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.     

Development of a digital turbine control system in a nuclear power plant

A digital turbine control system (TCS) has been developed for retrofitting an old analog TCS in a nuclear power plant. The developed TCS, which controls the speed of a turbine and the power load of a generator, is based on a triple modular redundant structure to ensure the system reliability. In addition, a turbine simulator has been developed to verify the perfection of the TCS prior to its actual installation. The simulator is composed of a graphic editor, a component model builder, and a system simulation solver. The tested TCS has been successfully applied to a CANDU type nuclear power plant. This paper describes major features of the developed TCS and the turbine simulator including thermal-hydraulic models. Also, the simulation result in a laboratory is compared with the pre startup simulation and the actual operation result. Recommended by Editor Hyun Seok Yang. In-Kyu Choi was born in Jeonjoo, Korea in 1967. He obtained his Master’s degree in Electrical Engineering from Chungnam National University in 2004. His research interests include control in power plant machines such as boilers, drums, turbines, and generators. He is now a Senior Member of the KEPCO Research Institute. Jong-An Kim received the B.S. degree in Electronic Engineering from Won-Kwang University, Ik-San, Korea in 1985. He joined the Korea Electric Power Corporation (KEPCO) in 1976, and has mainly worked in the control systems engineering areas of power plants. He is now a Principal Engineer in the Korea Electric Power Research Institute (KEPRI) and his research interests include the design of power plant control systems as well as new technology development. Chang-Ki Jeong was born in Daejeon, Korea in 1956. He obtained his Master’s degree in Electrical Engineering from Daejeon Industry College in 1998. His research interests include control in power plant machines such as boilers, drums, turbines, and generators. He is a Principal Member of the KEPCO Research Institute. Joo-Hee Woo was born in Sangjoo, Korea in 1970. He obtained his Master’s degree in Electrical Engineering from Kyungbook National University in 1995. His research interests include control in power plant machines such as boilers, drums, turbines, and generators. He is now a Senior Member of the KEPCO Research Institute. Ji-Young Choi received the B.S. degree in Mechanical Engineering from Sogang University in 2005. He is a graduate student of the Department of Mechanical Engineering at Sogang University in Seoul, Korea. Choi’s research interests are in the areas of heat transfer, PEM fuel cells, and microfluidics. Gihun Son received the B.S. and M.S. degrees in Mechanical Engineering from Seoul National University in 1986 and 1988, respectively. He obtained the Ph.D. degree in Mechanical Engineering from UCLA in 1996. Dr. Son is currently a Professor in the Department of Mechanical Engineering at Sogang University in Seoul, Korea. His research interests are in the areas of multiphase dynamics, heat transfer, and power system simulation.     

黔西电厂母差保护装置失灵保护动作分析

通过黔西电厂事故前运行方式和事故过程调查,详细地分析了该电厂母差保护装置失灵保护动作的原因,并提出整改措施和建议。     

核电厂备用循环冷却水系统的DCS设计

根据秦山第三核电厂备用循环冷却水系统的运行特点和控制要求,对其仪控设计采用了集散控制方式,并采用浙大中控WebField ECS-100系统对控制系统进行了整体设计。     

Elman's recurrent neural network applications to condition monitoring in nuclear power plant and rotating machinery

The purpose of this study is to show the capability of recurrent neural nets (RNN) for condition monitoring and diagnosis in nuclear power plant systems and rotating machinery. In the first application, the study addresses the use of RNN for detecting anomalies introduced from the simulated power operation of a high-temperature gas cooled nuclear reactor. In the second, it is used to detect the motor bearing damage using a coherence function approach, which is defined between the motor current and vibration signals, for induction motors. Hence, the high performance of Elman's RNN was shown by means of two different applications.     

