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A Leap for Fusion Simulation Technology: Planning Study for V-DEMO Development in Korea Fusion technology development in Korea faces three primary challenges: (i) Development of a high-performance operating mode for Tokamak, (ii) Building a blanket test facility to bridge KSTAR, ITER, and a fusion demonstration plant (DEMO), and (iii) Utilization of experimental data along with the integration of scientific and technological achievements to design a fusion DEMO. To achieve these three missions, KFE conducted a planning study for the development of V-DEMO. V-DEMO will be a virtual fusion demonstration plant, built by applying the 4th Industrial Revolution technologies including supercomputers, artificial intelligence, big data, etc. The ultimate goal of V-DEMO is to quantitatively realize the core functions of a fusion power plant and comprehensively reproduce one by integrating simulations of tokamak, blanket, and BOP (Balance of Power) systems. With these features, V-DEMO can be used to identify various physical and engineering requirements that can be used in the detailed engineering designs of a fusion power plant. Clarifying these requirements can help in optimizing and verifying plant designs, as well as assisting security and safety clearance studies by investigating various accident scenarios. Building V-DEMO will require examining available technologies and current technological levels, and then specifying strategies for each step. Therefore, the focus of this planning study was identifying the technological priorities required to resolve the challenges mentioned above. Technology development trends and development direction for V-DEMO Fusion simulation is the core technology for V-DEMO. It has been under development for the last two decades, mainly focusing on core plasma, heating, and PMI (Plasma Material Interaction). The current mainstream technologies are large-scale simulations capable of parallel expansion over tens of thousands of CPU cores. Korean researchers are presently working to elaborate and verify simulations using KSTAR’s advanced imaging diagnostics. The global goal in fusion simulation development is to develop the capability to quantitatively predict experiments using supercomputer-based simulations, and relevant studies are expected to play a large role in KSTAR studies. The core plasma in tokamak is connected to power facilities via a breeding blanket system, which converts fusion energy into electricity. Simulating fusion electricity generation involves both fusion and nuclear power studies. The former can take advantage of the latter. As a matter of fact, the TBM (Test Blanket Module) currently being tested in ITER uses nuclear analysis tools and safety analysis codes from the nuclear power community, demonstrating that nuclear simulation technologies can be expanded to enable V-DEMO’s targeted functions. AI (Artificial Intelligence) is also promising for fusion research innovation. AI can utilize machine learning based on numerous fusion experiments and simulation data to derive a data-driven fusion model. The big advantage of the data-driven fusion model is its combination of fast calculation and good precision. For example, according to research already published, a heating simulation can be generated in a much shorter time with machine learning, allowing real-time controls. Without it, the calculations would require thousands of CPU cores and considerable time. Various studies to accelerate simulations are ongoing, with the ultimate goal of developing a fusion simulator capable of the tremendous volume of repetitive calculations necessary for engineering design.   V-DEMO will need to integrate simulations from various fusion areas and therefore will need to develop an integrated platform. Fusion societies worldwide are working on simulation software integration frameworks. One of the most promising projects is the ITER-IMAS framework, which is currently under development for ITER. V-DEMO should expand its technological base to include plant features based on ITER-IMAS. Digital twin is a technology that can be used to virtualize machines and facilities, using machine design data, and is considered the basis upon which simulation software and integrated framework can be deployed. For fusion, “Virtual KSTAR” is being developed to perform virtual experiments that combine KSTAR design, experimental data, and heating simulations. The technology developed through KSTAR will be applied to ITER in the near future, to pave the way for V-DEMO development. Roadmap for V-DEMO development Presently, various technological developments including simulations, virtualization, supercomputers, and machine learning are needed for V-DEMO development. In this planning study, a total of five technology groups were identified as the key technologies for V-DEMO: (i) tokamak simulation group, (ii) blanket-BOP simulation group, (iii) accelerated fusion simulation group, (iv) enabling technology group, and (v) fusion big data group. The development plans and strategies for each group were also established. Roadmap for V-DEMO project V-DEMO development will go through four stages by the year 2040. In the first stage, simulation and virtualization of a middle-sized tokamak such as KSTAR will be carried out. In the beginning, technology verification using KSTAR data will be the key objective. In the second stage, the technologies from the first stage will be further developed for ITER, and simulation acceleration using artificial intelligence will begin. In the third stage, blanket and BOP simulation technology development will be performed in collaboration with the nuclear energy community. In the final stage, V-DEMO will be completed, integrating the K-DEMO design data. Verification and optimization of a demonstration plant will be carried out utilizing V-DEMO. Plan for experimental validations and key development targets in each phase Fusion research in Korea has been ongoing for the last two decades, focusing on KSTAR and ITER. Now, another leap is needed to accomplish a demonstration of fusion technology. Alongside hardware technological achievements, another foundation for the fusion demonstration should be established, by proactively developing fusion simulation technologies, including V-DEMO.  For more KFE NEWS: KFE NEWS vol. 30  - KSTAR's 30,000th shot  - AAPPS-DPP Young Researcher Award winner in KFE, Dr. Sanghoo Park  
