CODAC systems arrangement and connectivity

Deregulation in the electricity market has resulted in a number of challenges in the nuclear power industry. Nuclear power plants must find innovative ways to remain competitive by reducing operating costs without jeopardizing safety. Instrumentation and Control (I&C) systems not only play important roles in plant operation, but also in reducing the cost of power generation while maintaining and/or enhancing safety. Therefore, it is extremely important that I&C systems are managed efficiently and economically. With the increasing use of digital technologies, new methods are needed to solve problems associated with various aspects of digital I&C systems. Probabilistic Safety Assessment (PSA) has proved to be an effective method for safety analysis and risk-based decisions, even though challenges are still present. This paper provides an overview of PSA applications in three areas of digital I&C systems in nuclear power plants. These areas are Graded Quality Assurance, Surveillance Testing, and Instrumentation and Control System Design. In addition, PSA application in the regulation of nuclear power plants that adopt digital I&C systems is also investigated.

Context. Today, automated continuous casting control systems are developing rapidly, as process of manufacturing billets (products) of same size from metal in casting mold in mass production has long been outdated and “continuous casting stage” is coming. This process is suitable for non-ferrous metals and steel. However, each time during development, task of improving quality of resulting billet arises, which directly depends on optimizing efficiency and reliability of automated systems themselves. Optimization is key stage in development process, as it is aimed at ensuring accuracy and stability of casting process, which includes development of parametric model and accurate algorithms that ensure optimal temperature, metal pouring rate, oscillation frequency, oscillation amplitude, metal level in crystallizer, and position of position of industrial bucket stopper for each casting stage. In particular, this problem has not yet been fully solved in literature known to authors, so it is necessary to formulate problem and develop algorithm for system operation for specific safety casting unit. Objective. The aim of study is to develop automated control system to ensure accuracy and stability of casting process. Method. The developed control system for continuous casting plant is based on proposed parametric model, which is formalized on basis of set theory. The model takes into account key parameters for particular casting process: metal pouring rate, oscillation frequency, oscillation amplitude, metal level in crystallizer, and position of industrial bucket stopper. Results. The problem was formulated and key parameters were determined, which are taken into account in system’s algorithm, which made it possible to develop control system for continuous casting plant to solve problem of improving quality of resulting billet. Conclusions. A parametric model and generalized black box model representation were created, which are necessary for both new continuous casting projects and existing units to optimize metal casting process. To set up continuous casting system, controlled parameters such as pouring speed, oscillation frequency and amplitude, metal level in crystallizer, and position of industrial bucket stopper were determined. The algorithm of control system for continuous casting plant was developed, on basis of which system was developed that allows monitoring, regulation and control of obtaining steel process or non-ferrous billets. The developed user interface of control system is simple and easy to use.

Stability and steady state analysis of control and safety systems of Nuclear Power Plants

With the development of the nuclear technology, the instrumentation and control (I&C) systems have evolved from the analog systems to the current state-of-the-art digital systems. It has been reported that China has recently developed the digital systems based on Field Programmable Gate Array (FPGA) in CAP1400 nuclear power plant. And the lack of methods in the verification and validation work of the FPGA systems has become an important issue. This thesis describes the basic principles of FPGA, and the development process of FPGA. And then, the thesis proposes an effective improved method—formal verification, describing three methods of formal verification in detail, namely theorem proof, model checking, and equivalence proof. Describing the FPGA verification methodology and pointing out the shortcomings of traditional simulation, comparing the formal verification and traditional simulation verification in terms of complexity, timing, and applications. We also discussed the importance of formal verification method in FPGA. We selected the temperature and power control chip based on FPGA as an example, using System Verilog Assertions (SVA) method of model checking, and verifying the SRAM controller module and the internal calculation module. Through the analysis of the results, this paper proved the feasibility of formal verification methods in the instrumentation and control system of nuclear power plants, and provided some references of verification work for other system chips in instrumentation and control of nuclear power plant in the future work. The thesis showed that verification engineers can use the formal verification method based on SVA to verify the robustness of the system quickly and accurately. This method improves the controllability and observability which are the main drawbacks of the traditional simulation verification. It also avoids several issues in the debug process of traditional simulation verification, improving the accuracy and completeness of the chip verification.

Development of the supervisory systems for the ITER diagnostic systems in JADA

A novel approach for software reliability analysis of digital instrumentation and control systems in nuclear power plants

10 The objective of this chapter is to discuss two approaches for reliability analysis of digital 11 instrumentation and control systems in nuclear power plants taking into account the 12 regulatory side. Dynamic Flowgraph Methodology (DFM) and Markov/Cell-to-Cell 13 Mapping Technique (CCMT) are discussed and case studies developed are presented. 14 These case studies involve simplified control systems for a steam generator and a 15 pressurizer of a Pressurized Water Reactor (PWR) plant for the purpose of evaluating 16 each method. Advantages and limitations of each approach are addressed. For the DFM 17 approach, three concerns in the literature are addressed: modeling of the system itself, 18 incorporation of the methodology results into existing Probabilistic Safety Assessments 19 (PSA), and identification of software failures. The Markov/CCMT, which has been used 20 in dynamic probabilistic safety assessments, is approached by means of a simplified 21 digitally controlled water volume control system. The Markov/CCMT methodology 22 results in detailed data of the system reliability behavior in relation to time. However, 23 it demands a higher computational effort than usual as the complexity (i.e., number of 24 components and failure states) of the system increases. As a regulatory research 25 conclusion, the methodologies presented can be used on PSA risk informed assessment, 26 contributing to the regulatory side. 27