核电站仪表控制系统检修平台的开发

Bailey系列模块是广东核电集团的100万千瓦级核电站一回路过程仪表控制和保护系统的主体。核安全的重要责任和安全生产的任务,都要求Bailey模块可靠、稳定和安全运行。但是,由于备件、老化以及产品升级等原因使得Bailey模块的维护存在不小的困难。本文阐述了如何设计一种集信号的采集、发生、数据的分析处理、参数的校正、自动选择跳线功能于一身的小型专用的校验设备-Bailey系列模块综合试验台。该设备主要设计在实验室使用(也可用于现场操作),可以自动(也可以选择手动方式)实时地控制Bailey9020系列模块的输入信号,并对Bailey9020系列模块输出数据的进行实时显示、分析和处理,可记录测试数据和打印规定格式的报表。Bailey系列模块综合试验台作为一种小型化多功能的专用校验设备,在设计思想上具有独到之处。同时它作为适用性强的国产专用设备,在生产实践以及实现广核国产化方面作出了贡献。     

A combined fuzzy approach to determine the best region for a nuclear power plant in Turkey

When increase in energy needs of developing countries cannot be met by conventional energy sources, alternative energy sources are considered to substitute them. Nuclear energy that meets the needs of a greater proportion of energy demands for countries is one of effective alternative energy types. In this context, after deciding on the use of nuclear energy, the selection of the most suitable location for the production of nuclear power is one of the important decision making problems. In this paper, we performed a facility location selection model for Turkey in meeting the needs of energy with using new and unused source of nuclear energy. For this aim, a combined fuzzy multi criteria decision making (MCDM) methodology that consists of Interval type-2 fuzzy analytical hierarchy process (AHP) that is applied to determine weights of criteria and interval type-2 fuzzy TOPSIS that is applied for ranking alternatives is used to determine the best location alternative for the nuclear power plant. By the way, the obtained results have been analyzed depending upon the criteria that used for the evaluation process. The obtained results are compared with existing nuclear power plants location selection policy for Turkey and some suggestions have been made for the plants where would be the located are not decided. By the way, a sensitivity analysis has been conducted to analyze effects of changes in decision's parameters.     

核电站系统安全评价指标体系研究

核电站系统的安全性是影响核电发展的一个重要因素.针对事故发生概率,安全系统的性能,事故造成的后果3个指标采用全局安全评价指数(GSI),并基于MATLAB模糊逻辑工具箱,提出安全评估框架和方法.对国内目前比较常用的压水反应堆(PWR)和新引进的AP1000两种反应堆类型进行评价,并对结果进行了比较,发现AP1000具有更高的安全性能,GSI最终评价结果能够非常直观的供核安全管理部门参考.     

发电厂DCS网络异常引起的非停事件

主要论述一起发电厂DCS系统网络交换机电源切换装置故障引发的发电机组非停事件,重点对DCS系统失灵后的应急操作、原因分析和善后措施进行了详细阐述,同时结合事故案例提出DCS系统电源设计时必须遵循的的一些设计原则,对于新建电厂或已投产电厂在DCS系统电源方面的设计思路有一定的启示作用.     

Identifying and clustering performance shaping factors for nuclear power plant commissioning tasks

The commissioning of a nuclear power plant (NPP) is the last stage in the life cycle of an NPP before commercial operation. Human errors in this stage cannot only harm workers' safety but can also cause damage to system facilities, postpone the commissioning schedule, and become latent problems in the system if the errors are not discovered during the commissioning stage. Therefore, identifying and controlling potential human errors is of great importance at this stage. This study first reviewed existing performance shaping factor (PSF) models and related research on NPPs as well as in other industry fields. Based on these aspects, and with the consideration of the characteristics of commissioning tasks, 8 PSF components and 110 PSF indicators were identified through a literature review and interview. Then, a questionnaire survey was conducted with 269 respondents from 3 NPPs in China to determine commissioning workers' judgment of perceived occurrence frequency and impact of each indicator. Relevant PSF indicators were clustered into 24 PSF factors by exploratory factor analysis. Finally, the risk levels for identified factors and indicators were evaluated. The results show some commonalities with other PSF frameworks, and the differences are discussed.     

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.     

