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ITER NEWSLINE 163
11 Feb, 2011
The Korean Domestic Agency, in cooperation with Daebong Acrotec, has completed a full-scale mock-up of a 10° inboard section of the ITER Thermal Shield, and tested the main procedures of fabrication including cutting, bending, forming, buffing, welding, and machining.
"We are pleased to report that all the processes for thermal shield manufacture were demonstrated, with the exception of last-stage silver coating," said Wooho Chung, Technical Responsible Officer. "The fabrication of the mock-up allowed us to validate the design and manufacturing process for the ITER Thermal Shield."
Inserted between toroidal field magnets and the vacuum vessel, the ITER Thermal Shield (TS) system minimizes the thermal radiation to the superconducting magnets. Made of stainless steel panels coated with low-emissivity silver, connecting joints (flanges) and cooling pipes welded to the panels, the TS is operated within the range of 80-100 K during plasma operation. The TS surface area covers 10,000 square metres; once assembled, it will stand 25 metres at its highest point.
Two TS segments — the outboard segment and the inboard segment - will be manufactured separately by Korea and then assembled to form a full torus shape. As an open structure, each segment is susceptible to distortion caused by cutting, machining or welding. "It is very important to validate all design and requirement parameters before beginning fabrication," stresses Chung. "The tolerance requirements for the joints in particular are very strict."
During the fabrication of the 10° inboard section mock-up, each step of the manufacturing process was validated. Panel thickness and distortion were measured after the bending and forming stages; all welds were successfully verified; and the machining processes were tested. One important finding from the mock-up fabrication was that the inboard segment is more flexible than expected, making the handling jig essential during fabrication. However, the structural flexibility of individual segment is beneficial for the assembly of the 40° sector.
"We now plan to make another mock-up - the TS outboard 10° section - which will be assembled with the inboard section," says Chung. "These mock-ups will be used in the test of silver electroplating processes."
The detailed design of the ITER Thermal Shield will be reviewed in 2011. The beginning of fabrication is expected in early 2012.
Leaks and impurities are the giant ITER's most feared enemies. A submicron-size crack in a vacuum vessel weld, a puff of particles ripped from a plasma-facing component — these events would be enough to severally degrade the machine's performance and eventually bring it to a halt.
Keeping these microscopic enemies at bay is one of the responsibilities of the ITER Vacuum Group. "We have a mandate to assure vacuum quality," explains Liam Worth, the Group's Vacuum Leak Technical Engineer. "This means scrupulous testing during assembly and careful qualification of the materials that go into the vacuum vessel."
A 600 m2 ITER vacuum laboratory will be the centre of leak-testing activity and vacuum qualification during the main assembly phase of the ITER device.
In the meantime and until the facility becomes available, the ITER Vacuum Group will meet urgent vacuum qualification needs by using a "Temporary Vacuum Laboratory"... courtesy of CEA.
Some eight months ago "...an informal conversation around a cup of coffee" with CEA colleagues provided an unexpected opportunity. CEA Vacuum Group was offering their ITER counterparts "a nice piece of real-estate" in the form of a 60 m2 working space in one of CEA-IRFM's buildings, close to the Tore Supra installation.
Several meetings and a letter of intent later, the deal was sealed. "Having a temporary space at the CEA gives us the opportunity to begin building an effective facility ready to meet the challenge of construction," explains Jean Louis Bersier, ITER Vacuum Technical Engineer responsible for the planned full-scale ITER Vacuum Laboratory, which will ultimately be housed on the ITER site.
Equipped with an outgassing rig (outgassing is the process by which materials release the gas particles that are trapped on their surface and within their bulk), a leak detector and a laminar flow bench, the "Temporary Vacuum Laboratory" will meet the immediate needs of ITER with minimum cost to the project.
Results obtained in the ITER Temporary Vacuum Laboratory will feed the database of materials compatible not only with vacuum but with the very unique ITER vacuum — an environment where an artificial Sun ten times hotter than the actual one shines through an "atmosphere" one million times thinner than the air we breathe.
In the course of ITER's life, many things will be invented: new processes and innovative materials will be developed; unprecedented concepts and exotic tools will most certainly be elaborated. "We are building a device that is at the cutting edge of technology," says David Campbell (Directorate for Plasma Operation) and Chair of the newly-established Intellectual Property (IP) Board. "People will invent ... and their inventions will need to be protected."
The issue is a very serious one that has implications way beyond ITER. When fusion reactors are built the potential value generated by inventions and technological breakthroughs will be considerable.
In conformity with the Rules on Intellectual Property Management and Dissemination of Information that were adopted at the fifth meeting of the ITER Council in November 2009, an "IP Board" was established this week to assess "all aspects of intellectual property protection within the ITER Organization."
One of the founding principles of ITER is that knowledge acquired within the project is freely shared between the contributing Members. "We have to make sure that knowledge generated within ITER can be exploited effectively by the Members in their fusion development programs," says David Campbell.
