Category: OV1-1 Overview of CRAFT project progress J. LI, BN.Wan, Y.T.Song, K.Lu, Y.Wu, P.Fu, F.K.Liu, J.L.Chen, F.Liu, Y.Shi, H.J.Liu, L.Guo, Y.L.Hu, J.G.Qin, H.Jin, G.Gao, Q.Y.Zhang, H.S.Zhou, T.J.Xu, D.M.Yao, S.L.Liu, L.Chen, Z.H.Liu, J.F.Wu, Y.Cheng, X.J.Wang, L.Liu, C.M.Qin, Y.Fang, B.J.Xiao, Q.P.Yuan, G.Shen, Y.Fang, S.Z.huang, H.X.Yin and CRAFT team Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China 2 Institute of Energy, Hefei Comprehensive National Science Center, Hefei, Anhui 230026, China Email: [email protected] Abstract: Comprehensive Research fAcility for Fusion Technology (CRAFT) is a national big science project to develop key technologies and systems for Chinese Fusion Engineering Testing Reactor (CFETR). There are 20 subsystems within the project which cover the key technology and prototype system for CFETR [1-2]. The CRAFT project aims to establish the method and standard for manufacture and test the key materials, components and key system for CFETR. Significant progress have been made during past few years. Serious DEMO Relevant technologies, new materials, components and systems or successfully were made. All of the testing results show that CFETR construction technical base is established. Introduction The Chinese Fusion Engineering Testing Reactor (CFETR) is the next device for the Chinese magnetic confinement fusion (MCF) program after ITER. Steady-state operation and tritium self-sustainment will be the two key issues. Operation scenarios have been assessed by integrated modeling based on advanced H-mode physics with high magnetic fields up to 6.5T. High frequency ECRH, LHCD, ICRF and NNBI injection will be used together with high bootstrap current for achieving steady-state advanced operation. The detail engineering design has started together with many small scale R&D. For providing a solid technical base for construction, Comprehensive Research fAcility for Fusion Technology (CRAFT) was launched by central government together with Anhui local government financial support. CRAFT is a national big science project which started on 20, 2019, and significant progress has been made during the past 5 years. CRAFT used not only the technologies from ITER, but also those which need to be developed in future with significant challenges and efforts. Several new materials aimed at future reactor, which have better performance than those used in ITER, such as Nb3Sn [3], N50, ODS-Cu, ODS-Steel, were developed. Most of testing facilities have been finished which include superconducting material testing facility, TF testing facility, CS testing facility, plasma wall interaction facility (shown as Fig.1), blanket testing facility, high heat load testing facility (20MW/m2), vacuum chamber testing facility. Extensive experimental testing has been done during the past few years. There are 20 subsystems within the project which cover the key non-nuclear technology and prototype system for CFETR. The detail of each system is introduced in this paper. 1. SC Material testing facility Superconducting material testing facility is to master scientific and intrinsic physical property and serve the behaviors of fusion superconducting material for magnets in the complex and extreme environment. There are six devices for different purpose. Table 1 list of material testing facility - SC material performance research platform: 19 T, 2 kA, 150mm - AC Loss research platform: 0.01-0.2 Hz, 1500 kN/m - Structure material performance research platform: 2500 kN - Thermo-hydraulic research platform: 3.8-300 K - NDE technology research platform: 350 kV (X-Ray) - High voltage research platform: 0-100 kV All facilities were fully tested and passed the acceptance testing in the end of last year. Now it's fully open to the users for the material research purpose. 2. SC Conductor testing facility Superconducting conductor testing facility is to study the electromagnetic behavior of the superconducting conductor under the multi-field coupling conditions, It is to evaluate the performance of the conductor in the future demo future reactor operation conditions. The maximum magnetic field is 16.5T. The testing space is about 100 X165 X150 millimeters. The field homogeneity is over 98%. Maximum current is up to 100 kA. This facilities is bigger than the Sultan superconducting testing facility especially for future demo conductor testing. There are 32 coils are going to be wounded and also assembled together to set a very high magnetic field to test performance of the future demo conductors. All the coil have been wounded and the VPI has been done. The assembly is under way. 3. TF magnets testing facility TF magnet testing facility is To perform the DEMO-scale SC magnet research on mechanics, thermology and electromagnetics properties, To evaluate the DEMO SC magnet system compatibility, reliability, stability, and magnet safety in fault state and verify the reliability of magnet engineering technology. The device can accommodate the full size of the TF coil of CFETR. The dimension of the device is 28.5m X14m X6m. Operation temperature is about 4.5 Kelvin. Operation currents will be around 100 kA and helium liquid mass flow over 500 g/s. The facility is under construction for nearly four years all the technology related, such as power supply, quench protection, thermal shielding, vacuum, high current leads were developed. The facility now is in working condition and ready for TF coil testing. 