In October 1993, 12 renowned fusion scientists from major international fusion laboratories, led by Prof. Palumbo, the honorary director of the European *** Fusion Department, reviewed the HT-7 superconducting tokamak device and the Institute's strategy for the development of fusion research, which was then under construction at the Institute, and the Institute put forward for the first time a three-phase plan for fusion scientific research at the meeting.
1994
By the end of 1994, the Basic Bureau of Chinese Academy of Sciences invited 6 academicians and 8 experts to hold a symposium on HT-7U superconducting tokamak program in Hefei, and the HT-7U program was formally proposed for the first time.
In early 1996, some academicians of the two academies made a preliminary assessment of the "Ninth Five-Year Plan" national major scientific engineering projects in Beijing, and the construction of the HT-7U device was endorsed by the national experts for the first time, and it was included in the top ten projects.
In June 1997, the National Science and Technology Leading Group approved the application of the Chinese Academy of Sciences for the establishment of the HT-7U project, which formally entered the operational procedures for the establishment of major national scientific engineering projects.
In October 1997, the State Planning Commission commissioned CAS to host the "Expert Evaluation Meeting on HT-7U Project Proposal"; the construction program and plan of the project were highly praised by the experts attending the meeting.
April 10-11, 1998, HT-7U formally passed the assessment of the State Planning Commission commissioned the China International Engineering Consulting Company held under the auspices of the HT-7U project proposal expert evaluation meeting.
On July 8, 1998, the State Planning Commission formally approved the HT-7U project proposal (Planning and Investment [1998] No. 1303), agreeing that the Chinese Academy of Sciences, the Chinese Academy of Sciences Institute of Plasma to undertake a major national scientific project "HT-7U superconducting tokamak fusion experimental device" construction, with an investment of 165 million yuan.
1998, the Chinese Academy of Sciences agreed that the Plasma Institute of the Chinese Academy of Sciences should undertake the national major scientific project "HT-7U superconducting tokamak experimental fusion device", with an investment of 165 million yuan.
In October 1998, the feasibility study report of HT-7U passed the expert evaluation meeting hosted by the Infrastructure Bureau of Chinese Academy of Sciences.
In December 1998, the feasibility study report of HT-7U was approved.
October 1999, the HT-7U expansion design and budget proposal was approved .
October 2000, the State Planning Commission formally approved the start of construction of HT-7U (Planning and Investment [2000] No. 1656) .
On Nov. 4, 2000, the No. 2 chiller from Russia, after a year of modification, succeeded once in the first round of commissioning to supply cooling for the superconducting coil experiment. at 1 a.m. on Nov. 4, the chiller was brought down to helium liquefaction temperature and produced liquid helium.
On May 31, 2001, a signing ceremony was held for the contract for outsourcing the machining of two major components of the HT-7U mainframe - the external vacuum and the vacuum chamber body (right photo), marking the official entry of the HT-7U mainframe into the machining and manufacturing stage.
On Aug. 20, 2001, HT-7U current leads were loaded into the experimental dewar (left photo).
On August 22, 2001, the important machining equipment for the HT-7U longitudinal field coils - XK2425/IB CNC gantry milling machine (provided by Wuhan Machine Tool Works) - was installed and debugged, and successfully passed the acceptance test (right photo). The outermost part of the longitudinal superconducting magnet is a large D-shaped cross-section coil box designed with high dimensional accuracy, large volume, ultra-thin, deep slots, and fully welded. The welded blank parts of the coil box, machined through an outsourcing unit, will be finish-machined on a CNC machine after being seal-welded by placing the longitudinal field coils in a single VPI treatment.
On August 26, 2001, the 600-meter CICC dummy conductor for the HT-7U was successfully tested.
On October 29, 2001, the HT-7U large-scale superconducting model coil (left) was successfully experimented. 7:00 pm on the 22nd superconducting experimental system began to cool down, 2:20 on the 27th superconducting state, 14:00 model
model coils to reach close to the operating temperature of 5.5k, 14:20 model coils began to carry out a variety of modes of current experiments, 28th continuous high-current, large current experiments. On the 28th, the continuous experiments of high current and large current rate of change were successful, and the working status of each system was basically normal.
November 27-28, 2001, after the field test, VPI-1000 epoxy resin vacuum-pressure impregnation equipment (right) has reached and better than the contractual technical indicators, successfully passed the acceptance of the equipment.
February 6, 2002, the first cake of HT-7U 1:1 surrogate longitudinal field coils are wound (left).
