World's largest nuclear fusion reactor ITER begins assembly phase

Le réacteur à fusion nucléaire ITER © 2020 ITER

Le réacteur à fusion nucléaire ITER © 2020 ITER

The world's largest nuclear fusion reactor ITER is now being assembled in the South of France. This major international scientific project is followed up at the EPFL Swiss Plasma Center, one of the world’s top research labs on nuclear fusion.

The assembly phase of ITER, the world’s largest nuclear fusion reactor - a 30 x 30 m machine called a tokamak – kicked off on July 28 th 2020 in Cadarache, in the South of France. Ceremony attendees included dignitaries of the 35 countries that are taking part in this international research project: European countries including Switzerland, China, India, Japan, Russia, South Korea and the United States. ITER aims at harnessing nuclear fusion, a potential source of clean energy without carbon emissions or long-lived radioactive waste. This “scientific and technological achievement”, relies on the idea that “thanks to science, tomorrow might be better than yesterday”, French President Emmanuel Macron said in a video message. 

Clean energy without long-term radioactivity

Unlike fission that takes place in current nuclear power plants, fusion does not release long- lived radioactive waste. The reaction is obtained by heating hydrogen atoms to about 150 million degrees, ten times the temperature of the Sun. In the super-hot plasma, the hydrogen nuclei fuse together and form - non-radioactive - helium. By doing so, they release vast amounts of energy. The main current scientific challenges consist in maintaining a very high temperature for more than a few seconds, as well as optimising the plasma confinement. In ITER, researchers will test the feasibility of nuclear fusion in a much larger reactor than the machines they currently use. The goal is for the plasma to produce more power than is injected into it.

In Cadarache, Bernard Bigot, director general of ITER, guided journalists and scientists throughout the site. The visit was open to a global audience online. During the press conference, Bernard Bigot highlighted some of the scientific challenges and called for patience. The assembly of ITER’s millions of components will take at least five years, with the first plasmas tests scheduled in 2025. Then the last pieces will be installed for the machine to run at full power in 2035. 

EPFL Swiss Plasma Center at the forefront

The assembly of ITER is an exciting moment for scientists at the Swiss Plasma Center (SPC), at EPFL, too. As one of the main nuclear fusion research laboratories in the world, SPC analyses plasma behaviour, and the best ways of heating and confining it. It is engaged in a scientific exchange with ITER on a regular basis. The SPC also directly works on designing the microwave heating system for ITER. 

The promise of providing clean, almost unlimited energy for future generations is a career driver, and also a dream for many researchers at the Swiss Plasma Center and their colleagues around the world. “We came to fusion hoping to see its large-scale development during our lifetime, so it is a bit of an ideal”, said Yves Martin, physicist and deputy Director at the Swiss Plasma Center. To say the least, SPC will follow up closely on ITER.