The ITER group, in a ceremony on 28 July marked the start of the machine assembly of the international experimental tokamak nuclear fusion reactor under construction at Cadarache in France.
ITER construction is funded mainly by the European Union (45.6%) with the remainder shared equally by China, India, Japan, Korea, Russia and the USA (9.1% each). However, in practice, the members deliver little monetary contribution to the project, instead providing ‘in-kind’ contributions of components, systems or buildings.
The project has faced budget overruns and delays with partner countries trying to coordinate financing and cooperation on technical issues. Project Director Bernard Bigot, said the estimated budget for the European Union is about €20 billion ($23.5 billion).
The ITER project was launched in 2006. Its original timeline called for a test of its first super-heated plasma by 2020, with full fusion by 2023 but this has been revised several times. Bigot said he now expects first plasma in December 2025, which should prove the reactor concept works, and full power by 2035. However, he acknowledged the challenges in meeting that schedule.
“Constructing the machine piece by piece will be like assembling a three-dimensional puzzle on an intricate timeline,” he said. “We have a complicated script to follow over the next few years.” He noted that the coronavirus pandemic had impacted the initial schedule
French President Emmanuel Macron and leaders from the European Union, China, India, Japan, Korea, Russia, and the USA attended the ceremony. President Macron said: "ITER is clearly an act of confidence in the future. The greatest advances in history have always proceeded from daring bets, from journeys fraught with difficulty. At the start it always seems that the obstacles will be greater than the will to create and progress. ITER belongs to this spirit of discovery, of ambition, with the idea that, thanks to science, tomorrow may indeed be better than yesterday."
“I heartily congratulate the ITER Project,” said Japanese Prime Minister Shinzo Abe. “I believe disruptive innovation will play a key role in addressing global issues including climate change and realizing a sustainable carbon-free society.”
Alexei Likhachev Director General of Russian state nuclear corporation Rosatom, said that the start of assembly was a major event for the entire fusion community and for all of science. “It is important to note that despite the restrictions caused by the coronavirus epidemic the assembly and installation works start as scheduled,” he said. “The main task for all of us now is to ensure timely completion of the installation and assembly and to obtain the first plasma by the end of 2025. This will allow us to demonstrate in practice the concerted action on the part of all the project participants and the resultant effectiveness of our international cooperation.”
In recent months, in preparation for the machine assembly, huge first-of-a-kind components have been arriving in France - the culmination of more than five years of manufacture in factories, universities and national laboratories worldwide.
These include the Cryostat, manufactured by India, which surrounds the Tokamak Vacuum Vessel and superconducting magnets which confine the super hot plasma. At 30 metres high and 30 metres in diameter, it is the largest stainless steel vacuum chamber ever built.
The 1250t Cryosat base section is the heaviest ITER component. It was the first major piece to be inserted into the Tokamak Pit, in May and was settled into position with an accuracy of less than 3 millimeters.
ITER uses three types of superconducting magnets to contain the plasma. The 18 Toroidal Field (TF) Coils were manufactured by Japan and Europe with components coming from China, Korea and Russia involving more than 40 companies. These confine the ionised plasma particles. Each magnet is the height of a four-story building and weighs 360 tons.
The six Poloidal Field (PF) Coils were manufactured by China, Europe and Russia. These ring-shaped magnets will be situated outside the TF coil system. The PF coils shape the plasma and hold it away from the walls. These range in diameter from 10 to 24 metres and weigh up to 400t.
The Central Solenoid Module, manufactured by the USA, is the most powerful of magnet and will initiate a powerful current in the plasma in long pulses. Its six modules, when combined will weigh 1000t. It will have the magnetic power to lift an aircraft carrier.
The Vacuum Vessel was manufactured by Korea (four sectors) and Europe (five) sectors, with the protruding port stubs supplied by Russia. It is a hermetically sealed, donut-shaped stainless steel chamber within which the plasma particles spiral around continuously without touching the walls.
Buildings and civil works across the ITER worksite, constructed by Europe, are about 75% complete.
Assembling ITER is the responsibility of the central ITER Organisation and includes assembly of the Tokamak as well as parallel installation of support systems such as radio frequency heating, fuel cycle, cryogenics, cooling water, vacuum, control, and high voltage electrical systems. This will take place in the Tokamak Building, where the ITER device will be installed in a partially embedded concrete bioshield. More than 150 specialised tools, some weighing up to 800t, will be used in the assembly, which is expected to take 4.5 years.
“Today is an historic moment," said Bigot, adding that ITER is the first-of-a-kind machine made up of many first-of-a-kind components and breakthrough inventions. “To build this machine - a star on Earth - requires a level of international collaboration that is also first-of-a-kind." He added, "Building a fusion power plant isn't easy. We are moving forward as rapidly as possible, but in order to succeed we must also be deliberate. Quality and safety are always to be first. If we succeed, it will be worth all the time and effort that has brought us to this point.”
Photo: On 28 July in the ITER Assembly Hall, a virtual ceremony was opened by French President Emmanuel Macron marking the start of assembly Photo credit: ITER Organization