Recent Progress of JT-60SA Project

Transcription

1 Shirai DOI: / /aa5d01 OV/3-3 Recent Progress of JT-60SA Project H. Shirai 1, P. Barabaschi 2, and Y. Kamada 1 1 Japan Atomic Energy Agency (JAEA), Naka, Japan 2 F4E: Fusion for Energy, ITER EU Centre, Barcelona, Spain Corresponding Author: H. Shirai, shirai.hiroshi@jaea.go.jp The JT-60SA project has been promoted since June 2007 under the framework of the Broader Approach (BA) agreement and Japanese national fusion programme for an early realization of fusion energy by conducting supportive and complementary work for the ITER project and directing DEMO design activity. With the powerful and varied deposition profile of heating and current drive system, flexible plasma shaping capability and various kinds of in-vessel coils to suppress MHD instabilities, JT-60SA is sure to play an essential role to address essential issues to achieve long sustainment of high-β N burning plasmas expected in DEMO. Components and systems of JT-60SA are procured by the implementing agencies (IAs): Fusion for Energy in EU and JAEA in Japan. Their design, fabrication, installation and commissioning have been actively directed and supervised by the IAs. As of the end of 2015, twenty-seven procurement arrangement (PAs) have been concluded covering 95% of the values of in-kind contribution for JT-60SA. In spite of the size, components of JT-60SA have been manufactured well within the tolerance of 1 mm order. EU procures TF coils, most of the power supply systems, cryogenic system, cryostat and so on. The cold test of the first TF coil with a nominal current of 25.7 ka at K was successfully completed. JA procures EF coils, Central Solenoids, Vacuum Vessel, thermal shields, heating system, diagnostics system and so on. Vacuum Vessel sectors were welded on the cryostat base forming a 340 torus. The heating systems (P-NBI, N-NBI and ECRF) have been conditioned to operate at their full power (41 MW in total) for 100 s. The first plasma of JT-60SA is scheduled in Wide range of operational region of JT-60SA kept in mind, the JT-60SA research plan (SARP) has been regularly updated on the basis of intensive discussion among European and Japanese researchers. The latest SARP (version 3.3) open to the public in March 2016 shows that wide operational region of JT-60SA covers that of recent European and Japanese DEMO designs. DEMO oriented researches such as study of ECRF assisted startup, investigation of noninductive current overdrive scenario using TOPICS code were added. This paper summarize the recent progress of JT-60SA Project pushed forward by close collaboration of EU and Japan. Published as a journal article in Nuclear Fusion

2 1 OV/3-3 Recent Progress of JT-60SA Project H. Shirai 1, P. Barabaschi 2, Y. Kamada 3 and the JT-60SA Team 1 JT-60SA Project Team and 3 JT-60SA JA Home, National Institutes for Quantum and Radiological Science and Technology, Mukoyama, Naka, Ibaraki , Japan 2 JT-60SA EU Home Team, Fusion for Energy, Boltsmannstr 2, Garching 85748, Germany contact of main author: shirai.hiroshi@qst.go.jp Abstract. The JT-60SA Project has been implemented since June 2007 under the framework of the Broader Approach (BA) agreement and the Japanese national fusion programme for the purpose of an early realization of fusion energy. With variable heating and current drive profiles by powerful NBI and ECRF system, flexible plasma shaping capability, and various kinds of in-vessel coils to suppress MHD instabilities, JT-60SA is sure to play an essential role to address key physical and engineering issues of the ITER project and to promote DEMO design activities. It aims to achieve long sustainment of high integrated performance plasmas under the high N condition required in DEMO. Fabrication and installation of components and systems of JT-60SA procured by the European and Japanese implementing agencies, F4E and QST, are steadily progressing. Assembly of toroidal field coils around the vacuum vessel will start soon in the torus hall. Commissioning of the cryogenic system and power supply system has been implemented in the Naka site. The first plasma of JT-60SA will be achieved in The JT-60SA research plan covers a wide area of issues in ITER and DEMO relevant operation regimes, and has been regularly updated on the basis of intensive discussion among European and Japanese researchers. 