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Worksite photos | The view one never tires of

ma, 09/07/2018 - 20:44

For the past three-and a half years, ITER Communication has been documenting construction progress from the top of the tallest crane on the ITER worksite. Although shooting the same place from the same viewpoint might be considered repetitive and boring, in this case it never is: the ITER worksite is an ever-changing landscape one never tires of.     See the gallery below for a new series of images, the first since April. More filming and photographing is scheduled for later this month.

Optic sensors | Testing the resistance to radiation

ma, 02/07/2018 - 16:34



Inside the ITER machine, the divertor and the blanket will be equipped with more than 1,000 fibre optic sensors for recording temperature, strain, displacement and acceleration—important feedback to estimating the health and residual lifetime of these components that are located so near the plasma. Sensor prototypes designed by the ITER Organization have already been tested thermally, mechanically and optically; now—thanks to the first Implementing Agreement of the ITER Organization-Kazakhstan Cooperation Agreement—they will soon be tested for radiation resistance.

A large number of sensors on the divertor and blanket will tell engineers how these internal machine components are doing under the stress of operation.
Devices no larger than a postage stamp will be mounted on 3 of the 54 divertor cassettes and on 20 of the 440 blanket shield blocks installed inside the machine. These highly sensitive instruments—formed from steel-plate sensors embedded with neutron-resistant optical fibres—will be capable of measuring temperature, strain, displacement, or even the smallest vibration, and of transmitting the information to software for analysis.
"The optical operational instrumentation for the internal components is based on the analysis of transmission of light," explains Sergey Bender, instrumentation engineer in the Divertor Section. "As temperature or strain increases in the internal components of the machine, there is a corresponding shift in light wavelengths that can be measured and interpreted."
Optical fibre technology is attractive for fusion applications, in particular thanks to its immunity to the rapid and large variation of electromagnetic fields during plasma disruptions—exactly the moment when there is a major need for measurements. 
Neutrons can darken optical fibres over time, however, resulting in a reduction of their reflective index and hence their ability to transmit information. To overcome this drawback, ITER's instruments will use a special type of non-standard FBG optical fibre (for Fiber Bragg Grating) that is neutron-resistant. FBG measurements are based on wavelength shifts rather than on the amplitude of the optical wave, which is impaired by the reduction of reflective index.
According to Bender, the neutron immunity of this particular type of fibre makes it an essential feature in monitoring the internal components.
Under the first Implementing Agreement of the Cooperation Agreement that was signed between the ITER Organization and the National Nuclear Center of the Republic of Kazakhstan last year, samples of sensors and optical fibres for ITER operational instrumentation will be tested for neutron resistance in Kazakh research reactors to confirm all design assumptions and to clear the way for industrial manufacturing.
Two test phases are planned:
  • Several four-hour irradiation campaigns at the IVG -1M research reactor in Kurchatov to test how the operational instrumentation works under different temperatures and dose rates and to define the characteristics of the samples (fibre length, temperature) for the second campaign.
  • A 23-day campaign at the WWR-K research reactor in Almaty, under fully ITER-relevant neutronic fluence (up to 1020 n/cm2, for an energy higher than 0.1 MeV). (Neutronic fluence is defined as the number of neutrons per unity of surface cumulated during a given time.)
"What we are looking for from these irradiation tests, is a final demonstration that the optical FBG sensors, as developed by the ITER Organization, are substantially immune to neutron damage in terms of accuracy and stability of measurements. The neutronic fluence attainable in the WWR-K reactor is similar to the one expected on the surface of ITER's internal components at the end of operations. This is the key capability proposed by our Kazakh colleagues, and it makes the tests highly interesting to us," explains Frédéric Escourbiac who, as Divertor Section Leader, is in charge of the operational instrumentation for the internal components.

Under the terms of the collaboration, the ITER team has ordered a small amount of radiation-resistant fibres from different manufacturers, had them "marked" with lasers to print the FGB feature¹, and created the sensors. Kazakh colleagues will prepare a special canister called an "ampoule" (see photo, left) with these sensors to be tested during the irradiation campaigns. The Kazakh team is also responsible for campaign implementation as well as the analysis of all results.

The first radiation-resistance tests are planned in November this year after six months of preparation to manufacture and prepare the samples.

¹Fiber Bragg gratings are created by using a laser source to "inscribe" or "write" a systematic interference pattern along the optical fibre. The "marks" reflect narrow bandwidths of light, which respond to changes in temperature or strain by shifting.

