Intelligent decision support systems for nuclear power plants in Japan

This paper describes the MITI (Ministry of International Trade and Industry) projects for decision support systems for NPPs in Japan. Main attention is paid to the new project of an advanced man-machine system for nuclear power plants, of which a conceptual design was initiated in 1984. Some of the aspects of the design and the outline of the prototype system are discussed.     

On the representation of automation using a work domain analysis

Work domain analysis (WDA) has been applied extensively within cognitive engineering as an analytic framework for the evaluation of complex sociotechnical systems in support of design. However, the WDAs described in the literature have not explored the representation of automated system components, despite the documented problems associated with operator-automation interaction and the requirements for operator support in complex automated systems. The current research examines the application of WDA to model an example automated system – a camera – by representing the camera along with its automated components as separate systems using the abstraction hierarchy (AH). Additionally, we contrasted this modelling approach with the more typical approach of modelling automation within a cognitive work analysis (CWA) by performing a control task analysis using the decision ladder. The results of these analyses suggest that, similar to non-automated systems, considering a separate representation of an automated system within the WDA may provide useful system design guidance in terms of user support and information requirements. The comparison of the AH and the decision ladder (DL) models indicates that the models provide different information about the requirements and support different user needs: the AH provides information about specific subsystems and components of the automation that are used for control and how they support functions and purposes of the automation while the DL shows how the control tasks are achieved interleaving automated actions with those of the user. The information obtained from modelling automation with the AH is different from what would normally be obtained by performing only a control task analysis, yet is necessary for operator support.     

Software design specification and analysis technique (SDSAT) for the development of safety-critical systems based on a programmable logic controller (PLC)

This paper introduces a Software Design Specification and Analysis Technique (SDSAT) for safety-critical systems based on a Programmable Logic Controller (PLC). During software development phases, the design phase performs an important role in connecting the requirements phase and the implementation phase, and it is a process of translating software requirements into software structures. In this work, the Nuclear FBD-style Design Specification and analysis (NuFDS) approach was proposed for nuclear Instrumentation and Control (I&C) software. The NuFDS approach is suggested in a straightforward manner for effective and formal software design specification and analysis. Accordingly, the proposed NuFDS approach is composed of a software design specification technique and a software design analysis technique. In addition, for tool support in the design phase, we developed the NuSDS tool based on the NuFDS approach; this tool is used specifically for generating software design specification and analysis for nuclear fields.     

结构选型中基于模糊推理的评判系统

本文在基于自组织竞争神经网络检索机制与模糊逻辑评判的实例推理系统基础上，讨论了该系统用于结构选型过程中的模糊推理过程；建立了高层建筑结构高度适应性的模糊评价标准；并将其应用于模糊推理系统中；以剪力墙结构高度适应性评价为例展示了推理过程。证明采用模糊推理系统作为设计型结构选型决策支持系统的评价模块是理想的解决方案。     

Automated hazard analysis of digital control systems

Digital instrumentation and control (I&C) systems can provide important benefits in many safety-critical applications, but they can also introduce potential new failure modes that can affect safety. Unlike electro-mechanical systems, whose failure modes are fairly well understood and which can often be built to fail in a particular way, software errors are very unpredictable. There is virtually no nontrivial software that will function as expected under all conditions. Consequently, there is a great deal of concern about whether there is a sufficient basis on which to resolve questions about safety. In this paper, an approach for validating the safety requirements of digital I&C systems is developed which uses the Dynamic Flowgraph Methodology to conduct automated hazard analyses. The prime implicants of these analyses can be used to identify unknown system hazards, prioritize the disposition of known system hazards, and guide lower-level design decisions to either eliminate or mitigate known hazards. In a case study involving a space-based reactor control system, the method succeeded in identifying an unknown failure mechanism.     

过水围堰施工导流联合泄流管理决策支持系统

过水围堰施工导流联合泄流管理是典型的半结构化决策问题，为此设计开发了过水围堰施工导流联合泄流管理决策支持系统（CDDSS）。系统地介绍了CDDSS的结构框架、设计原则、开发思路、决策模式和基本功能，该系统由数据库子系统、模型库子系统、图形库子系统和人机界面四部分组成，此系统是建立在数学模型的基础上，综合利用系统科学、管理科学、施工导流的理论及方法的人机交互系统。工程实例分析表明，系统友好的用户界面帮助决策者/用户充分利用系统的功能做出有效的实时决策。     