1. Introduction The mission of the JT-60SA (Super Advanced) Project [1-3] is to contribute to an early realization of fusion energy by addressing key physical and engineering issues for ITER and demonstration fusion reactors (DEMO) [4,5] by utilizing JT-60SA, a superconducting tokamak being constructed in Naka Fusion Institute of the National Institutes for Quantum and Radiological Science and Technology (QST). Figure 1 is a schematic view of the JT-60SA tokamak. The JT-60SA project has been implemented since 2007 under the framework of the Broader Approach (BA) agreement as well as the Japanese national fusion programme (NA). Overall implementation of the BA activities is directed and supervised by the BA Steering Committee (SC), and examined by the Project Committee from the technical point of view. EU and Japan each designates an Implementing Agency, which substantially carries out pertinent activities for the project provided in the BA agreement. The European Implementing Agency (EU-IA) is Fusion for Energy (F4E) and the Japanese Implementing Agency (JA-IA) is QST. The Project Team (PT) coordinates the implementation of the project between the EU-IA and the JA-IA. The principle of the Japanese fusion research and development activities is laid down in the Third Phase Basic Program of Fusion Research and Development [6] formulated by the Atomic Energy Commission, which was released in June Achievement of selfignition condition, demonstration of long pulse (1,000 sec) burning plasma and development of fundamental fusion technology necessary for DEMO are the main targets. In 1992 ITER EDA and the operation of FIG. 1. Schematic view of JT-60SA tokamak

3 2 OV/3-3 upgraded JT-60 (JT-60U) started to achieve the above goals. JT-60U left remarkable records such as DT equivalent fusion energy gain factor of 1.25 and fusion triple product of 1.53x10 21 kev s m -3, and was shut down in 2008 to make way for JT-60SA, which opens up prospect toward DEMO. During past decades understanding of plasma physics has become deeper through intensive research by using worldwide tokamaks. At the same time, lots of critical issues have become clear, which may have strong influence on DEMO design. Under these circumstances, the Joint-Core Team for the Establishment of Technology Bases Required for the Development of a Demonstration Fusion Reactor was organized in the Working Group on Fusion Research under the Nuclear Science and Technology Committee in Japan, and they summarized a report on the basic concept of DEMO as well as physical and engineering issues to be solved with a timeline chart [7, 8]. This report clearly defined that outputs from both JT-60SA and ITER play critical roles to resolve issues related to the DEMO design and decide its construction. The first plasma of JT-60SA will be achieved in 2019, which is much earlier than that of ITER. Therefore JT-60SA can address expected issues of ITER in advance. 2. Objectives and Characteristics of JT-60SA The JT-60SA Project has three major objectives. The first objective is to provide supporting research for the ITER project to accomplish its technical targets. In order to realize a stable steady-state (300~500 sec) Q=10 operation in ITER, lots of critical issues have to be addressed: disruption avoidance and mitigation, ELM control for heat pulse reduction, heat load mitigation by radiative divertor, and so forth. JT-60SA can operate in the ITER-like configuration inductive mode under the break-even-equivalent condition. Thereby operation boundary of ITER high integrated performance plasmas without disruption or serious MHD instabilities will be investigated. Controllability of the plasmas due to the characteristics of superconducting coils is also examined. The second objective is to provide complementary research to ITER in order to promote DEMO design activities. Although ITER will demonstrate 500 MW steady-state DT burning and handle substantial amount of tritium, it will be operated at the normalized plasma pressure, N (=2 0aP/(IpBt)), up to about 3. Since the fusion power is approximately proportional to N 2, DEMO should be operated in a higher N (~5) regime as an economically competitive power plant. Thus such high N operation region will be investigated in detail by using JT-60SA. The third objective is to foster scientists and technicians in the younger generation, who are expected to play leading roles in ITER and DEMO. Quite a long period of time is necessary for fusion research and development. JT-60SA experiments provide opportunities for these people to build up their knowledge, skills and experiences. JT-60SA will examine and optimize operation scenarios in the ITER and DEMO parameter region. For that purpose, JT-60 has several distinct characteristics for flexible operation in a wide range of plasma parameters. Major parameters of JT- 60SA are shown in Table I. Large value of shape factor S=q95Ip/(aBt) enables JT-60A to flexibly change the shape of the plasma cross section. The 4.6 MA operation with ITER-like configuration is beneficial in exploring ITER operation scenarios. TABLE I: PARAMETERS OF JT-60SA

