The influence of the physical characteristics of fast reactor on the instrument control system. Fast reactor uses heavy nuclear elements (uranium or plutonium) to absorb the energy released by fast neutron fission, and its physical design is very different from that of thermal reactor, which makes its instrument control system different from that of thermal reactor.
1. Compared with thermal reactor, fast reactor with dynamic parameters has higher core enrichment, harder energy spectrum, smaller Doppler effect than thermal reactor, smaller delayed neutron share and shorter neutron generation time, which are unfavorable for fast reactor control and require better transient response characteristics of fast reactor control system.
2. Toxic effect In the fast reactor, thermal neutrons are almost non-existent, so the materials with high thermal neutron absorption cross section, which are very important in the design of the fast reactor, are almost not so important in the fast reactor. Fission products like "nuclear" are relatively unimportant, and there is no xenon poisoning problem in the fast reactor. The fast reactor core is small, and the average free path of fast neutrons is longer than that of thermal neutrons, so the core coupling platform of the fast reactor is closer than that of the hot reactor. There is no problem of regional instability, so it is not necessary to consider the control valve problem of power distribution fluctuation in fast reactor, nor to measure the core power distribution like pressurized water reactor. In this sense, it is beneficial to simplify the design of instrument control system.
3. Reactivity control Because fast reactors use sodium as coolant, soluble poisons such as boric acid cannot be used to control reactivity. Generally, a single control rod is used to control reactivity, so two independent control rod shutdown systems must be set up to ensure redundancy and safety.
4. Instrument efficiency At present, all nuclear measuring instruments are sensitive to thermal neutrons, and the efficiency of detecting fast neutrons is relatively low, so it is required to reasonably consider the setting and sensitivity of board measuring instruments. Status on July 21st, 21, China National Nuclear Corporation announced in Beijing today that the first fast neutron reactor in China, China Experimental Fast Reactor (CEFR), independently developed by China Institute of Atomic Energy of China National Nuclear Corporation, has reached its first criticality. This is a major independent innovation achievement in the field of nuclear power in China, which means that the fourth generation advanced nuclear energy system technology in China has achieved a major breakthrough. As a result, China has become one of the few countries in the world that have mastered fast reactor technology. China Experimental Fast Reactor (CEFR), China's first fast neutron reactor independently developed by CNNC China Institute of Atomic Energy, reached its first criticality today. Yang Changli, member of the party group and deputy general manager of China National Nuclear Corporation and leader of the China Experimental Fast Reactor Leading Group, said that this means that China has achieved a major breakthrough in the fourth generation of advanced nuclear energy system technology, becoming the eighth country in the world with fast reactor technology. Yang Changli introduced that the fast neutron reactor represents the development direction of the fourth generation nuclear energy system. The closed cycle of nuclear fuel formed by it can increase the utilization rate of natural uranium resources from about 1% of pressurized water reactors to more than 6%, and at the same time, it can fully burn nuclear waste, reduce the discharge of pollutants and minimize radioactive waste. Due to the improvement of utilization rate, relatively poor uranium mines also have the value of mining, which will increase the world's recoverable uranium resources by a thousand times. The development and promotion of fast reactors is considered to fundamentally solve the problems of sustainable development and green development of world energy.
It is understood that CNNC has initially established the R&D system and standard specification system of sodium-cooled fast reactor technology, comprehensively mastered the physics, thermodynamics, mechanics, overall, structure, loop, instrument control and electrical design technology of fast reactor, obtained a number of independent innovation achievements represented by sodium technology, and applied for more than 1 patents. It is worth mentioning that the experimental fast reactor has nearly 2 systems and more than 7, sets of equipment. The localization rate is over 7%.
In terms of engineering design, the experimental fast reactor has also made breakthroughs in many aspects: the passive accident residual heat discharge system was adopted for the first time in the world; Completed the design of reactor refueling system independently.