March 11, 2002, HT-7U first for superconducting longitudinal field coils of 604 meters of CICC conduit was born. 20 the conductor pressure square molding (right). HT-7U need to produce 58, 32 kilometers long conductor, *** there are more than 2900 joints. In order to ensure the quality of the joints, six testing methods (X-ray, ultrasound, coloring, endoscope plus plug gauge, vacuum leakage detection and pressurization) were used to test the joints one by one in strict accordance with the requirements. In order to solve the problem of cable passing through the 600-meter-long tube requiring a 1-millimeter gap, a specially designed small-diameter pulling rope snaps were patented.The process of pre-compression molding of the CICC conductor finally reached a dimensional control accuracy of 0.1 millimeter through continuous groping and practice.
On April 3, 2002, the HT-7U superconducting center solenoid model coil was successfully demolded, marking the successful end of the center solenoid model coil VPI.
On April 9, 2002, the second 600-meter CICC conductor of HT-7U was successfully press-squared and molded after completing cable penetration.
July 13, 2002, the gantry-structured CICC conductor pre-bending molding machine has begun to wind the TF002A coil (left photo), which can be wound simultaneously with the cantilever-structured molding machine, and the winding progress can be doubled.
On August 21, 2002, TF001B was wound on the cantilever CICC conductor pre-bending machine of the first production line in the winding shop, and on August 27, TF002A was wound on the gantry CICC conductor pre-bending machine of the second production line (right photo).
On December 9, 2002, the HT-7U superconducting coil VPI equipment - Model 4200 epoxy resin vacuum pressure impregnation equipment passed acceptance (left photo). This set of equipment specially developed for HT-7U is the first set of VPI equipment integrating the functions of vacuum, pressure and pouring in China, and it is the largest vacuum-pressure pouring equipment in China at present, and it is also the most technically demanding and technologically advanced VPI equipment of its kind. It has high vacuum, more advanced film degassing, safe, easy-to-control, temperature-averaging heat-conducting oil heating system and reliable performance, high degree of automation, hydraulic, wrong teeth, fluorine rubber sealing structure. The equipment has been strictly inspected before leaving the factory in Shenyang and obtained the certificate of conformity of pressure vessel.
On March 16, 2003, the HT-7U longitudinal field dummy cable coil completed VPI curing (right photo).On May 12, 2003, the first HT-7U longitudinal field coil VPI treatment was successful.The longitudinal field coils after the successful VPI treatment have a regular appearance and transparent color. Its integrality, insulation strength, and dimensional error are in full compliance with the design requirements.
On May 12, 2003, HT-7U made a significant progress - the first superconducting center solenoid prototype coil (the left picture shows the computer design) successfully passed the performance test. The center solenoid coil is the most critical component of the HT-7U, and its function is to generate plasma currents in the initial phase through rapid magnetic flux changes. "The superconducting center solenoid coil was installed and connected in the experimental Dewa on May 1, the experimental system began to cool down on May 6, and the performance test began on May 11, when the superconducting operating temperature zone was reached. Since the performance tests had to be done under rapidly changing high-current conditions, high demands were placed on the loss-of-super-protection technology, the power supply and its control technology, cryogenics, vacuum, and measurements, etc. On the 12th, all of the expected performance tests were completed, and a series of encouraging and important results were obtained. The experiment showed that the polar field power supply system fully met the design requirements, laying a solid foundation for the successful operation of the future HT-7U device. The success of this experiment indicates that the HT-7U's most difficult and challenging superconducting center solenoid coil has fully met its design requirements.
From June 30 to July 7, 2003, HT-7U successfully conducted tests on the superconducting electromagnetic, mechanical, and thermal-hydraulic properties of the longitudinal-field prototype coil (right). After 100 hours of cooling, the coil successfully entered the superconducting state. After that, simulating the operating conditions of the longitudinal field of the HT-7U device, the superconducting experiments of the longitudinal field prototype coil were carried out at 14.3 kA and 16 kA currents, respectively, and the loss-of-superconductivity current of this coil was tested at a temperature of 6.8 K. The results of the superconducting experiments are summarized in the following table. The results show that the performance of the coils meets the design parameters and fully satisfies the requirements for the future operation of HT-7U. The longitudinal field coils of HT-7U have a D-shape profile,**** 16 of them are arranged along the annulus to form a longitudinal field coil system, which provides a stable annular magnetic field to confine the plasma.
On July 28, 2003, the HT-7U ultra-large's 3rd coil winder went into production (left photo).