4 3 OV/3-3 Strong additional heating power of 41 MW for 100 sec enables break-even-equivalent operation with 5.5 MA full plasma current. Figure 2 shows the target operation region of JT-60SA. JT-60SA will be operated in a N region compatible to that of DEMO. Figure 3 shows JT-60SA operation region in (q95, N) and (q95, fbs) space, where fbs is FIG. 2. JT-60SA target regimes bootstrap current fraction. Operation target regions of several European and Japanese DEMO fall on the JT-60SA research region. There are many other important parameters [9] for designing DEMO: higher noninductive current drive fraction, fcd, to extend operation time, lower effective charge number, Zeff, in the plasma core region to enhance fusion power, higher ratio of radiation loss to the total heating power at FIG. 3. JT-60SA research regime for DEMO design the SOL/divertor region to ensure integrity of divertor target, higher normalized plasma density, ngw, and higher confinement enhancement factor, HHy2. These parameters should be realized concurrently in DEMO in a well-balanced manner. JT-60SA will tackle such a challenging task. While avoiding MHD instabilities and disruption, plasma controllability should be examined in high N plasmas. JT-60SA has several actuators to control profiles of plasma pressure, plasma current and plasma rotation: a Neutral Beam Injection (NBI) system and an Electron Cyclotron Range of Frequency (ECRF) system, which can independently change the deposition profiles of energy, driven current and momentum input. There are 12 units of positive ion-based NBI (P-NBI, 85 kev, 24 MW in total) and 2 units of negative ion-based NBI (N-NBI, 500 kev, 10 MW in total), whose beam trajectories are shown in Figure 4. Especially the off-axis N- NBI, the perpendicular P-NBI and the tangential P-NBI can be used for current profile control, pressure profile control and plasma rotation control, respectively. The ECRF system (9 gyrotrons, 4 launchers, 7 MW in total) can modulate power at 5 khz and vary the resonance position of the waves by using steerable mirror. A gyrotron can switch wave frequencies: 110 GHz and 138 GHz for 100 sec and a third frequency of 82 GHz for 1 sec. It will be a powerful tool for local heating and local current drive. Furthermore, stabilizing plates, Fast Plasma Position Control Coils (FPPCC), Error Field Correction Coils (EFCC) and Resistive Wall Mode Control Coils (RWMCC) will be installed inside the vacuum vessel as shown in Figure 5 to supress MHD instabilities and achieve high N plasmas. FIG. 4. (a) Top view of NBI and ECRF system, (b) NBI beam trajectories in cross-sectional view FIG. 5. Layout of in-vessel coils

5 4 OV/ Operation Plan of JT-60SA There are several research phases in the JT-60SA operation: (i) the Initial Research phase (~5 years), (ii) the Integrated Research phase (~5 years) and (iii) the Extended Research phase (thereafter). The NBI and ECRF power will gradually increase toward the later phases, which corresponds to the upgrade of diver target components for higher tolerable heat load. During the first half of the Initial Research phase, hydrogen operation is carried out to conduct full commissioning of the entire system. Plasma controllability is examined and operational region is gradually expanded. The plasma current is increased up to 5.5 MA. Although P-NBI and ECRF are not in full power, full-power N-NBI is available. The partially mono-block target is installed with lower single null (LSN) divertor configuration. During the second half of the Initial Research phase, deuterium operation is carried out. With additional NBI power, high N scenario, high p scenario for fully non-inductive operation, and high density operation above ngw are tried. Performance of profile control of the plasma current, the plasma pressure and the plasma rotation is confirmed. In the Integrated Research phase, almost full power heating is available. The LSN divertor target is upgraded to the full mono-block type to withstand the heat load up to 15 MW/m 2, which enables establishment of high power and long pulse operation scenario necessary for DEMO. Commissioning of the remote handling system is completed during the first half of the Integrated Research phase in order to prepare for the second phase with higher annual neutron production. In the Extended Research phase, full power heating of 41 MW for 100s is