Analysis of Standard System of Safety Instrument and Control System in Nuclear Power Plant

Introduction "Actively promoting nuclear power construction" is the basic principle of China's power development. "Independent design, independent manufacturing, independent construction, and independent operation" is a major strategic goal for the development of China's nuclear power. The National Nuclear Power Development Plan has painted a magnificent blueprint for the construction of nuclear power projects. China's nuclear power has now entered a phase of mass and rapid development. The nuclear power standard is a summary of people's technology and experience in the course of nuclear power development. The nuclear power standard system that is compatible with China's industrial base and technological capabilities is a concrete embodiment of China's nuclear power autonomy.

Nuclear power plant safety important instruments and control systems are neurons that control the safe operation of nuclear power plants. The standard system is an important part of the nuclear power standard system.

I. Current status and planning of nuclear power development in China 1.1 Development status of nuclear power in China The diversification of primary energy is an important guarantee for the national energy security strategy. Nuclear power is a safe, clean and reliable energy source. The development of nuclear power can improve China’s energy supply structure, ensure long-term stable supply of energy, and ensure national energy security and economic security. Since China’s first nuclear power plant, Qinshan Phase I, was connected to the grid in 1991, a total of 11 nuclear power plants in China (a total installed capacity of 9.068×106 million kw) have been put into commercial operation, of which 9 reactor units are Pressurized water reactors, and the other two units are heavy water reactors. The nuclear power generating units that have been put into commercial operation in China are shown in Table 1.

1.2 China's Nuclear Power Development Plan The “Nuclear Power Medium and Long Term Development Plan” formally approved by the State Council in early November 2007 clarified the goal of China’s nuclear power development. By 2020, the installed nuclear power capacity will reach 40 million kw, accounting for about 4% of the total installed capacity of the power generation. When the annual nuclear power generation capacity reaches 2600-2800 billion kw, it will account for more than 6% of the total power generation in the country. At the same time, taking into account the subsequent development of nuclear power, by the end of 2020, the nuclear power capacity under construction should be maintained at about 18 million kW. According to the actual situation of China's energy demand and the need for energy structure adjustment, the development goal of nuclear power will be appropriately adjusted. According to the planning and overall deployment of China's nuclear power development, the positive development of nuclear power will be one of the leading ideas for the adjustment and optimization of China's energy structure in the long run. At present, China has entered the phase of mass development of nuclear power. In order to unify and standardize nuclear power construction related work, ensure the safety of all aspects of nuclear power plants, and upgrade the overall technical level of related industries in China, it is imperative to establish a complete nuclear power standard system that is compatible with China's industrial system and technological infrastructure and is in line with international standards.

Second, the status quo of China's nuclear power standard 2.1 Nuclear power standard development process China's nuclear power standards started in the early 1980s, in the Qinshan Phase I, two nuclear power in two localization projects and the subsequent promotion of millions of kilowatt-class nuclear power projects, As of 2008, China has prepared more than 440 nuclear power standards, of which 20% are national standards and 80% are nuclear industry standards. Most of these standards are related to nuclear islands, while conventional islands and nuclear power plants (BoP (balanceofplant)) mainly use conventional electricity standards and other general industry standards. Existing nuclear power standards basically cover (or involve) all aspects of nuclear power construction, including site selection, building design and construction, overall and system design of nuclear power plants, design and manufacture of nuclear power plant machinery equipment, and design and manufacture of instrument power equipment for nuclear power plants. Radiation protection, fire protection/installation/debugging/in-service inspection and emergency of nuclear power plants.

2.2 Problems existing in nuclear power standards Although China's nuclear power standardization work has achieved certain achievements and has played an active role in the process of nuclear power autonomy, due to the controversial and self-designed projects in the past due to the long-term nuclear power construction on the technical route. Not many, and the introduction of projects are the use of foreign standards, which has brought great difficulties to the standardization work. In order to ensure the quality of construction projects under construction, all nuclear power standard work in the past has adopted the principle of “emergency preparation”, which has led to the unfavorable conditions of nuclear power standard system construction. For example, the lack of overall planning for standard system construction, and the fragmented standard construction standards, some standards Cross-cutting and duplication of contents, inconsistency of standards among relevant industries, and lagging of some standard technical levels.

2.3 Status of Nuclear Power Standards In order to implement the nuclear power development strategy of “adhere to the development of nuclear power technology for advanced pressurized water reactors of millions of kilowatts” and promote the process of nuclear power autonomy, under the leadership and organization of the National Energy Administration, the relevant professional and technical fields The units participated in the analysis and study of the current level of technical standards, the use of the more than 440 nuclear power standards, and the harmonization of relevant standards. At the same time, tracking the renewal of international or foreign advanced standards, combined with China’s more than a decade With accumulated engineering experience in the design, construction and operation of nuclear power plants, the “Standard System for PWR Nuclear Power Plants” (referred to as the “standard system”) has been formulated.

The PWR nuclear power plant standard system satisfies the requirements of the second-generation improved PWR nuclear power unit, while taking into consideration the special requirements of the three-generation PWR nuclear power unit. This standard system is a special standard system for nuclear power plants. It has adopted standards that have special requirements for nuclear power, and conventional industrial standards that apply to nuclear power are not listed among them. Figure 1 shows the structure of a standard system framework for a pressurized water reactor nuclear power plant.