Comparison between conventional and digital nuclear power plant main control rooms: A task complexity perspective,Part II: Detailed results and analysis

Part II of this study aims to provide detailed, diagnostic information about the complexity difference between conventional and digital main control rooms (MCRs) in nuclear power plants. Complexity factors were classified according to task components and complexity dimensions. The effects of operator experience and plant type on complexity factors were statistically analyzed from three levels, i.e., task components, complexity dimensions, and individual factors. Interface management complexity factors were compared with other factors in digital MCRs. The results suggest that generally operator experience had effects on several task components and complexity dimensions only in abnormal/emergency situations. Plant type affected several task component and complexity dimensions in both abnormal/emergency and normal situations. Complexity factors in the affected task components and complexity dimensions had higher frequency, complexity, or impact in digital MCRs than those in conventional MCRs. Factors related to crew activity and the dimensions of overabundance, temporal demand, and variability had relatively high frequency, complexity, or impact. Compared with other factors, interface management complexity factors had marginally higher frequency, but significantly lower complexity and impact.Relevance to industryThis study quantitatively addresses the complexity difference between conventional and digital MCRs in detail. It may provide rich information for how to improve operator working environments in NPPs. It may also contribute to other applied domains, such as human reliability analysis and interface design.     

Compensation of control-loop interaction for power plant wide-range operation

Power plants are being required to undertake large power variations to satisfy electricity demand, whereas their control systems comprise decentralized control loops and ad-hoc compensation schemes, to deal with loop interaction, for regulation and disturbance rejection at base load. This paper presents a compensation scheme that lessens control loop interaction, caused by the nonlinear coupled process dynamics, to ease power generation control throughout the power plant operating space. Compensation factors are systematically determined from a process gain matrix that conveys all interaction information. Numerical analysis and simulation experiments demonstrate the feasibility of power plant wide-range operation with the proposed compensator.     

核电厂维修文件管理系统的研发

核电厂维修工作的重要性不言而喻,而维修文件是维修工作的参考依据.但核电厂维修文件种类很多,为了能够正确地选择维修活动的依据文件,有必要对电厂所有的维修文件进行相互关联,并建立一套维修文件管理系统.该系统不仅能够实现数据的导入、导出、查询、修改等功能,还能够链接某项维修活动相关的所有维修文件,方便维修人员选择,同时实现了维修规程编制计划、工作任务提醒、权限分配及用户管理等功能.     

Developing a taxonomy of coordination behaviours in nuclear power plant control rooms during emergencies

Abstract

This study aims to develop a taxonomy of coordination behaviours during emergencies in nuclear power plants (NPPs). We summarised basic coordination behaviours from literature in aviation, health care and nuclear field and identified coordination behaviours specific to the nuclear domain by interviewing and surveying control crew operators. The established taxonomy includes 7 workflow stages and 24 basic coordination behaviours. To evaluate the reliability and feasibility of the taxonomy, we analysed 12 videos of operators’ training sessions by coding coordination behaviours with the taxonomy and the inter-rater reliability was acceptable. Further analysis of the frequency, the duration and the direction of the coordination behaviours revealed four coordination problems. This taxonomy provides a foundation of systematic observation of coordination behaviours among NPP crews, advances researchers’ understanding of the coordination mechanism during emergencies in NPPs and facilitate the possibility to deepen the understanding of the relationships between coordination behaviours and team performance.

Practitioner Summary: A taxonomy of coordination behaviours during emergencies in nuclear power plants was developed. Reliability and feasibility of the taxonomy was verified through the analysis of 12 training sessions. The taxonomy can serve as an observation system for analysis of coordination behaviours and help to identify coordination problems of control crews.     