available. Double null divertor configuration for further reduction of the divertor heat load is also available. In this phase, DEMO operation scenario with N ~5 and high integrated performance operation will be demonstrated. Originally the carbon divertor target will be replaced by the metallic one in the Extended Research phase after the principal mission of JT-60SA is accomplished. Now the possibility of replacement in the second half of the Integrated Research phase is under consideration in order to address issues such as compatibility of metallic divertor with integrated high performance plasmas as early as possible. Thereby obtained physical and engineering outcomes from JT- 60SA would be of great use for ITER and DEMO. 4. Research Collaboration The JT-60SA Project is implemented by close collaboration between the EU and Japan. The Integrated Project Team (IPT) was organized to promote collaboration, which consists of the EU Home Team (EU-HT), the JA Home Team (JA-HT) and the PT. The EU-HT consists of staff of F4E and European Voluntary Contributor designated institutes (VC), i.e. CEA, CIEMAT, Consorzio RFX, ENEA, KIT and SCK-CEN. The JA-HT consists of QST staff. In addition, European and Japanese researchers from universities and institutes come to join the JT-60SA Project through EUROfusion via F4E in Europe and also through Fusion Energy Forum in Japan to examine JT-60SA research items in detail. All of these researchers together with IPT members compose JT-60SA Research Unit as shown in Figure 6. On the basis of a wide operational range of JT-60SA, essential issues to be addressed for ITER and DEMO are examined in eight major research areas: (i) operation regime development, (ii) MHD stability and control, (iii) transport and confinement, (iv) high energy particle behavior, (v) pedestal and edge physics, (vi) divertor, scrape off layer and plasma-material interaction, (vii) fusion engineering, and (viii) theoretical models and simulation codes. They are

6 5 OV/3-3 summarized in the JT-60SA Research Plan (SARP) [10]. Research items of JT-60SA in each research phase necessary to promote ITER and DEMO are described in detail. The latest SARP (version 3.3) [10] by 378 co-authors from EU and Japan was opened to the public in March The SARP has been updated periodically incorporating FIG. 6. Structure of JT-60SA Research Unit the update of ITER research plan and the modification of the DEMO target region. JT-60SA Research Coordination Meeting attended by European and Japanese researchers has been held almost every year to discuss update of the SARP as well as related specific collaborative research. In order to establish an operation scenario from the current ramp-up through the flat-top Fig. 7. Integrated Modelling Code being developed in QST covering both core and SOL/divertor plasmas consistently, an Integrated Modelling Code made up of transport codes of energetic particles, bulk plasma and SOL/divertor plasma as well as MHD stability analysis code has been developed in QST as shown in Figure Procurement Status of Components and Systems Procurement of JT-60SA components and systems is made up of the BA part and the NA part. In the BA part, 27 procurement arrangements (PAs) in total (JA: 14 PAs, EU: 13 PAs) were established as of the end of September 2016, which cover about 95% value of the in-kind contributions of STP. The EU-HT is responsible for the procurements assigned to EU, in particular their manufacture and quality assurance. The JA-HT is responsible for procurements assigned to Japan, and also integration and quality assurance of NA contributions. Existing JT- 60U facilities, e.g. transformer substation, motor generators, etc., are also reused as much as possible in order to suppress the overall project cost. Progress meetings and technical meetings are held quite frequently among IPT members. They identify and settle problems in the early stages and develop strategies to keep momentum of the project. Such strong collaboration among IPT members is a powerful driving force of this project. 5.1.Magnets All of the major coils of JT-60SA are superconducting coils. Eighteen Toroidal Field (TF) coils and six Equilibrium Field (EF) coils use NbTi strand, and four Central Solenoid (CSs) modules use Nb3Sn strand. Twenty D-shaped TF coils including two spare coils with a height of 7.4m and a width of 4.5m are being fabricated in EU. Rectangular shaped steel-jacketed NbTi cable-in-conduit conductors (CICC) (outer dimensions: 22x26 mm 2 ) are used for the TF coils. One conductor is wound to form one D-shaped double pancake (DP). Six DPs are stacked up and connected to form a winding pack (WP) for a TF coil. Fabrication of WPs and their impregnation are being carried out in France and Italy. In parallel, TF coil casings are being manufactured. Impregnated

