Image shows the first piece of the tokamak being lowered. The reactor is expected to weigh 23,000 tonnes once the 5-year assembly phase is complete. (Image Credit: ITER)


On July 28th, engineers in southern France began the five-year assembly phase of the International Thermonuclear Experimental Reactor (ITER). This is the world’s largest fusion project, which is expected to operate in late 2025, generating 500MW of thermal fusion energy. Development was supposed to start in 1985, but it suffered through countless delays. The project, which has an estimated cost of $24 billion, is funded by the US, Russia, China, India, Japan, EU, and South Korea.


Scientists are building the fusion reactor to imitate the reactions that power the sun. It’s also designed to show that fusion power can be produced on a commercial scale. Scientists say that nuclear fusion has the potential to provide clean, unlimited power. Despite 60 years of research, it still needs to overcome the technical difficulties of harnessing huge amounts of energy.


Engineers are using millions of components to assemble the massive reactor, which is expected to weigh 23,000 tonnes. Around 3,000 tonnes of superconducting magnets are going to be connected by 200km of superconducting cables, all of which need to be cryo-cooled at -296C.


Nuclear fusion involves smashing hydrogen atoms together, forming helium and releasing huge amounts of energy. Temperatures must be at 150m C (10x hotter than the sun’s core) to fuse these atoms together. Hydrogen fuel is gathered from seawater, and it only requires a few grams. Massive magnets are also needed to hold the plasma in a torus-shaped vacuum chamber called a tokamak.


This project aims to be the first one to self-heat plasma, generating 10 times more heat than what is put in, which exceeds previous attempts. When the reactor is operating, it is expected to use up huge amounts of electrical energy to power the magnets and scientific instruments. It’s only intended to be a proof-of-concept of large-scale fusion.


One of the components being assembled is an Indian-manufactured 30-meter-diameter cryostat, which surrounds the reactor and keeps it at a very low temperature. A US-built electromagnet, known as the central solenoid, has enough magnetic power to raise an aircraft carrier.


Several private sector companies are also pursuing nuclear fusion from smaller devices. This includes companies like UK-based Tokamak Energy. Other companies such as Tri Alpha Energy harnesses particle accelerator technology. General Fusion, backed by Jeff Bezos and First Light Fusion, utilizes a vortex of molten lead and lithium to hold the plasma.    


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