Fusion for Energy is delivering 5 out of 6 ITER superconducting poloidal field coils (PF coils), which are composed of stacks of 6 to 8 double-layered circular coils - double pancakes (DPs). The double pancakes range from 17 m to 24 m in diameter and the wound conductor has a NbTi core inside a stainless steel squared jacked. Due to the size of the PF 2-4 coils, they have been manufactured on the ITER site, very close to the assembly hall. This article highlights the manufacturing processes, the learning curve, the main challenges and learned lessons during the winding activities of the 30 double pancakes that comprise 4 PF coils.
Fusion for Energy (F4E), the European Domestic Agency for the International Thermonuclear Experimental Reactor (ITER) is responsible for the manufacturing, test and delivery of 5 out of 6 Poloidal Field Coils of ITER. F4E has currently delivered 4 coils: PF2, PF4, PF5 and PF6, the last two are installed in the Tokamak pit in temporary positions while PF2 and PF4 are stored awaiting the Tokamak torus completion. At the PF coils manufacturing production site in Cadarache, France, few meters away from the ITER Tokamak assembly building, F4E is currently finalizing the manufacturing and testing of the largest coil: PF3, with 24 m diameter and a weight of 384 t , approaching to the end of an endeavor that started back in 2013. This article describes all electrical tests the PF coils underwent to meet the ITER technical requirements during their lengthy manufacturing process, and which lasted several years. Tests performed at key points of the manufacturing process avoided discovering non-conformities at later stages that could otherwise become critical for the project accomplition. The main electrical tests consisted of high voltage DC/AC, partial discharge tests, and local and global Paschen tests. The experimental setups and procedures are presented and discussed in more detail. We also summarize the acceptance test results for the finalized coils i.e., 80 K forced flow pressure drop testing, leak tightness in vacuum before, during and after the thermal cycle to 80 K .
Fusion for Energy (F4E), the European Domestic Agency for the International Thermonuclear Experimental Reactor (ITER), is responsible for the supply of 5 out of the 6 Poloidal Field (PF) Coils: PF2-PF6. One coil, PF1, is being manufactured by the Russian Federation Domestic Agency (RFDA). While the 10 m diameter PF6 was manufactured by the Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) and tested in the cold test facility at Cadarache under a collaboration agreement with F4E; coils PF2-PF5 are currently being manufactured on site, close to the Tokamak building, their size ranging from 17 to 24 m diameter and weights from 200 to 400 T. This article describes the final acceptance tests performed on the coils PF5 and PF6, the testing setup, paying special attention to the tests performed before, after and during the cool-down at 80 K. The tests cover a wide range of aspects of the operation at cryogenic temperatures: ranging from the high voltage electrical insulation performance during the potential fault conditions during plasma operation, leak tightness under vacuum and pressure drop behavior of its hydraulic system during operation with forced flow helium. In addition, we will briefly introduce the results for the current center line (CCL) calculation obtained for PF5 and PF6.
The plasma confinement of the International Tokamak Experimental Rector (ITER) is provided by the magnetic field generated by 18 toroidal field (TF) coils while 6 poloidal field (PF) coils and 6 central solenoid modules have the function to drive, shape and pre-heat the plasma. Fusion for Energy (F4E), the European Domestic Agency for ITER, is responsible for the supply of 10 TF coils and 5 PF coils to the ITER project. The PF coils utilize NbTi Cable-in-Conduit-Conductor (CICC) and have different diameters between 8 and 24 meters and a weight up to 400 tons. So far two EU PF coils, PF5 and PF6, have been completed. PF6 has been manufactured by the Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) under a collaboration agreement with F4E. The other 4 PF coils are being produced by EU at the ITER site by a cluster of suppliers managed and supervised by F4E. All PF coils will be completed by 2023. The TF coils utilize a Nb3Sn conductor. So far six TF coil have been completed, of which five delivered to ITER and one will be delivered within 2021. The remaining TF coils will be delivered by end of 2022. We will report on the main aspects of the coils completed so far, on the main results obtained together with some statistical analysis as well as on the status of the remaining coils.
