At ITER site, work begins to ‘build the sun’ on Earth

Japan and Italy sent the first two toroidal field coils, each the size of a four-story building. India built the cryostat, which at 16,000 cubic meters is billed as the largest stainless steel vacuum chamber ever made; it’s designed to wrap around a nuclear fusion device at ITER in Saint-Paul-lès-Durance in southern France.

All told, there are one million components made of some 10 million parts that, when assembled, are destined to become an experimental “tokamok.” The tokamok is a device meant to replicate the fusion process of the sun’s own energy, and scientists have contemplated for decades how this success in nuclear fusion might one day deliver clean, reliable energy without carbon emissions.

There are now 35 countries engaged in the ITER project, and the newly arrived parts have been fabricated in factories, universities and national laboratories all over the world. Scientists at ITER say it will take 4.5 years to build the tokamok before they can begin experiments.

“Constructing the machine piece by piece will be like assembling a 3-dimensional puzzle on an intricate timeline,” says Dr. Bernard Bigot, director general for ITER. “Every aspect of project management, systems engineering, risk management, and logistics of the machine assembly must perform together with the precision of a Swiss watch. We have a complicated script to follow over the next few years.”

The plant at ITER is expected to produce about 500 megawatts of thermal power, enough to generate electricity for about 200,000 homes. It runs on a fuel found in seawater and lithium, with scientists saying that a pineapple-sized amount of fuel is the equivalent of 10,000 tons of coal.

When a few grams of deuterium and tritium gas are injected into the tokamok, the hydrogen is heated into ionized plasma. The plasma cloud is shaped and controlled by tons of superconducting magnets, with fusion occurring when temperatures reach 150 million degrees Celsius. As neutrons escape from the magnets they transmit energy as heat, while water in the tokamok walls converts the heat to steam used to power turbines.

“A commercial fusion plant will be designed with a slightly larger plasma chamber, for 10-15 times more electrical power. A 2,000 megawatt fusion power plant, for example, would supply electricity for 2 million homes,” adds ITER. The cost of building and operating a fusion plant is expected to be similar to the cost of a nuclear fission plant, but without the large costs and long-term legacy of waste disposal.

“Unlike fission, there is no possibility of a meltdown,” says ITER spokesman Laban Coblentz. “If the reaction stops, everything just stops and that’s it.”

Now that tokamok assembly has begun, ITER has launched a website to make the process publicly accessible and visible. Check the link here to learn more about how the tokamok is being built.