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ITER NEWSLINE 141
The high-temperature superconductor current leads are designed to transmit high currents from the room-temperature power supplies to the low-temperature superconducting coils with minimum heat load.
For this they use a short segment with high temperature superconductor (HTS), which can carry much higher current-densities than normal conductors such as copper. It can therefore conduct the current using much less material (smaller cross-sections), thus reducing the heat conduction.
The heat load reduction by the HTS current lead results in a decrease of the power input (here cryo-power), greatly improving the efficiency of the ITER device. The HTS current lead technology is therefore one of the "enabling" technologies for a fusion tokamak.
The HTS current leads are part of the so-called feeders, a set of ITER components provided by China.
The Institute of Plasma Physics of the Chinese Academy of Sciences (ASIPP) in Hefei, China, started development of such current leads more three years ago. In Dec 2008, Newsline reported on a successful test of a 68 kA current lead prototype needed for a toroidal field coil feeder.
Now the ASIPP HTS team has successfully tested two prototypes of the 10 kA HTS current lead for the ITER correction coil feeders. On 4 July 2010, the HTS current lead was operated for several hours at the peak 10 kA current, which is 20 percent above the average current during a typical correction coil powering cycle.
The results were discussed at a special meeting of the ITER HTS working group at KIT in Karlsruhe, Germany, last week (15-16 July). This successful test completes the HTS current lead R&D conducted at ASIPP in preparation of the feeder final design review this coming September for which the feeder teams in China and at the ITER Organization are now feverishly preparing.
ITER will operate with a system of superconducting magnets that relies on the toroidal field coils, the central solenoid, the poloidal field coils and the correction coils (see ITER image).
Europe will manufacture 10 of the 19 toroidal field coils for ITER, including a spare, while Japan is responsible for producing the remaining nine.
The European Domestic Agency Fusion for Energy recently signed a contract for the supply of ten winding packs for the ITER toroidal field coils with a European consortium that brings together Iberdrola Ingeniería y Construcción SAU, ASG Superconductors SpA and Elytt Energy SL.
The signature of this EUR 156 million contract is a significant step for the ITER Project and an impressive technological milestone given the fact that winding packs of this size have never been manufactured before.
The heart of the ITER Tokamak is the toroidal field magnet system made up of 18 superconducting coils. Each coil is wound from cable-in-conduit (CICC) conductor, which consists of 900 niobium-tin-based superconducting strands (Nb3Sn) mixed with 522 pure copper strands and formed into a rope-like cable that is inserted into a circular stainless steel jacket. The conductors, cooled by a forced flow of critical helium, are designed to transport 68 kA in a peak field of 11.8 T.
In total, the toroidal field coils require 88 km of conductors whose in-kind procurement is shared among six Domestic Agencies—China, Europe, Japan, Korea, the Russian Federation and the US. Japan was the first Domestic Agency to sign a Procurement Arrangement with ITER Organization on 28 November 2007, for its 25-percent share of toroidal field conductor.
In March 2009, it was reported in Newsline that Japan had completed the production of its first batch of Nb3Sn-based superconducting strands; last April, it was reported that Japan had completed the manufacture of its first conductor unit lengths to be used for toroidal field coil trial winding.
On 20 June 2010, the ITER Organization approved a credit request submitted by the Japanese Domestic Agency for a total amount of 7.82 kIUA (ITER Units of Account), corresponding to EUR 12.14 million.
The credit request encompasses the order of 17 tonnes of Nb3Sn-based strands, 2.4 km of superconducting cables and one 760 metre-long copper dummy conductor. This material, produced by Japanese suppliers selected by the Japanese Domestic Agency, has successfully undergone all required quality control tests.
The results of these tests were inputted by the suppliers into the Conductor Database developed by the ITER Organization, and were verified and cleared at regular intervals by the Domestic Agency and ITER according to the control points defined in the Procurement Arrangement.
In total, the acceptance of this material required the clearance of 318 authorization-to-proceed points by the Japanese Domestic Agency (308 for strands and 10 for cables) and one conductor hold point by the ITER Organization.