4. CSMC and testing facility The CSMC testing facility is to develope the magnetic technology for future cfetr CS coil. A mode CS coil which is about half size of the CFETR CS coil are going to be made and testing will be done with similar tokamak working condition. Electromagnetics thermodynamic performance of the magnet, safety operation characteristics, AC property will be evaluated when CSMC is made. The system consists the five coils made Nb3Sn with a total store energy 125MJ. Up to 48kA of coil current has achieved which is above the design value 46kA. The central magnetic field reach 14T with a testing space 1.5m. Fast ramping testing was also carried out which simulates the CS working condition. The field change can reach 5T/s. All the internal joint resistance of coil is less than one nanometer. Further comprehensive experiments for all the performance of CSMC are under way. 5. HTS coil and testing HTc magnet is a challenge technology development aiming to explore high field application which is very important for DEMO. CICC HTc conductor and CS magnet were chosen for CFETR. Technology for YBCO tape was the baseline approach. CORK type wire and CICC conductor were developed. Short CICC conductor sample have been fully tested in Saulten facility. The first one was failed and 2nd one was successfully passed all QA testing without any degradation which meets the design requirements. Option operation current is 46 kA and up to 80kA was carried out. The maximum field on coil is 19.6 Tesla. Fast AC ramping test is also carryout and performance meets the design criteria. The second CICC approach is 2212 wire. Each of these conductor will be over 200 meters and internal joint will be used. 6. TF and testing One of the most challenge system is the full size CFETR TF coil. To meet the CFETR mission, higher SC magnets are needed, especially TF coil which need further material, technology beyond ITER. Specification of TF coil is shown in following table. Another challenge is cost and schedule. Hybrid design principle was adopted which using NbTi, ITER-type Nb3Sn and high performance Nb3Sn (3 times higher than ITER). 216 internal joints will be used for this design which induced difficulty for low resistance joint (<0.3 nΩ). TF Coil Specifications Table: - Iop: 95.6 kA - Bmax: ~14.5 T - Total Storage Energy of 16 TF coils: ~120 GJ - Total Inductance of 16 TF coils: 26.3 H - Operation temperature: 4.5 K - Insulation Voltage: > 10 kV - Height x Width: 21.7 x 12.3 m - Total weight: ~743 t New materials were developed which include high performance Nb3Sn, N50 for coil case and isolation material for VPI. Samples of 3 type of CICC conductors were fully tested in Saulten facility which meet design requirements. The coils were made successfully with all procedures which meet all QA control standards. The assembly and commissioning of the all the coils is on the way. The full testing will be in the end of 2025. 7. Cryogenic testing facility The purpose for cryogenic system is to develop cryogenic technology for DEMO and testing facility for CFETR SC magnets. The system consists six different helium refrigerators, which includes 6kW/4.5K, 250W/1.8K, 2X1kW/3.8K, 3kW/4.5K, 200W/4.5K refrigerator. Refrigerators were successfully made and fully commissioned and tested. Most of the refrigerators were used in NNBI, CSMC, and conductor testing facilities. 8. Power supply testing facility Power supply system is to solve the key drawback issues for the current superconducting coil power supply which needs huge peak power and develop new coil power supply for next generation power plant and also supporting research and testing for the CRAFT large superconducting magnets. Since TF coil operation needs operating current 100 kA, and the voltage will be 3 kV. The most difficult system is the TF quench protection system which including breaker and fast dumping load system. Two-stage breaker was design and manufacture. More than 20 full current testings were done which evaluates its reliability, availability and life time. The power supply system also provide magnets testing and quantification experiments routinely. 