While intellectual property on inventions or breakthrough technologies is pretty clear-cut, the notion of "background intellectual property" is more delicate to address. "Background intellectual property," explains the IP Board Chair, "is, for example, intellectual property that belongs to a company or institution, that is then used in fabricating an ITER component and that we need to access in order for instance to maintain the component during ITER operation. The project will most likely involve a lot of background intellectual property and we have to ensure that an adaquate protection system creates trust between us, the Domestic Agencies and industry."
The IP Board is scheduled to meet every six weeks and will convene for as long as the ITER Project exists. One item on its current agenda is designing a reward system to compensate "ITER inventors" who generate potential value; another is promoting the intellectual property training program, so that people recognize intellectual property when they see it, says David.
On 10 November, 2010, two trucks from the Siberian city of Novosibirsk rolled up to the COMPASS Tokamak at the Institute of Plasma Physics in Prague. The trucks unloaded box after box of high-tech components that had been shipped from the Russian Budker Institute of Nuclear Physics. A team of experienced technicians and physicists arrived from the Institute one week later. Their mission? To assemble and commission two powerful neutral beam injectors that will allow plasmas in the COMPASS Tokamak to reach temperatures ten times higher than previously achievable.
The Budker Institute of Nuclear Physics crafts neutral beam injectors for research centres all over the world, tailored each time to in-situ requirements. For COMPASS, the neutral beam injectors have been designed to deliver up to 300 kW of power to the plasma (one hundred times greater than the power of an electric oven) through a narrow aperture of 5cm for as long as 0,3 sec. In addition, beam modulation - where the neutral beam is switched on and off in a rapid sequence — is planned for measuring plasma characteristics, by directly comparing phenomena inherent to the plasma with phenomena induced by interaction of the injected beam and the plasma.
In COMPASS, two configurations will be possible. Either the neutral beam injectors will deliver parallel beams to the plasma - maximizing the heating effect - or they will inject beams in opposite directions to balance the force momentum on the plasma and keep plasma rotation very low. This flexibility considerably increases the plasma research possibilities on the COMPASS Tokamak.
At present, without the heating beams, the COMPASS Tokamak can reach plasma temperatures of several million Kelvin. With the two new neutral beam injectors, we expect to reach 50 million Kelvin - a record both for the Czech fusion research and for the COMPASS Tokamak.
French law requires that a Commission Locale d'Information (CLI) be established every time a nuclear installation is created. An independent body composed of representatives from local government, environmental groups, trade unions, businesses and health professionals, the CLI acts as an interface between the nuclear installation operator and the local population.
Anything that the public feels it should know falls under the jurisdiction of the CLI. The group can request from the operator any documents deemed necessary, or call on independent laboratories to proceed with environmental and health investigations.
The ITER CLI was formally established in December 2009. On Wednesday 9 February, 29 of its 42 members convened for their annual General Assembly in the "Council Room" at the Château de Cadarache.
The ITER CLI General Assembly was the occasion to provide the Commission's members with up-to-date reports on the project's progress, and also to convey the public's preoccupations to the ITER management.
On the ITER side, DDG Carlos Alejaldre gave a detailed overview of the ongoing licensing process, anticipating the opening of the Public Inquiry procedure in June of this year.
Head of the Civil Construction & Site Office Tim Watson described the "overall management strategy of the ITER worksite", and, more specifically, the "coordination procedures" that will be implemented in order to ensure that French regulations regarding health, security and social welfare are observed.
Thierry Brosseron, deputy Head of Agence Iter France (AIF), presented a striking graph showing the anticipated rise of the number of workers — to more than 5,000 in 2014-2015 — on the construction site.
He explained how a "one-stop service" (guichet unique) will be set up to help contractors deal with housing and transport issues. This "one-stop service", that AIF will subcontract, is expected to be operational in the first months of 2012.
Providing transport and housing for the thousands of workers, both French and foreign, who will be employed on the ITER site is among the issues that raise the most concern among CLI members and the local population.
While AIF is launching an inventory of all available housing in the area, local mayors have come up with some creative suggestions: a new bridge spanning the Durance River in the Château vicinity, the reactivation of the long-abandoned train station in the village of Mirabeau and even a bicycle path that would run on the left bank of the Durance, parallel to the route départementale, between Manosque and ITER.
The excavation works for the ITER Tokamak pit are making impressive progress: this week on Thursday the last blasting took place. The 87 m x 123,6 m pit is now officially 298,65 m above sea level - which means that the ultimate depth of 17 m is almost achieved. "We are well on schedule," said Jean Desfarges, Construction Manager for Engage, the company in charge of the follow-up of the excavation work on behalf of F4E, the European ITER Domestic Agency. "The next step now is to finalize the survey of the underlying rock for which 660 boreholes will be drilled. Then, a 5 cm blinding layer of concrete will be poured before the thick, 1,5 m concrete slab is filled in."
After just a year of modification work, the first experiments have proven successful. Eight magnetic control coils on the wall of the plasma vessel of the ASDEX Upgrade fusion device have now succeeded in reducing perturbing instabilities of the plasma, so-called ELMs, to the level required. If these outbursts of the edge plasma become too severe, they can cause major damage to the plasma vessel in devices of ITER's class. The results now achieved go a long way towards solving this important problem for ITER.
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