Magnet experts from the ITER Organization and the Japanese, European and US Domestic Agencies met at Naka from 9-11 March to carry out an intermediate design review of the central solenoid, the "backbone" of ITER's magnet system.
This review was chaired by Elwyn Baynham, formerly of the Rutherford Appleton Laboratory, UK, and hosted by the Japanese Energy Agency to assess the status of the central solenoid's baseline design and provide a benchmark to assess future changes. The overall conclusion is that the solenoid's design, including its six identical modules, is accepted by the review panel, although within the scope of this review it was not possible to fully assess the baseline design tolerances against the plasma physics requirements.
The review panel identified a number of top-level design issues which should be addressed as priority items by the ITER Organization design team. The first one is the conductor jacket material, submitted to high stress levels and cyclic loading. Two options were presented: one using JK2LB, a high-manganese steel specially developed by the Japanese Domestic Agency, and one using a commercially sourced high-grade stainless steel (316LN).
The review concluded that whereas it is possible to use the first as the jacket material owing to the already-existing database for stainless steel, a thorough qualification and materials mechanical property database would need to be developed for the second one.
Another issue is the material to be used for the precompression structure that holds the six coil modules together: if JK2LB is to be used as conductor jacket material, standard commercially available grades of stainless steel can be used for the structure. But if 316LN is to be used as jacket material, either high-performance grade stainless steel or aluminium plates would be required to meet the requirements in terms of yield strength and fracture toughness for the structure. Nevertheless, the review concluded that the low fracture toughness achievable with aluminium alloys would increase the risk in terms of fatigue life.
A third issue considered by the review is tolerances. One analysis presented a requirement of 33 mm as a clearance between the central solenoid and the toroidal field coil straight leg. The review recommended that this analysis be extended to include all manufacturing steps. The review also recommended that a detailed review should be made by the ITER Organization of the central solenoid and toroidal field envelopes and interfaces as part of the completion of the baseline design.
Two options are also being considered for quench detection, one using pick-up coils and the other relying on voltage taps. Studies are underway to evaluate the effectiveness of quench detection methods. Detecting a quench reasonably early in order to avoid increase of temperature in the coil above 150 K requires a sensitivity threshold of 200 mV, which was considered by the review as marginal given the high voltages applied to the central solenoid coils. The review panel also pointed out that the temperature margin of 0.7 K was not large for a system of this size and complexity. (The temperature margin is the amount the temperature of the superconductor needs to be increased for a voltage of 10microV/m to appear - i.e., it is on the verge of losing its superconductivity at which point a quench starts.)
Concerning manufacture, the panel draw the attention on the challenging concept of circular winding using joggles to change from one turn to next compared to the more conventional winding along a spiral providing a continuous variation of curvature. The circular winding with short transition from turn to turn has been adopted in the baseline design to maximize the available flux but the review suggested that the trade-off analysis between circular winding and spiral winding should be documented as part of the baseline design completion.
Since early March at ITER Headquarters in Cadarache, prototypes being developed for the ITER machine have been displayed inside and in front of the building. After the blanket module, three mockups for the ITER divertor arrived last week and are now on show in the entrance hall.
The divertor is one of the key features of the ITER machine. Its function is to extract heat and helium ash, as well as other impurities from the plasma, acting like a giant vacuum cleaner. It is also the main interface between the hot plasma and the material surfaces. The ITER divertor consists of a cassette body made up of 54 remotely removable cassettes, each holding three plasma-facing components: the inner and outer targets and the dome.
In the new exhibit, kindly provided to ITER by the Austrian company Plansee, there is a mockup of the inner vertical target, a qualification prototype of the same, plus the dome. The vertical target mockup is one-metre long; the final version will be 1.7 metres. It consists of four parallel high heat flux units, assembled on a steel support structure. The current design foresees two different types of armour: tungsten monoblocks on the upper curved section of the vertical target, and carbon-fibre composite monoblocks on the lower straight section. An alternative design was built that uses tungsten flat tiles on the upper curved section instead of monoblocks. Both designs comprise precipitation-hardened CuCrZr tubes which allow the coolant—in this case water—to pass through the composite just below the hot armour.
The third exhibit is a full-scale mockup of the dome. It consists of six parallel high heat flux units, assembled on a steel support structure. The high heat flux components are designed to have complete tungsten flat tile armour, joined by electron beam welding onto a CuCrZr-heat sink, comprising screwed tungsten heat shields in the lower portion.
