MAM has a word to say

There is a procedure for everything…and certainly more than one when it comes to building the world’s largest fusion device. One of the procedures established within the ITER Organization is the Model Approval Meeting (MAM), in which the design descriptions for critical components pass the final check before they are turned into hardware.

The 3D-viewer room on the neighbouring premises of CEA Cadarache has become a regular meeting spot for ITER engineers over the last weeks and months. On one morning in late August, about a dozen ITER staff working on the central solenoid, the centrepiece of ITER’s magnet system, have come together to review the compatibility of the detailed 3D CAD model provided by US Domestic Agency with the rest of the Tokamak. This model, developed by US ITER at Oak Ridge National Laboratory on the basis of the functional specifications provided by the ITER Organization, reflects the final design proposed by the US after feedback from industry and manufacturing trials.

The turn-to-turn spacing of the solenoid conductor had apparently been too tight to be guaranteed by the industrial manufacturer. The solution on the table, proposed by US ITER, is to extend the winding gaps by reducing the inner radius. The impact of this solution is the focus of the discussion.

Jens Reich, coordinator of Tokamak design integration and leader of the meeting, asks the 3D-room operators to overlay the original Configuration Model developed by the ITER Organization with the detailed model they have received back from the US.

A few seconds later, through their 3D-glasses, observers saw a real-size, down-to-the-detail central solenoid unfold on the screen in front of them. What impact would the changes have? And what about the margins at the perimeter—would they still allow for the assembly of this supersized magnet? The central solenoid will be lowered into the machine at the very end of the assembly process, a procedure that doesn’t leave much flexibility for manoeuvring.

The last word about the design of the central solenoid will have to wait until the Final Design Review planned for 18-20 November this year. „But this 3D-check is a very helpful tool to verify the details of a component and to identify any potential interface issues to be solved,” explains Jean-Jacques Cordier, leader of the ITER Design Integration team, before he and his colleagues put their glasses on again to look at the next client, the support structures for the poloidal field coils. 

2nd batch of Russian TF conductors en route to Italy

The superconductors for the ITER magnet system are among the longest-lead production items for the project; the first five Procurement Arrangements concluded by the ITER Organization between late 2007 and mid-2008 concerned the conductors for the toroidal field magnet system.

The Russian Domestic Agency is responsible for 20 percent of toroidal field conductor procurement and 14 percent of poloidal field conductor procurement. Production is ongoing according to the schedule of the Procurement Arrangements.

On 25 June, the second batch of toroidal field conductor unit lengths started on their way from the premises of the Kurchatov Institute in Moscow to the city of La Spezia, Italy, where the winding of ten toroidal field coils will take place.

Demonstrating the attachment of Russian industry to fulfill its contractual obligations on time, two 415-metre production lengths of niobium-tin (Nb3Sn) conductor for toroidal field side double-pancakes were loaded onto trucks at the Institute. This latest shipment follows the delivery of four conductor unit lengths to Europe in October 2012, including a copper dummy and a 100-metre qualification length.

Seven similar units lengths have passed all of the tests stipulated in the Procurement Arrangement and meet ITER Organization requirements; they will, in turn, be shipped as well.

Team work celebrated at last Conductors Meeting

In pre-ITER times, the world production of niobium-tin (Nb3Sn) strands did not exceed 15 tons per year. Discovered in 1954, this intermetallic compound that exhibits a critical temperature of ~18 K and is able to withstand intense magnetic fields was used mainly in high field coils and nuclear magnetic resonance equipment.

To match the needs of ITER’s 19 toroidal field coils (18 plus one spare), the world production capacity of Nb3Sn strand had to be ramped up by one order of magnitude. As of today, 400 tons of Nb3Sn have been produced by the industry of the six ITER Domestic Agencies involved in conductor procurement, representing 85 percent of toroidal field coil needs.

Nb3Sn conductors will also form the core of the central solenoid, the backbone of the ITER magnet system. Strand production has been launched in Japan for the lower module (CS3L) and conductor lengths will be shipped at a later time to the US where the central solenoid will be manufactured.

For ITER’s third major magnet system—the poloidal field coils—because the magnetic field they produce is less intense, they can be manufactured from the metallic alloy niobium-titanium (NbTi), which is cheaper and easier to produce than the brittle Nb3Sn.