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(photo) left: vacuum vessel after complete assembly / right: vacuum vessel in delivery unit The second sector of the vacuum vessel has shipped for France where it will serve as one of the key components of the ITER.  The vacuum vessel is where the high vacuum environment is created, to discharge and maintain the super-hot plasma whose temperature is over one million degrees. The ITER’s vacuum vessel consists of nine sectors, and each of them is 11.3 meters tall, 6.6 meters wide and weighs approximately 400 tons. When assembled all together in a doughnut-like shape, this monumental structure weighs around 5,000 tons. Korea is in charge of procuring four of the vacuum vessel sectors out of the nine, and completed and delivered the first sector (sector no. 6) in 2020. Previous experience with the first sector production helped in making this second sector (sector no. 7). The second sector took only 75 months to accomplish, which was 25% faster than the 101 months needed to produce the first sector.  Once the second sector arrives, the very heart of the ITER structure will start to be assembled – the assembly of the tokamak. First the “sector sub-assembly” will be completed by attaching one thermal shield and two TF superconducting magnets outside the vacuum vessel. Then each of the “sector sub-assemblies” will be connected in a circle like a doughnut. That is why the delivery of the second sector is necessary before the assembly can actually begin.   The shipment will arrive at Marseille-Fos Port in the end of July and will finally arrive at the ITER site at the end of August by land and canal. Now only two sectors remain to be produced by Korea. The two sectors will be delivered to the ITER site by 2022. “We are pleased to have the second sector shipped safely to France, despite the unexpected difficulties we had, such as the Suez Canal accident. We will stay alert for any incidents that may happen until it finally arrives at ITER,” said Hyunsoo Kim, the team leader of the Vacuum Vessel Tech Team of ITER KODA. ITER KODA Director-General Kijung Jung added, ”ITER KODA and Korean industries are collaborating and focusing their capabilities to meet the strict quality standards, as well as the deadline. We will do our best to successfully complete the remaining two vacuum vessels for the ITER construction.” For more KFE NEWS: KFE NEWS vol. 29  - The 2nd vacuum vessel departs for ITER  - Participation in the first online FEC2020  - KFE hosted HWS-15  - KFE and HFIPS sign research agreement for tritium breeding
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         (Photo: Dr. Minjun J Choi and his article in Nature Communications) Dr. Minjun J Choi of the KSTAR Research Center of KFE has successfully proven the direct effects of plasma turbulence on magnetic islands. The findings, from a collaborative investigation involving researchers from Korea and the United States, were published in Nature Communications in January. “This research is the reverse of a previous study that revealed the effect of magnetic islands on the distribution and development of background turbulence. This time, we analyzed how background turbulence affects the evolution of magnetic islands. Based on this work, we expect to be able to weaken or redistribute the turbulence near magnetic islands, to prevent or alleviate plasma disruption," explained Dr. Choi, who was first author of the paper. A magnetic island is an island-like magnetic structure that is created in a plasma by a magnetic field reconnection, due to plasma instabilities. It can degrade tokamak performance by interfering with its magnetic confinement or can even cause plasma disruption. Understanding its effect and behavior has been one of the most difficult conundrums to solve in fusion research, and doing so is essential to realizing fusion energy. Several projects were being carried out on multiple fusion devices to address the problem. Dr. Choi focused his efforts on the interactions between magnetic islands and background plasma turbulence. The collaborative research team successfully proved by experiments on KSTAR that turbulence directly influenced magnetic islands to evolve by turbulence spreading or magnetic reconnection acceleration. Contributing researchers include Dr. Laszlo Bardoczi (General Atomics, US), Dr. George McKee (General Atomics, US), Professor T. S. Hahm (SNU, Korea), Professor Hyeon K. Park (UNIST, Korea), Professor Eisung Yoon (UNIST, Korea), and Professor Gunsu S. Yun (POSTECH, Korea). Multiple physics models have emerged to explain how plasma turbulence affects the evolution of magnetic islands, though few have been supported by actual experiments. Recent studies have suspected that turbulence spreading was suppressing the magnetic islands, but verifying it experimentally was difficult. The advanced diagnostics of KSTAR allowed the team to observe the turbulence as it spread from the outside of the magnetic islands to the inside. They were also able to witness turbulence enhancement at the reconnection site in the event of a fast collapse of a magnetic island. The findings provide a solid explanation of the main plasma phenomena necessary to realize fusion power. The researchers expect to contribute to future fusion reactor operations by advising how to suppress the magnetic islands causing plasma disruption. Related publication: Effects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak For more KFE NEWS: KFE NEWS vol. 28