On Aug. 7, 2003, HT-7U's TF005 superconducting magnet began performance test experiments.
On October 2003, the project name was changed from HT-7U to EAST.
On October 10-11, 2003, 25 directors of renowned fusion research institutes and heads of international fusion research organizations from Britain, Germany, the U.S., Japan, Russia, France, and India, as well as the head of the International Thermonuclear Experimental Reactor (ITER) program, formed an international group. "The International Advisory Committee, composed of the heads of international fusion research organizations and the International Thermonuclear Fusion Test Reactor (ITER) program, made an inspection and evaluation of EAST. The experts concluded that: EAST will be an advanced scientific facility that will have a significant impact on the world's fusion research, the world's first tokamak with both an all-superconducting magnet and a flexible cooling structure, capable of achieving steady-state operation; EAST is a major step forward in China's fusion research, and has led to a great success in the cultivation of China's new generation of fusion researchers; EAST has an advanced plasma shape (non-circular cross-section), bias filter power and impurity handling capability, and is capable of carrying out research on key physics and engineering issues under steady-state conditions, which are directly related to the construction of fusion reactors and ITER.
On October 15, 2003, the winding of the first poleward field large coil of EAST was completed.
On March 2, 2004, EAST's first polar-field large bias filter coil was wound.
On March 30, 2004, the vacuum pressure impregnation of EAST's polar-field superconducting large coils was successfully completed (left photo). This is a high-tech, high-difficulty, high-risk innovative work, which is the first of its kind in China. The successful development of this project marks another breakthrough in the major technical challenges of EAST's big science project.
On April 1, 2004, EAST's first longitudinal superconducting magnet passed the acceptance of the expert review team (right photo). This large D-shaped superconducting magnet is the TF3 longitudinal field magnet of the EAST device. A variety of innovative key technologies and unique processes were adopted during the development process. Strict tests have shown that the magnet is of excellent quality and fully meets the requirements of the design index. The development of this magnet has filled the gap of large-scale superconducting magnets in China, and made an important contribution to the international fusion community. The experience and lessons learned in the research have accumulated valuable experience for the future ITER (International Thermonuclear Experimental Reactor).
On June 12, 2004, with the successful winding of the last superconducting conductor (CICC) in a tube-armored cable, the CICC production line completed all the CICC conductors needed for EAST with high quality.
On September 2, 2004, Wuhu Shipyard passed the acceptance of the welded blanks for the superconducting longitudinal field coil box, which is the core component of EAST and one of the most important structural components of superconducting magnets. Wuhu Shipyard has completed the processing of all the blanks for EAST, 4 months and 10 days earlier than the original plan (the picture on the left shows that the longitudinal field coil box was officially started on June 18, 2002 in Wuhu Shipyard). After many molding and welding process experiments, the company has overcome a large number of major technological difficulties such as large-area welding of 316LN ultra-low-carbon, high-nitrogen, non-magnetic stainless steel, welding stress relief and deformation control of large-scale and complex contour welded assemblies, which have filled the gaps in the domestic market and reached the international advanced level, and have made significant contributions to the construction of EAST.
At the end of September 2004, EAST completed the winding of all 34 longitudinal field coils, 7 central solenoid coils, 4 large coils for polar field, 4 bias filter coils and 2 test coils with high quality according to the requirements of the project schedule, and the deviation of the coil external dimensions was less than 1.5mm, which reached the international advanced level.
On October 14, 2004, the acceptance team of EAST went to Shanghai Boiler Works Nuclear Chemical Corporation to check and review the inspection data report and surface treatment status of the two components of the middle ring and head of the completed EAST outer vacuum dewar (right photo). The acceptance group considered that the overall quality of the two components of the Dewar is excellent and meets the design requirements, especially in the window position and indexing and other precision control to achieve a high level, and agreed to acceptance.
On March 18, 2005, EAST successfully completed the set of the ninth TF coil and started the pre-assembly of the fourth group of longitudinal field coils (16 TF coils, *** pre-assembled in four groups).
On August 22, 2005, EAST's 15.7-ton center solenoid assembly and 8.7-ton upper bias filter coil were installed in place (left photo).
In January 2006, EAST completed its pre-assembly, and on Feb. 20, it entered the stage of vacuuming and cooling, and power-on experiments.
