1. Compared with thermal reactor, dynamic parameter fast reactor has the characteristics of high core enrichment, hard energy spectrum, smaller Doppler effect than thermal reactor, smaller delayed neutron share and shorter neutron generation time, which is not conducive to fast reactor control, and requires fast reactor control system to have better transient response characteristics.
2. In the fast reactor, thermal neutrons are almost non-existent, so the material with high thermal neutron absorption cross section, which is very important in the fast reactor design, is almost not so important in the fast reactor. Fission products such as "nuclear" are relatively unimportant, and there is no xenon poisoning problem in fast reactors. The core of fast reactor is small, and the average free path of fast neutron is longer than that of thermal neutron, so the coupling platform of fast reactor core is tighter than that of thermal neutron. There is no problem of regional instability, no need to consider the control valve problem of fast reactor power distribution fluctuation, and no need to measure the core power distribution like PWR. In this sense, it is beneficial to simplify the design of instrument control system.
3. Reactivity control Because the fast reactor uses sodium as coolant, it can't control the reactivity with soluble poisons such as boric acid. Generally, a single control rod is used to control the 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 plate measuring instruments. Status 201July 2 1 day, China National Nuclear Corporation announced in Beijing today that China's first fast neutron reactor, China Experimental Fast Reactor (CEFR), independently developed by the Institute of Atomic Energy Science of China National Nuclear Corporation, has reached its first criticality. This is a major independent innovation achievement in China's nuclear power field, which means a major breakthrough in China's fourth-generation advanced nuclear energy system technology. 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), the first fast neutron reactor in China independently developed by CNNC China Institute of Atomic Energy, reached the critical state for the first time today. Yang Changli, member of the leading group of China National Nuclear Corporation, deputy general manager and leader of the China Experimental Fast Reactor, said that this means that China has made a major breakthrough in the fourth-generation 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 over 60%, and at the same time, it can fully burn nuclear waste, reduce pollutant emissions and minimize radioactive waste. Due to the improvement of utilization rate, relatively poor uranium deposits are also valuable for mining, which will increase the world's exploitable uranium resources by 1000 times. The development and popularization of fast reactor is considered to fundamentally solve the problems of sustainable development and green development of world energy.
It is understood that at present, 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, circuit, 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 100 patents. It is worth mentioning that the experimental fast reactor has nearly 200 systems and more than 7,000 sets of equipment. The localization rate is over 70%.
In terms of engineering design, the experimental fast reactor has also made many breakthroughs: the passive accident residual heat removal system was adopted for the first time in the world; Independently complete the design of reactor refueling system.
As a major project of the National 863 Program, 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 sodium-cooled fast reactor technology with many reactor operation experiences in the United States, France, Russia, Japan and other countries, with thermal power of 65 MW and electric power of 20 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.
At 2011July 22nd 10, the first China experimental fast reactor in China was successfully connected to the grid for power generation. The full realization of the major project objectives 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 to develop fast breeder reactor in China. The reactor adopts advanced pool structure, with nuclear thermal power of 65 MW and experimental power generation of 20 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, which meets 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 made improvements on the basis of learning foreign technology and improved management methods and safety. " Xu Li said that because the "fast reactor" adopted the advanced passive accident residual heat discharge system, the core melting accident of 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, and 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 60%. 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.
The 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 Atomic Energy Institute has organized hundreds of domestic universities, research institutes and enterprises to vigorously carry out international cooperation. Through continuous innovation and collaborative research, research, design, construction and debugging have been completed. Thermal debugging of the system began in May 2009, and the first nuclear criticality was achieved on July 2 10. In the research and development process of experimental fast reactor for more than 20 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 outstanding technical personnel. As the chief engineer, Xu Li led the team to build the first "fast reactor" in China from pre-research, conceptual design, preliminary design, construction design, construction, installation and commissioning. During the construction of 1 1 year, they have successively completed more than 5,000 design documents, more than 600 debugging technical documents, more than 600 operation and maintenance regulations, and more than 200 various research reports, and carried out nearly 53 design verifications and more than 0,000 debugging tests of 1000. 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 many independent innovation achievements represented by sodium technology, applied for more than one patent 100, and the localization rate of equipment is as high as 70%, laying a solid foundation for the development of "fast reactor" in China.