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The ITER Organization will host a 2-day Remote ITER Business Meeting presenting thecoming business opportunities, and the latest highlights of the Project on Wednesday 7 andThursday 8 April 2021.  In this virtual meeting, the ITER Organization presents the coming business opportunities. With six thematic sessions, experts from different areas give specific information about contracts and procurement needs in the next coming years. 1. Name of event: Remote ITER Business Meeting 2. Object: provide specific information about contracts and procurement needs in the next coming years 3. Date of event: 7-8 April 2021 4. Program  - Update of the ITER Project Status by Director General  - Procurement and Contract News  - Thematic sessions by ITER technical experts giving overview on coming business opportunities  - One-to-One meetings between interested companies and ITER experts  - Possibility to arrange Business-to-Business with other companies 5. Registration Period: 20 January - 6 April 2021 6. Linka: https://www.iter.org/ribm2021
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Aiming to operate continuously high-temperature plasma over 100 million degrees for 300 seconds by 2025 temperature plasma for 20 seconds with an ion temperature exceeding 100 million degrees.   On November 24, the KSTAR Research Center at KFE announced that in joint research with Seoul National University (SNU) and Columbia University in the United States, it succeeded in the continuous operation of plasma for 20 seconds with an ion temperature higher than 100 million degrees, which is one of the core conditions of nuclear fusion in the 2020 KSTAR Plasma Campaign. It is an achievement to extend the eight-second plasma operation time during the 2019 KSTAR Plasma Campaign by more than two times. In its 2018 experiment, KSTAR reached a plasma ion temperature of 100 million degrees for the first time (retention time: about 1.5 seconds). Recreating the fusion reactions of the sun, given its ultra-high temperature and density, on earth requires heating and the maintenance of ion temperatures exceeding 100 million degrees after fueling a fusion device such as KSTAR and dividing nuclei into ions and electrons to create a plasma state.  Thus far, there have been other fusion devices that have briefly managed plasma at temperatures of 100 million degrees or higher. None of them broke the barrier of maintaining the operation for ten seconds or longer. This represented the operational limit of a normal conducting device,* and it was difficult to maintain a stable plasma state in the fusion device at such a high temperature for a long time. * Limits of a normal conduction device: Unlike KSTAR, a fusion device that features a superconducting magnet, existing fusion devices based on normal conducting magnets such as copper magnets cannot be operated for an extended period of time because when a high electric current runs through the magnet to create a magnetic field that is strong enough to confine plasma, the magnet overheats due to its resistance. In its 2020 experiment, KSTAR improved the performance of the internal transport barrier (ITB) mode, one of the next-generation plasma operation modes developed in 2019 and succeeded in maintaining the plasma state for a long period of time, overcoming the existing limits of the ultra-high-temperature plasma operation. Director Si-Woo Yoon of the KSTAR Research Center at the KFE explained, “The technologies required for long operations of 100 million-degree plasma are the key to the realization of fusion energy, and KSTAR’s success in maintaining high-temperature plasma for 20 seconds will be an important turning point in the race for securing the necessary technologies for long high-performance plasma operation, a critical component of a commercial nuclear fusion reactor in the future.” “The success of the KSTAR experiment in the long high-temperature operation by overcoming certain drawbacks of the ITB modes brings us a step closer to the development of technologies leading to the realization of nuclear fusion energy,” added Yong-Su Na, a professor in the Department of Nuclear Engineering at SNU, who has been jointly conducting research on the KSTAR plasma operation. KSTAR is going to share its key experiment outcomes in 2020, including this success, with fusion researchers around the world at the IAEA Fusion Energy Conference to be held in May of 2021. The final goal of KSTAR is to succeed in continuous operation of 300 seconds with an ion temperature higher than 100 million degrees by 2025. For more KFE NEWS: KFE NEWS vol.27