The Russian-European collaboration that procures NbTi strands for ITER has already produced 80 tons of Strand 1, destined for poloidal field 1 and 6. China, responsible for the procurement of conductors for poloidal field coils 2 to 5, has registered nearly 50 tons of of NbTi Strand 2 into the Conductor Database (this essential tool monitors the strand, cable, jacket and conductor production of each Domestic Agency). China will send its first poloidal field conductor shipment to the ITER site within the next two months.

Altogether, conductors for the magnet systems account for 13 percent of the total ITER project credits.

_To_45_Tx_These figures and other information relating to correction coils, feeder conductors, manufacturing issues, quality control, test results and technical issues were presented and discussed at last week’s meeting on conductor production status at the Château de Cadarache.

The Conductor Meeting, which has been held twice a year since 2008 (at ITER in the spring and in one of the „Conductor Domestic Agencies” in the fall), gathers representatives of the ITER Organization, the Domestic Agencies and their suppliers.

„It is an opportunity to share and benefit from each other’s experience,” says ITER Superconductor Systems and Auxiliaries Section Leader Arnaud Devred who traditionally chairs the meeting. „As all conductors are now in the production phase, the feeling in our community is definitely optimistic. Everything is moving ahead and the collaborative spirit, not only between the ITER Organization and the Domestic Agencies but between the Domestic Agencies themselves, is truly excellent.”

A fusion nomad

Tough luck: six months after Carlo Sborchia submitted his thesis on „Thermo-mechanical behaviour of fuel rods in case of a loss of coolant accident in Pressurized Water Reactors,” Chernobyl’s Reactor #4 went up in a cloud of radioactive smoke. As a consequence, Italy decided to halt its four operating nuclear plants and to phase out two projects already well underway.

For the young nuclear engineer, job prospects at home looked rather bleak. However, like for many other Italian nuclear engineers Chernobyl was Carlo’s luck: while fission energy was becoming a thing of the past in Italy, other ventures elsewhere could make use of his skills. For Carlo of course, this meant leaving his native Tuscany— something which, with the exception of a couple of trips to Rome, he had never done in his life.

As if to compensate for the 26 years he had spent in and near Piombino, the small town that faces the island of Elba (of Napoleonic fame), Carlo commenced a nomad’s existence in 1986, never to come back to Italy: CERN first, then one and a half years at the Sultan group in PSI Villigen, Switzerland and a first encounter with fusion through the NET project; five years at JET as a structural analyst, where he was recruited by Euratom; six and a half years with the ITER joint central team at Naka in Japan, then with EFDA in Garching, Germany; two and a half years in Greifswald as Head of the Superconducting Group of the Wendelstein 7-X stellarator; a first one-year stint at ITER in Cadarache in 2007; followed by five years with Fusion for Energy in Barcelona as Head of the Magnet Group, responsible for 25 percent of the ITER magnet system procurement.

Over the course of his peregrinations—almost three decades' worth—the young engineer who specialized originally in structural analysis graduated along the way to become an expert in magnets, accumulating experience in mockup design and manufacturing, procurement management, installation and, perhaps most important of all, learning to drive and motivate a team in times of success and in times of crisis.

Carlo’s story is a perfect illustration of what the „worldwide fusion family” is all about: the recently appointed head of the ITER Vacuum Vessel Division has worked with most of the people that are part of ITER today, people who were his neighbours, colleagues and friends in Culham, Naka, Garching or Greifswald.

How will a „magnet man” deal with the complex issues facing the ITER vacuum vessel? „A vacuum vessel is not a foreign object to me,” explains Carlo. „I’ve actually spent six months inside JET’s vacuum vessel—not many people have had that experience. Sure, I’ve been a 'magnet man' for the best part of my career but, in reality, by taking on this responsibility at ITER I’m going back to my original calling which is nuclear engineering. A vacuum vessel is about just that: structure, welding, loads …”

Although he talks fast and at length, Carlo knows the importance of listening. „I’ve been here three days,” he said last week, „and what I basically did during that time was listen. You can’t motivate your people if you don’t listen to them, if you’re not present, if you don’t develop a personal relationship with them. And in the years to come, we’ll need a highly motivated team to tackle the technical challenges ahead.”

