Magnetic Attraction

An Abnormal Load for an Ambitious Plan

By Amy McLellan

The world’s growing population needs more energy, but it can’t afford to keep burning carbon if it is to avoid potentially catastrophic climate change. In a bid to produce more with less carbon, countries around the world are setting ambitious targets to decarbonize their economies and investing heavily in renewable energies and nuclear power.

Yet intermittency remains an issue for renewables, while nuclear energy faces a number of challenges, including high cost, public opposition and ongoing concerns about long-life radioactive waste management.
Enter fusion: the nuclear reaction that powers the Sun and the stars and is a potential source of safe, non-carbon-emitting and virtually limitless energy. It sounds like the stuff of science fiction, but in the south of France an international team is busy building an experimental fusion device – known as ITER – that could bridge the gap between today’s fusion research machines and tomorrow’s commercial-scale fusion power plants.

ITER is a collaboration between China, the European Union, India, Japan, Korea, Russia and the U.S., with the manufacturing of components spread across factories spanning three continents. Europe is responsible for the largest portion of construction costs (45.6 percent), with the remainder shared equally by China, India, Japan, Korea, Russia and the U.S. There’s little monetary contribution, however; instead 90 percent of contributions are in the form of completed components, systems or buildings.

Construction of the buildings on a 180-hectare site in Saint Paul-lez-Durance, Cadarache, southern France started in 2010. Since then, key contractors have been busy, with specialist factories around the world finishing key components ready for major assembly that will kick off next year. As of June 2019, this hugely ambitious project was 63 percent complete and on track for “First Plasma” in December 2025.

Pan-industry Project

This is a huge logistical exercise, coordinating parallel construction projects and the transportation of vital scientific equipment from across the globe to ensure the efficient integration and assembly of more than 1 million components.

In all, there will be 39 buildings and technical areas, with the ITER “Tokamak” device itself comprising a seven-story structure in reinforced concrete. Other key structures will be cooling towers, electrical installations, a control room, facilities for the management of waste, and the cryogenics plant that will provide liquid helium to cool the ITER magnets, which are the basis of fusion reactions.

The Tokamak – a Russian acronym that means “toroidal chamber with magnetic coils” – will weigh 23,000 tonnes, equivalent to the weight of three Eiffel Towers, making it the largest and most powerful fusion machine ever built.

Inside its vacuum vessel, hydrogen isotopes will be heated to temperatures in excess of 150 million degrees Centigrade – 10 times as hot as the sun’s core – to form 830 cubic meters of hot plasma. Magnetic fields created by an array of giant superconducting coils and a strong electrical current will act as a powerful magnetic cage to shape and confine the superhot plasma so that it floats within the magnetic field without touching the walls of the ITER vacuum vessel.

This superhot plasma will generate fusion reactions that will release 4 million times more energy than the burning of oil or gas. Inside a Tokamak, the energy produced through the fusion of atoms is absorbed as heat in the walls of the vessel. Should the ITER experiments prove successful, then in the future this heat would be used to produce steam and then electricity by way of turbines and generators.

Moving the Magnets

The 18 huge toroidal field coils that are being manufactured in Japan and Europe are already beginning their journeys towards ITER. On the European side, Italy’s ASG Superconductors was charged with building 10 of the coils at a dedicated 28,000-square-kilometer facility at La Spezia, a job that involves high precision design and manufacturing involving robotized and computerized machining.

The coil contains high performance, internally cooled superconductive cables, which can carry higher current and produce a stronger magnetic field than their conventional counterparts. The ITER coils involve 100,000 kilometers of niobium-tin, or Nb3Sn, superconducting strands, which have taken five years to produce at a rate of about 150 tonnes per year, a 10-fold increase in worldwide production. Stretched end to end, the Nb3Sn strand produced for ITER would wrap around the Earth at the equator twice. These bundled superconducting strands — mixed with copper — are cabled together and contained in a structural steel jacket. The resulting coil winding packs are huge – each one weighs 120 tonnes and measures 9 meters by 16 meters – but at this stage they are not yet a magnet.