7 6 OV/3-3 FIG. 8. TF coils with outer inter-coil structure FIG. 9. Upper equilibrium field coils WPs are incorporated with TF coil casings. Finally machining and piping installation are conducted to complete one TF coil. It takes about one year from the winding of the superconductor to the finished product in the first several coils. Every TF coil is sent to the cold test facility in Saclay, France, to conduct performance tests including full current (25.7 ka) test at the cryogenic temperature of 4.5~7 K. After the cold test, an outer inter-coil structure (OIS) is fixed to the outboard side (low field side) of each TF coil, which withstands electromagnetic force applied to the TF coils during operation. Both the inboard side (high field side) of the TF coil casing and the OIS also have helium cooling pipes to facilitate cooldown of the TF coil from outside. Figure 8 shows TF coils with OIS arrived at the Naka site. The poloidal field coil system of JT-60SA is made up of six different size EF coils (EF1~EF6) and four identical CS modules (CS1~CS4), both of which are procured by Japan [11]. The former uses NbTi CICC (outer dimensions: FIG. 10. winding packs of CS module 25x25mm 2 and 27.7x27.7mm 2 ), and the latter Nb3Sn CICC (outer dimensions: 27.9x27.9mm 2 ). EF1 (outer diameter 12.0m), EF2 (9.6m) and EF3 (4.4m) (see Figure 9) will be put above the mid-plane of the torus, and EF4 (4.4m), EF5 (8. 1m) and EF6 (10.5m) will be put below the mid-plane. All the EF coils except for EF4 were fabricated in the Naka site because they are too large to transport on the public road. In spite of their huge size, they are carefully fabricated to keep a high degree of circularity to avoid generating error field. The current central position of EF1, EF2, EF3, EF4, EF5 and EF6 is 0.3mm, 0.4mm, 0.2mm, 0.6mm, 0.6mm and 1.3mm from the stacking center, respectively, which are much smaller than the corresponding tolerances of 8mm, 7mm, 6mm, 6mm, 7mm and 8mm, respectively. One CS module with an outer diameter of 1.99m and a height of 1.60m is made up of six octa-pancakes and one quadra-pancake FIG. 11. High temperature superconductor current leads for TF coils

8 7 OV/3-3 as shown in Figure 10. After the winding of the conductors, heat treatment at 650 C is given. Fabrication of CS1 was completed and sent to National Institute for Fusion Science to conduct cold test under the operational condition. All the CSs will be delivered to the Naka site by November Magnet Shared Components High temperature superconductor current leads (HTS-CLs) using bismuth alloy (Bi-2223/AgAu) are set up between the superconducting coils (~4K) and the external feeders (~300K) [12]. HTS-CLs keep superconductivity up to 60 K and substantially save cooling power of the cryogenic system. Three pairs of HTS-CLs for TF coils (TF01~TF06, nominal current 25.7 ka) (Figure 11) as well as six pairs for EF coils and four pairs for CS modules (PF01~PF20, nominal current 20 ka) have been fabricated in Germany. They all receive a full current test by CuLTKa test facility. Delivery of the final ten HTS-CLs to Japan is planned in Five coil terminal boxes (CTBs) for current feeding and eleven Valve Boxes (VBs) for helium feeding will be set up around cryostat as shown in Figure 12 [13]. They contain HTS-CLs, feeders, helium cooling pipes of various temperature. Their design and layout have been carefully examined to secure accessibility of heating and diagnostics system to the ports. 5.3.Vacuum Vessel FIG. 12. Layout of Coil Terminal Boxes, Valve Boxes and Cryolines Figure 13 shows the Vacuum Vessel (VV) of JT-60SA procured by Japan. It is a double-walled structure made from SUS316L having 18mm shell thickness and a cavity of about 160mm wide between the shells [14]. This cavity is filled with borated water to reduce the neutron budget during deuterium operation. It also allows heated nitrogen gas flow for baking of the VV at 200 C after draining the borated water. The VV was divided into ten VV sectors: seven 40 sectors, two 30 sectors and one 20 sector. The inboard side and the outboard side of each VV sectors were manufactured separately in the factory and welded together in the Naka site. Then they were carried onto the Cryostat base (CB) one by one. Careful grooving processing was performed during welding of adjoining VV sectors. The end faces of each VV sector were locally corrected by applying pressure of jacks and heat input in order to avoid misalignment. The direct-joint welding and the welding with a splice plate were adopted. The degree of contraction observed during the welding R&D was taken into account when deciding the width of the splice plates [15]. Welding work and radiographic testing were carried out alternately to avoid formation of voids in the welded part. Finally they were welded to form a 340 torus structure in September The measured displacement of the VV sectors from the designed value is +5mm/-5mm horizontally and FIG. 13. Vacuum vessel, ports and bellows

