Is it safe to build inland nuclear power plants in China？ Designed to withstand a magnitude 9 earthquake.

[Global Military Report] The large-scale construction of nuclear power plants in China has always attracted the attention of all sectors of society. Nur Bai Keli, director of the National Energy Administration, revealed on the 6th that by 2020, the total installed capacity of nuclear power in operation and under construction in China will reach 88 million kilowatts. However, the painful lessons of several major nuclear accidents abroad have made many people "smell the nuclear color change". As the expectation of "the 13th Five-Year Plan" for inland nuclear power in China continues to heat up, many people on the Internet have questioned the safety of building nuclear power plants in inland China. Taohuajiang nuclear power station, Hunan Province is one of the first inland nuclear power plants in China. Zheng Yanguo, deputy to the National People’s Congress and general manager of Hunan taohuajiang Nuclear Power Co., Ltd., gave a detailed introduction to the multiple safety guarantees of China nuclear power plant in an interview with the Global Times reporter on the 6th.

What the hell is an inland nuclear power plant?

Recently, the controversial "inland nuclear power plant" on the Internet is actually not a professional concept. The International Atomic Energy Agency (IAEA) usually divides the site of nuclear power plants into three categories: coastal, riverside and lakeside according to the different water sources and receiving bodies. Zheng Yanguo said, according to the custom, we collectively refer to the sites of riverside and lakeside as inland nuclear power plants, and the nuclear power plants by the sea as coastal nuclear power plants. "In fact, apart from China, other countries in the world don’t have the term" inland nuclear power ". In China’s nuclear safety regulations, guidelines and standards, the word’ inland nuclear power’ is not seen. "

Zheng Yanguo said that the safety standards of Binhai, Binhe and Binhu nuclear power plants are the same at home and abroad. "The difference is that it is necessary to carry out adaptive design according to the conditions and environmental capacity of the site." He further introduced that, for example, as a coastal site, Japanese nuclear power plants consider the tsunami to a greater extent than Qinshan nuclear power plant, because Qinshan nuclear power plant does not have the conditions for a large-scale tsunami; Coastal nuclear power plants in cold areas should consider the freezing of water intake sources, while coastal nuclear power plants in subtropical areas are not necessary; Similarly, threats such as tsunami and wind wave should be considered in coastal sites, and there is no tsunami in inland areas, but floods should be considered; Because of the different receiving water bodies, the emission standard of coastal nuclear power plants is lower than that of inland, and the ability of coastal areas to withstand thermal pollution is higher than that of inland areas (so inland nuclear power plants will build cooling towers for secondary circulation cooling). He also said that in fact, more than half of the nuclear power units in operation in the world are located in inland areas.

Multiple technologies to ensure more reliable reactors

Some people also question whether the nuclear power plants built in China are safe even if there is no difference in safety standards between inland and coastal nuclear power plants. For nuclear power plants, the most terrible thing is the reactor accident. Zheng Yanguo said that two indicators, namely "core damage frequency (CDF)" and "early release frequency of a large amount of radioactivity (LERF)", are used internationally to show the safety level of the reactor. Core damage is a serious accident. The lower the CDF value, the lower the frequency of reactor melting. LERF refers to the probability that radioactive materials will enter the environment after a serious accident and the containment will fail further. In this regard, the safety indicators of China nuclear power plant are stricter than international standards. For example, he said, the International Atomic Energy Agency requires the CDF of nuclear power plants to be 10-4, and the requirements in the Requirements Document for Nuclear Power Users in the United States are 10-5, while the CDF of third-generation nuclear power technologies such as AP1000 and Hualong No.1 adopted by China is 10-7. Generally speaking, the CDF of AP1000 reactor used in taohuajiang nuclear power station is more stringent than the international standard, and the probability of accidents is lower.

How is this high safety of the reactor achieved? According to reports, at present, the AP1000 nuclear power technology adopted by China’s nuclear power plants has learned the lessons from the accidents at Three Mile Island in the United States, Chernobyl in the former Soviet Union and Fukushima in Japan, and learned from the experience feedback of the world’s nuclear power plants for decades and a large number of research results. On the basis of the traditional pressurized water reactor nuclear power technology, a "passive" safety system has been adopted. Zheng Yanguo said that the Fukushima nuclear accident was caused by the tsunami caused by the earthquake, which caused the power failure of the nuclear power plant, and the reactor could not be cooled, which led to the big explosion and the core melting. The "passive" technology of AP1000 safety system can drive the safety system of nuclear power plant by using natural phenomena such as gravity and material gravity, which can ensure that the Fukushima nuclear accident will not be repeated even if there is a power outage similar to that in Fukushima, Japan.