22nd ITER Council | Project on track for First Plasma in 2025

ma, 25/06/2018 - 15:49


The ITER Council, ITER's governing body, met for the twenty-second time on 20 and 21 June 2018 at the ITER Organization in Saint Paul-lez-Durance, France. Council Members approved refinements to the construction strategy which will optimize the installation of components in the Tokamak Complex. With this strategy in place, the project is on track to achieve First Plasma in 2025 while adhering to overall project costs.
Representatives from China, the European Union, India, Japan, Korea, Russia and the United States gathered in the fifth floor Council Chamber for a two-day review of the most recent reports on organizational and technical performance. They agreed that the project continues to sustain its strong performance and fast pace. Since January 2016, ITER has achieved 33 scheduled project milestones, including the recent commissioning of the first experiment of the ITER Neutral Beam Test Facility in Padua, Italy. 
The Council stated that significant progress has also been made on the manufacturing of technologically challenging components such as the vacuum vessel and the toroidal field magnets. They also highlighted progress in the installation of the cryoplant and in the build-up of the magnet power supply and conversion system. Based on their review of the latest performance metrics, Council Members confirmed that project execution towards First Plasma is now over 55 percent complete.
The Council acknowledged the efforts undertaken by each Member to reach approval of the overall project cost through their respective government budget processes. Having completed their internal consultation procedures, China, Europe, Japan, Korea and Russia are ready to approve the 2016 Baseline.
Expressing their resolve to work together to find timely solutions to facilitate ITER's success, Council Members reaffirmed their strong belief in the value of the ITER Project to develop fusion science and technology.
Download the full press release in English and French.

22nd ITER Council|Project on track for First Plasma in 2025

vr, 22/06/2018 - 09:51


The ITER Council, ITER's governing body, met for the twenty-second time on 20 and 21 June 2018 at the ITER Organization in St Paul-lez-Durance. Council Members approved refinements to the construction strategy which will optimize the installation of components in the Tokamak Complex. With this strategy in place, the Council asserts that the project is on track to achieve First Plasma in 2025 while adhering to overall project costs.
Representatives from China, the European Union, India, Japan, Korea, Russia and the United States reviewed the most recent reports on organizational and technical performance. They agreed that the project continues to sustain its strong performance and fast pace. Since January 2016, ITER has achieved 33 scheduled project milestones, including the recent commissioning of the SPIDER Neutral Beam Test Facility in Padua, Italy. 
The Council stated that significant progress has also been made on the manufacturing of technologically challenging components such as the vacuum vessel and the toroidal field magnets. They also highlighted progress in the installation of the cryoplant and in the build-up of the magnet power supply and conversion system. Based on their review of the latest performance metrics, Council Members confirmed that project execution towards First Plasma is now over 55% complete.
The Council acknowledged the efforts undertaken by each Member to reach approval of the overall project costs through their respective government budget processes. Having completed their internal consultation procedures, China, Europe, Japan, Korea and Russia are ready to approve the 2016 Baseline.
Expressing their resolve to work together to find timely solutions to facilitate ITER's success, Council Members reaffirmed their strong belief in the value of the ITER Project to develop fusion science and technology.
Download the full press release in English and French.