9 8 OV/3-3 up to -4mm vertically, which are within the tolerance of +30mm/-30mm and +6mm/-4mm, respectively. Various shapes of fifty-five ports and port bellows were fabricated for the VV. The largest port opening is 1.83m vertically and 0.66m horizontally. They cleared the dimensional tolerance of +2mm/-2mm. Nine VV Gravity Supports with spring plates and oilless bearing were also fabricated, which not only support the VV but also allow displacement of VV by thermal expansion due to the various operational modes. 5.4.Thermal Shields Several kinds of thermal shields procured by Japan are set up to cover major structures of JT- 60SA to keep them at low temperatures against the radiation from warm components. They are the Vacuum Vessel Thermal Shield (VVTS), the Cryostat Thermal Shield (CTS) and the Port Thermal Shield. Thermal Shields are normally cooled at 80K by gaseous helium and are of great use to reduce the electricity consumption of the cryogenic system. All the VVTS and lower port TS were already fabricated and delivered to the Naka site in March Designing, drawing and trial manufacturing of the other TS are being carried out. 5.5.In-Vessel Components Components such as cryopanels, divertor cassettes, the inboard first wall, the stabilizing baffle plate with outboard first wall will be installed inside the vacuum vessel. In addition, magnetic diagnostic coils including magnetic field probes, Rogowski loops, one turn loops, diamagnetic loops and saddle coils as well as control coils such as FPPCC, EFCC and RWMCC for high N plasmas will be installed. The lower divertor consists of a divertor cassette frame and plasma facing components mounted on it. Coolant pipes for each component are connected to the main coolant pipes of the cassette frame, and a remote handling (RH) maintenance pipe is connected to the coolant headers in the VV [16]. A mono-block type Carbon Fiber Composite (CFC) is adopted for the divertor target plates, which are bolted on cooled heatsinks and allows a heat load of 15 MW/m 2 [17]. All the 36 divertor cassettes were manufactured in 2013 and delivered to the Naka site. 5.6.Cryostat The cryostat of JT-60SA is made up of the cryostat base (CB) [18] and the cryostat vessel body cylindrical section (CVBCS) procured by the EU [19] as well as the cryostat top lid (CTL) procured by Japan (Figure 14(a)). The cryostat provides a vacuum boundary to insulate heat load from outside at room temperature to the components operated at cryogenic temperature such as superconducting coils. The CB with a diameter of 11.95m, a height of 2.84m and a weight of 260 ton installed in the torus hall in March 2013 becomes a gravity support for the vacuum vessel and superconducting coils. Careful fabrication of CB provides remarkable flatness of its top FIG. 14. (a) Structure of JT-60SA cryostat, (b) sectors of CVBCS

10 9 OV/3-3 plate within 0.5 mm accuracy. The CVBCS with a diameter of 13.47m and a weight of 175 ton is made up of four upper sectors and eight lower sectors. Vertical and horizontal ribs are set up on the surface of the vessel in order to avoid deformation of the structure which may be caused by a lot of openings for the pipes of feeder, cryoline, heating and diagnostics. It is being fabricated in Spain as shown in Figure 14(b), and will be delivered to the Naka site in the FIG. 15. Facilities of cryogenic system middle of Detailed design of the CTL with a diameter of 11.6m and a weight of 45 ton was already completed. The CTL PA will be concluded in 2016 followed by its fabrication. 