As can be seen from Figure 1, according to the importance of the main process of nuclear power engineering and certain types of standards, the standard system of PWR nuclear power plants can be divided into general and basic (a), pre-nuclear power work (b), engineering design (c), Equipment (d), construction (e), commissioning (f), operation (g) and decommissioning (h) 8 fields (English letters in parentheses are system codes).

III. Important Safety Instruments and Control Systems for Nuclear Power Plants 3.1 Overview of safety-critical instruments and control systems Important nuclear power plant safety instrumentation and control systems (abbreviated as “instrumentation and control systems”) refer to system failures or malfunctions that may cause overexposure to nuclear power plant site personnel or the public. Illumination and instrument control systems that prevent anticipated operational events from causing unacceptable consequences, including safety systems and safety-related instrument control systems.

Safety system refers to a safety-critical system. It is used to ensure safe shutdown of reactors, discharge of residual heat from the reactor core, or limitation of anticipated operational events and the consequences of design basis accidents under any operating conditions. Safety-related instrumentation systems refer to safety. However, it is not an instrument control system of a security system.

3.2 Nuclear Power Plant Safety Important Instrument Control System Functions Nuclear power plant safety The important instrument control system covers the entire nuclear island system. Its structure is shown in Figure 2.

Nuclear power plant safety important instrument control systems need to implement important safety functions during the normal operation of nuclear power plants, expected operational events (accidents), and/or accidents, mainly including automatic protection, process control, and automatic monitoring.

Detailed description of each function is as follows: 1 Automatic protection function, which triggers emergency shutdown of the reactor and starts the installation of dedicated safety facilities; 2 The process control function, that is, the important variables of the safety of the nuclear power plant are maintained within the operating limits; 3 The automatic monitoring function, ie It provides functions such as information display, recording and alarming for the operation status of safety-critical systems and equipment under various operating conditions of nuclear power plants, and supervises the operability of safety-critical systems during the operation of nuclear power plants.

IV. Standards required for safety-critical instrument control systems Given the diversity of functions and the complexity of the instrument control system in nuclear safety, its design, construction and operation involve a series of safety-related standards such as system design, equipment manufacturing and installation, and equipment maintenance. .

In terms of system design, the required standards are the determination of safety-critical instrument control variables and the configuration of their corresponding systems, the classification of safety-critical instrument control functions (covering technical requirements and warranty requirements), and the reliability and availability of functional systems (channels). Operational design, integrated design of the main control room, information processing and transmission, and application of human factors engineering; in the equipment manufacturing and installation, the required standards are the design, manufacture, and appraisal of equipment (with special requirements for nuclear power). The integration, installation and commissioning of the system; in terms of equipment maintenance, the required standards mainly include periodic supervision and inspection of equipment, aging management and maintenance.

V. Standard formulation strategy Actively adopting international advanced standards or foreign applicable standards, combining the existing experience of nuclear power projects in China to compile the standards applicable to the construction of nuclear power in China is the basic strategy for the preparation of standards for safety critical instrument control systems in nuclear power plants. Internationally available nuclear power plant safety important instrument control system standards are mainly international standards (IEC standards) and American national standards (such as IEEE standards, ANS standards, and ISA standards, etc.), in addition to some other standards, such as the federal German Standard (KTA), French Electric Equipment Construction Rules (RCC-E), etc. China's current standards for the safety of important nuclear power plant control systems (including national standards and industry standards) are basically transformed from the above-mentioned international standards or foreign standards. The following is only an analysis of the standard systems of the three important safety critical instrument control systems for nuclear power plants.

5.1 International Standards (IEC Standards)

Since the 1990s, the sub-technical committee SC45A of the International Electrotechnical Commission (IEC) has complied with the IAEA safety standard IAEANS-R-1-2000 "Safety Design Requirements for Nuclear Power Plants" and IAEANS-G-1.3-2002 "Nuclear Power Plants "Safety-critical instrumentation and control systems" and IAEA50-C/SG-Q-2001 "Nuclear Power Plant Safety and Quality Assurance", combined with the development direction of digital control technology in the important safety and control system for nuclear power plants, revised a number of standards, preliminary A new standard system for safety critical instrument control systems for PWR nuclear power plants was established.

5.1.1 Applicability of the standard system The new IEC standard system is applicable to conventional analog instrumentation control systems, fully digital instrumentation systems, or instrument and control systems that are integrated by analog and digital.

The technical level of the IEC standard reflects the advanced level of nuclear power engineering construction in the world today, and it is in line with the actual situation of China's pressurized water reactor nuclear power plant construction.

5.1.2 Standard System Scope The standard system includes all safety-critical instrumentation systems (including power source supply systems) based on the defense-in-depth safety principle for design, construction and operation, and safety-related standards covering nuclear Power (neutron flux rate) monitoring, monitoring of process and equipment status, and radiation monitoring are important safety and instrumentation systems in these three areas.