Three out of six Poloidal Field Coils (PFC) are already delivered to the ITER Organization. The PF Coils are built winding, impregnating, and vertically stacking double pancakes (DPs) of NbTi Cable-in-Conduit conductors into a Winding Pack (WP). Later, the Winding Pack (WP) is impregnated for ground insulation and clamping devices are installed for structural support and interface with the rest of the ITER machine. One of the main parameters characterizing the PFCs is the Current Centre Line (CCL), defined as the barycentre of its WP conductors. Ideally, the CCL would be in the WP's symmetry plane but due to solutions in the construction design and manufacturing deviations, it may vary. Double Pancakes (DPs) may be wound with different dimensions, or a deviation during their stacking would cause a misalignment of all the conductors contained in that ill-positioned DP, affecting the CCL. The manufacturing process starts with the conductor winding and insulation, forming a DP. The DP is then impregnated with resin and a scan of its surface is used to reconstruct the DPs virtually. The DPs are then stacked, forming a WP, and measurements of points on the surface are used to recreate the process virtually. Finally, the WP is insulated and impregnated with resin. At this stage, both surface scans and point measurements are used to align the WP in the coordinate system of the ITER machine. This paper explains the process to calculate the CCL of the three first PF Coils using manufacturing data, defining the uncertainty associated with the calculation and comparing against the target tolerances defined for the proper ITER machine operation.
The plasma confinement of the International Tokamak Experimental Rector (ITER) is provided by the magnetic field generated by 18 toroidal field (TF) coils while 6 poloidal field (PF) and 6 central solenoid coils have the function to drive, shape and pre-heat the plasma. Fusion for Energy (F4E), the European Domestic Agency for ITER, is responsible for the supply of 10 TF coils and 5 PF coils to the ITER project. The ITER Organization (IO) team is instead responsible for the design of such coils as well for the coordination of the activities of the different Domestic Agencies (DAs) producing the different components, and their assembly into the Tokamak. The PF coils utilize NbTi Cable-in-Conduit-Conductor and have different diameters between 8 and 24 meters and weights of up to 400 tons. Regarding the PF coils produced by F4E, so far one has been completed by the Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) under a collaboration agreement with F4E. The other 4 PF coils are being produced at the ITER site in Saint Paul lez Durance, France, under F4E supervision. The first of these (PF5) will be completed by July 2020 while the last coil (PF3) will be ready be the end of 2023. The TF coils utilize Nb3Sn conductor and are manufactured with the “Wind, React & Transfer” method. The first TF coil is close to completion and will be delivered to the ITER site in early 2020. Subsequent TF coils will follow at a rate of about one every 3-4 months. In this article we will report on the production status of both PF and TF coils and, in particular, the different manufacturing strategies employed. The main challenges faced so far and the results obtained are also described.
The first European superconducting winding pack (WP) and the first set of coil cases [toroidal field coil cases (TFCC)] for ITER are going to be delivered in 2017. The TFCC are steel structures that provide structural integrity to the WP, contribute to neutron shielding capacity, provide support to operating forces, and offer interface connections with the rest of the ITER machine. The TFCC assembly is formed by four main parts: two sectors with U-shaped section and two closure plates, which, after being welded together, enclose the WP. Each TFCC weights about 150 t and presents a wall thickness from 60 to 120 mm. The presence of distortions when welding such thick structures is particularly problematic in these components, which require tight tolerances and include several interfaces with other parts of the machine. In order to compensate the distortions, extra material is present in the critical areas to allow postwelding machining. The amount of extra material has to be optimized to reduce machining time and therefore the cost of the manufacturing. Thus, the evaluation of the welding-caused distortions is essential in order to confirm the extra-material strategy. In this scenario, an experimental and simulation campaign has been set up to predict the deformation of the TFCC during welding. First, welding coupons were welded in representative configurations. Then, these data were used to build a preliminary finite element method (FEM) model tool, using AN-SYS software, which was then benchmarked against a "blind test" coupon and three TFCC-like mock-ups of 1-m length. Finally, a full FEM model was constructed using the previous outputs and is currently under assessment to predict the deformation of the TFCC during the welding process. This paper presents the numerical and experimental activities carried out so far, being EnginSoft S.p.A. the developer of FEM models, SIMIC S.p.A. the responsible of welding processes and data acquisition, and Fusion for Energy the contractual and technical supervisor.
