​It's exciting to listen to! People south of this line in China have hope for winter

Recently, the news that "three communities in Haiyan, Zhejiang use centralized nuclear energy for heating" became a hot topic on Weibo.

This heating project utilizes the surplus thermal power of the units at the Qinshan Nuclear Power Base in winter to provide large-scale safe, zero-carbon and economical nuclear energy heating to Haiyan's public facilities, residential communities and industrial parks without affecting the safety performance of the units.

Upon hearing this, residents of other southern cities also expressed their great need and became curious about the nuclear energy heating method.

In 1938, when German scientist Otto Hahn first discovered the phenomenon of nuclear fission, he could never have imagined that it would later become a magical tool for humans to keep warm.

So, how does nuclear energy provide heating? Will the winter in the south no longer be cold and damp?

Text | He Fang

Editor | Xie Fang, Outlook Think Tank

This article is an original article from Outlook Think Tank. If you need to reprint it, please indicate the source Outlook Think Tank (zhczyj) and the author information at the beginning of the article, otherwise legal responsibility will be strictly pursued.

1

An “old” technology

When a neutron hits an atomic nucleus, it breaks into several pieces. If you collect these pieces and weigh them, you will be surprised to find that the mass of the pieces is less than the original mass of the nucleus. Mass does not disappear for no reason. As predicted by Einstein's mass-energy equation, the lost mass is converted into energy. This energy is nuclear energy.

There is no good or bad in nuclear energy. The key lies in how humans use it.

On December 2, 1942, physicist Fermi started up the world's first atomic reactor, the Chicago Reactor 1, in Chicago. From then on, a new energy source was added to the world and the nuclear age began.

On June 27, 1954, the Obninsk Nuclear Power Plant, the world's first commercial nuclear power plant built by the Soviet Union, began generating electricity. Although its total output power was only 5,000 kilowatts, the history of nuclear power plants began from then on, and it also meant that the peaceful use of nuclear energy became a reality. The Obninsk Nuclear Power Plant operated safely for nearly 50 years, was "decommissioned" in 2002, and was transformed into a Russian museum and science and technology museum in 2004.

Since the Obninsk Nuclear Power Plant, countries around the world have started a wave of nuclear power construction. The Soviet Union, the United States, Britain, France, Germany and other countries have built a large number of nuclear power plants.

When the feasibility, economy and safety of nuclear energy for power generation were verified, European countries that lacked fossil energy and suffered from cold winters began to study the use of nuclear energy for heating.

In 1964, the Swedish prototype nuclear power reactor Agesta was completed and put into operation. It was the world's first nuclear power plant to use nuclear energy for heating for civilian use. Since then, European countries have begun to use nuclear energy for heating.

Nuclear heating mainly adopts the form of cogeneration, in which the reactor is used to generate electricity in normal times, and when the heating season comes, the power is increased and the nuclear heating equipment is started to achieve heating. Currently, more than 50 of the more than 400 reactors in the world provide nuclear heating services.

However, the main purpose of a cogeneration reactor is to generate electricity, and heat supply is just an extension of the reactor's function. As a result, heating can only be achieved by transforming nuclear power plants in places where nuclear power plants were built. After all, nuclear power plants have high investment costs and high safety requirements, and it is impossible to build a nuclear power plant specifically for heating.

So, is it possible to build some heating reactors with low construction cost, fast construction speed and high safety level?

The answer is yes.

Nuclear energy has high energy density and low energy cost. Nuclear energy developing countries such as Canada, France, the Soviet Union, the United States, and Switzerland have all conducted research on low-temperature heating reactors and developed a series of heating reactor types. For example, Canada built a 2-megawatt SLOWPOKE (SDR) atmospheric pressure pool heating reactor in 1987, which provided heating for buildings for two years.

By the 1970s, the technical research on nuclear energy heating in various countries had become mature, and the safety and reliability of nuclear energy heating had also been verified. At that time, various countries had accumulated many years of operating experience in nuclear energy heating, and no nuclear accidents or safety accidents had occurred. It can be said that from the perspective of the maturity and safety of the technology, there is no fundamental problem in promoting nuclear energy heating technology.