5.1.3 Standard Architecture The IEC new standard system is divided into the following four levels. The first level (top level) standard is the IEC 615132001 Nuclear Power Plant Safety Critical Instrumentation and Control System Basic Requirements." The top-level standard comprehensively provides safety guidelines for safety-critical instruments and control systems during the entire life cycle of a nuclear power project (including the design phase, construction phase, and operation phase), and provides guidance for the overall design of the instrument control system. Some of the basic requirements of this layer of standards will be supplemented by or directly referenced by the standards of the second level.

The second-level standards include the determination and classification of important safety instrumentation and control functions for nuclear power plants, the design of system reliability and availability, the design of functional channels and equipment, information processing and transmission, the design of main control rooms, and equipment qualification. .

The third level of standards is the criteria for equipment (design, manufacturing, and qualification), technical methods (such as nuclear power plant reliability fault tree analysis), and some specific activities. This level of standards is not directly related to the top level standard, but it can be related to the second level of standards based on standard content characteristics.

The fourth level "standards" are only some technical documents, not as standards, but related to the preparation or revision of the above three levels of standards.

5.2 National Standards in the United States The United States is the mother of nuclear power. The relevant nuclear power standards are based on the Federal Regulations (ROCFR) and Management Guidelines (R.G.), and various technical societies (such as the Institute of Electrical and Electronics Engineers IEEE, Nuclear Society ANS, Instrumentation, and The Institute of Automation (ISA) prepares the "industry standard" for the scope of this profession and is recognized as a national standard by the National Institute of Standards. It can be seen that the US nuclear power standard system is integrated by standards developed by the various societies.

The IEEE nuclear safety related standards system is based on the IEEE 6O3 "Nuclear Power Plant Safety System Guidelines", IEEE308 "Nuclear Power Plant IE Level Power System Guidelines" and IEEE 323 "Nuclear Power Plant Class IE Equipment Qualifications" as basic standards, together with other related sub-standards to meet the requirements of nuclear power plants. Safety criteria Safety standards for electrical systems and equipment. After the San Francisco Island accident, the IEEE enriched the criteria of accident monitoring instruments, reliability analysis of safety systems, application of human factors engineering in the design, construction, and operation of safety systems to the safety system standard system of nuclear power plants. With the digitized instrumentation technology widely used in security systems, the IEEE standard has been revised accordingly.

The IEEE standard is based on the design, construction and operation experience of the United States nuclear power engineering and a large number of research and experimental results to be compiled and revised. It reflects the industrial level of the United States and the nuclear power engineering construction level. Based on the national conditions of the United States, the IEEE standard has three types: guidelines, guidelines, and implementation methods. Most of the current IEEE nuclear power standards have been converted into the corresponding standards in China.

5.3 The French national standard RCC-E “Rules for the design and construction of nuclear island electrical equipment” is based on French international standards (IEC nuclear power special standards and IEC general industrial basic standards), French standards and European standards, combined with French nuclear power engineering practical experience The "rules of technology" for the design and construction of a set of electrical equipment and systems are used in the design and construction of nuclear-system safety level electrical systems and equipment (including instrumentation, control, and power supply systems). RCC-E gives the "outline" for the design and construction of safety-grade electrical systems and must comply with the requirements of IEC or one of the French standards. It is an electrical device that has been summarized on the basis of the intension of the criteria for the design and construction of nuclear island electrical equipment. Design and build "key points."

5.4 Adopting a bid strategy Based on research and analysis of the above-mentioned international or foreign nuclear power standard system, combined with the development of China's current standard, we have determined that China's nuclear power plant safety important instrument control system standards adopt international or foreign advanced standards (abbreviated as the standard). The strategy is: Mainly based on international standards (IEC standards) supplemented by IEEE standards, ISA standards, and RCC-E.

6. The standard system structure is based on the characteristics of the safety-critical instrument control system of nuclear power plants. Based on the analysis and study of foreign standard systems, combined with the accumulated experience of domestic nuclear power projects and the demand for standards, the required standards for instrument control systems are divided into 4 levels: 1 The first level, related to how nuclear power plant safety instrumentation and control systems meet the design safety requirements for nuclear power plants in all stages of design, construction and operation, is the top standard in the standard system of instrument control systems; 2 Levels, standards related to the design of safety-critical instrumentation systems, etc. are the refinements of the safety requirements in the top-level standards; 3 the third level, which is not directly related to the top-level standards, but based on the characteristics of this level of standards Levels of standards are associated or coordinated; 4 Level 4, standards for equipment qualification, installation, and maintenance procedures.

In November 2009, the National Energy Administration issued (PWR Nuclear Power Plant Standard System) a total of 680 standards. The relevant standards for safety-critical instruments and control systems are 170, of which 39 are currently in effect and are under development. There are standard items, 46 items to be revised, and 70 items to be developed.

Concluding remarks The standard system of nuclear power plant safety instrument control system is based on the standards required for the design, construction and operation of the second-generation improved nuclear power unit. It is an open system and requires dynamic maintenance. With the development of China's nuclear power meter control technology, especially with the development of the localization and modularization of the three generations of nuclear power plants, the nuclear power plant control system standard system will be continuously adjusted and improved.