Toroidal Field coils manufacturing gains momentum

Ever since Dr Heike Kamerlingh Onnes walked the pace of superconductivity back in 1911, there have always been scientists endeavouring to exploit its tremendous properties through powerful;  high magnetic field magnets.

These endeavours are turning into a reality at ITER, as the largest and most powerful superconductive magnets ever designed, with an individual stored energy of 2.2 Gigajoules (GJ), are being manufactured.

The Toroidal Field Coils is the ITER magnet system responsible for confining the plasma inside the Tokamak vacuum vessel, using Cable-In-Conduit niobium-tin-based conductor technology.

Procurement for the 19 Toroidal Field Coils (TFCs) is shared between the Japanese Domestic Agency (JA-DA), and the European Domestic Agency Fusion for Energy(EU-DA).

Following the last call for tender in August 2012, the first of a series of procurement contracts of the nine Japanese TF coils has been awarded to Mitsubishi Heavy Industry as a main contractor, with Mitsubishi Electric Corporation (MELCO), as a sub-contractor — a well-known stakeholder in superconducting magnet world.

_To_39_Tx_TF Coils are encased in large stainless steel structures. The nineteen encasing stainless steel coil structures (TFCS) procurement is the responsibility of the Japanese Domestic Agency (JA-DA) who recently placed two contracts respectively for First of Series European TFCS with Hyundai Heavy industry  in Korea and for Japanese TFCS with Mitsubishi Heavy Industry in Japan.

With a total weight of 3400 tons, the „superstructure” of TF coils is pushing the limits of manufacturability. Millimetric tolerances require state-of-the-art welding techniques (plate thickness on 316LN is up to 180 mm) to reach high quality requirements. As a result it is necessary to use specialists in heavy industry.

From 1 to 3 October 2012, the Collaboration Toroidal Field Coil Working Group met in NAKA (Japan) after visiting Hyundai Heavy Industry, Mitsubishi Heavy Industry and MELCO manufacturing premises. This meeting was attended by TFC and TFCS Technical Responsible Officers (TROs) from the ITER Organization, the European Domestic Agency and JA-DA. Several specialists from JA-DA supplier Mitsubishi Heavy Industry were also invited to participate in the meeting.

Such meetings are essential for resolving common Toroidal Field Coil system issues between both DAs and their multiple suppliers, and to manage the interfaces and tolerances between the winding packs and the coil structures.

It goes without saying that regular contact with the Domestic Agencies industry, through meetings with TROs will guarantee the prompt solving of any issues that may arise within such a challenging production environment.

The manufacturing of the first series of double pancakes as part of first Winding packs by both DA is planned to start in September 2013, with delivery of the first winding pack in 2014 bringing up to full speed the.series production.

Given that the knowledge-based coil fabrication will be very dynamic, improving insight in those magnets tolerances will be essential as discussed with JA-DA TRO Norikiyo Koizumi and EU-DA TRO Alessandro Bonito Oliva.

Alexandro Bonito Oliva reported additionally on recent progress concerning the commissioning of the European TF winding tooling facility, the heat treatment oven and ongoing qualification tasks on joint, helium inlet and impregnation trials.

In spite of the difficulties of coordinating fabrication work with such a vast logistic and high production rate, the ITER Organization is confident in the ability of the DA suppliers and of the ITER TF IO-DA team project capacity to continue working in a cooperative and synergetic manner in order to reach our common goal.”

The TF Collaboration Meeting is also an opportunity to showcase the work done in the Japanese and European DAs. The substantial progress achieved by both European and Japanese domestic agencies would not have been possible without an effective collaboration with the TF team.

Russian TF conductor successfully tested in SULTAN

Having recently celebrated its fifth anniversary, the ITER Project has moved steadily from negotiations to real manufacturing, and from dummy testing to production of the tokamak’s construction elements.

One of the first systems to be manufactured in line with the ITER Organization (IO) Integrated Schedule Plan is the superconductor for the ITER magnet system. Russia has demonstrated high stability and reliability during this process, fulfilling all its obligations in time. This has not only been acknowledged by the IO experts, but also by the international superconductor community.