However, until the 21st century, single nuclear heating reactors were still rarely commercialized. The current mainstream form of nuclear heating is still to use the original nuclear power plant, add steam extraction heating equipment, and achieve cogeneration of heat and power.

The promotion of nuclear energy heating technology is mainly limited to the following two aspects.

The first reason is economic. Nuclear heating has a low fuel cost, but the cost of reactor construction site selection, equipment safety level, and supporting safety equipment is high. Compared with fossil energy, it does not have an economic advantage.

The second reason is the sensitivity of nuclear technology. The nuclear issue was originally a technical issue, but due to the involvement of nuclear weapons proliferation and the public's sensitivity to nuclear technology, it began to evolve into a political issue, which hindered the promotion and application of nuclear heating technology.

2

Combined Heat and Power

my country's nuclear heating technology started late, but research has been ongoing and the technology has made continuous progress. At present, my country's nuclear heating technology has the ability to be commercially applied, but due to sensitivity and economic reasons, the construction planning of nuclear heating reactors is very slow.

There are three buildings that use nuclear energy for heating at the Nuclear Research Institute of Tsinghua University in Changping, Beijing.

In 1983, Chinese scientists and engineers transformed a shielded room test reactor into a low-temperature heating test reactor, marking the beginning of my country's research on nuclear energy heating technology. In 1989, the reactor was officially put into operation and successfully provided heating to the 15,000 square meter building. On this basis, my country built a 5 MW low-temperature nuclear heating reactor and achieved cogeneration. Since then, my country has continued to complete the key technology research of the 200 MW commercial nuclear heating reactor NHR200-I, and in 2003, it developed the NHR200-II low-temperature nuclear heating reactor with higher operating parameters.

Looking back at the history of nuclear heating, we can easily find that the most convenient way to achieve nuclear heating is to use existing nuclear power plants, add a heating equipment to them, and achieve nuclear heating in the form of cogeneration.

The structure of a nuclear reactor is not complicated. Take the pressurized water reactor, which is the most widely built in mainland my country, for example: a bunch of compact nuclear fuel assemblies are "stacked" together, and control rods for controlling the reactor power are inserted into them, forming the main structure of the reactor - the core; then, the core is "soaked" in water, and the heat generated by the core is taken away by the high-speed flowing water. This is the basic structure of a pressurized water reactor.

These high-speed water flows pass through a collection of pipes called "heat exchangers" to heat the pipe walls; outside the pipe walls, in a space called the "secondary circuit," another water flow will flush these heated pipe walls at high speed, taking away the heat and converting it into high-temperature steam. Relying on this form of "inter-tube wall exchange," the reactor can safely "transfer" energy while retaining all radioactive products. Therefore, the high-temperature steam generated in the secondary circuit is essentially no different from the steam generated by the boiler of a thermal power plant.

When steam enters the steam turbine, it can drive the steam turbine generator to operate and generate a steady stream of electricity. This process is almost identical to that of a thermal power plant. If a portion of the steam driving the steam turbine is extracted at this time and used as a heat source to heat the water in the heating pipe, nuclear energy heating can be achieved. This is also the current technical method of commercial nuclear energy heating in my country.

Using this method for nuclear heating does not involve nuclear reactor modification or nuclear safety issues. The technology is simple to implement, the construction difficulty is low, and the economy is high.

At present, more than one-tenth of the more than 400 operating nuclear reactors in the world have achieved cogeneration of heat and power, and a total of about 1,000 reactors have been operating safely per year.

3

There is Shandong Haiyang in the north and Zhejiang Haiyan in the south

The latest data from the Ministry of Housing and Urban-Rural Development shows that my country's winter heating area has increased at an average annual rate of about 10%. As of the end of 2019, the country's centralized heating area has reached 11 billion square meters, and the energy consumption for heating in northern cities is 191 million tons of standard coal, accounting for about a quarter of the total building energy consumption.