Fusion machines | The second-hand market

ma, 18/06/2018 - 10:33



Whatever their size, fusion devices are fine pieces of technology that are complex to design and expensive to build. As research progresses and experimental programs unfold, however, scientific institutions routinely feel the need for machines with additional capacities, up-to-date equipment or exotic features. When an upgrade is not possible the "old" device appears on an unofficial "second-hand market," more often donated than sold—just like one might give away a perfectly functional but not-quite-cutting-edge computer to a nephew, a neighbour or a local association.
Russia, which built and upgraded tokamaks at a very fast pace throughout the 1970s and 1980s, has been one of the most generous contributors to this second-hand market.
In 1975, the Kurchatov Institute decommissioned an upgrade of TM-1—a machine that belonged to the early series of small tokamaks developed in the 1960s—and had it shipped to the Czech Academy of Science where it operated for some 30 years under the name CASTOR. (This grandfather of all tokamaks now serves educational purposes as GOLEM).
The LIBTOR tokamak, installed since 1982 at Libya's Tajoura Nuclear Research Centre, is the rechristened TM4-4 machine, which operated at the Kurchatov Institute from 1969 to 1973. Components from another Russian machine—the larger T-7 (1979-1985) and the first to be equipped with superconducting toroidal field coils— have been reused in China's HT-7.
A lesser known Russian machine, TVD, was handed over to Iran in 1994 where, in conformity with the long-standing tradition of giving fusion projects the name of mountains¹, it became Damavand, Iran's highest peak and a significant feature in Persian mythology.
Giving away second -and fusion devices is a way of planting the seeds of fusion research in aspiring countries. Portugal for instance, has been operating a small tokamak named ISTTOK since 1990 that is based on a machine that began its career in 1974 at the Dutch institute FOM (now DIFFER) under the name TORTUR (!).
In 1999 Brazil received the 20-year-old TCA tokamak from the Ecole polytechnique fédérale de Lausanne, in Switzerland. The device's French name (Tokamak à Chauffage Alfvèn) carries on in the Brazilian acronym TCABR (or TCA-Br). Brazil, which voiced interest in joining ITER in the late 2000s, also operates the NOVA-UNICAMP tokamak, which was the Nova II tokamak at Kyoto University, Japan, in a former life.
As they progress in their research, former "receivers" often become "givers." China for instance, after benefitting from Russian components for HT-7 and German components (from the original ASDEX) for HL-2A,  gave away HT-6B (1982-1992) to Iran, now installed as IR-T1 at Azad University in Tehran.
Nick Balshaw from the United Kingdom Atomic Energy Agency (UKAEA) tracks down "all the world's tokamaks" as a hobby. He has listed more than a dozen machines (including stellarators) that have changed hands in their lifetime—and not just once.
Take the present HIDRA (Hybrid Illinois Device for Research and Applications), which was transferred in 2014 from the Max Planck Institute of Plasma Physics (IPP) in Greifswald, Germany, to the University of Illinois in Urbana-Champaign.
The device, which was described by Physics Today as "a tokamak and stellarator rolled into one," had seen the light of day 40 years earlier in Grenoble, France, as a joint German-French-Belgian project under the name "Wendelstein Experiment in Grenoble for the Application of Radio Frequency Heating"—WEGA, in short.
WEGA operated in Grenoble for about 10 years, was transferred in 1984 to the University of Stuttgart, Germany, and resumed operation at IPP in 2001—still under the WEGA acronym, but with the "G" now standing for Greifswald and not Grenoble and the final "A" for Ausbildung ("training") in German.
By the end of 2013, as the latest incarnation of the Wendelstein project (Wendelstein 7-X) was nearing completion, WEGA was shut down and eventually sailed across the Atlantic. In sum, in over more than 40 years of existence the device has operated under four different roofs on two continents.
In the second-hand market, fusion devices are handed over free of charge (except for transportation costs, which are generally paid by the receiver). There is however one example of a "for sale" tag attached to a tokamak—and a hefty one at that.
Canada entered fusion research in the late 1970s, and by 1986 the Canadian Centre for Fusion Magnetics (CCFM) operated an experimental tokamak in the Varennes suburb of Montreal. This medium-sized machine, named Tokamak de Varennes, specialized in the study of plasma-wall interactions, and for more than one decade formed the kernel of CCFM activity.
Unfortunately, by 1997 the project had to be folded for lack of funding. CCFM was left with a perfectly operational machine on its hands, potentially worth millions of dollars, and it was ready to sell. Among the potential buyers was Iran, whose ambitious fusion research program had to rely on outdated machines.
The Iranian offer was in the range of USD 50 to 90 million (depending on the sources). It would have been enthusiastically accepted if the diplomatic context had been different: Iran was at the time under US-imposed sanctions and even in Canadian government circles, there was reluctance to realize the transaction.
The solution to the dilemma came from General Atomics: in order to upgrade its DIII-D tokamak, the company needed powerful gyrotrons ... of the kind, precisely, that equipped the Tokamak de Varennes.
Amputating one of the heating systems from the machine considerably reduced its operational value and, as expected, Iran pulled out of the deal.
As one final twist to the whole episode, the Tokamak de Varennes was transferred in 2001 to Canada's federal capital, Ottawa, where it now stands as one of the most spectacular exhibits at the Canada Science and Technology Museum — a unique example of a fusion machine on display for the general public.
¹ The tradition of giving the name of a mountain to a fusion research project originates with "Matterhorn", the secret program conducted at Princeton University in the 1950s. The choice reflected Lyman Spitzer's passion for mountaineering and called on the parallel between the difficulties of reaching the summit of a high peak and those of harnessing fusion energy. Several fusion projects have since been christened with mountain names—Wendelstein among them.

