Advanced Control Room Research Articles

Extended cognitive reliability and error analysis method for advanced control rooms of nuclear power plants

This study proposes a modified extended cognitive reliability and error analysis method (CREAM) for achieving a more accurate human error probability (HEP) in advanced control rooms. The traditional approach lacks failure data and does not consider the common performance condition (CPC) weights in different cognitive functions. The modified extended CREAM decomposes tasks using a method that combines structured information analysis (SIA) and the extended CREAM. The modified extended CREAM performs the weight analysis of CPCs in different cognitive functions, and the weights include cognitive, correlative, and important weights. We used the extended CREAM to obtain the cognitive weight. We determined the correlative weights of the CPCs for different cognitive functions using the triangular fuzzy decision-making trial and evaluation laboratory (TF-DEMATEL), and evaluated the importance weight of CPCs based on the interval 2-tuple linguistic approach and ensured the value of the importance weight using the entropy method in the different cognitive functions. Finally, we obtained the comprehensive weights of the different cognitive functions and calculated the HEPs. The accuracy and sensitivity of the modified extended CREAM were compared with those of the basic CREAM. The results demonstrate that the modified extended CREAM calculates the HEP more effectively in advanced control rooms.

A Novel Communication Framework for Reduction of Staffs in Advanced MCRs of SMRs: A Prototype Development of a NLP-Based System

As small modular reactors are gaining attention as the future of nuclear energy, it has become increasingly imperative to minimize the number of required operators in order to improve economic competitiveness. Although the tasks of operators have changed and their workloads have been relatively reduced as digital technologies have been applied to advanced main control rooms (MCRs), no change in the number of operators has been made when compared to conventional MCRs in the Republic of Korea. As a solution, the introduction of natural language processing (NLP) technology to replace certain operator tasks in advanced MCRs can be a valuable means of reducing MCR staff. In this paper, we suggest a novel communication framework utilizing NLP technology to minimize the number of operators in advanced MCRs. To do this, we analyze operator tasks in advanced MCRs and select those that can be replaced by NLP technology. We then develop a prototype NLP-based system and analyze the process and characteristics of the suggested communication framework.

Visual Style Elements in Human-System Interface Design for Nuclear Power Operations: Does Style Affect Performance and Preference?

As the world increasingly adopts renewable and sustainable energy systems, transitionary solutions include nuclear power, which currently provides 20% of the United States' electricity and is the largest single source of carbon-free electricity generation. Advanced reactors are a critical component of a carbon-free mixed energy portfolio that require careful design of first-of-a-kind control rooms. The application of Human Factors Engineering (HFE) is essential for scientific and iterative testing of novel human-system interface (HSI) concepts to ensure effective, efficient, and safe plant operations. Microworlds are simulators that use simplified physics models and control systems to distill nuclear power operations into essential functions. HFE scientists used the Rancor Microworld Simulator to obtain preference and performance metrics for novel and traditional static HSI design styles. Participants comprised advanced reactor company employees and nuclear industry consultants. A mixture of quantitative and qualitative data was captured. There was a preference for the basic graphical style that included high contrast and traditional color scheme elements. No single HSI design outperformed the others, and the participants did not perform better using their preferred HSI style. This experiment is the first in a series of HFE testing for HSIs in advanced reactor control room development. Clear user preferences emerged for elements within static displays. The cutting-edge neumorphic style was the least preferred. Future directions include tests of dynamic displays. HFE is used in evaluating and designing HSI devices that will improve the efficiency and safety of advanced nuclear power operations.

Digital transformation for the water industry: how a data-driven business intelligence platform can improve operations

Abstract The management of a water network is a complex and challenging job. Nowadays, thanks to the technology available, there is the opportunity to move to a data-driven decision process. To meet the increasingly stringent technical quality requirements from the Authority, water utilities need to increase the operational efficiency. The solution is to integrate and organize operational and business-related data into a common data lake and use these data as a source for a business analytics software able to assist and support daily operations and future investment programs. This paper describes the activities and results of a digitalization case study carried out in Italy where a leading water utility serving over 2 million residents implemented an integrated water management system to enhance the business performance by leveraging a data-driven approach. The project resulted in the establishment of an advanced control room at the company's headquarters, featuring real-time dashboards that are fully integrated with the utility's operational tools and software. The integrated system allows faster responses to operational needs and supports business decisions through streamlined access to relevant data.