9. Large Linear plasma testing facility In the future demo reactor, one of key issues is plasma wall interaction, especially on the normal high influence of particle and heat flux for base operations. The large linear plasma testing facility is to address the key issues for plasma facing material and components for CFETR in an appropriate physical regime and time scale for plasma material interaction. Our facility consists of large size linear machine with a superconducting magnet up to three Tesla. Particle flux is about 10^24 - 10^25 m^-2 s^-1 and heat flux up to 20MW/m2. Sample size can reach 250x250 mm. Target of divertor marker can be accommodated inside of this testing facility and the irradiated sample can be transported in a real time to analysis surface condition and to validate its performance. The second device is a copper magnet with 1T field which is pre-demo type linear machine. Plasma in both machines were achieved with helium, hydrogen and deuterium working gases up to 24 hours operation. Flux of 1x10^24 m^-2 s^-1 was achieved continuously with minimum time of 1000s duration. Now both facilities are fully opened to the users for material plasma interaction experiments. Fig.1 Superconducting Plasma Wall interaction testing facility. BT = 3 T, 20MW/m2, plasma flux 1X10^24/s m2 operates for over 24 hours. 10. Master Control facility Master Control facility is to provide IT web campus support and also establish a digital tokamak for CFETR which includes plasma control system, discharge scenario assessment, data simulation platform, integrated modeling and analysis platform and together with a synthetic diagnostic platform for plasma controls. All these software and the new method were verified not only through the data learning simulations and also used in EAST tokamak experiments. Over nine thousand shots was successfully fired using the platform with a success rate 99.4%. The system also running for over 24 hours continuously using the EAST discharge data which demonstrates controller, integrator, PCS and data handling can meet future CFETR days operation need. This facility also has a function to prediction and analysis of data between short, which is about in five minutes. All the system has been fully tested and ready for next generation device operation. 11. Divertor development The divertor is a key component for future demo reactors which will be suffering from very strong high heat flux, particle flux, neutral yield together with huge disruption force. The water cooled divert development includes developing advanced technologies for design, manufacture advanced materials, components, tools with RH capacity for repairing damages components. And eventually a fully qualified prototype demo divertor will be built for CFETR. Hybrid divertor configuration was adopted which combine plasma facing targets which can handle up to 20 MW/m2 heat flux. A breeding blanket beneath the divertor target was used which not only for support structure but also for the neutron shielding to magnets. Simulation and shape optimization were done which meets the physical design needs and particle exhaust for pumping. And remote maintenance capacity design was also carried out with fully validated tools for cutting, welding, gripping and replacement. The materials used for divertor include the doped W alloy for plasma facing material, ODS-Cu for heat sink, and ODS RAFM for the structure supporting material. All QA for materials (except neutron irradiation) were carried out which meet the design requirements. Qualifications for RH tools were also verified. Heat flux testing up to 20MW/m2 for small mockup, mid-size and full size targets were tested with ITER testing standard. Both ITER-type monoblock type and flat tile type divertor target could meet design needs. These two type divertor targets were using in EAST tokamak which operated for two years successfully. Flat tile target shows better performance with lower operation wall temperature. Flat-tile target divertor was chosen for CFETR baseline design. Now the prototype CFETR divertor was built and the further testing are underway. 12. Divertor testing facility CRAFT high heat flux testing facilities includes two electron beams together with vacuum vessel, pumps and cooling water systems, which to provide testing environment for high heat flux loading and thermal hydraulic performance for water cooled divertor and also can be used for blanket components. The two electron beams provide 800 kilowatts for steady-state heat load and 60kW@150kV, 0.1-10 kHz for simulating ELM working condition. IR camera, CCD camera and thermal coupler were used for real timely heat load measuring. Vacuum chamber is capable to accommodate full CFETR size target. This facility were fully manufactured and tested during past 3 years now is a fully open to the user and daily experiments are carried out. 13. Blankets developments Blanket is also another key component for future CFETR. Two kinds configurations of blanket were designed and manufactured: the first one is the water cooled ceramic breeder with ODS steel used for structure material and tungsten alloys used for first wall armor with a thermal efficiency of 33%. The second one is the supercritical CO2 cooled blanket which is aiming high thermal efficiency and much simpler cooling, along with high operating ratios. The global TBR is 1.18 and up to 45% of the thermal efficiency can be achieved. 