The Russian Toroidal Field (TF) conductor with bronze route strands  was tested in the SULTAN facility by Centre de Recherches en Physique des Plasmas- Ecole Polytechnique Fédérale de Lausanne (CRPP-EPFL) in late September — early October 2012. This is the fourth Russian sample to be tested in SULTAN but the first sample containing two sections of conductor made of real production length which will be used to manufacture real TF coils for the machine. The left section of the conductor was cut from side Double Pancake  pre-production conductor (Phase III) while the right section was made from first production (Phase IV) regular Double Pancake.

The results obtained with the the TFRF4 (Toroidal Field Russian Federation # 4) sample show very good agreement with results of the two last samples TFRF2 and TFRF3, which demonstrated the relatively good stability of the conductor during electromagnetic cycling, as well as its good durability during the warm-up/cool-down procedure.

Testing the TFRF4 sample was a very important milestone which completed the pre-production phase of the TF conductor procurement process. This means we can now proceed to the final production stage. At the same time, it opens the way to start shipping the real conductors to the coil manufacturer so they can be used to make coils for the ITER tokamak.

Where conductors are born

Manufacturing the toroidal field conductors for the ITER magnet system is a sophisticated, multistage process. Early this year, specialists at the All-Russian Cable Scientific Research and Development Institute (VNIIKP) in Podolsk, Russia twisted semiconductor strands into a 760-metre niobium-tin (Nb3Sn) cable—the second product of this kind manufactured in Russia. 

At the end of February, at the High Energy Physics Institute in Protvino, this cable was pulled through a stainless steel jacket that had been assembled on site. The process involved the most advanced Russian technology and knowhow. The jacket itself—reaching nearly a kilometre in length and composed of more than 70 tubes welded together by gas tungsten-arc welding technology—was exposed to triple testing of the weld seams' quality and reliability.

During the next stage in the process, the jacketed cable, called a conductor, was compacted and spooled into a solenoid measuring four metres in diameter. Following vacuum and hydraulic tests at the Kurchatov Institute in Moscow, the conductor will be shipped to Europe.

Follow this link to a 10-minute video in English that will bring you inside the Russian factories involved with toroidal field conductor manufacturing for ITER.

Click here to see the video in Russian.

A new database tool for magnet production

One of the greatest challenges to monitoring the production of the large and complex components at the heart of the ITER magnet system is the quick and efficient exchange of quality assurance/quality control (QA/QC) documents and data—important information that needs to be reviewed during the manufacturing process and cleared for acceptance by the responsible Domestic Agency and the ITER Organization.

Following the successful implementation of the Conductor Database tool that tracked production data for the ITER conductors at six Domestic Agencies and their suppliers right through to final acceptance tests, it was decided to develop and implement a Magnet Manufacturing Database (MMD) on the same model.

The Magnet Manufacturing Database will be the main tool for monitoring the QA/QC processes of the Procurement Arrangements for magnet coils, magnet structures and magnet feeders. This web-based application, integrated into ITER’s collaborative platform ICP, provides data and process integration with unified access and workflow. For the manufacturers, it offers an inventory control system with the possibility of integrating test result data and acceptance criteria functionalities, and of automatically generating barcodes and lot/serial numbers to facilitate tracking.

For the ITER Organization, the workflow management system included in the database matches the control points defined in each Procurement Arrangement and the manufacturing processes defined in the Manufacturing Inspection Plan. References to ITER documents are included for procedures, instructions, and specifications … allowing the ITER Organization to identify and manage critical operations such as welding.

The Magnet Manufacturing Database can manage any kind of complex manufacturing process chain, regardless of product type. Real-time production status and work-in progress monitoring will be also developed in a near future, using the IT online reporting system to extract and display data from the database in an efficient manner.

The success of such a tool will rely on the ability of its users around the world to input data in a timely manner. After a prototype implementation at the European Domestic Agency for the toroidal field coil winding packs, representatives of the ITER Magnet Division were in China mid-May to provide extensive training to the staff of the Chinese Domestic Agency, its supplier ASIPP, and some of the ASIPP sub-suppliers to launch the Magnet Manufacturing Database for the feeders, high temperature superconductor leads, and correction coils.