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 - ITER Korea DA succeeded to manufacture the first product of a blank shield block The first product of the International Thermonuclear Experimental Reactor (ITER) "Blanket Shield Block" has been successfully manufactured in Korea. It is designed to protect nuclear fusion reactor devices from plasma whose neutrons and more than 100 million °C temperature can damage the parts. "The ITER Blanket Shield Block is a primary barrier to protect the ITER devices from plasma’s neutron damages and enormous energy set from ultra-high temperature over 100 million °C. Like a blanket, it protects all the main components such as vacuum vessel, magnet and so on" said Sa-Woong Kim, the team leader. In other words, it is the part to shield major ITER devices from plasma and neutrons from nuclear fusion, and is to be installed in puzzle-like connections, surrounding the inner wall of the vacuum vessel. Total 440 blanket shield blocks are going to be installed at ITER, procured by South Korea and China each to supply 220 units. This achievement is remarkable in that the team has successfully resolved technical issues which they have encountered in every stage, including design, manufacture and testing. They have successfully met the high standards required by ITER and have established mass production system for the blanket shield blocks. First product of ITER blanket shield block ITER Korea Project Blanket Technology Team members including Byung-Il Park(senior engineer), Sikun Chung (senior engineer), Hee-Jin Shim(principal researcher), Sa-Woong Kim(principal researcher, team leader), starting from left Mission 1. Finding the best material and design: Stainless Steel ITER put forward strict standards in selecting and manage the block materials. This was the first to meet for the production of blanket shield blocks. "Good quality is essential for shielding from neutrons and for cooling plasma. It must be a low-radiation material with a short half-life when exposed to neutrons. On top of that, drilling and welding must be made possible to serve as a part to prevent plasma heat," commented Hee-Jin Shim, the principal researcher of the team. Accordingly, the researchers first of all worked on developing a special stainless steel (i.e. 316L(N)-IG) for the blanket shield block to withstand extreme environments, which succeeded in satisfying all the strict criteria of ITER. Next, the design was completed in such a complex form considering, on the one hand, the shape of plasma inside, and on the other hand, all coils and pipes outside to tightly adjoin vacuum vessel. "We had to wait till finishing the design of ITER vacuum vessel to start designing blanket shield blocks in earnest. This is because we had to consider the blanket shield blocks’ location which is internally adjacent to plasma and externally to the vacuum vessel. The shape of blanket shield blocks was decided based on ITER’s idea of the most stable plasma form and by the location of coils and pipes inside the vacuum vessel,” said Dr. Kim. Mission 2. Carving ‘Stainless Steel 316L(N)-IG’ as elaborately as if it were made of clay In the production stage, a technique to delicately process difficult-to-machining materials of large size was developed to enable complicated shapes. "First of all, we introduced a precision drilling equipment to make a path of cooling water into the stainless steel 316L(N)-IG which weighed around 5 to 6 tons. And the cover plate was welded precisely by welding craftsmen. Then, we finished machining the external into complicated shapes by a large precision-machining-device which can move both horizontally, vertically and tilting as well" said Sikun Chung, a senior engineer of the team. It was a challenge of carving very huge, sturdy surface with a very fine knife. Drilling was another challenge to create a path for coolant. One shield block, whose size is 1m in height, 1.4m in width and 0.4m in thickness, requires as many as 220 drillings to create coolant passage. For the smooth flow of coolant, a hole of 1.4m length must be drilled through by one single drilling without mistake. If the way is drilled from both ends of the shield block towards the middle point, even a tiny miss of the point will lead to slow down the water flow on the spot, causing turbulence and drop in cooling performance. Therefore, it must penetrate 1.4 m with one single drilling, not to mention all the 220 coolant paths drilled inside a blanket shield block must meet each other accurately within 1mm tolerance. Senior engineer Byung-Il Park explained the difficulty of drilling as follows: "The 1.4 m should be drilled in one way within a 16-32mm diameter. Stainless chips from drilling may interfere with the way, and the drill may go astray due to the collision of power between the stainless steel and the drilling. We gathered initial mistakes and errors to come up with the best processing method. The ways in and out for coolant were finished by welding approximately 55 pieces of cover plate. Another trial and error was inevitable in welding as well to minimize distortion while welding total 160 meters.” In addition to the initial trials and lessons, the partnership with domestic companies also enabled engineers to find the best processing method. The blanket shield block passed a non-destructive test designed to fully inspect for all welds. By using the world's first developed ultra-high temperature helium leakage test facility, it also proved its performance by completing ITER-like operation test under high-temperature, high-vacuum conditions. Dr. Kim recalled that the various performance tests of the blanket shield block were like a series of endeavors trying to find something invisible. In particular, regarding the high temperature helium leakage test, the lack of both such a device and such experience demanded countries participating in ITER to gather for workshops to find a breakthrough together. It is notable that ITER Korea DA successfully passed the stringent testing standards of ITER for the first time among ITER members, with some of the technologies developed during the tests waiting for their patents to be approved. For more KFE NEWS: KFE NEWS Vol.26