5.7.Cryogenic System The Cryogenic System procured by the EU is composed of six gaseous helium storage vessels, eight warm compressors, four helium compressors, a Refrigerator Cold Box (RCB) for producing helium at cryogenic temperature, an Auxiliary Cold Box (ACB) for distribution of the cryogenic flows as shown in Figure 15 [20]. The Cryogenic System supplies helium to the magnet system (4.4K), cryopumps (3.7K), HTS- CLs (50K) and the thermal shields (80K). The total equivalent power at 4.5K is about 9kW. It is the largest refrigerators for a nuclear fusion facility before ITER. The ACB and RCB were delivered to the Naka site in April 2015 and the helium storage vessels in May Commissioning of the Cryogenic System with various operation modes related to the actual experimental condition (operation, baking, stand-by, etc.) were completed in October Power Supplies Most of the power supply systems of JT-60SA have been newly manufactured due to the adoption of superconducting magnet system [21]. Additional power supply systems for invessel normal conductor coils have been also fabricated. The Super Conducting Magnet Power Supplies (SCMPS), a procurement shared by France and Italy, are based on ac/dc thyristor converters: one unit for TF coils (25.7 ka, 80 V, steady state) and ten units for PF coils (±20 ka, ±1 kv, 100s/1800s duty cycle). About half of SCMPS were delivered to the Naka site in June 2016 and were installed (see Figure 16). All the remaining SCMPS will be delivered by autumn The Quench Protection Circuits (QPC) protect the SC coils (TF coils, EF coils and CS modules) in case of quench by fast extraction of the stored energy. The QPCs made up of three units (25.7 ka, 2.8 kv) for TF coils and ten units (±20 ka, ±3.8 kv) for PF coils are based on dc hybrid mechanicalstatic circuit breakers. They were developed and fabricated in Italy and FIG. 16. SCMPS installed in the Naka site

11 10 OV/3-3 delivered to the Naka site in September The commissioning and final acceptance tests of the QPC were completed in June The Switching Network Unit (SNU) for CS modules which produces high voltage for the plasma break down and current ramp-up were manufactured in Italy in 2015 and delivered to the Naka site in September Two SNUs for EF3 and EF4 procured by Japan were delivered to Naka in All the SNUs are rated for 20 ka and 5 kv and implement dc hybrid mechanical-static circuit breakers too. The PS for the upper/lower FPPCC (±5 ka and ±1 kv) are ac/dc thyristor converters which control the vertical and horizontal position of the plasma against small plasma perturbations such as a minor disruption. They are procured by Italy and were delivered to the Naka site in June The PSs for the RWMCC, EFCC and ECRF are also being manufactured. The Magnet Power Supply Water Cooling System (MPS-WCS) procured by Japan for the PS of TF coils and PF coils was installed on the Naka site. On-site work and commissioning were completed in March Electric power supply system in the Naka site has been also carefully reconsidered. Former JT- 60 used three motor generators (MGs) to accumulate and supply electric power to the coils and heating system in order to mitigate perturbation to the commercial power grid. JT-60SA will reuse two motor generators: H-MG with 400MVA/2.6GJ and T-MG with 215MVA/4.0GJ, as well as electric power directly from 275kV power grid. All of them in total cover 100 sec operation with 41 MW heating and current drive. H-MG was overhauled and component parts were carefully examined in No serious damage was spotted after the Great East Japan earthquake in The design of the supervisory control system and data acquisition system (SCSDAS) is also under development. It has roles of human machine interface, discharge sequence control, plant monitoring, plasma real-time control, power supply control, device protection and discharge result data acquisition/storage as well as database management roles. 5.9.Auxiliary Heating System Auxiliary heating systems for the long pulse plasma operation has been developed. Performance of a gyrotron enabling operation at two frequencies (110 and 138 GHz) was remarkably enhanced up to 1 MW for 100 sec in 2014 [22]. In 2015 an additional frequency of this gyrotron at 82 GHz was demonstrated for 1 sec at 1 MW, which is applicable for plasma start-up assist and wall cleaning. Modification of the magnetic structure of the negative ion source to extract a uniform beam and control of the plasma grid temperature for stable negative ion generation allowed 500 kev, 15A beam for 100 sec [23]. Final goal of 22A beams for 100 sec is to be fulfilled. Positive ion beam acceleration with 2MW (80 kev, 25A) for 100 sec was already demonstrated for one unit in 2015 by the careful control of arc power and gas injection rate. Twelve units of P-NBI ensure 24MW heating power. 6. Assembly and Commissioning of JT-60SA 6.1.Assembly Work Assembly work in the torus hall started in January First of all the cryostat base (CB) was placed right in the middle. Three lower EF coils (EF4, EF5 and EF6) were temporarily set on the CB. The assembly frame surrounding the CB was installed in May 2014.

