Decoupling and Coupling Simulation Analysis in Small Nuclear Power Plant

The design framework of human-machine interface (HMI) provides guiding principles for the display of digital information on the system interface. In order to solve the problem of human error caused by the unreasonable design of information interaction interface of complex system, this paper takes the feedwater flow control system (ARE) of nuclear power plant as an example to optimize . The design of the human-machine interface of the system is based on the framework of function behavior state (FBS), defines the mapping relationship between various levels of the system interface, defines the information requirements of the monitoring system interface and presents the information according to the cognitive decision-making theory, and improves it on the basis of the original interface. The purpose of this research is to make the monitoring interface more consistent with the mental model of the operator and reduce the cognitive workload and error probability, so as to ensure the safe and reliable operation of the nuclear power plant. This research also provides some reference for the optimal design of the HMI of the monitoring system of the nuclear power plant in the future.

The seismic response of piping systems in nuclear power plants is commonly separated into two parts - the inertial or dynamic response and the pseudostatic response due to relative motions of the systems supports. Various analysis procedures have been developed to calculate each portion of the response separately. The present study investigates calculational procedures and parameter values used for the calculation of the inertial response component. It also investigates the possibility of removing snubbers and restraints in piping systems. Removal of snubbers and restraints will reduce the seismic stresses due to relative support motions. The scope of the present study was to evaluate the PVRC-proposed changes relative to piping responses calculated by response-spectrum methodology and a multi-support time history analysis procedure which is less conservative because it does not require any form of enveloping of support motions. Numerous response-spectrum analyses of three selected piping systems in Zion nuclear power plant were performed, using different combinations of damping values (RG 1.61 and proposed PVRC), peak-broadening (RG 1.22), and the alternative to peak broadening (proposed PVRC).

Biological pollution creates significant obstacles in the operation of power plants' technical water supply cooling systems (SCS). To minimize biological pollution, methods of corrective treatment with biocides are implemented. While these biocides effectively prevent fouling of the cooling system, they can also adversely affect the environment and structural materials. By evaluating structural materials' corrosion resistance and biocides' environmental safety for the cooling water during biocide treatment, any potential issues can be identified and addressed before they become a safety or operational concern. The paper presents the results of bench tests of the corrosion resistance of structural materials SCS, corrosion aggressiveness of the biocides: sodium hypochlorite NaClO and 2, 2-dibromo-3-nitriloropionamide (DBNPA), and the results of measurements of the concentration of biocides and their decomposition products to assess compliance with environmental standards when discharging return water when applying from biocides treatment. The cooling water SCS of the Rivne NPP (Nuclear Power Plant) was chosen as the research object. Bench corrosion tests were carried out using samples of corrosion indicators from materials: steels Ст20, 08Х18Н10Т; copper alloy МНЖ-5-1 and aluminum, which are defined as analogs of structural materials of the technical water supply system of the Rivne NPP. The conditions of operation of the technical water SCS of the Rivne NPP were simulated on the test bench, and corrosion rate measurement was carried out by the gravimetric method.

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.

14 - Nuclear power plant systems

Modeling primary and secondary coolant of a nuclear power plant system with a unique framework (MCUF)

This review paper aims to present a comprehensive overview of the evaluation, simulation, and control of heating, ventilation, and air conditioning (HVAC) systems in nuclear power plants (NPPs), specifically highlighting their importance in maintaining operational safety, thermal performance, and energy efficiency. The study’s authors summarize recent developments in HVAC technologies, such as passive cooling systems, data-driven energy management frameworks, and intelligent control strategies, to cope with the specific challenges of NPPs. Various passive cooling systems, including heat pipes, thermosyphons, and loop heat pipes, have proven themselves by their ability to remove residual heat from spent fuel pools and reactors power plants with high efficiency. Through experimental studies, they have shown their ability to eliminate operational vulnerability to accidents or guarantee any desired long-term cooling. Intelligent sensor networks allow a more data-driven approach to HVAC control, enabling online energy management frameworks and advanced intelligent control systems. These exhibit considerable promise for optimizing HVAC performance, decreasing energy consumption, and improving operational flexibility in multi-zone systems. Such capabilities are ideal for addressing the dynamic and safety-critical nature of NPPs. They are first enabled by the use of these technologies for real-time monitoring, predictive maintenance, and adaptive control. When applied with advanced HVAC control systems, passive cooling techniques provide an exciting route to improve safety and energy efficiency. An overview of the key findings is that robust thermal management solutions combined with intelligent control and intelligent adaptation are essential when addressing the rapidly evolving demands of nuclear energy systems. This work highlights the priorities in the next generation of nuclear power plants, which should actively pursue seamless integration of out-of-system technologies into existing NPP infrastructures, enabling scalable, cost-effective, and resilient solutions.