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German company Siemens realizes smart factory based on digital technology Virtual reality ITER When Tony Stark, the protagonist of Iron Man, creates Iron Man nano suit with the arc reactor in his chest, he goes through a series of processes such as designing the suit, making a prototype, trying out the prototype, checking its size, testing its performance. Such technology to embody real machines, systems or environment in a virtual space including computer and to reflect all available variables such as materials, time, temperature, and pressure in real time to use them for the production of a prototype, monitoring, simulation, and optimization is known as ‘digital twin.’ Digital twin, which perfectly combines real physical world and digital virtual world, is also to be used in nuclear fusion research.  As the name implies, ‘digital twin’ refers to digital twins that exist in the virtual world. It is the concept advocated by U.S.-based consumer electronics company General Electric (GE) and is characterized by the interactions between twins in the computer and in reality based on data. Digital Twin enabled people to experiment with various circumstances reflecting reality, predict results, save technology development costs, and enhance the efficiency of industrial sites.  Although the concept spread mainly in the manufacturing industry in the 2000s, it is now acting as a problem solver in a wide range of areas such as aerospace, defense, construction, energy, and urban design. For example, Singapore pursued the national digital twin platform called ‘Smart Nation Project’. It created digitally twinned smart cities in collaboration with global companies, and used these cities as a test stage for various urban administrations, including urban population distribution, transportation, environment, and commercial districts. The result was, of course, a successful city construction.  Various digital twins have been also witnessed in the field of nuclear fusion. Digital twin is a key tool that leads to success in large construction projects such as International Thermonuclear Experimental Reactor, or ITER. ITER Organization is operating a virtual reality room (VR room) that adds 3D visualization technology to simulation. The ITER cannot allow even small errors in the assembly and manufacturing process because hundreds of thousands of components must be perfectly aligned and interlock like cog wheels. That is because ITER experts are looking for optimal assembly method and sequence in the VR room. The large 2.5m (wide) x 4m (high) screen displays vivid 3D images featuring the nuclear fusion device’s cooling water piping system, vessel support, and other plant systems or components, thereby serving as a venue where experts of each ITER device can gather together to discuss the optimal interface. They can also send and receive 3D data directly with the ITER CAD database through software. Digital twin is also an effective tool to overcome the extreme environment of nuclear fusion. The inside of the fusion reactor, where the ultra-high temperature plasma of 100 million degrees Celsius is faced with superconducting magnetic fields, is an environment hardly accessible by humans. The Joint European Torus (JET), an experimental nuclear fusion reactor, manages the nuclear reactor by means of remote handling of robots in the control room built outside the reactor. Such technology of remote handling that transmits human movements to robot arms is a kind of digital twin. In addition, France’s nuclear fusion device called Tore Supra and China's nuclear fusion device called East have introduced digital twin for remote maintenance of nuclear fusion reactors. South Korea’s KSTAR can also encounter digital twin in the next two years. In May 2020, NFRI started the ‘digital twin-based nuclear fusion energy facility operation’ project in May 2020. The project is being participated by SF Technology and VR Media, companies specializing in digital twin, and Sangmyung University.  Dr. Kwon Jae Min, Director of Advanced Physics Research Division of NFRI, who is in charge of this project, said, “It is possible to maximize the performance of KSTAR by reflecting all operational elements such as plasma temperature, pressure, and magnetic field strength, as well as all device properties that make up KSTAR in digital twin”, adding “Prevention of collapse in ultra-high plasma and control of superconducting magnetic fields are challenges that the nuclear fusion industry has long faced. I expect that a more challenging and reliable nuclear fusion research would be possible if experiments on each variable are conducted and an optimization method is derived.”  In order for digital twin to be competent as expected, digital KSTAR must realize even the same plasma motions as real ones. What is needed to this end is to maximize the performance of computer simulation with high quality data secured by KSTAR. A variety of simulation codes and physical models for tokamak plasma have been developed so far. In particular, this year, a new supercomputer will start operation, which is the key resource for the simulation researchs has also been strengthened.  The goal of the digital twin project is the first stage of development that simulates various nuclear fusion issues and derives an optimal solution. Such issues include how plasma is generated and sustained, how heating beams energize plasma and create hot spots in tokamak walls facing plasma. The project aims to remotely control the actual KSTAR via digital KSTAR in the later stage of the development.  Digital twin is also in line with the Virtual DEMO (V-DEMO) which is being prepared by NFRI for the purpose of construction of a nuclear fusion demonstration reactor. In the near future, we hope that the digital KSTAR can be used with real KSTAR through expanding collaboration with NFRI, fusion community, and industries.