At 21:55 on March 13, 2006, EAST's No. 12 pole-to-field coil was successfully energized (the right figure shows the waveform of the energization experiment). The purpose of this experiment is to test the thermal and hydraulic characteristics of the magnet, coil box, transmission line and other parts of the loss of ultra detection of the poleward field coil compensation debugging, electromagnetic measurement system debugging, joint resistance debugging and optimization of the poleward field power control system and so on. The collected experimental data show that the maximum current of No.12 polar field coil energized for the first time is 1 kA, the energization time is 45 seconds, and the rise and fall rate is 50A/sec. The experiment was conducted with 22 energizations of the No. 12 and No. 14 poleward field magnets***. Participating in this experiment were eight systems, including vacuum, cryogenics, poleward field power supply, longitudinal field power supply, technical diagnostics, electromagnetic measurements, water and electricity supply, and general control, and each system met the experimental objectives to varying degrees. From the next day onwards, the remaining polar field coils will be separately energized for the experiment, and after the success, the overall energization experiment of the polar field coils will be carried out, and the longitudinal field coil will be energized for the experiment.
On March 17, 2006, EAST completed its first engineering commissioning (left). The main purpose of the first engineering commissioning is to test the performance of the mainframe as well as the capability of the related subsystems, to explore feasible operation modes in the future, to measure the key technical parameters of the mainframe and the main subsystems, to verify the reliability of the various safety protection systems, and to provide the necessary data and accumulate experience for successful operation. During the commissioning, the most concerned low-temperature commissioning and magnet energization test were a complete success. After the vacuum and low-temperature conditions were put in place, 260 energization tests were conducted from March 13 to March 17 on the longitudinal field magnets and 12 poleward field magnets respectively. The longest energization time reached 5,000 seconds, the maximum current reached 8,200 amperes, and the corresponding field strength at the center of the device has reached 2 Tesla. The general control system, vacuum system, cryogenic system, data acquisition system, water-cooling system, power supply system, technical diagnostic system of the device, loss-of-overrun protection, vacuum magnetic shape measurement system, superconducting transmission line, high-temperature superconducting current lead, copper current lead and plasma control system operated normally, which guaranteed the safety and success of energization test.
On September 26, 2006, EAST successfully obtained a high-temperature plasma discharge with a current of more than 200 kA and a time of nearly 3 seconds during the first plasma discharge experiment (left), marking that the world's first all-superconducting non-circular cross-section tokamak fusion experimental device has been built and officially put into operation firstly in China.
The EAST has started to turn into the phase of physical experiment. EAST is the first all-superconducting non-circular cross-section tokamak fusion experimental device in the world, which has been completed and put into operation in China. Related design concepts and technological innovations also include the design and manufacture of large-scale superconducting magnets, large-scale ultra-low-temperature refrigeration technology, arbitrarily controllable rapid changes in high-current equipment technology, etc. are the first of their kind in China and have reached the international advanced level.
On October 13-14, 2006, the second meeting of EAST's International Advisory Board was held in Hefei (right photo). 29 senior scientists and leaders from the International Thermonuclear Experimental Reactor (ITER) program and the world's first-class fusion research institutes in Europe, the U.S., Russia, Japan, South Korea and India attended the meeting. The meeting listened to the reports on the general theory of the EAST project, the progress of the project, the results of the first experiment and the future experimental plan, and visited the discharge experiment and various sub-systems on site in the experiment hall. The international consultants had a 10-hour in-depth discussion on the construction of EAST, system improvement, future experimental plan and research, etc. The report of the meeting pointed out that EAST is the only tokmak device in the world similar to ITER's all-superconducting magnetic field design. The committee was impressed by the high quality of the EAST construction. The independent completion of the design, pre-study, construction and commissioning within such a short period of time is a remarkable achievement in the world of fusion engineering. This outstanding achievement is an important milestone in the development of fusion energy worldwide. High-power heating, current drive, and improved diagnostics are essential to EAST's future in-depth research programs. Once these programs are realized, EAST will be at the forefront of a scientific research program to develop steady-state high-performance plasma physics, which in turn will contribute to supporting ITER and fusion energy development. It is recommended that adequate resources be provided to support the achievement of these scientific goals as soon as possible.
