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ITER NEWSLINE 251
The ITER Tokamak will rely on the largest cryogenic plant (cryoplant) infrastructure ever built. Three liquid helium plants, working in parallel, will provide a total average cooling capacity of 75 kW at 4.5 K and a maximum cumulated liquefaction rate of 12,300 litres/hour.
On Tuesday, 11 December, ITER Director-General Osamu Motojima and the Managing Director of Air Liquide Advanced Technologies, Xavier Vigor, signed the contract for ITER's three identical liquid helium (LHe) plants. The contract comprises the design, manufacturing, installation and commissioning of the LHe plants, which are adapted to the long-term, uninterrupted operation of the ITER Tokamak. The contract is worth EUR 83 million.
The cryoplant and cryo-distribution system will supply cooling for the ITER superconducting magnets to confine and stabilize the plasma. They will also provide the refrigeration for the cryosorption panels that are necessary to evacuate the helium ashes stemming from the fusion reaction and to assure the required vacuum for the cryostat and the vacuum vessel. All these users require helium cryogen at different temperature levels ranging from 4.5 K, to 50 K and up to 80 K.
The key design requirement is to cope with ITER's large dynamic heat loads ranging from 40 to 110 kW at 4.5 K mainly deposited in the magnets due to magnetic field variation and neutron production from deuterium-tritium fusion reactions. At the same time, the system must be able to cope with the regular regeneration of the cryopumps.
Manufacturing of the LHe plant main components will start after design finalization in 2014. The first compressor station will be delivered at the end of 2015 and the LHe plants will be ready for the cool-down of sub-systems in 2018.
"This is a major milestone not only for the cryogenic system but for the whole project," said the Head of the ITER Plant Engineering Division, Luigi Serio. "The contract covers the principal component that will drive the cool-down of the machine, seting the pace toward First Plasma."
"We are very happy and excited to participate in the great ITER adventure," Xavier Vigor said. "Be assured that we, the team from Air Liquide, are fully committed to making ITER a success."
Air Liquide is the world leader in gases for industry, health and the environment, and is present in 80 countries with 46,200 employees. Oxygen, nitrogen, hydrogen and rare gases have been at the core of Air Liquide's activities since its creation in 1902. In 2011, the Group's revenues amounted to EUR 14.5 billion, of which more than 80% were generated outside France.
Five large-scale drain tanks are planned for ITER's tokamak cooling water system (TCWS)—two safety drain tanks; two normal drain tanks; and one drain tank for the neutral beam injection system. These drain tanks are the largest captive components of the TCWS, planned for installment in Tokamak Building level B2 in mid-2014. Fabrication of the drain tanks is underway as part of the US Domestic Agency (US-ITER) commitment to ITER.
Four of the tanks measure 10 m in height and have an internal diameter of 6.25 m (the neutral beam injection drain tank is about half the height, with the same internal diameter). The stainless steel plates used for the fabrication of these tanks are polished prior to manufacturing in order to achieve a minimum surface finish of 1.6 micrometres.
Polishing work on the stainless steel is currently underway in Philadelphia, Pennsylvania (USA) at Stainless Steel Services, a US Domestic Agency and AREVA FS subcontractor. During the second week of December, members of the ITER Organization Cooling Water Section and Quality Assurance Division visited the US-ITER subcontactors and their sub-tier suppliers in order to review the progress of drain tank fabrication work.
The largest facility in the world capable of testing the ITER divertor's plasma-facing components began operation in October at the Efremov Institute in St. Petersburg. A series of high-heat flux tests were performed on the first full-scale prototype of the divertor outer vertical target, which had been manufactured and delivered by the Japanese Domestic Agency.
ITER's divertor components will be manufactured by the European, Japanese and Russian Domestic Agencies. These heat-capturing elements will be in direct contact with the plasma—a first barrier that will withstand the main heat flux from plasma during operation. With plasma temperatures of up to 150 million °C and an expected heat load on the divertor surface up to 20 MW/m2, the components under test have challenging requirements to meet.
"The inner and outer divertor targets are the most highly loaded components of the ITER machine," says the leader of the Tungsten Divertor Section Frederic Escourbiac. "The aim of this testing is to verify the thermal performance of the plasma-facing components, and to make choices about materials and technology before the manufacturing phase."
The ITER Divertor Test Facility in Russia was established following the signature in February 2010 of the Procurement Arrangement for the High Heat Flux Testing of ITER's Plasma-Facing Components. In the vacuum chamber of this unique test facility, an 800 kW electron gun focuses its heat directly on the target, exposing the materials to the same heat load expected during normal operational conditions in the ITER machine.
"This first test series was remarkable in a number of ways," says Frederic. "It was the maiden run for the ITER Divertor Test Facility, allowing our colleagues at the Efremov Institute to verify that all was functioning as planned and to work out the initial kinks. For the divertor program, it was the first opportunity to demonstrate that our scale one components can withstand the demanding thermal conditions of the ITER machine."
The results of the three-week test run are currently under the scrutiny of Frederic, ITER Technical Engineer Andrey Fedosov, and colleagues at the Russian and Japanese Domestic Agencies, and will be reported early in the new year.
Click here to view a video on the high heat flux testing of plasma-facing components (produced by ITER Russia).
There's poetry in mathematics and this may be the reason why Cedric Villani, one of the most brilliant mathematicians of his generation, dresses as a 19th century romantic poet—long, dark riding coat; a large, loose cravat that the French call a lavallière; and, of course, shoulder-length hair. (Oftentimes, a large brooch in the form of a spider is also pinned to his lapel.)
A professor at the École normale supérieure and the director of the Institut Henri Poincaré, Villani, 39, was awarded the Fields Medal two years ago. The Fields—equivalent in prestige to a Nobel Prize (not awarded for mathematics)—is the highest prize a mathematician can receive.
Although not directly connected to fusion research, Villani's work stands "at the extreme theoretical end of ITER," exploring the properties of some of the equations that describe the behaviour of particles in a plasma, or the movement of stars in a galaxy.
In the summer of 2010, he taught a course at Marseille's international centre for mathematics meetings (Centre International de Rencontres Mathématiques) as part of a program on mathematical plasma physics related to ITER. Last Thursday 20 December, before giving a seminar on non-linear Landau damping at the CEA Cadarache-based Institute for Magnetic Fusion Research (IRFM), he paid a visit to the ITER site with a party of IRFM physicists.
In a previous Newsline interview the Fields Medal laureate had stressed the importance, when one deals with abstractions, of remaining solidly "anchored in reality." The mathematical equations he explores, after all, are the true foundations of the ITER Project.