Neutral beam test facility | First ITER test bed enters operation

ma, 11/06/2018 - 22:49



For all those who had contributed to designing and building the world's largest negative ion source, it was a deeply symbolic moment. ITER Director-General Bernard Bigot pressed down, and sent into motion a chain of signals that resulted in the appearance of a brief plasma on the screen.
The negative ion source SPIDER was officially launched at the Consorzio RFX facility in Padua, Italy, in the early afternoon of 11 June. "Where else but here in Padua would we want to celebrate such a technological breakthrough," wondered the ITER Director-General in his address. "Padua—home to such scientific figures as Nicolaus Copernicus and Galileo Galilei who, I'm sure we all agree, changed the cultural and scientific history of humanity.  Fusion energy, too, has the potential to change the course of mankind, and ITER will pave the way."
The main hall of the PRIMA Neutral Beam Test Facility had been cleared and turned into a staged theatre to welcome the 300 guests that had made their way to participate in the event. As the guests took their seats, the machine's vacuum pumps made a steady "breathing noise" behind the thick concrete wall that hid the SPIDER equipment, a long-term vision now come to life. 
The importance of the event for the ITER Project, for science in general and for the host region could be measured by the line-up of speakers: Francesco Gnesotto, the president of Consorzio RFX, was followed in short succession by the mayor of Padua, Sergio Giordani; European MEP Flavio Zanonato; Carles Dedeu i Fontcuberta from the European Commision; Salvatore La Rosa from the Italian Ministry for Education, University and Research; and representatives of the ITER Organization and the European and Indian Domestic Agencies.
Finally the technical team in the control room, assembled around Consorzio RFX Director Piergiorgio Sonata, connected in to the event by video conference. Sonata explained what the audience would be seeing—a short plasma-generating experiment that would be evidenced by a flash of light on the screen. Next month, he explained, this type of experiment will be run for longer periods to begin extracting negative ions. The countdown started, the button was pressed and—a few seconds later—the experiment was confirmed as a success.
As the music of Vivaldi played in the background, a thick concrete door opened to review the SPIDER vessel and beam source. When the microphone was handed around, pride in the first-of-kind technological achievement—as well as in the success of the international collaboration that made it possible—was tangible.
"I am really proud to see this achievement," said the ITER Director-General. "As you know we are committed to deliver, and the most important for us is to keep the trust of all the stakeholders. When we complete something on time, according to specification and schedule, it is the best possible outcome."
SPIDER is one of two test beds planned on the ITER Neutral Beam Test Facility in Padua. All contributions are voluntary (i.e., outside the scope of in-kind contributions to the ITER Project): Italy and Consorzio RFX have provided the facility and a large contribution towards the personnel; the European Domestic Agency has financed and procured most of the components, building on the expertise of European industry and research organizations; the Indian Domestic Agency has contributed the calorimeter and the acceleration grid power supply; and the ITER Organization is responsible for the design and oversight.
See this webpage for full information on the experiments planned at PRIMA.
View a video prepared for the inauguration in this week's Newsline, or click here.

Cryopump | Big cold trap under test

ma, 04/06/2018 - 21:07



Creating an ultra-high vacuum inside the vast toroidal chamber of the ITER Tokamak—the aptly named "vacuum vessel"—is imperative to initiating plasma operations.
Mechanical pumps will do the first part of the job, evacuating the air and most of the molecules from the 1,400 m³ vessel and reducing pressure to 1/10,000th that of the atmosphere (pressure is how vacuum is measured).
This, however, will not be sufficient. The quality of the vacuum needed on ITER is in the range of 1/10,000,000,000th that of the atmosphere, close to the deep-space void and impossible to achieve with a mechanical pumping system.
By chance, there is a simple law of physics that can take over when pumping machines reach their limits.
When a molecule or an atom encounters an extremely cold surface, it loses the best part of its energy and slows down to near immobility. This phenomenon is called "adsorption" and its intensity is proportional to surface temperature: the colder the surface, the more irresistible its holding power ...
A cryogenic pump—or cryopump for short—is based on this very principle. In ITER, there will be six torus cryopumps positioned around the vacuum vessel and entrusted with a double mission: perfecting the high vacuum inside the vacuum vessel prior to operation and evacuating helium ash, unburnt fuel and all exhaust gases during plasma shots. Another two cryopumps will be installed on the cryostat to provide the vacuum that thermally insulates the magnet system from the environment.
Every ITER cryopump is equipped with 28 "cryopanels" that will be cooled down to 4.5 K (minus 268.5 °C) by a flow of supercritical helium. These extremely cold surfaces will make an extremely effective particle trap.
The cryopanels (one metre long, 20 centimetres wide) are coated with a very fine, porous carbon matrix obtained from ground coconut-shell charcoal. Despite their relatively small size, they provide an immense surface for particles to stick to: if developed (flattened out), each carbon matrix would cover 5.5 square kilometres—an area close to 13 ITER platforms.
In August last year, a pre-production cryopump for the torus pumping system, built in collaboration by the ITER Organization and the European Domestic Agency, was delivered to the ITER site. The massive and highly sophisticated component is presently being tested in a laboratory that the ITER vacuum team has set up in the neighbouring CEA-Cadarache, close to the hall that hosts the WEST tokamak.
"No one has ever built a cryopump comparable to this one. It's absolutely unique and we have to familiarize ourselves with it," says Roberto Salemme, the ITER vacuum engineer who oversees the small team from the Air Liquide-40/30 consortium implementing the test program.
The valve inside the cryopump—the world's largest all-metal high vacuum valve—is one of the main focuses of the tests. Its head is 80 centimetres in diametre, weighs 80 kilos and travels along a 40-centimetre shaft stroke. When closing, it must lock with a precision of 0.1 millimetre to tighten its all-metal seal.
"We need to characterize the valve's mechanical properties and behaviour and precisely measure the forces that need to be exerted to move it along the shaft and obtain the required sealing at both atmospheric pressure and under vacuum," explains Roberto.
Once installed in the ITER machine, the cryopump will connect directly to the vacuum vessel. In order to mimic this configuration in the lab, the pump has been equipped with a dome that seals its open end and allows the creation of a vacuum inside—not ITER-grade, but sufficient to characterize the mechanical operation of the valve in "real" conditions.
There is a lot that still needs to be explored, measured and characterized before the cryopumps can enter series fabrication, and tests under cryogenic conditions will be essential to establishing the detailed succession of ITER operational sequences.
All that can be done in advance—like the ongoing tests at the ITER lab at CEA— will simplify the commissioning to be performed by the vacuum team for First Plasma and beyond.