The 21st World Fusion Energy Conference (IAEA), known as the "Olympics of fusion," was held in Chengdu from October 16-22, 2006 (left). The IAEA is the highest-level international academic conference in the field of nuclear fusion research, held every two years, and this is the first time that it has been held in a developing country. More than 800 Chinese and foreign scientists, including Prof. Burkart, Deputy Director General of the International Atomic Energy Agency (IAEA), and the President of the International Council for Fusion Research (ICF), attended the conference. In the past IAEA conferences, only three tokamaks, JET from Europe, DIII-D from the US and JT-60U from Japan, were listed in the first section of the report, and EAST General Manager Wanyuan Xi made the first report (key note) in this conference, which shows that the international fusion community pays great attention to EAST, the first all-superconducting tokamak. At the end of the presentation, the whole audience gave a standing ovation, which was the first time in the history of the fusion energy conference. During the conference, many foreign research institutes and universities, in addition to congratulations, have expressed their strong willingness to cooperate with EAST, and more than ten bilateral cooperation projects have been reached and one bilateral cooperation agreement has been signed. President Lu's congratulatory letter pointed out that: the realization of the first discharge experiment of the EAST fusion experimental device of the all-superconducting non-circular cross-section tokamak marks that the engineering experiment of the EAST device has entered into a new stage, and also demonstrates that Chinese science and technology workers have the ability to independently realize the construction and operation of large-scale experimental devices of the world's advanced level of science and engineering. EAST will provide a new experimental platform for nuclear fusion research in China and the world.
At 23:00-1:00 on January 14-15, 2007, EAST continuously discharged four times, each time for about 50 milliseconds, and the second round of physical experiments began. The main goal of this round of experiments is not to pursue the length of the discharge time, but aims to obtain non-circular cross-section plasma on the basis of the circular cross-section plasma obtained in 2006, which is of great significance.
On January 29, 2007, China's major technological and engineering advances in 2006 were announced in Beijing by Science and Technology Guide, a core scientific and technological journal under the China Association for Science and Technology, and 14 projects were selected, including the completion of the EAST device and the successful development of the Taihang engine, and the acceptance of the Qinshan II nuclear power plant.
2007
On February 15, 2007, the Center for Basic Research Management of the Ministry of Science and Technology and the Academic Department of the China Association for Science and Technology announced the results of the "Top Ten News in China's Basic Research" in 2006, and the EAST project was selected because of its representativeness in terms of originality, newsworthiness, and broad social impact.
On March 1, 2007, EAST passed the national acceptance test. The National Development and Reform Commission (NDRC) hosted the EAST National Acceptance Meeting in Hefei (left photo). The acceptance committee listened to the project construction, expert testing, expert appraisal and pre-acceptance opinions of the Chinese Academy of Sciences (CAS), reviewed the relevant professional acceptance materials, and inspected the EAST device on the spot, and unanimously agreed that: the project's technological process meets the design requirements, and the device mainframe and its subsystems have met or exceeded the design specifications, and it has become the first all-superconducting, non-circular cross-section tokamak experimental fusion device that is successfully operated in the world. The project has completed its construction tasks in a comprehensive and high-quality manner. The project has completed the construction tasks in a comprehensive and high-quality manner and realized the predetermined targets, and it is agreed that the project will pass the national acceptance test.
On April 10, 2007, the "Sino-US Joint Research on Advanced Operation Modes of Tokamak" project undertaken by the Institute of Plasma passed the acceptance (right), in which the Southwest Institute of Physics of the Nuclear Industry (SWIP) participated. The group of experts reviewed the materials of the project, listened to the summary report of the project implementation, and conducted on-site inspection and consultation. The expert group concluded that the project has fully completed the stipulated contents of the contract and reached the expected goals, agreed that the project passed the acceptance, suggested that the project undertaking unit adhere to the effective way of international cooperation and expand the field of cooperation, and hoped that the relevant departments would give further support. The implementation of this project has effectively utilized the U.S. magnetic confinement fusion scientific and technological resources, mastered the key technologies of diagnosis, numerical simulation and control, solved some of the bottlenecks constraining China's magnetic confinement fusion research, improved the level of China's technological and physical research in the field of fusion, and shortened the gap between China and the international fusion research, and cultivated a group of urgently-needed talents in the field of magnetic confinement fusion, trained up the team, and laid a good foundation for broader international cooperation. It has also trained a group of much-needed talents in the field of magnetic confinement fusion, trained the team and laid a good foundation for more extensive international cooperation.
On August 27, 2007, EAST successfully passed the acceptance of the last batch of KU-2.45 microwave tacho tubes for the low clutter system from ISTOK Research Institute in Russia (left photo).
