Fri. Mar 31st, 2023
Take a look at ITER, EUROfusion's clear favorite child.  Foreground buildings: contractors canteen, changing rooms, showers, etc. ||  Green, yellow and red buildings: contractors' offices ||  White building: canteen and infirmary for contractors ||  High Building: Assembly Hall ||  To the right of the Assembly Hall and behind the other buildings: Cryostat Assembly Site.

Take a look at ITER, EUROfusion’s clear favorite child. Foreground buildings: contractors canteen, changing rooms, showers, etc. || Green, yellow and red buildings: contractors’ offices || White building: canteen and infirmary for contractors || High Building: Assembly Hall || To the right of the Assembly Hall and behind the other buildings: Cryostat Assembly Site.

Dave Loschiavo

ST. PAUL-lez DURANCE, France – Rolling hills and oak forests dominate rural southern France. About 22 miles north of Aix-en-Provence, however, nature has given way to a team of 1,000 construction workers working around the clock to build the largest physics experiment ever discussed by Sheldon, Leonard, Raj and Howard.

This experimental Tokamak fusion reactor, known as ITER, is intended to be the final necessary step to prove the scientific and technological feasibility of fusion as a commercial energy source. It is a joint effort between China, the European Union (via Euratom), India, Japan, Korea, Russia, Switzerland (also via Euratom) and the United States. In total it will cover 35 countries.

The magnitude of this project, in so many dimensions, is nothing short of awe-inspiring and humbling. Physically, the main buildings used to assemble and house the Tokamak reactor are 200 feet (60 m) tall and are located on a 40-hectare (~100 acres) flat site. The total site, including open space and office buildings, measures 180 hectares. Logistically, as a construction project, the ITER team keeps track of more than 200,000 actions required to bring the effort to a successful conclusion.

The chronology of the project is equally great. It began with talks between Secretary General Gorbachev and President Ronald Reagan in 1985, and ITER is scheduled to run until 2046 – representing more than 60 years of effort.

Yet none of these metrics will measure ITER’s weight on the scale of human performance. The project’s potential impact on humanity is immeasurable. In short, fusion could be a much safer and cleaner method of generating energy than current methods using fission and fossil fuels.

Contains a plasma

The Tokamak fusion reactor, which the ITER team calls ‘the machine’, will use deuterium and tritium (two hydrogen isotopes) as fuel. Under extreme heat, the hydrogen isotopes fuse to helium, releasing high-energy neutrons. When operational, ITER’s Tokamak reactor will contain 10 times more plasma than current reactors. The knowledge gained from plant operation, materials and control experiments and study of plasma will pave the way for the commercial production of fusion power.

Within the Tokamak, superconducting electromagnets will create fields that contain and control the plasma. The coils are composed of niobium-titanium (Nb-Ti) and niobium-tin (Nb3Sn) and cooled by supercritical helium at four Kelvin. The toroidal field created by the coils gives the particles in the plasma a spiral path through the machine, aiding in confinement. The coils also create a poloidal field that prevents the plasma ring from expanding and keeps it in the desired shape. The central solenoid in the center of the machine drives the plasma stream.

The magnets create fields in the 12 to 13 Tesla (T) range — for comparison, the Large Hadron Collider (LHC) magnets produce about 8T. ITER’s magnets can also store more than 50 Gigajoules (GJ) of energy, while the magnets in the LHC are limited to about 12 GJ. In certain parts of the magnets, a one-meter coil can take more than 50 tons (112,000 lbs) of force to push it. At the central solenoid, the inward pushing forces can reach 40,000 to 50,000 tons. Because the forces generated by the magnets are greater than the mass of the structure housing the machine, they could theoretically lift the entire building.

Sustainable fusion

In addition to functioning as a platform for plasma experimentation, the machine offers the opportunity to test ways to use fusion to produce additional tritium fuel. It will house various configurations of tritium breeding blankets, a critical technology for large-scale fusion power production.