 

Open Door Day | An awe-inspiring experience

ma, 28/05/2018 - 19:18

In a one of the videos on a continuous loop in the ITER Visitors Centre, Director-General Bernard Bigot introduces the fundamentals of fusion energy by saying: "The principle is simple..."
On Saturday, as ITER's doors were opened wide to staff, families and the general public, some 700 visitors were offered a unique opportunity to see the simplicity of the principle and the massive complexity of its implementation for themselves.
DIFFER, the Dutch Institute for Fundamental Energy Research, had brought to ITER its Fusion Road Show—a stage-magic-style operation that explains plasmas and magnetic confinement using props like  a microwave oven, a horseshoe magnet, a smoke box, matches and neon tubes.
Brilliant, simple and fun, the show made a perfect introduction for what was to follow: a worksite tour that included a unique opportunity to view the ongoing operations in the Assembly Hall and, even more exceptional, a descent into the Holy of Holies of the ITER installation—the basement level of the bioshield where machine assembly will soon begin.
With the "simple principles" fresh in their mind, the visitors could now take in the sheer size of what it takes to turn them into reality. They had all seen ITER from afar, driving up and down the thruway or along the country road between the villages of Saint-Paul-lez-Durance and Vinon-sur-Verdon. Now, they were inside the project's most emblematic structure. And they could barely believe how massive, tall and unique it was.
At every stage of the visit, volunteers from the ITER Organization, the European Domestic Agency and from Europe's contractors Engage, Energhia and Apave provided the necessary explanations on the whys and hows of the project, answering thousands of questions and sharing their enthusiasm for this potentially world-changing venture.
Saturday was the 12th edition of the ITER Open Doors Day. And like all editions since 2012, it was a moment of awe and wonder for the visitors.

ITER DNA | A "case" study...

ma, 21/05/2018 - 20:34


In December last year, and again this year in early May, pre-welding fitting tests demonstrated that steel components as tall as a four-storey building (and weighing close to 200 tonnes) could be adjusted with sub-millimetric precision.   Performed at Hyundai Heavy Industries in Ulsan, Korea, the tests consisted in matching the two main sections of a toroidal field coil case—the steel "box" that encases ITER's vertical magnets, the toroidal field coils—to within gap tolerances half the size of a grain of sand.   Achieving that level of accuracy was a truly exceptional achievement—even for the world of high-precision industry.   The fitting tests also aptly illustrated what ITER is about and the challenges its very nature entails.   The two main sections of the D-shaped coil case—the straight-backed inboard leg  and the curved outboard leg—are manufactured by companies in different countries with different industrial cultures: one leg is made in Japan by Mitsubishi Heavy Industries, the other in Korea by Hyundai Heavy Industries.   Once the fitting tests are concluded, the case sections are individually repacked and shipped from Korea to the company responsible for the insertion of the winding pack (manufactured by yet other companies) into the case and the "closure welding" operations: if the case is for a "European" coil, its sections head for the SIMIC facility in northern Italy; if the coil is part of Japan's procurement, they sail to either the Mitsubishi plant in Futami or to Toshiba in Yokohama¹.   Why did ITER opt for such a ponderous and taxing work organization? Because ITER is not just about building a tokamak — it is also a teaching project, one in which all participating countries and their industry are meant to acquire expertise in fusion science and tokamak technology.   This dimension, which is sometimes overlooked in the day-to-day hardships and frustrations of such a complex, world-spanning project, remains at the core of the ITER DNA.   The toroidal field coil production process is an example—indeed the most extreme—of the constraints that ITER has imposed upon itself: conductor coils were manufactured in half a dozen countries; cases are under Japan's responsibility but partly subcontracted to Korean industry, and the cold testing and insertion operations have been entrusted to yet other companies—one in Europe and two in Japan...   This mind-boggling complexity, which no reasonable industrial venture would dare accept, is the price to pay for the ITER miracle — in the long-term project to provide future generations with a safe and inexhaustible energy source, the participating nations need both the training and the short-term technological and industrial benefits.   This is how project's Founding Fathers, more than three decades ago, intended it: accept and learn from the difficulties of building ITER today in order to acquire the capacity, tomorrow, to make fusion energy available to all.   1- The procurement of the 18 toroidal field coils (plus one space) needed for the ITER tokamak is shared between Europe and Japan.