敏捷供应链管理决策支持系统的研究

首先介绍了敏捷供应链管理技术,然后提出了一种支持敏捷供应链管理的决策支持系统,最后以企业为背景,给出了该决策支持系统的应用。     

Electronics in nuclear power programme of India—An overview

This paper presents an overview of state-of-the art developments in electronics for nuclear power programme of India. Indigenous activities in instrumentation and control (I&C) in the areas of detector development, nuclear instrumentation, monitoring and control electronics and special sensors paved the way to self-reliance in nuclear industry. Notable among the recent I&C systems developed for 540 MWe reactors are Liquid Zone Control System (LZCS), flux mapping system and advance reactor regulating system. In a nuclear plant, apart from ensuring functional requirements, design of electronics needs to meet high level of reliability, safety and security standards. Therefore, a lot of importance is attached to activities such as design review, testing, operation, maintenance and qualifications of I&C systems. Induction of computer based I&C systems mandated a rigorous verification process commensurate with the safety class of the system as specified in Atomic Energy Regulatory Board (AERB) safety guides. Software reliability is assured by following strict development life cycle combined with zero-defect policy and is verified through verification and validation (V&V) process. Development of new techniques in data transmissions with optical fibres as transmission medium and wireless networks in control systems is being pursued. With new I&C systems, efforts were made to utilize the same hardware and software platforms for various plant applications, i.e., for standardization. Thrust was given to use Field Programmable Gate Arrays (FPGA) and Application Specific Integrated Circuits (ASIC) in order to improve the reliability of system by reducing component count. It has become imperative to develop modern contemporary solutions like ASICs, HMCs, System on Chip (SOC) and detector mounted electronics and towards that various ASICs and HMCs have been developed in-house to meet the challenges.     

Addressing dependability by applying an approach for model-based risk assessment

This paper describes how an approach for model-based risk assessment (MBRA) can be applied for addressing different dependability factors in a critical application. Dependability factors, such as availability, reliability, safety and security, are important when assessing the dependability degree of total systems involving digital instrumentation and control (I&C) sub-systems. In order to identify risk sources their roles with regard to intentional system aspects such as system functions, component behaviours and intercommunications must be clarified. Traditional risk assessment is based on fault or risk models of the system. In contrast to this, MBRA utilizes success-oriented models describing all intended system aspects, including functional, operational and organizational aspects of the target. The EU-funded CORAS project developed a tool-supported methodology for the application of MBRA in security-critical systems. The methodology has been tried out within the telemedicine and e-commerce areas, and provided through a series of seven trials a sound basis for risk assessments. In this paper the results from the CORAS project are presented, and it is discussed how the approach for applying MBRA meets the needs of a risk-informed Man–Technology–Organization (MTO) model, and how methodology can be applied as a part of a trust case development.     

A principled approach to the design of healthcare systems: Autonomy vs. governance

In this paper, we look at decision support for post-operative breast cancer care. Our main concerns are to support autonomy of decision making whilst maintaining the governance and reliability of the decision-making process. We describe the context of our work in the wider medical setting. We then present a set of decision support tools based on the situation calculus as a means of maintaining the integrity of rule bases underlying the decision-making system. The decision support system, Neptune, allows for the authoring, maintenance and delivery of decisions in a self-governing framework. Finally we discuss the implications of our work.     

NAROAS: a neural network-based advanced operator support system for the assessment of systems reliability

We have developed and implemented a computerized reliability monitoring system for nuclear power plant applications, based on a neural network. The developed computer program is a new tool related to operator decision support systems, in case of component failures, for the determination of test and maintenance policies during normal operation or to follow an incident sequence in a nuclear power plant. The NAROAS (Neural Network Advanced Reliability Advisory System) computer system has been developed as a modularized integrated system in a C++ Builder environment, using a Hopfield neural network instead of fault trees, to follow and control the different system configurations, for interventions as quickly as possible at the plant. The observed results are comparable and similar to those of other computer system results. As shown, the application of this neural network contributes to the state of the art of risk monitoring systems by turning it easier to perform online reliability calculations in the context of probabilistic safety assessments of nuclear power plants.     

河北省可持续发展决策支持系统研究

阐述了河北省可持续发展评价指标体系及其评价方法，分析了建立河北省可持续发展决策支持系统（HBSDDSS）的意义、系统目标及其设计原则；最后给出了HBSDDSS的总体框架。     

Diversity in computerized reactor protection systems

Based on engineering judgement, the most important measures to increase the independency of redundant trains of a computerized safety instrumentation and control system (I&C) in a nuclear power plant are evaluated with respect to practical applications. This paper will contribute to an objective discussion on the necessary and justifiable arrangement of diversity in a computerized safety I&C system. Important conclusions are:

(i) diverse equipment may be used to control dependent failures only if measures necessary for designing, licensing, and operating a computerized safety I&C system homogeneous in equipment are neither technically nor economically feasible;

(ii) the considerable large operating experience in France with a non-diverse equipment digital reactor protection system does not call for equipment diversity. Although there are no generally accepted methods, the licensing authority is still required to take into account dependent failures in a probabilistic safety analysis;

(ii) the frequency of postulated initiating events implies which I&C functionality should be implemented on diverse equipment. Using non-safety I&C equipment in addition to safety I&C equipment is attractive because its necessary unavailability to control an initiating event in teamwork with the safety I&C equipment is estimated to range from 0.01 to 0.1. This can be achieved by operational experience.

