[The temperature of science] How does China build the hard-core "firewall" of the world's largest "artificial sun"?

　　China News Service, Chengdu, February 24 (Wang Liwen) The sun releases light and heat through nuclear fusion reactions. Scientists hope to use this principle to develop a steady stream of clean energy for human beings.

Therefore, the controllable nuclear fusion device for the purpose of exploring clean energy on the earth is also vividly called "artificial sun".

Nuclear fusion fuel can be derived from seawater, which is inexhaustible and sufficient for human use for tens of billions of years.

Nuclear fusion energy is also known as the ideal clean energy for the future of mankind.

　　In November 2022, the world's largest "artificial sun" core component "firewall" made significant progress in China. The International Thermonuclear Experimental Reactor (ITER) plans to increase the heat load and complete the first part of the first wall, marking China's realization of the core Leading the way in science and technology has effectively enhanced our country's voice in this field.

Chen Jiming, chief expert of CNNC Nuclear Industry Southwest Institute of Physics and Chinese director of the first wall key component development project of the International Thermonuclear Experimental Reactor ITER, accepted an interview with Chinanews.com, telling how China built the world's largest "artificial sun" Nuclear "firewall".

How to realize "artificial sun"?

The first wall of the International Thermonuclear Experimental Reactor (ITER) enhanced thermal load completed the first piece of manufacturing.

Photo courtesy of CNNC Nuclear Industry Southwest Institute of Physics

　　According to Chen Jiming, the research on "artificial sun" can be traced back to before the 1950s. After scientists discovered the most basic principle of nuclear fusion, various countries gradually carried out related research.

Due to the great difficulty of research, in the 1980s, multiple parties jointly proposed to build the world's largest "artificial sun" device, and the global joint construction of the ITER project kicked off.

　　At present, more than 30 countries have participated in the design, research and development, construction and operation of the later-stage devices of the ITER project, forming shared technologies and intellectual property rights, and laying the foundation for the next generation of "demonstration reactors".

Chen Jiming said that China has undertaken 18 manufacturing tasks of the ITER project, including core parts such as the first wall of the vacuum chamber components and the magnet support system.

　　The reason why nuclear fusion research is so difficult is because of its harsh reaction conditions.

"Deuterium-tritium fusion is the most common and easiest way to realize nuclear fusion, but only under extremely high temperature conditions above 100 million degrees Celsius, can deuterium, tritium and other light nuclei collide and fuse to release huge energy." Jiming Chen Explain that nuclear fusion ignition can only be achieved when the temperature, density, and maintenance time are all up to standard, and at the same time control at high temperatures is required to effectively output nuclear fusion energy.

"Therefore, the ITER device consists of two major systems, the host and the peripheral for power generation, and the host system is more complex."

How to build the "firewall" of "artificial sun"?

International experts came to the Southwest Institute of Physics of CNNC Nuclear Industry for exchanges.

Photo courtesy of CNNC Nuclear Industry Southwest Institute of Physics

　　Since the nuclear reaction in the "artificial sun" needs to be carried out at a high temperature of hundreds of millions of degrees Celsius, a clean high-vacuum environment is required, that is, a large annular vacuum chamber.

After research, scientists use a "doughnut"-shaped tokamak controllable thermonuclear fusion device to confine high-temperature and high-pressure plasma and suspend it in the annular space to achieve the environment and control of nuclear fusion reactions.

　　In this device, the first wall directly facing the extremely strong heat radiation is one of the most important core technologies.

According to Chen Jiming, the first wall plays a huge role. It not only restricts the plasma from crossing the boundary, but also protects the peripheral equipment from being damaged by high temperature. It also brings out the energy released by the nuclear fusion reaction for peripheral energy storage and power generation.

　　The inner side of the first wall of ITER enhances the heat load component is one of the key components that China undertakes to design, develop and manufacture.

The surface of the first wall of the entire 660-square-meter vacuum chamber consists of 440 components, of which 12% is undertaken by China. It is one of the most difficult components to manufacture, and the surface heat radiation it receives reaches 4.7 megawatts per square meter. This is equivalent to 4,700 times the heat that the sun irradiates on the earth's surface.

With more than 50 years of research experience in controllable nuclear fusion, the Southwest Institute of Physics of the Nuclear Industry has become the "contractor" of the "firewall".

In order to ensure quality and submit components on time, after nearly 20 years of development and catching up, China has solved many technical problems in material processing, manufacturing, connection, etc., and achieved a substantial engineering breakthrough in the research and development of ITER key components.

　Why continue to lead in the future?

CNNC Nuclear Industry Southwest Institute of Physics ITER enhanced thermal load first wall project team is overcoming difficulties.

Photo courtesy of CNNC Nuclear Industry Southwest Institute of Physics

　　With the manufacture of all fingers of the prototype and the final assembly progress, in November 2022, the first wall of ITER enhanced thermal load has completed the first part manufacturing. Preliminary testing shows that the core indicators of this part are better than the design requirements, and it is capable of mass production. condition.

Chen Jiming pointed out that this also marks that China has fully broken through the key technology of "ITER enhances the first wall of heat load", and has achieved the global leadership of this core technology. The delivery of products by the international team provided the conditions to ensure the smooth operation of the ITER device.

　　To ensure a clean environment for nuclear fusion, it is necessary that all parts in the vacuum chamber must not have coolant leakage.

"If the plasma and nuclear fusion are polluted, the reaction will be unsustainable." Jiming Chen said, therefore, in 2018, the team successfully developed a helium leak detection technology that simulates the actual operating conditions of fusion. MPa, that is, under the high pressure of 40 atmospheres, it is tested.

With the support of the Ministry of Science and Technology, the team successfully developed the world's first technology that can detect components and the test results meet the requirements of ITER, and submitted an application to the ISO international organization, and successfully approved a high-temperature and high-pressure thermal helium leak detection method for fusion reactor pressure components international standard.

　　"This is Chinese wisdom in the field of global nuclear fusion, which is of great significance." Chen Jiming said that this international standard recommended by China will become the first international standard in the field of global nuclear fusion, making contributions to the field of nuclear fusion engineering.

"I hope we can deliver the components on schedule or even ahead of schedule, fulfill our international commitments as soon as possible, and jointly help the 'artificial sun' turn from ideal to reality as soon as possible." Chen Jiming said.

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