Advisory system for the diagnosis of lost electric output in nuclear power plants

The enhancement of efficiency is world-wide trend to survive under intense competition. In recent years, the efficiency in the power industry is also one of the important topics. In case of nuclear power plants(NPPs), the period and quality of maintenance is an especially important factor to increase efficiency as well as availability. Therefore, the accurate identification of the root causes for lost electric output is indispensable to decrease the period and to increase quality of maintenance. The diagnosis in NPPs is more difficult because the turbine cycle of NPPs uses saturated steam as working fluid. In this study, authors tried to develop an advisory system with the quantitative diagnosis model consisting of statistical regression analysis and Bayesian network for the support of nuclear turbine cycle diagnosis. The proposed advisory system includes the knowledge-base representing the normal or abnormal behavior of nuclear turbine cycle. Authors selected 34 boundary parameters that independently influence to electric output. Using the data collected from a turbine cycle simulation tool, the statistical correlation between a boundary parameter and electric output was analyzed. To give the belief, that is the degree of accuracy, of root causes under various uncertainty sources, belief module for the boundary parameters is developed on the basis of Bayesian network. In conclusion, this diagnosis module can give the impacts of the root causes and their uncertainty simultaneously, so we call it ‘Lost MW calculator’. After the validation using simulated data and actual performance data, this module was installed in Younggwang NPP units 3 and 4 in Korea.     

核电站燃料厂房辅助吊车抗震分析

为较精确地分析核电站燃料厂房辅助吊车在承受地震载荷时的结构抗震特性,用MSC Marc求解吊车桥架静挠度和静刚度,并采用反应谱法分析吊车在给定地震反应谱作用时的结构抗震特性.该方法可为同类起重机抗震分析提供参考.     

Development of a systematic checklist for the human factors evaluation of the operator aiding system in a nuclear power plant

In the safety systems review of the Korean nuclear power plants, the Human Factors Program Plan for the OAS (Operator Aiding System) has been executed mainly by an expert review. The reviewers had to integrate all the relevant sources of information and make judgement based on their own criteria. Consistency and thoroughness of this process was always in question and a systematic approach to correct these problems was in need. The purpose of this work was to design a methodology for supporting an effective and efficient ergonomic evaluation of the user interface of the OAS. By collecting and systematically structuring all the critical considerations in the human factors review process, an ergonomic evaluation checklist for the CFMS (Critical Function Monitoring System) in an MCR (Main Control Room) was designed and implemented in this study. Application of the developed checklist was used during the licensing review process for the CFMS of the Ulchin unit 3&4. Efficiency and effectiveness of the human factors review process was enhanced significantly with the aid of the integrated checklist and the standardized evaluation format developed in this study.

Relevance to industry

Human factors review process is an integral component of the safety of a nuclear power plant. The methods and procedures developed in this study will provide valuable support for the enhancement of the safety and usability of the human interface of the nuclear power plant.     

Experiences with component‐oriented technologies in nuclear power plant simulators

This paper proposes the application of modern component‐oriented technologies to the development of nuclear power plant simulators. On the one hand, as a significant improvement on previous simulators, the new kernel is based on the Common Component Architecture (CCA). The use of such a high‐performance computing oriented component technology, together with a novel algorithm to automatically resolve simulation data dependencies, allows the efficient execution of both parallel and sequential simulation models. On the other hand, RT‐CORBA is employed in the development of the rest of the applications that comprise the simulator. This real‐time communication middleware not only makes the management of communications easier, but also provides the applications with real‐time capabilities. Software components used in these two ways, simulation models integrating the kernel and distributed applications from which the simulator is comprised, improve the evolution and maintenance of the entire system, as well as promoting code reusability in other projects. Copyright © 2006 John Wiley & Sons, Ltd.     

Cognitive simulation as a tool for cognitive task analysis

Cognitive simulations are runnable computer programs that represent models of human cognitive activities. We show how one cognitive simulation built as a model of some of the cognitive processes involved in dynamic fault management can be used in conjunction with small-scale empirical data on human performance to uncover the cognitive demands of a task, to identify where intention errors are likely to occur, and to point to improvements in the person-machine system. The simulation, called Cognitive Environment Simulation or CES, has been exercised on several nuclear power plant accident scenarios. Here we report one case to illustrate how a cognitive simulation tool such as CES can be used to clarify the cognitive demands of a problem-solving situation as part of a cognitive task analysis.