Plant-level maintenance decision support system for throughput improvement

In the current global scenario of extreme competition, factors such as productivity, availability, quality and cost of operations play a vital role in the success of a company. A critical component relating to all of the above is maintenance. The conventional maintenance decision support systems have primarily focused on maximising the gains of a single machine system. However, a real life application usually consists of multiple machines, and the operational level decisions are more complex. In this paper, an on line plant-level maintenance decision support system (PMDSS) is developed by combining the short term and long term decision making process to improve the overall system performance while continuously attempting to maximise immediate profits in the short term. The PMDSS works towards two basic aims: (1) unplanned downtime reduction by predicting the remaining useful life of the machines, and (2) efficient utilisation of the finite maintenance and production resources through identifying the throughput-critical machines. The benefits of this approach are presented by considering an industrial case study of an automotive assembly line. The results obtained using this PMDSS approach shows a big throughput improvement as compared to the conventional maintenance policies.     

Risk-based emergency decision support

In the present paper we discuss how to assist critical decisions taken under complex, contingent circumstances, with a high degree of uncertainty and short time frames. In such sharp-end decision regimes, standard rule-based decision support systems do not capture the complexity of the situation. At the same time, traditional risk analysis is of little use due to variability in the specific circumstances. How then, can an organisation provide assistance to, e.g. pilots in dealing with such emergencies?A method called ‘contingent risk and decision analysis’ is presented, to provide decision support for decisions under variable circumstances and short available time scales. The method consists of nine steps of definition, modelling, analysis and criteria definition to be performed ‘off-line’ by analysts, and procedure generation to transform the analysis result into an operational decision aid. Examples of pilots' decisions in response to sudden vibration in offshore helicopter transport method are used to illustrate the approach.     

节水灌溉管理智能决策支持系统研究

应用人工智能中的专家系统技术,开发并集成了3个不同层次的节水灌溉管理决策支持系统：灌溉预报与节水灌溉决策子系统、灌区计划用水与水量调配管理系统、灌区管理体制改革子系统;介绍了节水灌溉管理智能决策支持系统的理论基础,系统结构,实际应用以及陕西省旱情决策子系统等。     

Interactive decision support in radiation therapy treatment planning

This paper proposes the use of an interactive decision support system to guide the treatment planning process for external beam radiation therapy. Based on multicriteria optimisation our research treatment planning software CARINA calculates efficient (also called Pareto optimal) treatment plans. These are stored in a database and accessed for evaluation by the treatment planner. The interactive component consists of navigation among the pre-calculated plans using free search, fine search and exact search as well as sensitivity analysis, which extracts dose dependence information for all structures from the plan database. As a result, plan quality is improved by finding advantageous trade-offs in competing treatment plans, trial-and-error is avoided, and effectiveness of treatment planning is increased.     

In-house development of scheduling decision support systems: case study for scheduling semiconductor device test operations

Most manufacturing processes can benefit from an automated scheduling system. However, the design of a fast, computerised scheduling system that achieves high-quality results and requires minimal resources is a difficult undertaking. Efficient scheduling of a semiconductor device test facility requires an information system that provides good schedules quickly. Semiconductor device testing is the last stage of the long semiconductor manufacturing process, and therefore is subjected to customer service pressures. The cost of an off-the-shelf computerised scheduling system may be prohibitive for many companies. In addition, many companies are taken aback by other characteristics of off-the-shelf scheduling systems, such as code confidentiality, maintenance costs, and failure rates. We draw upon the literature and our field case to discuss some of the trade-offs between in-house development and off-the-shelf acquisition of software. We describe the in-house design and implementation of a scheduling decision support system for one device test facility. Using the design and implementation process of this system as a case study, we discuss how one facility uses in-house design of systems in a strategic way, as a competitive capability.     

Development of a safety critical software requirements verification method with combined CPN and PVS: a nuclear power plant protection system application

Safety-critical software systems such as certain nuclear instrumentation and control (NI&C) systems should be developed with thorough verification. This study presents a method of software requirement verification with a case study for a nuclear power plant (NPP) protection system. The verification introduces colored petri net (CPN) for system modeling and prototype verification system (PVS) for mathematical verification. In order to aid flow-through from modeling by CPN to mathematical proof by PVS, an information extractor from CPN models has been developed in this paper. In order to convert the extracted information to the PVS specification language, a translator has also been developed. This combined method has been applied to the functional requirements of the Wolsong NPP Shut Down System #2 (SDS2); logical properties of the requirements were verified. Through this research, guidelines and a tool support for the use of formal methods have been developed for application to NI&C software verification.