The neutrons released in fusion reactions can produce tritium when they interact with lithium (high energy neutrons react with the lithium atoms and produce tritium and helium). Tritium has a short half-life; it is also rare and expensive. That combination makes it a limiting material for fusion. By placing a “blanket” of lithium around the reactor, fusion itself can help us overcome this limit. During its functional life, ITER will use tritium already in the global supply, but it will produce critical data needed for tritium breeding blankets.

Ultimately, the Tokamak reactor is expected to produce 500 MW of fusion power and consume 50 MW to heat the hydrogen. Because the primary purpose of the reactor is to learn about the properties of plasma, the means to control plasma, and the production of tritium through lithium breeding blankets, the excess energy will not be used to produce electricity.


The project recently reached an important milestone with the delivery of the first parts of the machine. These pieces, once assembled on site, will form the cryostat – the world’s largest stainless steel high vacuum vessel with a capacity of 16,000 m3. The cryostat is essentially a large thermos that will house the rest of the machine. Eventually it will be almost 30 meters high with a similar width. The cryostat maintains its internal temperature at -269°C, allowing the magnets to function as superconductors.

The size of some of the components used on site during construction presented its own set of logistical challenges. For example, a set of two cranes provides a combined lifting capacity of 1,500 tonnes. They were delivered partially assembled, but even then one section was 47 meters long. To get the cranes from the port of Marseille Fos to ITER, they were put on a barge and transported across the inland sea of ​​Étang de Berre, transferred to a special vehicle in Berr-L’etag and then driven at 5 km/h over 104 km driven. specially reinforced road. The cranes were only moved at night to minimize disruption to local traffic.

As with many projects of this physical size and duration, progress has not been without difficulties and missteps. Over the years, overly optimistic projections for budgets and schedules were made. As a result, cost overruns and schedule delays have taken a toll on the project’s credibility. Most recently, ITER announced 4 billion euros ($4.4 billion) in overruns and said the first tests with plasma would likely be delayed another five years until 2025.

Since one of the aims of the project was to disseminate scientific and technological knowledge across the participating countries, decisions were not always made with the aim of keeping costs low. While it may be less expensive to have a set of components built by a single source, that doesn’t necessarily ensure a fair distribution of technology growth. In many cases, components were made in more than one country. In addition, this arrangement has sometimes not led to a fully cohesive team environment.

The new head of ITER, which took over in 2015, is Director General Bernard Bigot. Bigot recognized these concerns before assuming his role, so he accepted the function that comes with having the authority to manage ITER as a cohesive project rather than 35 different efforts spread across member nations.

But a big project doesn’t run on a dime. And this project has been around for 31 years, spans manufacturing efforts on three continents, and involves politicians and engineers from 35 countries. It turns slowly. Nevertheless, effects of changes in the management approach are visible. Domestic agencies of the member countries have already recognized the need for more cooperation and a wider acceptance of working together as a team for the benefit of the whole project.

The total construction cost is expected to be around 15 to 20 billion Euros (~$20 billion). Because member countries produce and contribute components (rather than simply funding ITER), the exact cost will probably never be known. Yet delays and increased costs are being noticed, creating challenges and forcing Member States to make decisions about what they will and will not fund. The morning I arrived at Marseille Provence Airport, Director General Bernard Bigot and Chief of Communications Laban Coblentz were there to catch a flight for a short trip to testify before the Subcommittee on Energy and the Committee on Science, Space and Technology in the United States House of Representatives.

The optimist in me believes that decision makers will see the potential value of a cleaner fuel source for a planet that desperately needs it, and as such will find a way to keep this project going. After all, the potential it has to influence the future course of humanity is immeasurable. No cost or challenge should be insurmountable.

Dave Loschiavo is a cybersecurity consultant lucky enough to live in the beauty of the northern Sierra Nevada. He previously wrote for Ars about the experience of fiber optic connectivity in his remote area.

By akfire1

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