The ITER correction coils are an integral part of the ITER magnet system, forming a layer of coils inserted in between the toroidal and poloidal field coils. Some of them, such as the six bottom correction coils, will be among the first components to be installed during assembly thus requiring early delivery to the ITER site.
On 4 and 5 December, the correction coil manufacturing line in China underwent a thorough check-up to assess whether it is now ready for the long marathon of correction coil manufacture. This critical examination was carried out by a group of „doctors” from Europe, Japan, USA and China under the chairmanship of Michel Huguet, former director of the ITER Naka site during the Engineering Design Activities for ITER. This first Manufacturing Readiness Review was organized by the ITER Organization and held at ASIPP (Hefei, China), the institute that was awarded the responsibility of correction coil manufacture by the Chinese Domestic Agency following the signature of the Procurement Arrangement in May 2010.
Four years ago, in November 2009, the Final Design Review was held in Hefei for this component. Since that time, a new manufacturing line for the correction coils was designed, manufactured or procured, and commissioned by ASIPP, including the winding line, the resin system for vacuum pressure impregnation (VPI), and the laser welding system for case enclosure. All the manufacturing drawings have been designed and approved, the qualification of various manufacturing processes has begun, and the winding qualification is finished.
The qualification items falling into the scope of the review included the winding of the 10 kA niobium-titanium (NbTi) conductor; the helium inlets and outlets which will provide supercritical cooling at 4.5 K; the terminal joints connecting the coil to the feeders; the glass-polyimide insulation and its impregnation by epoxy resin; the terminal service box hosting piping and insulating breaks; and the stainless steel case enclosing the winding-pack. The requirements and deliverables for each one were presented by Li Hongwei, the Technical Responsible Officer at ITER China, and the qualification work was presented by Wei Jing and her team at ASIPP.
The review panel commended both for the quality of their presentations, fully impressed by the achievements of the R&D and qualification activities. In particular, conductor winding has successfully passed all qualification examinations, opening the way for the winding of the first-of-series ITER correction coil with real superconductor in 2014.
A visit of the correction coil manufacturing workshop allowed the review panel the chance to see the various mockups built for the qualification of the manufacturing procedures, including the insulated side correction coil dummy double pancake and the bottom correction coil dummy double pancake (above right) ready for impregnation, as well the correction coil case models (above left).
As the ITER Project evolves and becomes more „concrete,” ITER Communication has to evolve too. Over the end-of-year holidays and into January, we’ll be stopping the publication of Newsline. This longer-than-usual break will allow us to take the time to develop some new communication tools and refresh the ITER website. Our aim is to reach a wider audience with high quality information.
Many ITER visitors often call on us to devote more resources to public communication, reaching out not only to the fusion community but also to the public, to young people and to the business world. The argument given is nearly always the same: too many people do not know about ITER at all! Public awareness is a key factor for the success of the Project as a whole. As public interest increases we have to develop the tools to answer their questions and concerns.
Last week we launched a new magazine in French (an English version will follow). Through a journalistic approach, it aims to popularize the science and technology behind and beyond ITER. Ahead, we’ll be taking a fresh look at the public website to make it more attractive and up-to-date. And we’ll be simplifying Newsline production to make it more reactive, punctual and comprehensive.
The ITER Project is entering a new era and so is its public communication. Best wishes for the New Year to all of you!
In the cold, predawn hours of Wednesday, 11 December, concrete pouring began for the basemat of the Tokamak Complex, the suite of buildings that will house the ITER fusion experiments as well as diagnostic and tritium management systems.
„We are all very happy and may I say relieved to have reached this important and visible milestone for the ITER Project,” said Laurent Patisson, leader of the Nuclear Buildings Section who had signed off the night before on the final documents clearing the way for operations to begin. „This is the beginning of B2 basemat slab realization, and as I savour the moment I measure all of the work and effort that it has taken to reach this point.”
The first concrete began flowing at 6:24 a.m. under powerful spotlights and in the presence of observers from the ITER Organization and the European Domestic Agency, F4E. Over the long day, teams divided into two shifts directed the concrete from the trucks above into the rebar and formwork of a 550 m² segment in the northwest corner of the Seismic Pit, at the location of the future Diagnostic Building. This first „plot” is one of 15 that must be poured over the next six months to complete the B2 slab.
Pouring at such early hours, and during the winter months, require some special measures to maintain the temperature of the concrete at a minimum level—heated water and gravel at the concrete batching plant and tents and hot air blowers at the worksite. In all, 15,000 cubic metres of concrete and 4,000 tons of reinforcement will be necessary for the B2 slab, which will act as a single foundation for the three buildings of the Tokamak Complex (Tokamak, Diagnostic and Tritium buildings).
„The concrete qualified for the B2 basemat has been the object of particular care,” specifies Laurent, „answering to the rigorous requirements of a nuclear facility in terms of stability, water permeability and gas confinement.” Over qualification 20 tests have been run by the contractor GTM Construction on the concrete formulation.
In the coming months, additional rebar will be added to the central area of the B2 slab. „In the context of design consolidation we have refined the rebar arrangement under the Tokamak Building,” explains Laurent. The building contractor will realize a mockup of the new arrangement to test and qualify the proposed concrete.
„For the realization of the B2 slab we are relying on the experience and methodology of the contractors (GTM Construction) who already carried out the first works in the Seismic Pit, including the basemat, seismic columns and retaining walls,” says Laurent. „Up to now we have been working on paper. We’re all eager to get to the next level and see the B2 slab take shape.”
Nb3Sn strand is the basic building block of ITER’s large magnets, the key element that makes them superconducting. Superconductivity is essential to pursuing fusion energy generation because superconductors consume less power and are cheaper to operate than conventional counterparts, while carrying higher current and producing stronger magnetic field. Six Domestic Agencies (China, Europe, Japan, Korea, Russia and the US) are responsible for procuring over 400 tons of toroidal field conductor for ITER.
The Korean milestone was validated late November with the approval the Authorization To Proceed Points (ATPPs) by the ITER Organization for the final batch of strand billets. (A billet is the smallest traceable production unit of strand.) In order to assure quality and full traceability for ITER, the manufacturing information and test results of every billet are registered electronically in the Conductor Database, and then reviewed by the procuring Domestic Agency and finally given approval by the ITER Organization to proceed to next step. Remarkably, 2 038 individual Korean billets passed the thorough review by the Korean Domestic Agency and ITER.
The Korean share of toroidal field strand procurement amounts to 93 tons (20 percent of toroidal field strands). The manufacturing contract was awarded to Kiswire Advanced Technology (KAT), which began producing in 2009. To have completed the manufacturing in four years is an impressive rate of production considering that, worldwide, the production of Nb3Sn strand before ITER did not exceed 15 tons per year.
„The toroidal field conductor Procurement Arrangement with Korea is a good example of an ITER success story,” states Arnaud Devred, who is responsible for the Superconductor Systems & Auxiliaries at ITER. „The close collaboration of the Korean Domestic Agency and the ITER Organization to monitor execution enabled both parties to address production issues in a timely and effective manner. This milestone is all the more remarkable in that the strand supplier KAT was new to the business when the contract was launched, but managed to adapt to the world-class standards imposed by the Procurement Arrangement.”