As a major project of the National 863 Program, the China Experimental Fast Reactor is the focus of the fourth generation nuclear energy technology research and development of China National Nuclear Corporation. The reactor adopts the sodium-cooled fast reactor technology with many reactor operation experiences in the United States, France, Russia, Japan and other countries, with a thermal power of 65 MW and an electric power of 2 MW.
the construction of experimental fast reactor is the first step in the development of China fast reactor. Yang Changli also said that in the future, CNNC will accelerate the construction of the fourth generation nuclear power unit-China demonstration fast reactor, and promote the development of China's uranium-plutonium mixed fuel manufacturing technology and other supporting technologies.
On July 22nd, 211, at 1: a.m., China's first China experimental fast reactor, which was caused by fast neutrons, was successfully connected to the grid for power generation. The full realization of the major project goal of the National 863 Program marks a major breakthrough in fast reactor technology, which has been included in the frontier technology of the national medium-and long-term scientific and technological development plan, and also marks an important step for China to occupy the commanding heights of nuclear energy technology and establish an advanced nuclear energy system with sustainable development.
fast neutron reactor is the main reactor type of the fourth generation advanced nuclear energy system in the world. China experimental fast reactor is the first step in the development of fast breeder reactor in China. The reactor adopts advanced pool structure, with nuclear thermal power of 65 MW and experimental power generation power of 2 MW. It is one of the few high-power experimental fast reactors with power generation function in the world at present, and its main system settings and parameter selection are the same as those of large-scale fast reactor power stations. The experimental fast reactor makes full use of the inherent safety and adopts a variety of passive safety technologies, and the safety has reached the requirements of the fourth generation nuclear energy system. According to Xu Li, chief engineer of China Experimental Fast Reactor, "Compared with previous generations of nuclear energy systems, Fast Reactor has good safety, less waste and obvious advantages. Although China is one step behind some developed countries in developing "fast reactor", we have improved on the basis of learning foreign technology and improved our management methods and safety. " Xu Li said that because the "fast reactor" adopted an advanced passive accident residual heat removal system, the core melting accident at Fukushima nuclear power plant in Japan would not happen in the "fast reactor".
According to the relevant person in charge of China National Nuclear Corporation, the advanced nuclear fuel cycle system with fast reactor as traction has two major advantages: First, it can greatly improve the utilization rate of uranium resources, which can increase the utilization rate of natural uranium resources from about 1% of pressurized water reactors widely used in nuclear power plants to more than 6%. Second, it can transmute the long-lived radioactive waste produced by PWR and realize the minimization of radioactive waste. The development and popularization of fast reactor technology is of great significance to promote the sustainable development of nuclear power and the establishment of advanced fuel cycle system in China, and to the sustainable development of nuclear energy.
this project is headed by the Ministry of science and technology and the national defense science and technology bureau, organized by China National Nuclear Corporation and implemented by China Institute of Atomic Energy. Over the years, the Institute of Atomic Energy has organized hundreds of domestic universities, research institutes and enterprises and vigorously carried out international cooperation. After continuous innovation and collaborative research, it has successively completed research, design, construction and commissioning. In May 29, it began thermal commissioning of the system and achieved the first nuclear criticality on July 21, 21. In the research and development process of experimental fast reactor for more than 2 years, China has fully mastered the fast reactor technology, obtained a large number of independent innovation achievements and patents, realized independent research, independent design, independent construction, independent operation and independent management of experimental fast reactor, formed a complete research and development capability, and trained a group of excellent technical talents. As the chief engineer, Xu Li led the team to create the first "fast reactor" in China from pre-research, conceptual design, preliminary design, construction design, construction, installation and debugging. During the 11-year construction, they have successively completed more than 5, design documents, more than 6 debugging technical documents, more than 6 operation and maintenance procedures, more than 1,2 research reports, nearly 53 design verifications and more than 1, debugging tests. As a brand-new major scientific project, Xu Li and his research team have always insisted on independent innovation and strengthened international cooperation, and have achieved a number of independent innovation achievements represented by sodium technology, applied for more than 1 patents, and the localization rate of equipment is as high as 7%, laying a solid foundation for the development of "fast reactor" in China.