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Figure 1. Toroidally symmetric dual shattered pellet injectors, which are 180 degree apart from each other, installed in KSTAR. They share the ports with ECE imaging and ECH antenna, respectively. ITER adopts a strategy to evenly distribute the radiated power during disruption mitigation and reduces the time to prepare pellets using multiple shattered pellet injections (SPI) at the same time [1]. However, since there were no existing devices with fully symmetrical SPIs, as planned in ITER [2], sufficient studies on the effects of simultaneous multiple injections have not been conducted. To confirm the feasibility of ITER's disruption mitigation strategy, KSTAR installed two SPIs of exactly the same design in opposite locations as shown in figure 1 [3]. Each SPI can use three barrels of different diameters to selectively control the number of particles injected. The species used can vary deuterium, neon, argon, or mixtures thereof, depending on mitigation purposes, such as mitigating heat loads or suppressing runaway electrons.    Last year, we investigated differences in disruption mitigation, primarily by deliberately changing the arrival times of the two SPIs to assess the possible jitter effects between multiple SPIs. As can be seen in figure 2a), the current quenching rate changes proportionally as the time difference varies from a few percent to tens of percent over the thermal quenching (TQ) period (1 to 2 ms). This has been experimentally proven that more energy can be released when multiple SPIs are injected simultaneously, as planned by ITER. The results resolved the ambiguity for simultaneous multiple injections observed in previous experiments performed with two SPIs 120 degrees apart [4]. In addition, the sensitivity to jitter identified by KSTAR experiments provided guidance for the design of the ITER Disruption Mitigation System (DMS).  On the other hand, in the disruption mitigation process, it is also important to form a high plasma density to prevent the transfer of magnetic energy towards the runaway electrons. For this study, a dispersion interferometer with a short wavelength of 1064 nm was developed and installed to measure the density during the disruption process where the conventional interferometer with a long wavelength typically suffers the cutoff and refraction. The dispersion interferometer can measure 1 or 2 orders of magnitude higher than that of a conventional interferometer. For the dual SPI, we measured a peak density of 1.2x1021 m-3 near the TQ end, which is almost twice the single SPI value. Figure 2. a) Current quench rates depending on the difference of arrival time between two SPIs, b) density rise during TQ in single SPI case (KSTAR #23456), and c) density rise during TQ in well-synchronized dual SPIs case (KSTAR #23464). Red vertical dash-lines. Excessive particle injection of SPI and subsequent radiation creates a strong MHD instability in the plasma. Conversely, this MHD mode significantly affects the behaviour of the injected particles. As can be seen in figure 3, the well-synchronized dual SPI showed a much milder MHD instability than the asynchronous SPI. Figure 3. n=1 MHD mode amplitudes during TQ depending on the synchronization of SPIs. Mitigation of disruption with SPI is a complex phenomenon depending on plasma and SPI parameters. Studies of interactions with existing MHD modes, such as the cause of disruption, are also important in establishing realistic mitigation strategies. Among the various topics of DMS, we first plan to focus on multiple injections at different toroidal locations by changing the parameters mentioned above, as well as multiple barrel injections at the same poloidal/toroidal location according to ITER DMS's plan. To do this, the largest sized barrel (8.5 mm) is changed to medium size barrel (7.0 mm), simulating an ITER SPI with all the same sized barrels. It is expected to provide the data underlying the ITER DMS design.