Deregulation forces Nuclear Power Plants (NPPs) to operate not only safely, but also more economically. Instrumentation and Control (I&C) systems in NPPs play an important role to reduce operational related costs. Therefore, a well-planned test and maintenance (T&M) strategy for I&C systems is more important then ever in this deregulated energy market. This paper presents a general T&M framework for digital I&C systems in NPPs. There are three main parts within this framework: probabilistic safety assessment (PSA), reliability analysis, and costs evaluation. PSA is used to set risk-informed unavailability limits. Reliability analysis is used to derive the relation between the unavailability and the T&M interval. Costs associated with not only T&M, but also reactor mal-shutdowns are evaluated. The Shutdown System Number One (SDSI) in Canadian Deuterium-Uranium (CANDU) based NPPs is used as an example system to illustrate the proposed framework.

Corrosion mitigation in coolant systems in nuclear power plants

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.

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

As an important barrier to prevent adversaries from destroying nuclear facilities or transferring nuclear materials, the cyber security of physical protection systems in nuclear power plants are receiving increasing attention under the current digital, networked and intelligent development trend in the world. In this paper, the authors analyze the cyber security risks faced by the physical protection systems and countermeasures, propose the idea of building an cyber security test platform for physical protection systems based on digital twin technology, and explore relevant key technologies, which provides a new perspective for the cyber security protection of physical protection systems in nuclear power plants around the world.

Water/electricity cogeneration system in nuclear power plants and its peaking operation modes are analyzed in this work. The large-scale water/electricity cogeneration system can use the valley nuclear power during nighttime for seawater desalination, which can improve the peaking capacity, decrease desalination water cost and alleviate the water shortage in coastal cities. The peaking operation mode results show that the reverse osmosis desalination system runs better with variable load mode "12-1-10-1" (day 50% - night 100%) under the full load operation of nuclear reactor. In this mode, the peaking capacity of the water/electricity cogeneration system is 33%, the desalination water cost is 3.49 Yuan/m3 and the peaking cost is 65 Yuan/MWh. Development of the large-scale water/electricity cogeneration system in nuclear power plants has multiple benefits in China.

Dynamic analysis program for hydraulic piping systems in nuclear power plants

As a method to reduce periodic inspection time and mean recovery time on fault occurrence, remote maintenance systems for nuclear power plants (NPPs) are proposed, which augment efficiencies in maintenance operations for the plants by surveying them remotely and achieving collaborations between on-site operators and remote plant designers and expert operators [1]. In particular, with the spread of Internet technology and Internet security protection technology in recent years, there is a tendency to build remote maintenance systems using the Internet without dedicated communication lines [2]. However, the biggest concern of customers such as electric power companies is security. It is highly necessary to give assurance of the security of remote maintenance systems coherently and consistently in order to introduce such systems based on Internet technology into NPPs. However, there exist various ways of thinking about security. Furthermore, there has not been a general agreement on how to give assurance of the security of remote maintenance systems for NPPs. So we have applied ISO/IEC 15408 [3] to remote maintenance systems for NPPs. It is used to evaluate the security level of IT products and systems. Based on ISO/IEC 15408, we have listed assets to be protected, threats to the assets, security objectives against the threats, and security functional requirements that achieve the security objectives. Also, we have shown relations between the threats and the security objectives, and relations between the security objectives and the security functional requirements. As a result, we have concretized a necessary and sufficient security design of remote maintenance systems for NPPs that can protect the instrumentation and control (I&C) system against intrusion, impersonation, tapping, obstruction and destruction. In this paper, we describe the background of the remote maintenance systems for NPPs, a summary of the systems, and its security design based on ISO/IEC 15408.