Some experts said that the demand for heating in the north is growing rapidly, but the heat source is decreasing, and it is necessary to vigorously develop clean energy heating, including nuclear energy heating.

In 2019, Shandong Haiyang Nuclear Power Station achieved nuclear energy heating for the first time by extracting part of the steam.

After nearly two years of development, the 4.5 million square meters of the second phase of the commercial demonstration project of nuclear energy heating at Haiyang Nuclear Power Station was officially put into operation in early November this year. Haiyang City has completely bid farewell to coal-fired heating and has become the first "zero-carbon" heating city in the country, benefiting 200,000 residents. At the same time, the commissioning of this project has also achieved a "zero breakthrough" in domestic commercial nuclear energy heating.

The application of nuclear energy has promoted the transformation and upgrading of traditional thermal power companies.

The head of an energy company in Haiyan said that after nuclear energy heating, the original boilers and environmental protection equipment are no longer used. The boiler room that used to require nine people to work in three shifts has become an unmanned heat exchange station that only requires regular inspections. In one heating season, his company can save up to 3 million yuan in environmental protection, electricity, and labor costs.

Luan Jian, director of the Shandong Provincial Energy Bureau, revealed that Shandong Province will focus on building a tens of millions kilowatt nuclear power base on the Jiaodong Peninsula, and simultaneously promote the comprehensive utilization of nuclear energy for heating. It is expected that by 2030, the scale of installed capacity in operation will reach more than 13 million kilowatts, and all areas in the Jiaodong Peninsula with conditions will realize nuclear energy heating.

There is Haiyang, Shandong in the north and Haiyan, Zhejiang in the south.

Every winter, cities south of the Qinling-Huaihe line often suffer from damp and cold weather because they are located in illegal centralized heating areas. As people's living standards continue to improve, southerners are calling for more winter heating.

Previously, due to factors such as energy shortages and infrastructure shortages, the central heating campaign in the south was not fully launched. Now, nuclear energy, as a clean energy, brings hope to the people in the south.

Haiyan County in Zhejiang Province is located south of the Qinling-Huaihe line, and there is no heating company engaged in central heating in the county. However, Haiyan County has the Qinshan Nuclear Power Plant.

On December 15, 1991, the Qinshan Nuclear Power Plant was connected to the grid, ending the history of mainland China without nuclear power. my country also became the seventh country capable of independently designing, building and operating nuclear power plants.

On December 3 this year, Qinshan Nuclear Power Station installed heating equipment on the original commercial nuclear power plant and extracted part of the steam as a heat source to heat the heating system, allowing 4,000 households to have nuclear heating. This is the first nuclear heating project in southern my country and a landmark event in southern heating.

It is worth noting that the Qinshan Nuclear Power Plant's nuclear heating project took less than five months from the start of construction to completion and commissioning.

Qinshan Nuclear Power Nuclear Energy Heating Demonstration Project. Photo provided by the author

At present, Haiyan County has put into operation the first phase of the project, which only involves nuclear heating in three communities (because these three communities already have heating pipelines). According to the plan of the Qinshan Nuclear Power Nuclear Heating Project, by the winter of 2022, nuclear heating will be provided to the west and north of the main urban area of ​​Haiyan County. In the future, the Qinshan Nuclear Power Nuclear Heating Project will radiate the entire Haiyan County and the surrounding streets and towns, making Haiyan County a landmark city for nuclear heating in the south.

4

Economic and environmental accounts

So, is nuclear heating expensive?

Nuclear heating is not expensive. In the past, one of the important reasons why Western countries developed nuclear heating was the high cost of fossil heating. Today, my country uses nuclear power units to generate heat and power in a cogeneration way to achieve nuclear heating. Excluding the cost of laying and maintaining heating pipelines, the main cost of nuclear power plants is fuel costs. In other words, when nuclear heating is carried out in winter, nuclear power plants only need to make the reactor "furnace" burn more "vigorously", and the cost of nuclear fuel is quite economical compared to the cost of fossil energy.