Component logistics | Consistency "from the cradle to the grave"

ma, 14/05/2018 - 16:30


There's a fun and easy way to demonstrate the importance of having all ITER parts properly tagged and identified in storage—organize a workshop and ask four competing teams to build a pipe assembly with items retrieved from a makeshift warehouse. Teams each have a drawing and 20 minutes to complete the work, and penalties are inflicted for leftover items, return trips to the warehouse and, of course, incorrect or incomplete construction.
Unbeknownst to the participants, the competition is rigged—except for Group 1, all groups have to deal with information that is either missing, incomplete or not consistent. Of course Group 1 wins, completing the work in less than 12 minutes. Group 2 (with one part unlabelled) and Group 3 (with identifier discrepancies) both need an extra six minutes to figure things out. Group 4 is still puzzling over its scattered pipe sections, elbows, supports and connexions when the referee calls the end of the game.
"Just think of the consequences when you have to deal with millions of parts," smiles Aaron Shaw, ITER Materials Management Officer and workshop organizer.
Every day the main ITER warehouse receives dozens of components, large and small, for the machine and plant systems. Based on a numbering system established in 2007, every single item delivered—from individual screws to complete electrical transformers—is supposed to carry an identifier that originates in the drawing and is replicated on the bill of material, the goods themselves, the packing list and the installation manual.
"What we are building is unique," explains Aaron, "but the process of managing components and issuing them to construction is the same as in any industry."
But the complexity, the sheer amount of components to assemble, and the multiplicity of providers on three continents all make for a particularly daunting task at ITER.
"On very large projects, one can at best achieve 95 percent accuracy in identifying and tracking all the components," explained participant James McGee, who works for ITER's Construction Management-as-Agent contractor MOMENTUM.
For the moment at ITER the percentage is significantly lower—which explains why Aaron Shaw is running workshops for a number of ITER divisions and why he will be extending this approach to all seven Domestic Agencies involved in the project.
The competition he organized recently for the Tokamak Engineering Department perfectly mirrors some of the situations that are actually encountered.
"There can be no material flow without proper data flow," says Aaron. "Missing or inconsistent data on a component triggers a sequence of events that ultimately harms the project. Eventually, we end up with lost time, extra work hours, and an obvious impact on schedule and budget. It's a butterfly effect ..."
One of the slides presented during the workshop showed that a manual sequence, triggered by an item with no part number, was over twice as time-consuming (2.5x) than the available "system-to-system" process that is designed to accompany an item all the way from design to construction—the "cradle-to-grave" approach for the complete supply chain.
In ITER's largest on-site warehouse, just about a quarter of storage space is occupied by "quarantined" items that have no or incorrect identification. "If an item is delivered to ITER without a part number, it simply cannot be 'received' into our integrated data flow," says Aaron. System owners or technical responsible officers may know what the item is and where it is supposed to fit but in order to access it they need to go through the warehouse staff, who does not necessarily have the technical knowledge.
The situation, however, can be fixed. "The butterfly effect works both ways," says Aaron. "We are looking at possible improvements for data flow; organizing pilot operations with Domestic Agencies, refining the ITER numbering system with additional data for interfaces, etc."
And of course there are the competitions—although they are unfair to some of the contenders, they astutely illustrate the necessity of attaching clear and consistent information to each and every item involved in ITER construction.

State visit | ITER on Macron-Trump agenda

za, 28/04/2018 - 10:05

The State visit by French President Emmanuel Macron to Washington dominated the news this week. The main media interest ranged from the Iran nuclear deal and the Paris agreement to presidential handshakes and the symbolism of dinnerware. But under the radar, another important issue was on the Trump-Macron agenda: US support for an ITER Project that is on track for success.
France is not only the host country of the ITER Project; it also funds about 16 percent of the overall project cost—more than any other single nation. This means France is heavily vested in ITER's well being. Even more importantly, as he emphasized during his address to the US Congress, the French President places high value on scientific discovery and technological innovation. He is a strong vocal advocate for a clean energy future—underscoring the value of ITER.
As a clear signal of ITER's priority, President Macron asked ITER Director-General Bernard Bigot to accompany his presidential delegation to Washington. On Tuesday, in his speech at the French embassy, President Macron singled out ITER as an example of how large cooperative projects and common initiatives in the field of science can be used to build and strengthen bilateral and multilateral relationships among the ITER Members. The ITER Director-General was asked to participate in meetings with President Trump and the US Congress, and built on these discussions in his interactions with Secretary Perry and other US officials.
The time was well spent; the discussions were fruitful. According to the ITER Director-General: "It was clear from President Trump and President Macron's statement that both countries remain committed to maintaining global leadership on nuclear energy, including advanced nuclear technology. In that context, they stated that the US and France will support the ITER program and related scientific cooperation projects."
This outcome, together with the recent positive actions by the US Congress related to ITER funding, is clearly a meaningful step forward.

