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ITER - replicating the Sun

Energy By Tony Centola, Partner, Building Services – 16 November 2021

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Tony Centola

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As an engineer, I am always interested in engineering advancement and concepts that come to fruition, the ITER project in Cadarache in Southern France has this in abundance!

The ITER project (initially the International Thermonuclear Experimental Reactor) also meaning "the way" or "the path" in Latin is an international nuclear fusion research and engineering megaproject aimed at replicating the fusion processes of the Sun to create energy on earth.

The purpose of the project was really ‘proof of concept’ or a large-scale experiment if you like, to demonstrate the technological feasibility of fusion energy by controlled ignition and extended burn of plasmas. The numbers behind recreating fusion on earth are mind-boggling, the design requirements called for “the mechanical design of the device shall withstand the expected temperatures, pressures, electromagnetic fields, chemical environment, and radiation environment under all projected operating conditions and assumed accident conditions”. (International Atomic Energy Agency 2021) (International Atomic Energy Agency 2021)
So, what are these parameters that the machine and its components need to meet, well to achieve fusion, it is necessary to heat a gas to very high temperatures to form a plasma (referred to as the “fourth state of matter” after solids, liquids and gases), in the ITER this means 150 million °C!

The presence of charged particles makes plasma conductive (it has a high ability to conduct electrical current) and this property is used to confine it around a tokamak, in effect a doughnut-shaped vacuum chamber with powerful magnets placed around it.

The heat from the plasma is absorbed as heat in the walls of the vessel, the vessel is water-cooled and just like a conventional power plant, a fusion power plant will use this heat to produce steam and then electricity by way of turbines and generators.

What fuel does the machine use to create the plasma? ITER will use the reaction between deuterium (D) and tritium (T) hydrogen isotopes as the most efficient, as the DT fusion reaction produces the highest energy gain at the "lowest" temperatures. Although tritium is rare, deuterium is abundant in water and there is enough in Lake Geneva to fuel the fusion generating process long after man has disappeared for the planet with tritium manufactured from a process in the reactor.

Radioactivity is a major concern when people think of nuclear power, this is due to disasters such as Chernobyl and Three Mile Island. However, these were nuclear fission plants, fusion on the other hand does not create any long-lived radioactive nuclear waste.

The fusion process is inherently safe, unlike fission, it is not self-sustaining as the process is not based on chain reactions. The plasma requires external heating and is confined by the magnetic field, so if anything does go wrong the plasma cools very quickly and is in effect self-extinguishing.

I am not an expert in nuclear fusion but marvel at the ingenuity and prowess of the scientists and engineers that have been working on this project for over 16 years, whose budget has grown from €5bn to an estimated €22bn to completion.

However, for the sake of humanity, we should all hope that all challenges are overcome and the ITER project is a huge success. I firmly believe that Fusion is the panacea for humanity’s energy needs, although it will not save us from the current climate crisis, it has the potential to provide limitless and safe energy with zero emissions for generations to come.

We just need to make sure that there is a planet left for their arrival.

References
Www-pub.iaea.org. 2021. [online] Available at: <https://www-pub.iaea.org/MTCD/...> [Accessed 2 November 2021].

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