12 11 OV/3-3 VV sectors were welded together up to 340 torus structure in September Thereafter a rotary crane was set up on top of the assembly frame, which carries VVTS and TF coils to the right position surrounding the VV. Since February 2016, 20 VVTS sectors with helium cooling pipes have been installed around the VV as shown in Figure 17. Installation and connection of seventeen VVTS sectors covering 340 VV will be completed in November From December 2016, the TF coil will be inserted through the 20 gap in the torus one by one FIG. 17. Assembly of VV thermal shield onto VV and installed at their exact positions. The final 20 VV sector with the last TF coil and VVTS will close the gap of the VV and will be welded with splice plates to complete the 360 rigid VV structure. Then the lower EF coils (EF4, EF5 and EF6) will be lifted up and attached to the TF coils. The upper EF coils (EF1, EF2 and EF3) will be mounted on the TF coils. Four CS modules are combined by a support structure and tie plates to form a single component. Then it will be inserted in the center of the torus. Thereafter the CVBCS with CTS, ports with PTS, coil terminal boxes, valve boxes, feeders, piping for cryogenic system and cooling water and so forth will be installed. Finally the CTL will be place at the topmost part and welded to the CVBCS to complete the cryostat structure. In parallel with the tokamak assembly in the torus hall, commissioning of other components and systems such as the cryogenic system, power supplies, heating and diagnostics system are being steadily carried out. 6.2.Assembly Coordination In order to implement the successive assembly works in the torus hall listed above while keeping the tight schedule, detailed assembly procedures have been examined beforehand. In order to avoid rework or serious matters which may cause a great impact on the schedule, design coordination meetings have been held in QST on a regular basis. In the meeting, interface issues arising from updated design of components, improvement of assembly procedures to promote work efficiency and schedule compression, reconsideration of in-factory work and on-site work for a component, and so on are discussed and optimized. The solution is surely shared among the people concerned in EU and Japan. Such close communication and information exchange established between EU and Japan is one of the reason of steady progress of the JT-60SA Project. 6.3.Integrated Commissioning toward the First Plasma After the installation work, commissioning of each component and system will be carried out individually. Then data linkage test including transmission of interlock signal between systems such as power supply system, superconducting system, heating system and so forth will be carried out. The supervisory control system and data acquisition system (SCSDAS) is utilized for this purpose. Integrated Commissioning (IC) will be implemented thereafter. A detailed plan of the IC among multiple systems is being arranged: the list of test items for IC is complied, sequence of test

13 12 OV/3-3 items is decided, necessary implementation time, workforce, consumables are examined and defined for each test item. The IC plan covers both machine operation and plasma operation, and the first plasma in Summary The JT-60SA Project has progressed quite well since Procured components and systems of JT-60SA have been manufactured and delivered to the Naka site one after another. Assembly of 340 VV and VVTS is almost completed, and installation of TF coils will start soon. In parallel, commissioning of cryogenic system, power supply system and so on has been carried out in the Naka site. Thanks to the strong cooperative spirit between EU and Japan, the first plasma will be achieved in The collaborative work on JT-60SA is also quite active. The JT-60SA Research Plan which covers a wide range of research area by using JT-60SA has been developed on the basis of intensive discussion among European and Japanese researchers. The JT-60SA Research Plan is periodically updated to fully support the ITER project and DEMO design activities. Acknowledgements The authors gratefully acknowledge members of EU-IA, JA-IA, PT and VC for their strenuous efforts to get over a lot of technical difficulties and persistently proceed with the JT-60SA Project. The authors also appreciate the members of the European and Japanese fusion communities who have made great contribution to update the JT-60SA Research Plan in order to bring out capability of the JT-60 facility to the maximum. References [1] KAMADA, Y., et al., Nucl. Fusion 53 (2013) [2] DI PIETRO, E., et al., Fusion Eng. Des. 89 (2014) [3] BARABASCHI, P., et al., Proc. 25th Fusion Energy Conf. (St. Petersburg, 2014) OV/3-2. [4] HIWATARI, R., et al., Nucl. Fusion 45 (2005) [5] TOBITA, K., et al., Nucl. Fusion 49 (2009) [6] OGAWA, Y., Journal of Physics, Conference Series 717 (2016) [7] [8] [9] KAMADA, Y., et al., Nucl. Fusion 51 (2011) [10] [11] KOIDE, Y., et al., Nucl. Fusion 55 (2015) [12] HELLER, R., et al., Fusion Eng. Des. 86 (2011) [13] YOSHIDA, K., et al., Fusion Eng. Des. 88 (2013) [14] MASAKI, K., et al., Fusion Eng. Des. 87 (2012) [15] ASANO, S., et al., Fusion Eng. Des. 86 (2011) [16] HAYASHI, T., et al., Fusion Eng. Des. 89 (2014) [17] HIGASHIJIMA, S., et al., Fusion Eng. Des. 84 (2009) [18] RINCON, E., et al., Fusion Eng. Des. 86 (2011) [19] BOTIJA, J., et al., Fusion Eng. Des. 88 (2013) [20] LAMAISON, V., et al., AIP Conf. Proc., 1573 (2014) [21] NOVELLO, L., et al., Fusion Eng. Des (2015) [22] KOBAYASHI, T., et al., Nucl. Fusion 55 (2015) [23] KOJIMA, A., et al., Nucl. Fusion 55 (2015)