International collaboration sometimes takes its toll. Representatives from the ITER Organization and the Domestic Agencies travelled last week to Korea to convene for their monthly coordination meeting. While the party at one end of the planet saw the sun rising over Daejeon, those who attended the live link back in Cadarache at 1:00 a.m. could see the moon rising on a starry Provençal sky. Last Sunday near Manosque, during the weekend break from busy work days at ITER, Indian scientists and engineers and their families celebrated Holi, the festival of colours.
Holi is one of the most important Indian festivals, and is a celebration of colour and the arrival of spring. Traditionally it is understood that the strong sunlight that arrives with warmer days brings life to plants, and plants provide health to us all. By making colours and dyes from plants, the health-bringing properties of the sun can be shared with family and friends.
In Holi, celebrants play with colours, and colour each other artistically, having fun all the while. Incredible India—where science, health, humanity, arts and entertainment all mix.
On 16-17 March 2009, an Expert Group met in Daejeon, Korea. On the agenda were: transfer of ownership, transfer of responsibility, transport and insurance of the large components of the ITER machine. Participants from the Domestic Agencies and the ITER Organization discussed these topics as had been requested by the ITER Council. For each, it will be important to arrive at a coherent solution as part of a global risk management program.
For the transport of the 300 largest components, the Expert Group agreed that a global approach coordinated by the ITER Organization would be the most logical, thus reducing the number of interfaces and the risk in this area. The Expert Group agreed that a global solution needed to be found for insuring the cargo, and construction and assembly activities. With regard to the transfer of ownership and responsibilities, it was agreed that reasonable acceptance conditions would be defined based on the nature of the component.
The conclusions from the Expert Group were supported at the ITER Organization-Domestic Agency meeting which took place the next day. The ITER Organization, together with experts from the Domestic Agencies, will now develop the specifications and selection criteria for the invitation to tender.
Progress in this area will be reported in more detail at the upcoming Management Advisory Committee and ITER Council meeting.
God moves in mysterious ways. It was an article about thermonuclear fusion entitled "God's Big Fix," published in Playboy back in November 1974, that made Joe Snipes curious about fusion—a curiosity that has not diminished since. Not in the least.
Joe Snipes joined the ITER team in Cadarache in July 2008 as Senior Scientific Officer for Integrated Scenarios. This essentially means that once the machine is up and running, he will drive it. Or, as he puts it, "make the plasma work." Keeping in mind that ITER will be the biggest and most sophisticated tokamak ever built, it sounds like Joe has a challenging job on his hands. But he has come a long way—"it was quite a roller coaster ride over the years"- and he seems to be well prepared. "I got a pretty good education!"
Joe was born in Atlanta, Georgia, USA. He received a Bachelor's degree in physics from the University of Chicago where as an undergraduate he worked at the Enrico Fermi Institute. He then moved to the University of Texas at Austin for his PhD in plasma physics, and worked on the TEXT tokamak. From there he moved on to Europe, to the JET facility in Culham, UK, "looking for a place that really did fusion." An Italian lady then convinced him to investigate the Italian fusion landscape, which he proceeded to do for a few years in Latium. He returned to the Massachusetts Institute of Technology (MIT) in Boston where he helped develop a lithium-pellet injector for the Tokamak Fusion Test Reactor at Princeton. From there he went on to operate the newly built Alcator C-Mod at MIT. And last summer, he packed up his suitcase again and moved to southern France.
As Officer for Integrated Scenarios, Joe interfaces with many other disciplines such as power supply, diagnostics and fuelling—hence the "integrated" in his title. It will be his job to tune the machine so that it reaches a power amplification factor of 10 (Q ≥10) with a net power output of 500 MW. In order to achieve this ambitious goal, Joe currently compares the results of computer model scenarios with experimental data gained from operating machines. "It is very hard to predict how ITER will behave." One day, he will see it with his own eyes. "I am young enough to hope to see a deuterium-tritium reaction in ITER."
Fusion powers our Sun, and holds the promise of unlimited and clean energy for the future of humanity. But how real is this promise? Can it be achieved? After decades of slow progress, scientists are coming closer to answering these questions. Two huge experiments are currently being built—ITER in Cadarache, France, and Wendelstein 7-X in Greifswald, Germany. A documentary follows new developments in the quest to harness the power of the Sun on Earth. The German television station 3sat is showing the program at 21:30 on 23 March.
When did you last run into one of your ITER colleagues from the other side of the fence?
In the "old days" we were all housed together, so bumping into colleagues or stopping for a chat was easier. Now that we have spread out into different buildings, we have less and less opportunity to meet.
But THAT is about to change, because we are introducing a monthly Happy Friday!!
From now on, every last Friday of the month from 12:00-14:00 you are invited for a sandwich and a soda in front of the Headquarters building.