Advanced Reactor Control and Operations (ARCO): A University Research Facility for Developing Optimized Digital Control Rooms

The Advanced Reactor Control and Operations (ARCO) facility was constructed in January 2018 to serve as a test bed for advanced reactor control rooms and operator support systems. Since then, it has supported human-machine interface user experience research, fault detection and mitigation technology development, control room concept of operations development, and remote operations research. ARCO serves as the control room for the Compact Integral Effects Test (CIET) facility, which replicates the primary-side flow paths and thermal-hydraulic behavior of a fluoride-salt-cooled high-temperature reactor (FHR) using simulant fluids and scaling principles. New reactor designs feature different operating conditions and scenarios than those in existing reactors. ARCO supports the research and development of digital tools for operator communications, intuitive real-time data analysis, online health monitoring and prognostics, and control room cybersecurity. By integrating these different technologies, ARCO acts as a prototypical control system to iteratively develop methods and tools of operation in advanced small modular nuclear reactors. This paper describes the features of and challenges to operating advanced small modular reactors underlying the design basis for ARCO and its operator support systems.

Modeling digital main control room operator’s resilience under extreme conditions: An Experiment design scheme

Human reliability is one of the most important factors that make effects in nuclear power plant(NPP) operation. In advanced digital NPP main control room with high levels of automation, the systematic operation which require a sufficient mental workload to address those undesired events has become a critical challenge for operators. The aim of this research is to identify the operator’s reliability by developing a resilience model. In this work, a seven-stage technique framework is proposed, which includes the skeleton of theoretical analysis, experimental design and hardware setting to how to establish the model for NPP operator in a downsize main control room cabin. The resilience model for operators’ reliability via assessing their basic skill tasks performance and evaluating their cognitive workload in the framework hence can be used for assessing the level of training of the new employed operators as well as human reliability in other critical process industries.

Functional Information of System Components Influenced by Counteractions on Computer-Based Procedure

In an emergency condition of nuclear power plant, operators have to mitigate the accident in order to remove the decay heat and to prevent the release of radioactive material to the environment following the emergency operating procedures (EOPs). The action of operators on a component, for example, changing the parameter level of a component, which is described in a procedure step, will impact other components of the plant and the plant behavior. Nowadays, the advanced main control rooms have been equipped with the computer-based procedures (CBPs) which provide some features and benefits which are not available in paper-based procedures. However, most of CBPs do not provide information of the impact of the counteractions on each procedure step (components influenced and future plant behavior) although it is useful for operators to understand the purpose of the procedure steps before making decisions and taking the actions. This paper discusses the functional information and the method to generate the information using multilevel flow modeling (MFM) model of operator actions on some procedure steps of a simplified EOP of pressurized water reactor (PWR) plant, as an example.

Role of Pre-processing in Textual Data Fusion: Learn From the Croydon Tram Tragedy

Tram/train derailment subject to human mistakes makes investments in an advanced control room as well as information gathering system exaggerated. A disaster in Croydon in year 2016 is recent evidence of limitation of the acquired systems to mitigate human shortcoming in disrupted circumstances. One intriguing way of resolution could be is to fuse continuous online textual data obtained from tram travelers and apply the information for early cautioning of risk discovery. This resolution conveys our consideration regarding a resource of data fusion. The focal subject of this paper is to discuss about role of pre-processing ventures in a low-level data fusion that have been distinguished as a pass to avoid time and exertion squandering amid information retrieval. Inclines in online text data pre-processing is reviewed which comes about an outline suggestion that concede traveler's responses through social media channels. The research outcome shows by a case of data fusion could go about as an impetus to railway industry to effectively partake in data exploration and information investigation.

