The clock is ticking for one of the most delicate steps in the fabrication process of the
ITER Toroidal Field (TF) coils. “Operation Insertion” may sound like a classified
mission to be carried out by experts in a remote location. The stakes are high and
there is no room for improvisation. If you didn’t know any better you would think this is
the teaser for an action blockbuster. Reality, however, often surpasses fiction and can
be even more fascinating. A few kilometres from Venice (Italy), at the port of
Marghera, where SIMIC has one of its facilities, Europe’s first Toroidal Field coil has
been inserted in its case. The massive winding pack, the inner-core of the magnet with
all its equipment, measuring 14 x 9 m, weighing 110 t, is now wearing its heavy
stainless steel panoply of approximately 150 t. The TF coil cases, under the
responsibility of ITER Japan, have been produced by Mitsubishi Heavy Industries
(Japan), and Hyundai Heavy Industries (Korea). They measure no less than 17 x 10 m
and almost like an “overcoat” they will protect the magnets whose mission is to confine
the super-hot plasma when ITER is up and running.
How did we reach this important technical milestone? Once a winding pack has gone
the cryogenic tests it gets wrapped with Tedlar® tape. In parallel, the coil cases go
through a series of checks together with the tooling that will be used in insertion.
When technicians give the green light, the winding pack is lifted and positioned on the
assembly rig. Pads are placed on the ground reflecting the D-shape geometry of the
winding pack to rely upon them. With the help of the insertion tooling, the cases
embrace the massive coil from left and right, and from top to bottom. Operation
insertion lasts roughly one month.
From the moment the component is tucked in its coil case it will be officially considered
a TF coil. “What makes insertion such a delicate process is the size and weight of the
component –roughly 300 t with its cases— plus the extreme precision required. We
are working with accuracies of 0.2 mm” says Boris Bellesia, following closely this
contract on behalf of F4E’s Magnets team.
After the massive magnet is inserted into its coil case it’s time to start welding.
Normally, it will take between four to six months to complete the welding procedure
which initially will be conducted manually and afterwards automatically with two
synchronised robots (narrow gap TIG welding). Then, for nearly two weeks, resin will
be injected to fill the gap and to create a mechanical continuity between the cases and
the winding pack. After this step is concluded, it’s time to procced with the machining
of the magnet which is expected to last approximately four months. The magnet will
then have to go through another round of final tests and get wrapped to be transported
“We have entered the final production stage of the TF coils and it is the first time that
we are performing these manufacturing steps. We have reached this point thanks to
the excellent technical work and perseverance demonstrated by the different industrial
partners who have contributed to the previous manufacturing phases, and thanks to
the good collaboration with ITER Organization and ITER Japan. We look forward to
this new exciting manufacturing stage during which we will use, just like in the past,
our problem-solving skills and our technical expertise,” explains Alessandro BonitoOliva, F4E Project Team Manager for Magnets.
Paolo Barbero, SIMIC Project Manager, following this operation in collaboration with
F4E, confirms that the insertion of the first winding pack into the TF coil cases has
been completed. “Here at SIMIC, it gives us great satisfaction to have reached one of
the most important milestones in the TF coil manufacturing process. This operation is
technically very challenging, mainly due to the huge size of the parts and the very tight
tolerances which need to be achieved. The assembly rig, a special machine designed
and manufactured specifically for this purpose, is an extremely complicated automatic
gigantic tool, considered as one-of-a-kind. We are impressed by the fact that it has
worked remarkably well since the very beginning. We are very satisfied with the high
level of precision obtained and this will pave the way for the next manufacturing steps
such as the robotized narrow gap TIG welding, where we aim to get top quality results.
We would like to thank all teams which spent the last years trying to make this