The proposed nuclear power plant can withstand a magnitude 9 earthquake.

One of the major natural risks faced by inland nuclear power plants is earthquakes. Zheng Yanguo said that according to the requirements of China’s nuclear safety regulations, a detailed seismic safety evaluation should be conducted at the site selection stage of nuclear power plants, and the evaluation should be completed by professional technicians from the national seismological department. According to the evaluation results, the inland nuclear power plant site needs to be in the low seismic activity area, and the near area of the plant site does not have the conditions for a major earthquake.

At the same time, according to the requirements of China’s nuclear safety regulations and the seismic safety code for nuclear power plants, the horizontal and vertical acceleration of the AP1000 unit to be built in the inland site is 0.3g. The evaluation of seismic margin shows that when the horizontal and vertical acceleration of the ground is lower than 0.5G, it can ensure the safe shutdown and maintain a safe state, which is much higher than the design reference ground motion (0.15G) of the nuclear power plant site. The peak value of ground horizontal acceleration in the vicinity of the nuclear power plant in the Fukushima earthquake of magnitude 9 in Japan is estimated to be 0.41G to 0.50G, that is to say, the AP1000 nuclear power plant to be built by inland nuclear power can also ensure safety in an environment similar to the Fukushima earthquake of magnitude 9 in Japan.

As a "just in case" response, the nuclear power plant has carefully considered the feasibility of emergency preparation and response for nuclear accidents before going to Malaysia. At the site selection stage, it has formulated a regional nuclear emergency plan according to the site conditions (population distribution, transportation, meteorology, medical care, communication, agricultural and sideline production, water resources utilization and external events), and demonstrated the feasibility of implementing emergency protection and medium-and long-term protection actions. These measures can ensure the safety of nearby residents as much as possible when accidents occur.

At the same time, considering the concerns of the public in China, inland nuclear power plants must formulate emergency plans to ensure the safety of water resources under serious accident conditions and ensure that environmental risks can be controlled. These measures include: using safe factory buildings to store radioactive sewage, and equipped with a number of large-capacity discharge tanks as a supplement or backup to the storage capacity of waste liquid; The foundation and foundation of the nuclear power plant adopt leak-proof design, and the pipelines entering and leaving the containment are separated by double valves, and radioactive pollutant inhibitors and zeolite filtration devices are equipped. Space shall be reserved in the factory area for installation of mobile emergency waste liquid treatment device in case of emergency. Through these measures, even in extreme cases, radioactive sewage can be stored, blocked, isolated and treated.

Zheng Yanguo emphasized, "In summing up the lessons of the Fukushima nuclear accident, the international nuclear energy community did not mention that inland nuclear power plants have the risk of endangering water resources security, which shows that the risk of inland nuclear power plants to water resources security belongs to’ residual risk’ which is lower than the risk of various serious accidents. For such’ residual risks’, the international nuclear energy community no longer requires fortification in regulations and standards. "

Nuclear science popularization has a long way to go.

In February, 2008, the National Development and Reform Commission approved three inland nuclear power projects in taohuajiang, Hunan, Dafan, Hubei and Pengze, Jiangxi to carry out preparatory work. Taohuajiang nuclear power project was originally planned to formally start construction in 2011 and put into commercial operation in 2015. However, the accident of Fukushima nuclear power plant in Japan in 2011 brought the inland nuclear power projects in the above three places to an abrupt end. Nur Bai Keli said on the 6 th, "We are still conducting in-depth argumentation on the construction of nuclear power plants in the inland and listening to opinions from all walks of life. There is no clear timetable at present."

In recent years, the development of clean energy in China has advanced by leaps and bounds, but the total amount of nuclear power is still at a low level. Relevant statistics show that the total installed capacity of nuclear power in operation in China only accounts for 1.78% of the total installed capacity of electricity, far below the average level of 15%-20% in developed countries. Many China nuclear power experts interviewed by Global Times generally believe that there are no technical problems in the construction of inland nuclear power plants, but there are obvious deficiencies in nuclear science popularization. The current development of nuclear power in China is largely related to the public’s acceptance of nuclear power.

Zheng Yanguo said that taohuajiang nuclear power station has carried out a series of popular science work for the people around it. For example, through the nuclear power open day, the surrounding organs and villagers are organized to visit the built Qinshan nuclear power base to eliminate nuclear fears and doubts. In the process of communication with the public, he felt that it is the common work of the whole industry or society to carry out public communication on nuclear power.

[Global Times reporter Guo Yuandan Ma Jun]