practical and economic evaluation, and suitability of evaluation criteria. Measures generally used in various industries and empirically proven to be useful are adopted as the main measures with some modifications. In addition, complementary measures are developed to overcome some of the limitations associated with the main measures. The development of the measures is addressed based on theoretical and empirical background. Finally we discuss the way in which the measures can be effectively integrated. The HUPESS (HUman Performance Evaluation Support System) which is in development is also briefly introduced.

An analytical approach to quantitative effect estimation of operation advisory system based on human cognitive process using the Bayesian belief network

The design of instrumentation and control (I&C) systems for nuclear power plants (NPPs) is rapidly moving towards fully digital I&C systems and is trending towards the introduction of modern computer techniques into the design of advanced main control rooms (MCRs) of NPPs. In the design of advanced MCRs, human–machine interfaces have improved and various types of decision support systems have been developed. It is important to design highly reliable decision support systems in order to adapt them in actual NPPs. In addition, to evaluate decision support systems in order to validate their efficiency is as important as to design highly reliable decision support systems. In this paper, an operation advisory system based on the human cognitive process is evaluated in order to estimate its effect. The Bayesian belief network model is used in the evaluation of the target system, and a model is constructed based on human reliability analysis event trees. In the evaluation results, a target system based on the operator's cognitive process showed better performance compared to independent decision support systems.

Investigation on relationship between information flow rate and mental workload of accident diagnosis tasks in NPPs

The objective of this study is to investigate experimentally the relationship between an operator's mental workload and the information flow rate of accident diagnosis tasks and further to propose the information flow rate as an analytic method for measuring the mental workload. There are two types of mental workload in the advanced main control room of nuclear power plants: the information processing workload, which is the processing that the human operator must actually perform in order to complete the diagnosis task, and emotional stress workload experienced by the operator. In this study, the focus is on the former. Three kinds of methods are compared to measure the operator's workload: information flow rate, subjective methods, and physiological measures. Information flows for eight accident diagnosis tasks are modeled qualitatively using a stage model and are quantified using Conant's model. The information flow rate is obtained by imposing time limit restrictions for the tasks. National Aeronautics and Space Administration-Task Load Index (NASA-TLX) and Modified Cooper-Harper (MCH) scale are selected as subjective methods. For the physiological measurements, an eye tracking system analyzes eye movements related to the operator's blinking and fixation on regions of interests. Through the experiments, the relationship between the information flow rate of accident diagnosis tasks and the selected measures is investigated. Results indicate that the information flow rate of diagnosis tasks is in high agreement with both subjective rating scores and eye movement parameters related to blinking and fixation on the regions of interest. It appears, then, that information flow rate can be an alternative as an analytic approach for measuring mental workload. By using data on the information flow rate, we can predict the mental workload required for a task without performing experiments in advance.

An Evaluation of Computerized Procedure System in Nuclear Power Plant

This paper reports an observational study of a Computerized Procedure System (CPS) under development for an advanced main control room in Korea. The purpose of this study was to examine possible effects of using the CPS. The crew, a shift supervisor and two operators, admitted that the CPS reduced their mental workload and they thought the CPS was better than or as good as paper-based procedures. One significant effect was that the amount of communication between the shift supervisor and two board operators was reduced considerably.