The crown | Unique but inspired by history

ma, 23/04/2018 - 17:32


On the floor of the vast amphitheatre that will accommodate the ITER machine, one of the most complex and most strategic structures of the Tokamak Building is taking shape.
Reminiscent of a spiked crown—not unlike the one atop the Statue of Liberty—the structure is designed to support the combined mass of the cryostat and Tokamak (25,000 tonnes) while transferring the forces and stresses generated during plasma operations to the ground.
Aptly enough, the structure sitting at the bottom of the Tokamak Pit is called ... a "crown."
Its principle is inspired by the "flying buttress"—an architectural solution that was implemented eight centuries ago to prevent a cathedral's walls from collapsing outward under the weight of its stone ceiling and slate roof.
In the long story of the design of the ITER buildings, the crown is a relative newcomer: up until 2012, the baseline solution to support the machine consisted of a circular arrangement of 18 sturdy steel columns.
However as models and simulations were refined, it became clear that the load transfer from the Tokamak's mass and movements to the floor of the Tokamak Complex (the B2 slab) was not totally satisfying.
Machine "up lift" from a potential vertical displacement event,  cryostat "shrinkage" from a possible ingress 1 cooling event  ... these potential events were of particular concern to safety experts.
Developing an alternate option to the columns led to a one-year collaborative effort involving several ITER departments, the European Domestic Agency responsible for building construction, and their architect engineer Engage.

Engage eventually suggested mobilizing the resistance capacity of the bioshield wall (3.2 metres thick at its base) and using it as an abutment for a set of 18 deeply imbedded radial walls—the "flying buttress" solution.
The full constructability of this innovative structure, both inspired by history and unique to ITER, needed to be demonstrated however. In October 2017, a full-scale mockup, three metres high, was erected on the ITER platform to answer the questions that even the most detailed 3D models couldn't.
Six months have passed. Down on the floor of the Tokamak Pit the steel reinforcement for about one-fourth of the crown has been set into place and—thanks partly to a recently-implemented night shift—work is progressing quickly on the remaining three-fourths.
Massive steel transition pieces, 3.5 tonnes each, have been placed atop every radial wall to optimize the transfer of loads to the ground. Lengths of thin red plastic piping are being inserted into the steel rebar to circulate cooling water during the concrete pouring phase; two kilometres of this piping will be required in all for the crown. Finally, workers are busy welding a thin "fire mesh" to the outer face of the walls to within millimetric tolerances. (See gallery below for details.)
"Everything we are implementing now has been tested and validated on the mockup: the rebar installation sequence, the concrete formulation and pouring procedures, the temperature monitoring, the cooling system arrangement and sequences ..." explains Armand Gjoklaj of the ITER Building & Civil Works Section.
And the mockup's mission is not over yet—the installation procedure for high-strength "top plates" still needs to be tested and validated. These 3.5-tonne elements will sit on top of the steel transition pieces to receive 18 semi-spherical "bearings."
The first concrete pour for the crown is scheduled in mid-May and the entire structure should be finalized by September. And as all surfaces of the nuclear buildings need to be clean and decontaminable, a huge paint job will follow on the bioshield inner walls, on the crown's radial walls and on the floor.
The concrete amphitheatre of today will turn into a polished jewel box, ready to accommodate one of the most extraordinary creations of the human mind: the ITER Tokamak. 
¹The liquid helium cooling circuits for the superconducting magnets pass through the cryostat. In case of a breach, the sudden drop in temperature would cause a "shrinking" of the cryostat.