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Vessel to contain artificial sun of one hundred million degree Celsius Plasma - First sector of ITER vacuum vessel completed Vacuum Vessel The first segment (sector #6) of the ‘vacuum vessel’, a key component for the International Thermonuclear Experimental Reactor (ITER) project has been completed in South Korea and has arrived in France, the construction site of the ITER.  NFRI held a ceremony to celebrate the successful manufacture of the first ITER vacuum vessel sector at Hyundai Heavy Industries Co., Ltd. (HHI) in Ulsan on April 20, 2020 (Monday) with about 30 people from the government, research institutes, and industries in attendance considering COVID-19 situation. The ITER construction will enter the stage of assembly and installation beyond stage of manufacturing & construction up to now. NFRI and HHI. have overcome numerous technical challenges for the past ten years and successfully completed the first sector of the vacuum vessel under the support of ITER organization.  The ITER vacuum vessel, which is made up of nine sectors, is a doughnut-shaped heavy mechanical structure which will measure 13.8 meters in height, 19.4 meters in outer diameter, and total weigh about 5,000 tons after assembly. The sector #6 (11.3 meters in height, 6.6 meters in width, and weight 400 tons), the first-completed sector #6 is the reference point for assembly and installation of the vacuum vessel system. Only when it is successfully installed, other sectors can be assembled and installed sequentially. Now that the sector #6, which will be first fabricated among nine sectors of the ITER vacuum vessel, is faced with difficulties that it has to first resolve various technical challenges as a First-of-a-Kind(FOAK).  The vacuum vessel located at the innermost part of the nuclear fusion reactor serves as a vessel that creates a high vacuum environment so that it can generate and maintain an ultra-high temperature plasma of more than 100 million degree Celsius in which nuclear fusion reaction occurs. In addition, it acts as a primary confinement barrier that shields neutrons generated during nuclear fusion processes and a platform that precisely fixes in-vessel components of the nuclear fusion reactor such as the blanket and the divertor.  In particular, the vacuum vessel, which is a 3D-shaped, double wall structure, made of a special stainless steel, requires addressing the most difficult technical challenges and complying with rigorous quality control in the manufacturing process in order to provide a perfect vacuum condition. It also needs precious fabrication and welding technology, including following tolerances of several millimeters or below for the purpose of the precious assembly of numerous in-vessel components during the welding process for total 1-kilometer-special stainless steel with a thicknesses of 60mm. In addition, in order to comply with the French nuclear safety regulations, which requires a 100% precise non-destructive testing, a new non-destructive testing technology that can completely inspect major welded parts has been developed and applied. “We are really happy to overcome many technical limitations and successfully complete the sector #6 of the vacuum vessel in ten years,” said Han Young-seuk, President and CEO of HHI which is responsible for manufacturing the vacuum vessel. “Based on our experience in completing the first sector, we will make every effort to procure the remaining three sectors in a timely manner to contribute to the successful construction of ITER.” Currently, HHI is in charge of four of the ITER’s nine vacuum vessel sectors. The remainder has been built in the European Union (EU). After winning an order to supply two vacuum vessel sectors, HHI won an additional contract to supply two sectors from the EU. Bernard BIGOT, Director-General of ITER Organization, who was not able to visit South Korea due to the spread of COVID-19, said in a video, “The successful completion of the vacuum vessel sector #6 despite numerous challenges is a real victory achieved through the cooperation between South Korea and the global vacuum vessel team and I am grateful for the strong support from the South Korean government, as well as the country’s academy-industry cooperation which have played a crucial role in pursuing the ITER project.”
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Front view of NFRI On May 19, partial amendment to the “Act on the Establishment, Operation, and Fostering of Government-funded Science and Technology Research Institutes, etc.”, which includes provisions to make NFRI an independent corporate entity. The amendment will come into effect six months later, and NFRI, an affiliated research institute of the Korea Basic Science Institute (KBSI) will be promoted to Korea Institute for Fusion Energy on November 20, 2020. Until now, NFRI has been conducting research and development as an affiliated institution instead of a corporate entity although it is the only nuclear fusion research institution in Korea. According to the amendment, NFRI secures an independent status legally and will actively carry out research and development for global joint research and nuclear fusion commercialization.  

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