N. Valle

Fabrication of the first European full-size joint sample for ITER

The European Home Team is responsible for the design, the fabrication and the test of the Toroidal Field Model Coil (TFMC) of the ITER project. Within this task, three full-size samples have to be fabricated in industry and tested. Each sample is made of two parallel straight bars of full-size conductor, connected at the bottom through a joint designed according to the EU proposal for the ITER coils, and having at the top, two connections for the test facility. The first sample uses an ITER type Nb/sub 3/Sn cable-in-conduit embedded in a thick steel square jacket, the lower joint being similar to the inner joints of the TFMC. The second sample uses the TFMC conductor which is an ITER type Nb/sub 3/Sn cable-in-conduit embedded in a thin steel circular jacket, the lower joint being similar to the outer joints of the TFMC. Last, the third sample will use the same cable embedded in a thin incoloy jacket, fully relevant to the ITER TF coils. This paper reports on the fabrication by Ansaldo of the first sample, emphasizing the differences between the original design and the final design produced after preliminary trials, as well as pointing out the main technical issues.

Completion of the ITER Toroidal Field Model Coil

In the scope of the ITER EDA a Toroidal Field Model Coil (TFMC) has been manufactured accompanied by a thorough Quality Assurance (QA) test program. This large superconducting coil has been conceptually designed by the ITER European Home Team (EUHT) and manufactured by European industry. The coil is being completed and will be tested at the Forschungszentrum Karlsruhe in spring 2001. The race track shaped winding is made of a cable-in-conduit conductor in a circular 316LN stainless steel jacket. From this conductor five double pancake (DP) modules were fabricated. Results of conductor and DP manufacture were already presented at previous conferences and are therefore only summarized here. The paper concentrates on the subsequent manufacturing steps, namely the stacking of the DP modules, the insulation and impregnation of the winding pack, the outer joint manufacture by electron beam welding, the assembly of the winding pack with the stainless steel case, the mounting of the helium pipes, the sensors and the busbars. To assemble the coil into the TOSKA facility and to fit it to the EU-LCT coil a heavy Inter-Coil Structure (ICS) has been built, in which the TFMC will rest on four wedges.

Progress in the F4E Procurement of the EU ITER TF Coils

The ITER magnetic system includes 18 Toroidal Field (TF) Coils constructed using Nb3Sn cable-in-conduit superconductor. Each TF coil comprises a Winding Pack (WP) composed of 7 Double Pancake (DP) modules stacked together, impregnated and inserted into a stainless steel coil case. Fusion for Energy [the European Domestic Agency (DA)] is responsible for the procurement of the ten while the Japanese DA is responsible for remaining nine coils. The conductors are being produced by 6 different DAs, while the coil cases only by the Japanese DA. F4E has implemented a procurement strategy aimed to minimize costs and risks, consisting of subdividing the procurement into three main procurement packages, each foreseeing first an R&D and qualification phase. One procurement package is related to the construction of 72 radial plates (RP), another to the fabrication of the ten WP, and a third to the cold test and coil-case insertion of ten WP. In collaboration with industry, F4E has successfully produced two RP prototypes. Regarding the DP, the construction of the first DP prototype has started. In this paper, we will report on the results achieved so far and the status of each of the procurement packages.

Manufacture and preliminary tests of a 12 T "wind and react" coil

As already reported ENEA is engaged in the realization of a 12 T wind and react Nb/sub 3/Sn coil, a subsize magnet designed to simulate many technological problems to be faced in NET-ITER magnets. EM-LMI and Ansaldo are the industrial partners in this project. A preliminary winding has been built and successfully tested. This winding has been cut in pieces and carefully inspected to be sure that the impregnation process after the heat treatment works well. No particular flaws have been detected. Then manufacturing of the 12 T magnet has been started and completed in about three months. Heat treatment, impregnation and electrical tests at 300 K have been successfully performed and the magnet is now ready for final tests. In order to obtain the most significant scientific and technological informations from this magnet, the original test programme (insertion of the coil in the SULTAN facility) has been modified according to a decision of the Fusion Technology Steering Committee (FTSC) of EURATOM. Details of the new test programme are given in the paper. >

Zeus Magnets Construction Status Report

The construction progress status of the superconducting magnets for the ZEUS detector, commissioned by INFN Frascati and to be installed in the HERA e- p+ring (DESY, Hamburg), is reported. The first one is a double layer, two densities, aluminum stabilized coil 1849 mm in inner dia., 2487 mm in length and 32.6 mm thick, with a central field of 1.8 T and high particle transparency. The second one is a compensating magnet, wound by a copper stabilized Nb-Ti cable. Its coil has a central field of 5 T, inner dia. 370 mm, a length of 1200 mm and is inserted into a cold iron yoke. The main problems encountered during the large coil construction and the geometrical accuracy obtained are reported. Four splices among the high purity aluminum stabilized cable length were made. An outer support cylinder, 18 mm thick, was shrink fitted around the coil and then the temporary inner mandrel was removed. The distribution of mechanical stresses was measured in the different configurations. A large aluminum alloy vacuum chamber with high radiation transparency was built. The compensating coil is ready to be installed inside its stainless steel cryostat. The cryostat critical features are the high design pressure (20 bar) and the heavy cold mass.