The International Thermonuclear Experimental Reactor (ITER) magnetic system includes 18 toroidal field (TF) coils constructed using Nb3Sn cable-in-conduit superconductor. Each TF coil comprises a winding pack (WP) composed of seven double pancake modules stacked together, impregnated and inserted into a stainless steel coil case. Ten TF coils are being produced in Europe, under the responsibility of Fusion for Energy (F4E, the European Domestic Agency), while the remaining nine TF coils are being produced in Japan. F4E has implemented a strategy dividing the procurement into three packages. One is related to the construction of 70 radial plates (RP), another to the fabrication of 10 WP, and a third to the cold test and coil-case insertion of 10 WP. After 7 years of R&D and qualification activities and of industrial production, the first ITER TF coil WP has been completed in Europe. Factory acceptance tests, including leak, dimensional, and electrical tests at room temperature, were completed in May 2017 and the series production of the remaining nine TF WPs in Europe is underway. The first package has been completed and all 70 RP have been delivered. Commissioning of major tooling for the third package is to be performed at the end of 2017. In this paper, we report on the test of the first TF WP and on the status of the remaining production.
The ITER magnetic system includes 18 Toroidal Field (TF) Coils constructed using Nb3Sn cable-in-conduit superconductor. Each TF coil comprises a Winding Pack (WP) composed of 7 Double Pancake (DP) modules stacked together, impregnated and inserted into a stainless steel coil case. Fusion for Energy [the European Domestic Agency (DA)] is responsible for the procurement of the ten while the Japanese DA is responsible for remaining nine coils. The conductors are being produced by 6 different DAs, while the coil cases only by the Japanese DA. F4E has implemented a procurement strategy aimed to minimize costs and risks, consisting of subdividing the procurement into three main procurement packages, each foreseeing first an R&D and qualification phase. One procurement package is related to the construction of 72 radial plates (RP), another to the fabrication of the ten WP, and a third to the cold test and coil-case insertion of ten WP. In collaboration with industry, F4E has successfully produced two RP prototypes. Regarding the DP, the construction of the first DP prototype has started. In this paper, we will report on the results achieved so far and the status of each of the procurement packages.
This paper reflects the status of the manufacturing of 70 radial plates (RPs) for the EU ITER TF Coils. About 3700 t of stainless steel 316 LN have been forged and 240 t of cover plate (CP) raw material bars have been procured for the procurement of the RPs. Each RP is composed of six forged segments welded using local vacuum EB Welding technology for 35 RPs and narrow-gap TIG for the other 35 RPs. All RP plates are finally machined to final dimensions (9 m × 14 m) and tolerances using large portal milling machines. The groove length, planarity, and D-shape form tolerances are the most challenging required tolerances: ±30 ppm for the groove length and 1 mm for both planarity and D-shape form. The main challenges faced and results achieved so far are presented and improvements with respect to the prototype phase are described.
The European share of the ITER magnet superconductors includes the supply of around 20 km of Toroidal Field and 7 km of Poloidal Field conductors. This represents 20% and 11% of the total conductor amounts respectively needed for all ITER Toroidal Field (TF) and Poloidal Field (PF) coils. For TF conductor, around 97 tons of superconducting niobium tin strand and 60 tons of copper wire are needed to be purchased, cabled and inserted within a stainless steel jacket tube to form the Cable-In-Conduit-Conductor (CICC). For PF conductor, about 45 tons of superconducting multifilamentary niobium titanium wire need to be cabled and jacketed. Altogether, Fusion for Energy (F4E) placed 4 supply contracts for the European TF and PF coil conductors (one for copper strand, two for niobium tin strand and a single contract for cabling and jacketing). In addition, the PF conductor procurement is based on a bi-lateral agreement with the Russian Federation Domestic Agency (RF DA) where NbTi cables are supplied by RF DA and their jacketing is provided by F4E. In this article, the procurement strategy and the current procurement status are reported for the European contribution of TF and PF conductors.