14. Blanket testing facility All these components material and manufacture for this two kinds of blanket developed. Meanwhile several testing bench for these two kinds of the blankets were built which consist of the liquid metal MHD blanket experimental facility, supercritical CO2 blanket testing facility, and thermal-hydraulic testing facility for water cooling blanket. All these three big facilities with superconducting magnets up to three Tesla will be built and tested. Now these three are routinely operated under different working conditions. 15. NNBI system Negative neutral beam up to 1 MeV will be used for future CFETR. For this stage a comprehensive research facility for negative ion based neutral beam injection system have been developed which includes the negative ion source, beam line cryopump and high voltage power supply. Two kinds based on the RF ion source developed: dual driver negative ion source (200 kilowatts were developed and fully tested after 2.3 megawatts and neutral beam were achieved which operate up to 120 seconds); a single driver negative ion source also was built and tested up to 20 seconds for 1.5 megawatts achieved with duration times for testing. Experiment for 400 kilowatts is under development. 16. LHCD system Lower hybrid current drive system will be used for CFETR in the future. A prototype system was developed; the objective for this system is to explore the possibility for CW LHCD systems including developing all the technology needed for CW LHCD system to build all components up to four megawatt systems. All the components were fully developed with 4.6 GHz 500 kilowatt CW klystron and CW converter, waveguide transmission line, and a 4 megawatt PAM antenna will be tested on EAST in the near future. 17. ICRF system Ion cyclotron resonant frequency system is to provide a testing facility with two megawatts of power for finding a solution to use ICRF in CFETR. The purpose is trying to solve technical challenges and developing required technology, manufacturing, testing and validating the components and prototype system for CFETR. The RF generator will be two megawatts (combining two generators into two megawatt level). The frequency is from 40 to 80 MHz. All components including each type of antenna module, ceramic window, transmission line and matching system, and combined generator power supply were developed. The whole system integration and commissioning was finished up to 2.2 megawatts of RF power for over 1000 seconds was successfully achieved, meeting the design criteria. 18. ECRH system ECRH is a pioneer heating and current drive system for future CFETR. The facility is to address technical issues as well as provide technical solutions for critical components for future advanced CFETR systems, focusing on designing, manufacturing, and assembly for key components and conditioning for the whole systems. The whole system was successfully constructed with two megawatts. A 170 GHz gyrotron tube was fully tested up to 1000 seconds. The other components including the switch, windows, transmission line all meet the design requirements. Designing the launcher is ongoing aiming for future reactor working conditions in a neutron and radiation environment. 19. VV and installing testing facility Vacuum vessel is another key issue for future CFETR: mastering high precision and high quality manufacturing technology for full scale vacuum vessel sectors. A vacuum vessel manufacturing environment was made, including auto welding assembly and real-time measurement for size and quality. The second purpose for the vacuum vessel testing facility includes assembly and testing dimension detection and control. After a few years effort, a 1/8 sector of the vacuum vessel was successfully manufactured with tolerance reach less than three millimeters. Welding, cutting, and inspection tools were made. 20. RH & testing facility The final facility is a remote handling technology development and testing facility. The purpose for this facility is to develop DEMO remote maintenance technology and build testing facilities to validate working conditions in future reactors. The remote maintenance includes a vertical removal philosophy and related tooling for future CFETR blanket sectors. Links for internal cutting, welding and inspection were fully developed. A transport cask was also made. All these facilities for remote maintenance are under further development and testing together with the joint team from the European DEMO design team. Summary CRAFT project is a national big science facility aiming to develop key technology and systems for the construction of CFETR. Started in September 2019, it is scheduled to be finished within five years and 10 months with joint funding from the central government and local government. CRAFT utilizes technologies from ITER while addressing future DEMO challenges. The completeness of the project is about 92%. Most subsystems and related technologies were finished, with only two systems delayed by about eight months. The CRAFT facility provides a solid technical basis for future successful construction of CFETR. References: 1. Song, YT, Li, J, Wan, Wan YX et.al., FUSION ENGINEERING AND DESIGN, (2022), 183 2. Hu, L Q, Liu, Y, CFETR Diagnostic Team, FUSION ENGINEERING AND DESIGN (2020), 155 3. Dai, Chao, Wu, Yu, Li, Jiangang, et al., NUCLEAR FUSION, (2021), 61 (3)