EU conductor development for ITER CS and TF Model Coils

A significant effort is underway in the European Union for the manufacture of superconducting conductors for ITER TF and CS Model Coils. For the CSMC the EU will contribute about 6.5t of bronze Nb/sub 3/Sn strand, 1200 m of full size cable and the jacketing of the entire conductor length, 5787 m. The TFMC conductor, on the other hand, will be entirely manufactured within EU: 4t of internal tin Nb/sub 3/Sn strand, cabling and jacketing of 1 km of TF conductor. This paper deals with the present status of the industrial activities. The achievements and lessons learned from the various manufacturing processes are presented.

Progress in Europe of the Procurement of the EU ITER TF Coils

The ITER magnetic system includes 18 toroidal field (TF) coils constructed using a Nb3Sn cable-in-conduit superconductor. Each TF coil comprises a winding pack (WP) composed of seven double pancake (DP) modules stacked together, impregnated, and inserted into a stainless steel coil case. Ten TF coils are being produced in Europe, under the responsibility of Fusion for Energy (F4E) (the European Domestic Agency), whereas the remaining nine TF coils are being produced in Japan. F4E has implemented a procurement strategy aimed to minimize costs and risks by subdividing the procurement into three main packages, each foreseeing first an R&D and a qualification phase. One procurement package is related to the construction of 72 radial plates (RP), another to the fabrication of the ten WPs, and a third to the cold test and coil-case insertion of ten WPs. All industrial contracts have now been signed and are running. The situation as of September 2015 is as follows: 2 RP prototypes and 32 production RPs (enough for four TF coils) have been successfully (enough for four TF coils) produced and delivered to the winding pack supplier. A full-size superconducting DP prototype has been successfully fabricated and subjected to a thermal cycle at 80 K. So far, 33 DPs have been wound, 27 DPs have been heat treated, and 26 DPs have been successfully transferred into the RP grooves. The cover plate welding has been successfully completed on 18 DPs. Regarding the insertion contract, an alternative way to insert the WP inside the coil case has been devised, and the corresponding transfer tooling is being procured. The qualification for the most important manufacturing processes is underway.

Development and tests of electrical joints and terminations for CICC Nb/sub 3/Sn 12 Tesla solenoid

Ansaldo Componenti, under a contract with ENEA, has developed the interlayer electrical points and coil terminations for a 12-T solenoid, 0.6-m bore, Nb/sub 3/Sn, wound with the wind and react technique with a cable-in-conduit (CIC) conductor. Both the interlayer joints and terminations under the coils operating conditions, will be subjected to a magnetic field of about 8-10 T with a 6-kA current. Tests on shorter length interlayer joints and terminations, at different magnetic fields and currents, were carried out. The resistance of a 140-mm-long interlayer joint at magnetic field B=8 T and I=6 kA was 2.4*10-9 Omega . The measured resistance for a joint between two terminations, under the same conditions, was 1.5*10-8 Omega .<<ETX>>

Manufacture, assembly and QA of the ITER toroidal field Model Coil

The conceptual design of the ITER TF Model Coil (TFMC) was produced by the European Home Team based on the ITER TF coil design. The test configuration in the TOSKA facility of FZK comprises the TFMC coupled with the existing European LCT coil by an intercoil structure (ICS). The elements of the TFMC are being constructed by European industry under the supervision of ITER European Home Team and are currently nearing completion. The primary objectives of the TFMC program are to gain experience of all aspects of the coil manufacturing process (including QA methods) and to establish realistic manufacturing tolerances for the actual ITER TF coils. At the current state of the project many of these objectives have already been achieved. The various technical problems encountered during engineering design and manufacture have been solved and have produced very useful information which can be applied in the ITER procurement documents for the TF coil system. This paper presents a description of the manufacturing process and related QA procedures.

Risks and benefits of Incoloy 908

Abstract The central solenoid and toroidal field coils of ITER are designed with cable-in-conduit Nb 3 Sn superconducting conductors jacketed with Incoloy 908. This material, developed to limit the critical current degradation of the Nb 3 Sn strands, shows excellent mechanical properties at 4 K, particularly under cycling. Nevertheless, it is a crack prone material when heat treated in the presence of oxygen, which requires careful control of the atmosphere during manufacture. A programme of extensive mechanical testing of samples and manufacture of a pancake with incoloy conductor jacket was carried out in Europe. The origin of cracks in the incoloy jacket after heat treatment was investigated.