Translation-dependent mRNA quality control systems protect the protein homeostasis of eukaryotic cells by eliminating aberrant transcripts and stimulating the decay of their protein products. Although these systems are intensively studied in animals, little is known about the translation-dependent quality control systems in plants. Here, we characterize the mechanism of nonstop decay (NSD) system in Nicotiana benthamiana model plant. We show that plant NSD efficiently degrades nonstop mRNAs, which can be generated by premature polyadenylation, and stop codon-less transcripts, which are produced by endonucleolytic cleavage. We demonstrate that in plants, like in animals, Pelota, Hbs1 and SKI2 proteins are required for NSD, supporting that NSD is an ancient and conserved eukaryotic quality control system. Relevantly, we found that NSD and RNA silencing systems cooperate in plants. Plant silencing predominantly represses target mRNAs through endonucleolytic cleavage in the coding region. Here we show that NSD is required for the elimination of 5′ cleavage product of mi- or siRNA-guided silencing complex when the cleavage occurs in the coding region. We also show that NSD and nonsense-mediated decay (NMD) quality control systems operate independently in plants.

With the development of modern automatic control technology, digital control technology has advanced technology and inherent advantages compared with traditional analog control technology. Therefore, the use of digital instrument and control system has become an inevitable trend of global nuclear power construction. Nuclear power embedded real-time operating system is an important part of digital instrument and control system in nuclear power plant. It is responsible for managing the hardware resources of the whole system and providing operation environment for application software. Its safety directly affects the safety of instrument and control system. This paper studies the application of embedded information technology in the safety of nuclear power plant, and puts forward a safety related scheme of embedded information system. The scheme fully considers the confidentiality, integrity and availability of information in the digital instrument and control system of nuclear power plant. The application results show that the scheme can meet the information security requirements of nuclear power instrument and control system, and has reference and guiding significance for the research and development of nuclear power embedded real-time operating system.

The aim of the publication is to provide an overview on the current knowledge, up to date best practices, experiences, benefits and challenges related to the subject approaches on instrumentation and control (I&C) systems life cycle management. This includes the coordination of life cycle management methods applied to I&C systems and those applicable to any safety systems that they might interconnect or otherwise interface with. The report is intended to be used by Member States to ensure that appropriate considerations are made to support the introduction of life cycle management approaches for all relevant stakeholders involved in the development of I&C for nuclear facilities and to discuss how these activities can support their safe, reliable and long-term operation. The publication is intended for all personnel involved in the design, development, verification and validation, manufacturing, licensing, operation and maintenance of nuclear power plant instrumentation and control systems and equipment.

Verification of safety critical and control systems of Nuclear Power Plants using Petri nets

In order to study the mechanism of the condensation and feedwater system of nuclear power plant, some simplified mathematic models are presented. The controlling principle of condensation and feedwater control system is explained, and their controllers are designed. Matlab/Simulink module is used for the simulation, result shows that the water level control system of steam generator could make the feedwater flow rate well track the change of the steam flow rate, reduce the false action of the feedwater valve and make the water level keep invariant. The control system of the vacuum and condensate subcooling degree of the condenser could timely regulate the flow rate of cooling water. Thereby, the vacuum and condensate subcooling degree could be limited in certain range. The validity of the control system is proved which could provide reference for the design of the condensation and feedwater control system of nuclear power plant.

This article proposes a cyber-security improvement plan for the DCS control system of nuclear power plants. Firstly, a brief introduction was given to the traditional architecture of DCS control systems of nuclear power plants. Secondly, the current cyber-security risks faced by DCS control systems in nuclear power plants were summarized, including identity authentication issues, access control issues, communication protocol issues, and data storage issues. Based on the cyber-security risks faced by the DCS control system in nuclear power plants, an improvement plan has been proposed for the DCS platform without increasing external cyber-security equipment. Firstly, regarding identity authentication, it is proposed that nuclear power plants have a very good physical protection that can effectively protect the operator station. However, for the engineer station, a dual factor identity authentication method needs to be added. Secondly, regarding access control, the shortcomings of role-based access control models were pointed out, and a location-based and task-based access control model was proposed. Then, in terms of security communication networks, the sensitive data range of nuclear power plants was analyzed, and communication was divided into internal communication and external communication. For internal communication, pre-stored keys can be used for encrypted communication. For external communication, certificates should be used for identity authentication, and then encrypted communication should be carried out. Finally, for data integrity, control system configurations can be saved through encryption. For passwords, they can be transmitted and saved through hash values.

This paper presents a novel control system for chiller plants that is decentralized and flat-structured. Each device in chiller plant system is fitted with a smart node. It is a smart agent, which collects, handles and sends out information to its neighbours. All the smart nodes form a network that can realize self-organization and self-recognition. Different kinds of control strategies can be converted into series of decentralized computing processes carried on by the smart nodes. The principle and mechanism of this decentralized, flat-structured control system for chiller plants are described in detail. Then a case study is presented to show how to build the decentralized, flat-structured control system actually. The measured data shows that the decentralized control method is energy efficiency. Moreover, it is much more flexible and scalable compared with the traditional centralized control method.

The upgrade of data processing and storage system for EAST NBI