On December 3, 2007, after several months of efforts, EAST internal component modification has completed the installation of heating bushings, boronized water pipe, high field side single-turn ring fixing bracket, etc., carried out ultrasonic flaw detection of heat-sinking material full inspection, completed in the simulation of 1/16 section of the tooling on the heat-sinking support and simulation of heat-sinking test fitting, the heat-sinking cooling water pipe molding, opening and welding of the adapter flare, the heat-sinking cooling water pipe. It also completed the machining of the first piece of heat-sinking for the high-field side and outer target plate, and proceeded with the process review and acceptance of the first piece one after another, and the modification of the internal components has begun to enter the overall installation stage.
On December 31, 2007, the EAST internal components 1/16 section pre-assembly project passed the acceptance. 1/16 section pre-assembly using 1:1 real simulation of the EAST vacuum chamber heat sink components, cooling water pipe installation process (right). This pre-assembly verified the rationality and practicability of the technology, process, fixtures and tools for the modification and installation of the internal components of the EAST vacuum chamber.
On March 26, 2008, good news came from the 2008 annual working meeting of the Chinese Academy of Sciences (CAS) that the EAST Big Science Engineering Research Collective was awarded the 2007 Outstanding Scientific and Technological Achievement Award of CAS.
On April 23-24, 2008, the IO (International Organization)-DA (Domestic Agency) Coordination Meeting, the most important business meeting of ITER, was held at the Institute of Plasma (left photo). Norbert Holtkamp, First Deputy Director General of ITER International Group, and Eisuke TADA, Director of ITER Project Office, presided over the meeting, which was attended by senior representatives of DAs from China, the European Union, India, Japan, South Korea, Russia, and the United States. The meeting is a regular meeting for communication and coordination of major affairs between IO and DAs of member countries, which informs and discusses major design changes and reviews, informs and studies the recommendations of the meetings of the Scientific and Technical Advisory Committee (STAC) and the Technical Advisory Committee (TAG), discusses and prepares the report to the ITER Council, and discusses the progress of the plan of each country's procurement packages, the resource plan, and the adjustment of the funding, and other matters. The conference delegates visited the EAST device and the TAG. Delegates visited the EAST device and the ITER CICC pipeline project under construction.
On May 12, 2008, at the overall acceptance meeting for the installation of the internal components of the vacuum chamber of the EAST device, Director Li Jiangang of the Institute of Plasma announced the successful completion of the installation of the internal components of the vacuum chamber of the EAST device. The installation of the internal components of the vacuum chamber involves nine major projects and more than 59,000 parts. The installation project started on January 14, 2008 and ended on May 8, 2008. After more than three months of hard work, the installation of the internal components of the vacuum chamber of the EAST device was successfully concluded with high quality and high speed. This is the first major project since the establishment of EAST.
On December 3, 2008, the second modification project of EAST internal components was fully completed and passed the acceptance. All the related departments made a report on the work, introducing the responsible engineers and construction units' sincere cooperation and concerted efforts to break through many technological difficulties, formulate safe, reliable and practicable solutions and strictly implement them. (The picture on the right is the vacuum chamber after transformation) The transformation project started from October 13th and lasted 53 days, involving mechanical installation, vacuum leakage detection, collimation measurement and other disciplines, with a large amount of engineering and complex technology. With the efforts of Jurong Energy Company, Keye Company, Overall Design Office, Room 6 and other departments, the project was finally completed 7 days ahead of schedule, with high quality and high speed, which was a glorious and arduous mission, and bought valuable time for the smooth realization of next round of discharge experiment. The discharge experiment has gained valuable time and accumulated experience for future fusion project construction; this internal component modification is not a simple installation repetition but a technical battle, and important breakthroughs have been made in areas such as anti-loosening and tightening, displacement measurement, graphite tile modification, disassembly and maintenance, etc., which have accumulated valuable engineering practice for future work." The experts in the meeting fully affirmed the quality and speed of the completion of the transformation project, and gave high appraisal to the good cooperation and collaborative research as well as quality management work embodied in the transformation process, and at the same time put forward hopes and requirements for the work in all aspects. The meeting passed the acceptance of the remodeling project agreed to acceptance of the acceptance opinion.
On November 13, 2009, the liquid nitrogen transfer line modification project, a sub-project of the EAST/HT-7 cryogenic system modification project, was successfully completed, and the liquid nitrogen transfer function has been successfully realized. The transformed liquid nitrogen transmission line has a span of about 150 meters (about 30 meters before the transformation), and the longer the transmission line is, the easier it is to produce gas blockage, liquid leakage, vacuum pumping and other difficulties; the maximum drop of the transformed liquid transmission line is nearly 10 meters (from the trench to the bridge), and the large drop is prone to produce gas blockage, liquid nitrogen transmission and large consumption problems.