Judging from the operation of the Shandong Haiyang nuclear energy heating project, excluding the cost of nuclear energy heat transmission pipelines, the cost of nuclear power heating is equivalent to that of coal burning; for the Qinshan Nuclear Power Nuclear Energy Heating Project, the heating costs of users in the communities that have achieved nuclear energy heating services have also decreased to a certain extent compared to before.

Residents of Haiyan County said that the community used natural gas boilers for heating, and the charge for one heating season was 46 yuan per square meter. Now it has been changed to nuclear power heating. In addition to the external pipe network, the indoor heating equipment is still the same, but the price will be reduced to 30 yuan per square meter. According to their 70 square meters, one heating season used to cost 3,220 yuan, but now it has been reduced to 2,100 yuan, saving 1,120 yuan.

In addition to the economic considerations, nuclear energy heating, as a highly efficient and clean form of heating, also needs to take environmental considerations into account.

Taking the Qinshan Nuclear Power Nuclear Energy Heating Project as an example, after the project is fully put into operation, it can save 196 million kWh of electricity consumption per year compared with electric heating; compared with coal-fired thermal power units, it can reduce the use of standard coal by about 24,600 tons per year, and accordingly reduce sulfur dioxide emissions by 1,817 tons, nitrogen oxides by 908 tons, and carbon dioxide emissions by 59,000 tons per year. This is just a project serving the county. If subsequent nuclear energy heating projects are fully promoted, it will be of great significance to my country's carbon peak and carbon neutrality.

At present, my country's carbon emission trading market is gradually being established, and nuclear power plants have also begun to join the carbon emission trading market. On the one hand, this can stimulate the enthusiasm of nuclear power companies to participate in nuclear heating, and on the other hand, it can further reduce the cost of nuclear heating.

However, as mentioned above, the current nuclear heating is to transform existing nuclear power plants and install heating systems without affecting nuclear safety. All of my country's commercial nuclear power plants are located in coastal areas, and only a few are located in the northern coastal areas, which makes it difficult to achieve nuclear heating in inland areas.

As of October 31, 2021, there are 71 nuclear power units under construction and in operation in mainland my country, including 52 in operation. Source: National Nuclear Safety Administration

With the advancement of long-distance heat transmission technology, it is expected that nuclear energy heating will be possible within a 200-kilometer radius of a coastal nuclear power plant in the future. From this perspective, there is still great potential for the current use of commercial nuclear power plants to install heating systems to achieve nuclear energy heating.

It should be noted that using the existing nuclear power plant cogeneration method to provide nuclear energy heating can ensure safety, economy and efficiency. However, facing the vast territory, nuclear energy heating at this stage has little effect on changing my country's winter heating method that mainly relies on fossil energy. In the future, vigorously developing multi-purpose small reactors can better play the role of nuclear energy heating in low-carbon emission reduction and serving the people.

At present, my country has studied various types of advanced small reactors. At the same time, my country has built a fourth-generation advanced gas-cooled reactor project in Shandong and started the Linglong No. 1 small reactor project in Hainan. These advanced reactors adopt a modular construction method, which has a shorter construction period and can perform functions such as power generation, steam supply, heating and even seawater desalination as needed. Compared with traditional nuclear power plants, they are safer, more advanced and more economical in design.

In the future, if these small reactors are built on a large scale, they will become the main force for nuclear heating.

References:

1. Fermi: Pioneer of the Atomic Age | Guo Shicong. Science World. 2002(03)

2. First scene: Exploring the secret of the first nuclear power plant's "zero accident" | Chen Xiaowei, Xie Yahong. People's Daily Online. 2014-06-26

3. The first nuclear energy heating project in the south is put into operation. Can it be replicated and promoted? | Yang Yang. The Paper. 2021-12-05

4. "Warm core"! Haiyang becomes the first "zero-carbon" heating city in China | Wang Hao, Jing Yi. Peninsula Metropolis Daily. 2021-11-15