Preliminary Investigation of Time Remaining Display on the Computer-based Emergency Operating Procedure

One of the important thing in the mitigation of accidents in nuclear power plant accidents is time management. The accidents should be resolved as soon as possible in order to prevent the core melting and the release of radioactive material to the environment. In this case, operators should follow the emergency operating procedure related with the accident, in step by step order and in allowable time. Nowadays, the advanced main control rooms are equipped with computer-based procedures (CBPs) which is make it easier for operators to do their tasks of monitoring and controlling the reactor. However, most of the CBPs do not include the time remaining display feature which informs operators of time available for them to execute procedure steps and warns them if the they reach the time limit. Furthermore, the feature will increase the awareness of operators about their current situation in the procedure. This paper investigates this issue. The simplified of emergency operating procedure (EOP) of steam generator tube rupture (SGTR) accident of PWR plant is applied. In addition, the sequence of actions on each step of the procedure is modelled using multilevel flow modelling (MFM) and influenced propagation rule. The prediction of action time on each step is acquired based on similar case accidents and the Support Vector Regression. The derived time will be processed and then displayed on a CBP user interface.

Development of an EEG-based workload measurement method in nuclear power plants

The environment of main control rooms of large scale process control systems such as nuclear power plants (NPPs) has been changed from the conventional analog type to the digital type. In digitalized advanced main control rooms, human operators conduct highly cognitive work rather than physical work compared to the case of the original control rooms in NPPs. Various operating support systems (OSSs) have been developed to reduce an operator’s workload. Most representative techniques to evaluate the workload are based on subjective ratings. However, there are some limitations including the possibility of skewed results due to self-assessment of the workload and the impossibility of continuously measuring the workload due to freezing simulation for workload assessment. As opposed to subjective ratings techniques, physiological techniques can be used for objective and continuous measurements of a human operator’s mental status by sensing the physiological changes of the autonomic or central nervous system. In this study, electroencephalogram (EEG) was used to measure the operator’s mental workload because it had been proven to be sensitive to variations of mental workload in other studies, and it allows various types of analysis. Based on various research reviews on the characteristics of brainwaves, EEG-based Workload Index (EWI) was suggested and validated through experiments. As a result, EWI is concluded to be valid for measuring an operator’s mental workload and preferable to subjective techniques. Furthermore, EWI was applied to evaluate the effects of OSSs on human operators through experiments. Finally, it is expected that the results of this study can be used to measure the operator’s workload in NPPs.

Analysis of errors of commission for a CE type plant with the advanced control room in the full power condition

This study analyzes errors of commission (EOCs) committed by operators of an Combustion Engineering (CE) type plant with the advanced control room during full power operation, by using the Commission Errors Search and Assessment (CESA) and Misdiagnosis Tree Analysis (MDTA) methods. The contribution of EOCs to plant safety is significant in the digital control room of the reference plant, where the cognitive behavior of an operator plays more important role in the control than in the analog control room. In this study, the CESA and MDTA methods are applied to the identification and quantification of EOCs, respectively. This study chooses eight initiating events that account for approximately 90% of the total core damage frequency (CDF) in the full power condition of the reference plant. As a result of applying the CESA method, twelve EOCs are identified along with the accident sequence groups. Then, the probabilities of those EOCs are quantified through the MDTA method. Finally, this study discusses the effect of EOCs on system failure probability, as well as the necessity of considering EOCs in the probabilistic safety assessment (PSA) of the reference plant.

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

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.

Operations strategy for workload balancing of crews in an advanced main control room

The advanced main control room (advanced-MCR) is the one that allows for reactor operations based on digital instrumentation and control (I&C) technology. Thus, the operators of an advanced-MCR operate the plant through digital I&C interfaces, and for this purpose, an additional digital manipulation task for the operating equipment should be performed that cannot be observed in a conventional-MCR. As a prior study proposing the cognitive, communicative, and operational activity measurement approach (COCOA), COCOA enables an evaluation of the operator's workload in an advanced-MCR, which includes newly generated tasks for Man-Machine Interface System based secondary operation under a digital environment, which does not exist in a conventional-MCR. As a result of observations on the workload level by utilizing COCOA for a reference plant with an advanced-MCR when conducting an emergency operating procedure, it was observed that the workload of the shift supervisor is about two times greater than that of other operators. This is because operators therein stuck to the old guidelines customized to a conventional-MCR and failed to accomplish load balancing in consideration of the operation environment that an advanced-MCR provides. In this context, it would be imperative to develop and apply an operations strategy for an advanced-MCR operation. This study proposes an operations strategy in an attempt to make a balanced workload of operators in an advanced-MCR.