The transformation from coil to magnet will take place at the SIMIC facility on the opposite side of Italy, just outside Venice. Here the coil winding pack will undergo cryogenic tests before being inserted into the coil cases, which have been manufactured by Japan’s Mitsubishi Heavy Industries and Korea’s Hyundai Heavy Industries, and will act as a very heavy “overcoat” to protect the magnets.

For insertion, the winding pack is lifted and positioned on an assembly rig, then a one-of-a-kind automated tool will embrace the massive coil from left and right, and from top to bottom, in an operation that lasts roughly one month. What makes insertion such a delicate process is the size and weight of the component plus the extreme precision required.

As a member of the magnets team for Fusion for Energy, the EU organization managing Europe’s contribution to ITER, puts it, the team is working with accuracies of just 0.2 millimeter on a structure that weighs in at more than 300 tonnes. After insertion, there then begins four to six months of welding – both manual and using robots – followed by the injection of resin and machining of the magnet.

Taking the Scenic Route

Getting the coil winding pack from La Spezia to SIMIC’s facility on the other side of Italy is a huge project in itself. This is ordinarily a 350-kilometer road journey that would take 3.5 hours by car, but which is out of the question for this heavy, precious load. Instead the coils need to be transported by ship around the boot of Italy to reach Port of Marghera, a five-day transit.

“The load is too big for the road, so ASG built the factory as close as possible to the port at La Spezia to minimize the time on the road,” said Alessandro Bonito-Oliva, Fusion for Energy’s program manager for magnets.

Stefano Pittaluga, Magnets & Systems Unit at ASG Superconductors, added: “It is only a 2 kilometer journey from the workshop to the harbor, but we travel very slowly, at a maximum of 0.5 kilometers per hour, so it takes all night.”

The reason for the cautious speed is that the high-performance superconducting properties of the coil are highly sensitive to deformation, making it vital that it is handled with care to adhere to strict tolerances for vibration and acceleration. A special-purpose lifting tool was used to prevent deformation, Pittaluga explained.

Special permits had to be arranged with the local authorities and the port authority, a bridge had to be strengthened to handle the heavy load and it all took place at night to minimize disruption to local communities.
The coils are also sensitive to humidity and corrosion, the risks of which are heightened given the sea journey that lies ahead. Before the journey, the coils were packed in a special watertight cylinder and sealed with dry nitrogen to ensure no external atmospheric agents could enter.

High Pressure

Among those handling this precious cargo is Master Projects, a Tarros Group Co., which deployed 20 workers, two self-propelled modular trailers, support vehicles and two mobile cranes to handle the heavy load, which, once packed for traveling, weighed in at more than 200 tonnes. The team worked through the night and into the following morning to complete the load out of the magnets at Tarros’ Terminal del Golfo facility. Paolo Pellegrini, CEO of Master Projects, said these oversize superconductors require “technical skills and top-grade specialization that are not so common in the project cargo sector.”

This was a high-pressure job. “It is so important to do this right,” said Fusion for Energy’s Bonito-Oliva. “It has taken three to four years to get to this point, and if we had to produce a new one it would knock out timings for everything, which would be very expensive.”

On arrival at Port of Marghera just outside Venice, the whole process was reversed, although the SIMIC premises are very close to the harbor reducing the road portion of the journey, Pittaluga said.

He admits it was a stressful time. “I did not sleep well the night before, but it did go according to plan; there were no real problems,” he said. “We’ve never done anything on this scale, it’s a really huge coil. I’m not a logistics manager, I’m a physicist, so this was a new experience for me.”

After the work at Venice, the coils will become a magnet and then be specially packed ready for their long journey by sea to Marseille, from where they will be loaded on a special convoy truck for delivery to the ITER facility, a route that has been planned and prepped to every last detail to ensure everything goes smoothly, as the multiple components from across the globe arrive ready for assembly.

With more of the critical path magnets to deliver in the coming months, Stefano Pittaluga and his team can look forward to more sleepless nights as part of one of the most complex and most ambitious science projects anywhere on the planet.  

Freelance journalist Amy McLellan has been reporting on the highs and lows of the upstream oil and gas and maritime industries for 20 years.

Image credit: ITER