It is reported that Daya Bay Nuclear Power Station is located in Dapeng Peninsula, Longgang District, Shenzhen City, Guangdong Province. It was started construction in 1987 and put into commercial operation in 1994. It is China's first large-scale commercial nuclear power plant. Since the unit was put into operation, it has been operating safely and stably. Since 1999, Daya Bay Nuclear Power Plant has won 21st place in the safety performance challenge competition of 64 international units of the same type.
Technology is more advanced and reliable
The first is the different technical route. According to Ji Jilong, an expert from the State Nuclear Power Commission, the Fukushima nuclear power plant uses an old-fashioned single-layer circulating boiling water reactor. The cooling water is directly introduced into the seawater cooling circuit. The boiling water reactor does not have a steam generator. The steam generated by boiling water directly drives the turbine. At the time of operation, the steam is radioactive, and in the event of a malfunction, the radioactivity will increase. It is an early nuclear power technology built in the late 1960s and early 1970s.
Ji Jilong said that the Daya Bay nuclear power plant uses pressurized water reactor technology. It has technically used the experience of the 1979 US nuclear power plant accident in Sanlit Island and the 1986 pre-Soviet nuclear power plant accident in Chernobyl. The technology has been greatly improved and has security. High-tech, advanced, reliable and mature, etc., belong to more advanced nuclear power plants built after the 1990s. At present, there are more than 70 similar units in operation around the world, and more than 1,000 years of experience in the operation of nuclear power units of the same type have been accumulated.
Lower probability of hydrogen explosion
The second is different special security facilities. Ruan Jilong said that the Fukushima nuclear power plant uses technology 40 years ago, and the reactor containment space is small, only about 3,400 cubic meters of space. In the event of a serious accident, the boosting process is rapid and hydrogen explosion is prone to occur.
The containment of the Daya Bay Nuclear Power Plant consists of reinforced concrete cylinders, with a space of 49,000 cubic meters, which can effectively reduce and dilute the hydrogen concentration and delay the pressure rise of the containment vessel. At the same time, a hydrogen elimination system was installed in the containment vessel, and dozens of hydrogen complexes that deal with hydrogen risks could resolve the risk of hydrogen explosion caused by hydrogen accumulation in the containment under severe accidents.
In addition, the Daya Bay nuclear power plant is also equipped with a sand filter. Under extreme conditions, if the pressure of the containment vessel exceeds the design value, the sand filter can allow the gas in the containment to be discharged to the atmosphere. The sand filter can retain the gas. Most of the radionuclides are to avoid the direct loss of control of radioactive materials in the primary loop to the environment.
Site site is safer and more stable
The third is different geological conditions. According to Li Zhongcheng, an expert at the National Energy Nuclear Power Engineering Technology Research and Development Center, Japan is located at the junction of the Asia-Europe plate and the Pacific plate, and is located on the Pacific plate to the Asia-Europe plate subduction zone. The crustal movement is active. The strong earthquakes mainly occur in the plate subduction and collision zone. on.
The Daya Bay nuclear power plant site is selected from more than a dozen alternative sites in the coastal area of ​​Guangdong Province. It is located in the coastal zone in the southeastern part of the Eurasian plate, far from the structurally deformed North-South tectonic belt and the Philippine Sea Plate subduction zone. There are no fractures near the site. In addition, the Earth's crust is safe and stable, and there have been no earthquakes with a magnitude of more than 5 in history. Therefore, an earthquake with a magnitude equivalent to that of the Japanese earthquake will not occur at the Daya Bay nuclear power plant site.
Greater ability to deal with tsunami
Fourth, the ability to deal with tsunami is different. The Japan Fukushima nuclear power plant is safe and controllable after the earthquake, and the related plants and facilities are basically complete. According to the current accident analysis, the tsunami inundation of diesel engines is the cause of the uncontrollable and progressive deterioration of the accident. Therefore, whether the Daya Bay nuclear power plant can cope with a similar tsunami is an issue of concern to the outside world.
Li Zhongcheng said that the waters of Daya Bay are fringe seas. Because sea water is not deep enough, it is only 20 to 30 meters, and the propagation of tsunami requires a water depth of nearly 1,000 meters. There are generally "island arcs" between the marginal sea and the open sea. The "island arc" is a series of island chains. The tsunami caused by seismic waves can only be transmitted from the gaps in the island chain and has limited energy. The tsunami recorded on the coast of China is at the maximum of 0.5 meters. Therefore, there will be no strong tsunami similar to Japan in the Daya Bay nuclear power plant site.
The biggest natural disaster risk facing the nuclear power plant sites in China's coastal areas is a super typhoon. Daya Bay Nuclear Power Station is in a place where hot typhoons frequently occur. The design flood control water level of the site is the sum of the astronomical orgasm that exceeds the probability of 10%, the possible maximum storm surge, and the rise of sea level during the lifetime of the power plant.
Second, the Daya Bay nuclear power plant is more capable of responding to tsunami than the Fukushima nuclear power plant. Even if the Daya Bay Nuclear Power Plant loses all its internal and external power supplies, it can also use the steam generated by the core waste heat to drive the nuclear safety-related steam-powered feed pumps to the steam generators. At the same time, the second circuit is equipped with an atmospheric emission system. After the power is lost, the reactor core can be cooled by natural circulation to dissipate the heat to the atmosphere, so as to prevent the temperature and pressure in the reactor pressure vessel from rising continuously. In addition, the Daya Bay nuclear power station is equipped with a second diesel engine for emergency use in addition to two emergency diesel engines for each unit.
Awe and watch for nuclear safety
Fifth is the long-term adherence to the "safety first" nuclear safety culture. Jiang Xinghua, director of the Daya Bay Nuclear Power Station, said that the Daya Bay Nuclear Power Station has always followed the principle of “safety first, quality first†during the production and construction process. It regards safety as the lifeline of nuclear power and respects and watches nuclear safety with a high degree of responsibility for the country and society. When other work elements conflict with security, they must give way unconditionally. At any time and under any circumstances, safety and quality should be put first, and quality should not be used for progress, and no safer exchange should be used for power generation. For example, in September 1987, shortly after the commencement of the Daya Bay nuclear power plant, the quality inspectors discovered that some of the steel was leaked from the base of the nuclear island during work. In order to ensure the quality of the project, Daya Bay Nuclear Power Station conducted a month-long rectification at a cost of US$1 million a day for each stoppage of work, and resolutely refused to change the quality of the progress or change the investment. In February 1995, when Unit 1 of the Daya Bay Nuclear Power Station carried out a reactor rod drop test, the staff found that a small number of control rods fell time compared with the design standards. Although the test results are within the safety margin and do not affect the operation of the unit, the Daya Bay Nuclear Power Station strictly adheres to the principle of “nuclear safety first, responsible to the publicâ€, and stops the unit decisively, and opens the reactor pressure vessel five times to process it thoroughly. After clearing the cause of the deviation and improving it properly, the unit was started to operate. This incident lasted five months. Although it paid a huge economic price, it replaced the Daya Bay Nuclear Power Plant's safety first, strict and serious, conservative decision-making, and a good reputation of "zero tolerance, zero defect, zero mistakes." Through rigorous training, the practitioners of the power station have formed a style of acting according to procedures, and have established the concept of “having done everything well and everyone is a barrierâ€.
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