The busy port of Marseille in France will soon receive a batch of special cargo from China weighing over 60 tons. This shipment will be sent from Zunyi, Guizhou, and will be transported to Shanghai via the Yangtze River and then transported by sea to Marseille, France. It will be delivered to the International Thermonuclear Experimental Reactor Project (ITER) Organization Headquarters. It is the base and frame of the 'Artificial Sun'.
Acquiring inexhaustible clean energy is the dream of mankind. Controlled nuclear fusion has ignited this dream of mankind. This batch of supporting devices of the Southwestern Institute of Physics of the Nuclear Industry has brought this dream closer to reality. A step.
Compared with nuclear fission, nuclear fusion fuel resources are almost unlimited, and safety is even better. Twelve years ago, the ITER project was moving towards the implementation stage, attracting countries including China, the European Union, India, Japan, Korea, Russia and the United States. The main nuclear countries and scientific and technological powers are participating together. Because of their similarity to the principles of solar luminescence and heat, they are also known as 'artificial sun'.
As one of the two Western hospitals that participated in the ITER program in China, the National Institute of Magnetic Confinement Nuclear Fusion Energy Development Research was established in 2008. In 2010, it signed a magnet support procurement contract with ITER, and joined hands with Guizhou Aerospace. The high-end manufacturing companies such as Xinli Casting & Forging Co., Ltd., after eight years of designing, manufacturing, and completing the first batch of components of this procurement package, were delivered to ITER International Organization on June 9. This shipment includes 18 sets of poloidal field coil supports. PFCS5 and the first set of gravity support GS, polar field coil support PFCS3, PFCS4 products. It is worth mentioning that the magnet support purchase package is the only domestic 100% large-scale purchase package made in China. This group of parts accounted for about ITER whole magnet. One-tenth of the support system, the rest will be completed by the end of 2020.
In the process of participating in the ITER project, China sent more than 100 people and took up 9% of the workload. It was responsible for 18 out of a total of 140 procurement packages and became the country with the highest number of tasks except the EU. On the one hand, this is a major country. The responsibility and commitment, on the other hand, is also to use this platform to demonstrate China's wisdom to the world. 'ITER magnet support is one of the earliest components delivered and entered for installation, its volume and delivery schedule for ITER's overall installation and post installation The stability of the operation plays a crucial role. Therefore, the delivery of magnet support components is not only a major milestone in the ITER program's first plasma discharge process in 2025, but also indicates to the world that China is fulfilling its international commitments. At the delivery ceremony, Cornelis BEEMSTERBOER, project leader of ITER International, spoke highly of the completion of the Chinese mission.
From unpredictable to accurate perception
When it comes to magnet support, one has to mention its 'parent' ITER device, which is a superconducting tokamak that produces large-scale nuclear fusion reactions. Inertia and magnetic confinement are two common ways of producing nuclear fusion. Tokamak is a type of annular container that uses magnetic confinement to achieve controlled nuclear fusion. The ITER program consists of a special form of magnetic field that consists of light nuclei and free electrons such as helium, neon, and so on. The UHT plasma in a thermonuclear reaction state The body is confined within a limited volume, causing it to undergo a large number of nuclear fusion reactions under controlled conditions, releasing heat.
'30 meters high, 28 meters in diameter, close to the size of the Temple of Heaven in Beijing. ' This is the metaphor of the ITER device by the director of the China International Nuclear Fusion Energy Program Executive Center. To withstand this 10,000 tons of giants, gravity support (GS ), The poloidal field coil support (PFCS) and the correction field coil support (CCS) constitute the four-beam and eight-column ITER device. Their weight is up to 1600 tons. As one of the important structural safety components of ITER, these devices It is the first part of the ITER installation that enters the factory building and installation. Its quality and schedule are related to the operational stability and assembly progress of the entire ITER installation.
'Nuclear fusion is the coupling of various fields including gravity field, temperature field, strong electromagnetic field, radiation field, etc. While nuclear fission only requires higher temperature field, it also means that the operating conditions of controlled nuclear fusion are more complicated. The requirements for the equipment are also more stringent. 'Person Li Yongyuan, who is responsible for the ITER magnet support project, told the reporter. For magnet supports, they not only carry the weight of a 10,000-ton magnet system, but they also have to withstand the huge pulse electromagnetic forces generated under extreme conditions. Force and strong thermal stress, its complex working environment, determine the high requirements for design and manufacturing.
Gravity support GS is the heaviest component of the magnet support system and consists of 18 complex support structures, each weighing 23 tons. The superconducting magnets it supports can only be operated in extremely low temperature environments, ie absolute zero (-269). In the vicinity of °C), the temperature of the bottom of the magnet support part is room temperature, and the whole part will experience a change from a very low temperature to a very high temperature, with a temperature difference of nearly 300 times. 'Because of thermal expansion and contraction, the GS shrinks 31 mm at the top, This value cannot be accurately predicted at the beginning of design. ' Li Pengyuan said.
Although the understanding of the human substance in the world is constantly evolving, it is still very limited for the vast universe. 'Because of the enormous electromagnetic force generated by the plasma discharge, the physics community has not formed a complete understanding of it and this There is no ready-made standard for the technology. We only have to change it. So we made changes to the design of the GS. There are countless experiences in the design. We often see success being revisited and overturned. ' Li Pengyuan continues to say .
From unachievable to proposed China
In the research and development of technology, from design to engineering application, it has never been a smooth path. ITER is no exception. The design programs provided by ITER are based on physical experiments and do not take into account engineering realizability. In engineering, we discovered that some designs could not be implemented. ' Li Pengyuan said.