This credit request is the first for actual hardware being produced within the framework of industrial contracts for ITER and that will be used for components installed in the Tokamak. It confirms the leading role played by Japan in ITER conductor production. It is also a good example of how tight collaboration between personnel at the ITER Organization and the Domestic Agencies can drive the project and lead to significant accomplishments.
A slight tremor was felt in Manosque on Thursday, 8 July, followed by another one last Wednesday—twenty days later. Could this be the sign of an impending earthquake? And if it is, what will be the consequences for the installations at CEA-Cadarache and ITER?
In the edition of the local daily newspaper La Provence of Friday 23 July, the best part of its front page and the totality of pages 2 and 3 were devoted to this subject. "Experts have no worry," read the large front page headline.
Michel Villeneuve, a specialist in geodynamics from the French National Scientific Research Center (CNRS), explained that "the more we'll have small earthquakes, the better." Tremors that reach a mere 2.3 to 3 on the Richter scale, he explained, enable the faults to dissipate their energy.
"I have no worry for Manosque," adds Villeneuve. Nor does the geophysicist worry for Cadarache "where the maximum risk is taken into consideration" in the design of the installations.
In another article, Lina Rodriguez, ITER head of the Safety Control Section, explained how the ITER Tokamak Complex will rest on about 600 seismic pads that will isolate it from ground motion in the case of an earthquake.
The article states in its conclusion that on the days Manosque felt the tremors, none of the 10,000 sensors installed on the Cadarache site registered the slightest movement.
On 8 July, the EURATOM-ENEA Association on Fusion
in Frascati near Rome, Italy, celebrated its 50th anniversary. Since 1960 the Italian Association, with more than 600 engineers, technicians and physicists, has made a valuable contribution to the fusion program both in physics and in technology in the field of superconductivity, plasma-facing components, remote maintenance and metrology, neutronics, heating and current drive, plasma control, fuel cycle and safety. In all these fields, the achievements were of utmost importance for ITER.
The Italian Association also played an important role in the European enterprises JET and NET. It is also very active in promoting industry participation in ITER procurement. During the very lively event, Giovanni Lelli (ENEA Chairman), Aldo Pizzuto (EURATOM-ENEA Association Director), Romano Toschi, (Italian Representative at CCFU), Francesco Romanelli (EFDA Leader), Maurizio Gasparotto (ITER Department Director, F4E), Maurizio Lontano (IFP-CNR Director), and Giorgio Rostagni (Consorzio RFX Leader) retraced the history of the EURATOM-ENEA Association and its main scientific and technological achievements. Particular attention was given to the contribution of the first ENEA Director, Prof. Bruno Brunelli, and the first European Fusion Program Director, Prof. Donato Palumbo.
Octavi Quintana Trias (EURATOM Director) attended the meeting and emphasized with words of appreciation the Italian Association's contribution to Fusion. Alessandro Giordani, Italian Consigliere dell'Ufficio Diplomatico della Presidenza del Consiglio dei Ministri, focused on the challenges of the coming years and he particularly underlined the importance of the ITER Project and the Italian participation, as well as the realization of the FAST project as a part of the EURATOM program.
More than 150 people gathered in Aula Bruno Brunelli. Among them, such distinguished guests as Carlos Varandas (Chairman of the F4E Government Board), Yvan Capouet (Head of Fusion Association Agreement, Euratom), Ambrogio Fasoli (CRPP Executive Director ); local authorities Stefano Di Tommaso (Mayor of Frascati) and the ENEA present and retired
staff members. Great emotion was reached when Prof. Bruno Brunelli was reminded in presence of Mrs. Maria Brunelli, his widow, and Dr. Giovanni Brunelli, his son, and when the significant contribution made by Arturo Tanga to our community was mentioned.
After the lunch and the cut of the anniversary cake by Yvan Capouet, Head of Fusion Association Agreement, Euratom, and Giovanni Lelli, ENEA Chairman, participants visited the fusion laboratories. A concert by "Il Quartetto di Spoleto" delighted the participants at the end of the ceremony.