Development of task analysis method for operator tasks in main control room of an advanced nuclear power plant

Task analysis methods provide an insight for quantitative and qualitative predictions of how people will use a proposed system, though the different versions have different emphases. Most of the methods can attest to the coverage of the functionality of a system and all provide estimates of task performance time. However, most of the tasks that operators deal with in a digital work environment in the main control room of an advanced nuclear power plant require high mental activity. Such mental tasks overlap and must be dealt with at the same time; most of them can be assumed to be highly parallel in nature. Therefore, the primary aim to be addressed in this paper was to develop a method that adopts CPM-GOMS (cognitive perceptual motor-goals operators methods selection rules) as the basic pattern of mental task analysis for the advanced main control room. A within-subjects experiment design was used to examine the validity of the modified CPM-GOMS. Thirty participants participated in two task types, which included high- and low-compatibility types. The results indicated that the performance was significantly higher on the high-compatibility task type than on the low-compatibility task type; that is, the modified CPM-GOMS could distinguish the difference between high- and low-compatibility mental tasks.

An optimal range of information quantity on computer-based procedure interface design in the advanced main control room

The quantification of information in the interface design is a critical issue. Too much information on an interface can confuse a user while executing a task, and too little information may result in poor user performance. This study focused on the quantification of visible information on computer-based procedures (CBPs). Levels of information quantity and task complexity were considered in this experiment. Simulated CBPs were developed to consist of three levels: high (at least 10 events, i.e. 3.32 bits), medium (4–8 events, i.e. 2–3 bits), and low information quantity (1 or 2 events, i.e. 0 or 1 bits). Task complexity comprised two levels: complex tasks and simple tasks. The dependent variables include operation time, secondary task performance, and mental workload. Results suggested that medium information quantity of five to eight events has a remarkable advantage in supporting operator performance under both simple and complex tasks. This research not only suggested the appropriate range of information quantity on the CBP interface, but also complemented certain deficient results of previous CBP interface design studies. Additionally, based on results obtained by this study, the quantification of information on the CBP interface should be considered to ensure safe operation of nuclear power plants.

Operator’s cognitive, communicative and operative activities based workload measurement of advanced main control room

An advanced man–machine interface system (MMIS) with a computer-based procedure system and high-tech control/alarm system is installed in the advanced main control room (MCR) of a nuclear power plant. Accordingly, though the task of the operators has been changed a great deal, owing to a lack of appropriate guidelines on the role allocation or communication method of the operators, operators should follow the operating strategies of conventional MCR and the problem of an unbalanced workload for each operator can be raised. Thus, it is necessary to enhance the operation capability and improve the plant safety by developing guidelines on the role definition and communication of operators in an advanced MCR. To resolve this problem, however, a method for measuring the workload according to the work execution of the operators is needed, but an applicable method is not available. In this research, we propose a COgnitive, Communicative and Operational Activities measurement approach (COCOA) to measure and evaluate the workload of operators in an advanced MCR. This paper presents the taxonomy for additional operation activities of the operators to use the computerized procedures and soft control added to an advanced MCR, which enables an integrated measurement of the operator workload in various dimensions of cognition, communication, and operation. To check the applicability of COCOA, we evaluated the operator workload of an advanced MCR of a reference power plant through simulation training experiments. As a result, the amount of high workload of the shift supervisor (SS) was observed in relation to the computerized procedure system newly introduced into the environment of an advanced MCR, and the overall increase in the workload was also observed owing to the screen operation for the soft control of MMIS. On the basis of these observations, it is necessary to reestablish the role and communication method of MCR operators suitable to the new operational environment and changed work, and develop appropriate operating guidelines.

Empirical investigation of workloads of operators in advanced control rooms

This paper compares the workloads of operators in a computer-based control room of an advanced power reactor (APR 1400) nuclear power plant to investigate the effects from the changes in the interfaces in the control room. The cognitive–communicative–operative activity framework was employed to evaluate the workloads of the operator's roles during emergency operations. The related data were obtained by analyzing the tasks written in the procedures and observing the speech and behaviors of the reserved operators in a full-scope dynamic simulator for an APR 1400. The data were analyzed using an F-test and a Duncan test. It was found that the workloads of the shift supervisors (SSs) were larger than other operators and the operative activities of the SSs increased owing to the computer-based procedure. From these findings, methods to reduce the workloads of the SSs that arise from the computer-based procedure are discussed.