Plasma physics | Be clean, be strong

ma, 16/04/2018 - 17:33

To achieve maximum fusion efficiency in a tokamak device it is essential to limit the impurities in the plasma. But this can be a challenge, as interaction between the hot plasma and the material surfaces of the vacuum vessel causes material particles to detach and enter the swirling cloud of gas.
The laws of physics dictate the maximum plasma density that can be achieved for a given current in a tokamak, which means that in ITER—as in other tokamak devices—there will be an upper limit to the number of atoms that can be confined.
Within this limit, it is important that the plasma contain as many atoms as possible that are capable of reacting to produce fusion—in ITER's case, atoms of deuterium and tritium.
Even in trace amounts, other atoms ("impurities") dilute the core of the plasma by taking the space that could be occupied by the fusion fuels, resulting in fewer reactions and a reduction in energy production. And because fusion reactions occur in a roughly proportional manner to the square of fuel density, the "multiplier" effect sets in quickly—fewer fuel atoms result in a dramatic drop-off in fusion reactions, while more fuel results in a rapid increase.
Impurities originate from vacuum vessel and the in-vessel component materials ... iron from the steel components, beryllium from the top layers of the first-wall panels protecting the vacuum vessel, and tungsten from the divertor targets. 
Impurities not only dilute the plasma but—depending on the physical properties of the atoms involved (the number of electrons)—they can also cool it to differing degrees. "The process is similar to that in a fluorescent lamp," explains Alberto Loarte, who leads the Confinement & Modelling Section at ITER. "The electrons of the impurity atoms run into the electrons in the plasma and drain their energy, re-emitting it as electromagnetic radiation—including visible light."
The heavier elements, in particular, drain a lot of energy from the plasma through radiation because of a high number of electrons (tungsten has 74). The energy lost through impurity radiation cools the plasma down and the fusion reactions stop.
In ITER, to keep these radiative losses to a minimum, the divertor will be working from its position at the bottom of the machine to continually exhaust impurities from the plasma and limit contamination.
The very properties that make impurities unwelcome in the core of the plasma, however, can be applied to beneficial effect in the plasma edge region.
Because the energy confinement provided by the machine's magnetic fields is not perfect, large power fluxes can find their way to the edge of the plasma and onto the divertor targets. To avoid localized depositions that would be too high for the material components to withstand, scientists will inject impurity gases at the plasma edge. The radiative properties of the impurities will act to reduce the power fluxes to the material elements by dissipating their energy over a larger zone.
As the plasma in this edge/divertor region is already at temperatures much lower than those required to produce fusion power, this plasma cooling will not affect fusion power production in ITER.

Ring coils | Hot resin before the deep cold

ma, 09/04/2018 - 16:23



It has been almost one year since the fabrication of the first ring coil was launched in the on-site Poloidal Field Coil Winding Facility by European Domestic Agency contractors. Out of the eight "double pancake" conductor windings needed to finalize the 350-tonne magnet, three have been wound and are ready to pass through the resin-impregnation phase—an operation that contributes to both electrical insulation and structural strength.
On one of the circular platforms on the southern end of the silent, clean and temperature-controlled facility, a double pancake sits, still attached by 24 lifting points to the circular spreader beam that has just moved it from the stacking station.
A few metres away, technicians are busy assembling the vacuum containment vessel—the "mould"—that will enclose the double pancakes throughout the lengthy and delicate resin impregnation process.
"During impregnation, we inject some 600 litres of epoxy resin at a temperature of 55-60 °C through entry ports in the mould," explains Gian Battista Fachin of the European Domestic Agency, who works in the facility where Europe is fabricating the four largest ITER poloidal field coils. "At that temperature the resin is as liquid as water and easily penetrates through the fiberglass wrapping of the double pancake."
Once extra pressure has been applied inside the leak-tight mould to insure that all micro spaces are properly filled, the resin's temperature is ramped up first to 100 °C for a few hours of "gelling," then to 140 °C for a full day and a half of "curing." By then, the resin has become rock solid and the shining white double pancake has turned into a massive block the colour of caramel.
The resin impregnation process was tested and validated on a "dummy" conductor winding that is presently stored at the far end of the building.
"We learned a lot from the dummy, right from the beginning operations that began in November 2015," confirms Gian. "We established metrics and procedures, refined bending parameters, impregnation and injection durations ... everything a dummy is for."
The dummy is a perfect replica of an actual double pancake for the 17-metre-in-diameter poloidal field coil #5 (PF5). For reasons of cost however, it is wound from copper conductor rather than from superconducting niobium-titanium alloy.
When all eight double pancakes for PF5 are finalized (winding is underway on the fourth in the series now) they will be stacked to form a winding pack—the coil's very core—which will be wrapped with insulating fiberglass tape and impregnated with resin as one single component.
The winding pack will then receive additional equipment such as clamps, protection covers and pipes. At that point, one last crucial operation remains to be performed before the component can be considered fit for duty.
When ITER enters operation, liquid helium circulating inside the conductor will bring the coil temperature down to 4 K (minus 269 °C) to create the physical conditions for superconductivity in the niobium-titanium conductor.
Throughout the manufacturing process, sample tests and quality control have insured that the conductor's performance in such extreme conditions is in line with the magnet system's requirements.
What remains to be tested however, is the coil's behaviour as a whole. How is it affected by the thermal contractions generated by the ultra-cold temperature? Does the liquid helium circuit within the cable-in-conduit conductor remain leak-tight? Can cracks develop in the resin and hinder electrical insulation?
These questions can be answered without having to cool the coil all the way down to 4 K. At the temperature of liquid nitrogen (80 K or minus 193 °C) thermal contractions have already reached their maximum and all the potential issues can be identified. Also, cooling with liquid nitrogen is much cheaper and easier to implement than cooling with liquid helium.
In May, the cold testing equipment will arrive from Italy for installation in the northern end of the workshop. The four coils manufactured on site (ranging from 17 to 24 metres in diameter) will be tested one after the other in the cold testing vacuum vessel, as will a smaller coil (10 metres in diameter) that is being manufactured in China under an agreement with Europe.
Cold-testing operations are scheduled to begin in the summer of 2019 and last for more than one year.