This paper reflects the status of the manufacturing of 2 Radial Plate prototypes for the EU ITER TF Coils. The production of these prototypes will supply valuable information for the manufacturing of the total required number of 70 Radial Plates, in terms of manufacturing technologies, optimization of cost, manufacturing time and risks.
A principal part of the ITER fusion reactor is the Toroidal Field magnet system which consists of 18 “D” shaped coils. Fusion for Energy, (F4E), the European Domestic Agency for ITER, is responsible for the procurement of 10 such coils. The completed coils, measuring approximately 14 m × 9 m and weighing 300 tons, comprise an outer structural case into which a “winding pack”, itself made up of 7 conductor double pancake and radial plate assemblies, is inserted. The winding packs will be the largest ever built using Nb 3 Sn conductor and their manufacture, using a wind, react and transfer process, presents significant technological challenges. In particular, the conductor double pancakes must be wound with high accuracy and their change in dimension during heat treatment correctly predicted in order to facilitate the transfer to their associated radial plates. These processes require novel and sophisticated tooling to be constructed on a large scale. The contract for the manufacture of 10 ITER TF Coil Winding pack was awarded in July 2010 by F4E to a consortium of three main partners-Iberdrola IC, ASG Superconductors and Elytt Energy and in this paper we present the progress made to date. Particular reference is made to the design and procurement of major items of tooling, including the winding line, heat treatment furnace and transfer tool, and the steps taken to minimize risk by design are described.
The International Thermonuclear Experimental Reactor is an international scientific project with the aim of building a tokamak fusion reactor capable of producing at least 10 times more energy than that spent to sustain the reaction. In a tokamak the fusion reaction is magnetically confined and the toroidal field coil system plays a primary role in this confinement. Fusion for Energy, the European Domestic Agency for ITER, is responsible for the supply of 10 out the 19 toroidal field coils. Their procurement has been subdivided in three main work packages: the production of 70 radial plates (the structural components which will house the conductors), the manufacture of 10 winding packs (the core of the magnet) and cold test and insertion into the coil cases of 10 winding packs. The cold test/insertion work package presents significant technological challenges. These include the cold test of the winding packs 14 m high, 9 m wide and weighing 110 t, the welding and inspection of the 316 LN stainless steel coil case, with welded thicknesses of up to 144 mm accessible only from one side combined with the need to minimize the deformation during the welding process (more than 70 m of weld per coil and up to 90 passes to fill the chamfer) and the resin filling of the coil case after insertion of the winding pack (the total volume to be filled up is about one cubic meter per coil). From 2009 up to mid 2011, F4E has carried out an R&D program in order to investigate the most challenging steps of the manufacturing processes associated to this work package, both to meet the demands of the ITER schedule and to minimize technological risks; in this paper an overview of the results obtained is presented.
The superconducting magnet system of ITER consists of four main sub-systems: Toroidal Field (TF) coils, Central Solenoid (CS) coils; Poloidal Field (PF) coils; and Correction Coils (CC). Like many other ITER systems, the magnet components are supplied in-kind by six Domestic Agencies (DAs). The technical specifications, manufacturing processes and procedures required to fabricate these components are particularly challenging. The management structure and organization to realize this procurement within the tight ITER construction schedule is very complex. Fusion for Energy (F4E), the European Domestic Agency for ITER, is in charge of about 25% of the contribution to the ITER magnet system, namely part of the TF and PF conductors, 10 TF coils, 5 PF coils and 9 TF system pre-compression rings. Good progress towards full scale construction has been achieved with the launch of large manufacturing contracts for the production of the superconductor lengths, the fabrication of two full-scale prototypes of the TF coil radial plates, and the start-up of the contract for the construction of 10 TF winding packs. Several tons of advanced Nb3Sn and NbTi strand have been produced, large cabling and jacketing facilities for the conductors and winding lines for the TF coils are being set-up. Tendering actions for the PF coils and pre-compression rings are in progress. Later in 2011 the contracts for the production of the TF radial plates and insertion of the TF coils in the cases will also be launched. This paper reports the progress of the F4E activities as per June 2011.