디지털 기기 기반 직무 수행 시 인적오류위험성에 대한 실험적 평가

The application of advanced Main Control Room(MCR) is accompanied with lots of changes and different forms and features through the virtue of new digital technologies. The characteristics of these digital technologies and devices give many opportunities to the interface management, and can be integrated into a compact single workstation in advanced MCR so that workers can operate the plant with minimum physical burden under any operation conditions. However, these devices may introduce new types of human errors and thus a means to evaluate and prevent such errors is needed, especially those related to characteristics of digital devices. This paper reviewed the new type of human error hazards of tasks based on digital devices and surveyed researches on physiological assessment related to human error. An experiment was performed to verify human error hazards by physiological responses such as EEG which was measured to evaluate the cognitive workload of operators. And also, the performances of four tasks which are representative in human error hazard tasks based on digital devices were compared. Response time, <TEX>${\beta}$</TEX> power spectrum rate of each task by EEG, and mental workload by NASA-TLX were evaluated. In the results of the experiment, the rate of the <TEX>${\beta}$</TEX> power was increased in the task 1 and task 4 which are searching and navigating task and memory task of hierarchical information, respectively. In case of the mental workload, in most of evaluation items, task 1 and 4 were highly rated comparatively. In this paper, human error hazards might be identified by highly cognitive workload. Conclusively, it was concluded that the predictive method which is utilized in this paper and an experimental verification can be used to ensure the safety when applying the digital devices in Nuclear Power Plants (NPPs).

Applying the Skill-Rule-Knowledge Framework to Understanding Operators’ Behaviors and Workload in Advanced Main Control Rooms

For the past years, a number of researches have focused on operators’ behaviors and workloads in advanced main control rooms (MCRs) in either the procedure-domain or knowledge-domain and in either workload-increased or workload-decreased conditions. Different job positions connote different responsibilities and abilities that are required to perform the job successfully. However, it may be inappropriate to apply a dichotomy in these issues. In this study, we clarified these controversial points through the analysis of the time, frequency, and workload of the behaviors based on Rasmussen's skill–rule–knowledge classification (SRK framework) according to the supervisor operator (SRO), reactor operator (RO), and assistant reactor operator (ARO). The results showed that, for the SRO, rule- and knowledge-based behaviors occurred more often than skill-based behavior in terms of time and frequency, and knowledge-based behavior was the main source of workload. For the RO, no significant differences were found among the three behavior types in terms of frequency and workload, but more time was spent on rule-based behaviors than on skill- and knowledge-based behaviors. The ARO spent more time performing skill-based behaviors than rule- and knowledge-based behaviors, but in terms of frequency and workload, rule-based behavior was the predominant type. Operators’ behaviors contribute to a plant's defense-in-depth approach to safety and serve a vital function in ensuring its safe operation. Research on behavioral taxonomies of advanced MCRs has many significant benefits in both scientific-theoretical and applied practical fields.

Design-related influencing factors of the computerized procedure system for inclusion into human reliability analysis of the advanced control room

This paper presents major design factors of the computerized procedure system (CPS) by task characteristics/requirements, with individual relative weight evaluated by the analytic hierarchy process (AHP) technique, for inclusion into human reliability analysis (HRA) of the advanced control rooms. Task characteristics/requirements of an individual procedural step are classified into four categories according to the dynamic characteristics of an emergency situation: (1) a single-static step, (2) a single-dynamic and single-checking step, (3) a single-dynamic and continuous-monitoring step, and (4) a multiple-dynamic and continuous-monitoring step. According to the importance ranking evaluation by the AHP technique, ‘clearness of the instruction for taking action’, ‘clearness of the instruction and its structure for rule interpretation’, and ‘adequate provision of requisite information’ were rated as of being higher importance for all the task classifications. Importance of ‘adequacy of the monitoring function’ and ‘adequacy of representation of the dynamic link or relationship between procedural steps’ is dependent upon task characteristics. The result of the present study gives a valuable insight on which design factors of the CPS should be incorporated, with relative importance or weight between design factors, into HRA of the advanced control rooms.