This will give us all the opportunity to meet and catch up with one another. Nothing formal—just a moment to get together, chat, mix, mingle and feel like a team again.
So don't miss this first Happy Friday, on 27 March at the Headquarters building. We are looking forward to seeing you there!
Last week, the Tritium Plant Project Team came together in Cadarache for a three-day meeting to discuss issues such as plant integration, plant interface and interface control, and process modelling. The team meets two times per year, and includes experts on tritium handling as well as cryogenics and vacuum engineers from the all ITER Members involved in building the Tritium Plant (ITER Organization, Europe, Japan, Korea, and the US). They look very inviting indeed, but sorry: no swimming, no fishing! The four large basins on the ITER site that will take the cooling water from the Tokamak Complex before its release into the Durance River are currently undergoing waterproof testing. It is a two-step process: after close inspection of the welded joints in each of the 3,000 cubic-metre basins, the first is filled with water. The waterproof membrane coating the inside of the basin is verified, before draining the water into the second basin—and then the third and fourth—to repeat the process.
The test time for each basin, not including filling and emptying, is estimated at about one week. Once all the tests have been successfully completed, the Cari company responsible for the work will add 15 centimetres of cement to each basin to protect the waterproof membrane. Work on the basins should be complete by the end of April.
Sixty million years ago, what is now Provence was a narrow ribbon of land surrounded by ocean, a mere isthmus connecting the present-day Maures and Massif Central mountain ranges. Mount Sainte-Victoire had not appeared yet, and there was no one to paint it. Hominoids were not due for another 55 million years. Our closest parent then was a tiny mouse with an uncertain future.
The late Cretaceous Period was the realm of dinosaurs. They had been around for some 150 million years and had evolved into hundreds of species; some huge, some small; some carnivorous, others feeding on grass; some who flew and some who ran. They are known to us as Diplodocuses, Triceratopses, Raptors, Pterodactyls, and Titanosauruses, and others.
The Titanosauruses, along with some smaller-size breeds, were at home in the tropical marshes where Mount Sainte-Victoire now stands. There, they would waddle in the mud and build nests to lay their eggs. The "terrible lizards"—which is what the word "dinosaur" means—are long gone, but their fossilized eggs still abound in the massif, some as large as a football.
The egg deposits around Mount Sainte-Victoire have no equivalent in the world. Thousands of fossilized eggs and hundreds of fully-preserved nests have been brought to the surface over the years by palaeontologists and deposited in museums in Aix, Marseille and the villages around the mountain. Others have been sold for a fortune to rich amateurs all over the world.
In some areas of the range, the ground is literally covered with eggshell fragments. It is a strange feeling to hold these tiny, fragile remnants of gigantic animals in your hand. Studying the eggs has shown that in some species there was a factor of 10,000 between the size of the embryo and that of the grown animal.
Walking freely among the eggshell fields is now impossible. A natural reservation was established in 1994 that closes off access to the most spectacular of the deposits. Rangers on horseback patrol the area and one can be severely fined for trying to bring home one of these souvenirs from 65 million years ago. Visits can be organized, however. In the village of Saint-Antonin-sur-Bayon, 10 kilometres east of Aix-en-Provence, the Maison de Sainte-Victoire offers permanent exhibits and guided tours every weekend.
At the Mount Sainte-Victoire, one can travel in time as easily as one travels in art.
Jérôme Paméla, Head of the European Fusion Development Agreement (EFDA), and former Director of the Joint European Torus (JET), has been appointed " Chevalier dans l'Ordre National de la Légion d'Honneur" (Legion of Honour). The decoration was awarded by the CEA Administrator-General Bernard Bigot at the Château de Cadarache today, 23 March.
Spring is back, and we are finally getting the warm sunny days we deserve. Consequently, most of us are feeling the urge to shed some of our heavy winter clothes and get some quality outdoor time.
In the rush for fresh air, let's not forget that sun exposure also means ultraviolet (UV) exposure. So you need to think about protecting your skin and your eyes.
The most likely short-term effect for fair-skinned people is sunburn. As little as half an hour around midday may be all it takes. Repeated exposure over a long period contributes to accelerated skin aging and an increased risk of skin cancer. We all develop wrinkles with age, but people who spend a lot of time in the sun usually have that truly wrinkled weather-beaten look. And guess what? Most skin cancers develop on sun-exposed parts of the body. Your eyes should be protected as well: prolonged exposure to sun increases your chances of getting cataracts, which is a clouding of the lens.
Be careful to not catch a cold in the shade or the wind: spring temperatures can be quite chilly. There is a common French saying: "En avril ne te découvre pas d'un fil », which means 'In April, keep your warm clothes on!'
Safely enjoy the return of spring!