1,000th milestone in magnets
Worlds away from the quiet ITER platform in Cadarache, manufacturing for the ITER Project has begun. Production of superconducting strand for ITER's toroidal field coils is underway, led by Japan, Korea and the Russian Federation.
Strand production is the first step in a complex fabrication process for ITER's "cable-in-conduit" conductors: strand is twisted into cables; cables are inserted into steel jackets; final conductors undergo testing and coiling. Last week, strand manufacturing for ITER reached an important milestone: billet #1,000 was entered into the ITER Conductor Database, which has been used since February 2009 to track and monitor production.
Made up of a very precise combination of elements (niobium, tin, copper, bronze ...), billets contain all the raw materials for the superconducting strand in precursor form. These precursors are then "drawn down" into lengths of one kilometre or greater to be used inside ITER's superconducting cables.
"This 1,000th billet represents approximately 60 tonnes of material," says Arnaud Devred, Section Leader for ITER's superconducting magnets. "That's enough superconducting strand for three of the eighteen toroidal field coils. In the end, we expect to have 8,000 to 10,000 superconducting billets registered in our Conductor Database."
Six Domestic Agencies will be involved in the procurement of ITER's conductors, contracting with two to four suppliers each. The ITER Conductor Database will centralize data from all suppliers related to strand/cable/jacket/conductor production—from raw materials and process information, to the many test results required for quality control. Only strands that are approved in the database by the relevant Domestic Agency can be sent on for cabling; similarly only approved cable lengths can be used for jacketing.
"The database will allow us to track the properties of every conductor length used in our magnets, right down to the level of the individual strands," says Matt Jewell, ITER-Monaco Fellow in the Magnets Division, and closely involved with the Conductor Database. "Given the complexity of the ITER conductor fabrication process, a tool like this was absolutely essential."
All ITER conductors—no matter the supplier—must strictly match the performance characteristics set out in the Procurement Arrangements. The Conductor Database will allow the management of thousands of control points built into the procurement process to check quality along the way. "The Domestic Agencies will split conductor procurement between suppliers, but will retain sole responsibility for organization and process," explains Arnaud. "We've provided the Domestic Agencies with a tool for tracking production data and quality control—it's a good example of how the ITER Organization can play a coordination role."
Day-to-day development of the Conductor Database falls to Gregory Bevillard, who came to ITER after six years spent at CERN where, in particular, he developed the first database of this kind for the LHC project. Through close collaboration with the Magnets Division, ITER IT, CERN and the Domestic Agencies, the last module of the Database went online last week. "The challenge at ITER has been to develop a tool flexible enough to be used by a large number of suppliers," says Gregory. "After one-and-a-half years of development, the tool is now complete. We're continuing to train users at the Domestic Agencies and the suppliers, and working on the development of statistical tools for analysis of the conductor data."
The Conductor Database will track production data through the final acceptance tests for the conductors. A similar database for the next phase in the process—coil fabrication—is currently under discussion.
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