Initially, the team used welding methods to connect the upper and lower parts of the GS. In actual welding, it was found that the deformation was very serious and could not be processed again. 'After a ductile plate produces welding defects, the entire value of millions of gravity support parts will be scrapped. So we redesigned 21 bolts and splints to hold the 21 ductile plates instead of the original welding scheme. We analyzed the stress environment through software and tested on the model, which proved the feasibility of the design and passed the international expert group. The review, which overturned its original design, became ITER's final manufacturing solution.' Sun Zhenchao, deputy director of the Fusion Materials Research Group, said.
In the Western House in Chengdu, there is a one-story pilot plant in the shade of green trees. Five or six test equipments are working at the same time. The project staff is doing many tests on the magnet support system. The parts delivered this time are via these devices 'grinding 000-1000' test, design, manufacture evidence for the magnet support system which is the largest body in accordance with GS 1:. magnet support simulation test model 1 ratio, this device can include seismic analysis included 32 The possible working conditions, and simulation tests, and then certified to Guizhou mass production.
'Since all magnet support products in the ITER project are working in a very low temperature environment, the raw materials and some products of the magnet support products will do ultra-low temperature tests here. Although there are similar equipment abroad, there is no uniform standard. We are fully based on international Executable standards can be referenced, several sets of ultra-low temperature test platforms have been built to check the reliability of materials from the parts to ultra-low temperatures, and a set of standards has been formed, and foreign products can also be tested with our equipment. ' Sun Zhenchao said. At the same time, these devices can also provide powerful support for the design and manufacture of China Fusion Engineering Experimental Reactor (CFETR).
In order to better balance physics needs with engineering feasibility, the magnet support project team and several manufacturers have tackled various designs and manufacturing problems. During this period, Sun Zhenchao and another staff member worked in France for half a year. The actual design and manufacturing of China were communicated with ITER, and many technological changes were realized.
In addition, since the superconducting coil can only operate at liquid helium temperature, the cooling of the sealing performance is critical conditions, liquid helium leak once the temperature rises appear likely to lead to a superconducting coil quench even burned. In March, the magnet support The team completed the manufacture and commissioning of three large-scale vacuum crucible leak detection equipment. This series of equipment is specially designed to detect the risk of leakage of the magnet support cooling system.
From and to the leader
Of the parts delivered this time, the most numerous was Pole Cylindrical Coil Support (PFCS), which are 18 pieces of U-shaped components that look like a single weight of about 3 tons. They spliced the Tokamak frame like an orange flap. ' Although this technology is relatively simple, but the production of high precision requirements, manufacturing is relatively more difficult.' Li Peng Yuan said that at the time they tried to use welding to manufacture, but many companies have failed to achieve, not defective, There was a distortion, so the top experts and scholars in the field of domestic welding were invited to discuss how to solve this problem. The Guizhou Aerospace Xinli Company proposed a cutting plan using the whole forgings, and after trying to successfully explore this technology, it won this. Manufacturer qualification of a component.
These U-shaped parts look ordinary from the outside, but they create a gap in the middle of each plate of the left and right plates to withstand pressure in a more flexible posture. In response to this, ITER requests that the gap between left and right be controlled to be positive. Within 2 mm of negative, if the gap difference exceeds this value, it will lead to one side thick and thin, resulting in non-uniform force, damage to components, or even failure of the overall test. The overall forging cutting technology adopted by Guizhou Aerospace Xinli Company achieved Above the standard required by ITER, the error is controlled within plus or minus 1 mm. This is a powerful demonstration of Chinese power in the ITER project.
During the past eight years, China has established a series of testing platforms for materials and prototypes ranging from room temperature to cryogenic temperature (-269°C) and has achieved major breakthroughs in several key technologies. Oversized large-size forging technology, 316LN Austenitic nitrogen-controlled stainless steel manufacturing technology, nickel-base 718 and A286 superalloy fastener manufacturing technologies, etc. have reached the international cutting-edge level. The workers not only solved the defects of the original ITER design, but also obtained the ITER organization's unanimous recognition and high evaluation. Highlights the Chinese wisdom of ITER International Project.
Li Pengyuan told the reporter candidly that before China joined the ITER organization, China’s R&D in this area with some developed countries had a large gap in manufacturing capacity. After participating in ITER, we gradually realized and ran, even in some fields. The leader of the China International Nuclear Fusion Energy Project Implementation Center has also delivered evaluations at the delivery site: China has been implementing the project in accordance with schedule requirements and is currently in a leading position in ITER R&D and manufacturing. In the process of China's participation in the ITER project, The attention of the whole society to nuclear fusion has been improved. The two Chinese scientific research units have rapidly improved their scientific research capabilities in this process, and have greatly improved our country’s engineering manufacturing. Some of these projects have reached the world’s leading level. At the same time, we also cultivated A talent team in engineering technology, scientific research, project management, and international negotiations has played an active role in leading large-scale international projects in China.
The ITER device will be built in 2025 and realize the first plasma discharge. In the future of human energy exploration, the Western House and a number of Chinese companies have contributed Chinese forces and supported the dream of 'Artificial Sun'. We achieved a breakthrough in the complete chain of materials science, equipment manufacturing, and processing technology supported by ITER magnets. We are full of confidence in the completion of the Chinese procurement package. 'The president of the Western House Liu Yong said. We have reason to believe that More Chinese wisdom will ignite the ultimate dream of human use of clean energy.