This fusion machine becomes the hottest place in the solar system when turned on

Humans can't access them- super 'MASCOT' robots are trained to do the maintenance work.
Sade Agard
Tokamak inside heated plasma for sustainable energy
Tokamak inside heated plasma for sustainable energy


Fusion is the process by which two light atomic nuclei merge, a process that liberates a significant amount of energy. It is based on the same fundamental reactions that power the sun and stars. Future generations could benefit significantly from the safe, sustainable, and low-carbon energy that this technology has the potential to provide.

Only a few days ago (October 3, to be exact), the U.K. announced the site for its prototype fusion energy plant, to be built by 2040. We know that if successful, this would be quite fitting for a country that, in the 1950s, built the first nuclear fission reactor used for commercial purposes.

Interesting Engineering (IE) attended New Scientist Live over the weekend (Oct. 8-9) and spoke with Jordan D' Arras, Graduate Development Engineer at U.K. Atomic Energy Authority, to learn more about the ambitious program.

"We're the U.K. Atomic Energy Authority, and the vast majority of our work is based around the fusion and magnetic confinement fusion, specifically," explains Jordan D' Arras.

'We can heat [the plasma] to around 150 million degrees

This fusion machine becomes the hottest place in the solar system when turned on
Model 'spherical' tokamak at the New Scientist Live event

The 'T' in 'STEP' refers to 'tokamak,' the fusion 'machine' used in the program. This doughnut-shaped vessel holds and confines plasma made from hydrogen isotopes. "We can heat that hydrogen up into a plasma; we can heat it to around 150 million degrees [Celsius]," reveals D'Arras. That's ten times hotter than the center of the sun!

D' Arras tells IE that when the fusion device is turned on, it actually becomes the hottest place in the solar system.

In the STEP program, the tokamak for energy production has a unique compact shape that is spherical rather than toroidal. "We find that [this shape] gives a more efficient reaction within the plasma. Hopefully, it makes manufacture easier because the units are smaller, more compact," explains D'Arras.

Reaching the 2040 goal is underway as the team continues to work on the plant's design

The team is reportedly at the threshold between phases one and two, with the U.K. Atomic Energy Authority announcing earlier this week that the plant's location will be in West Burton, North Nottinghamshire.

"We're still working on the design of this plant. We have a spherical tokamak on-site at the Culham Centre in Oxfordshire," discloses D' Arras. The crew looks forward to using the wealth of data already received from the Oxfordshire plant to learn more about how the prototype will be used to provide power to the U.K. energy grid.

D' Arras describes the plants that currently exist as "science experiments"- because they're not sending power to the grid. IE is told that such plants continue to help the team learn about plasma and the challenges involved in fusion to carry that forward into the STEP program.

The first magnetic confinement fusion vessel produces more energy output than input

During the interview, IE discussed the ways that the U.K. Atomic Energy Authority is also working with an international fusion program called ITER (International Thermonuclear Experimental Reactor). This project involves collaboration between 35 nations to build the world's largest tokamak in the south of France.

"It is going to be the first magnetic confinement fusion vessel to produce more energy output than input," D' Arras tells IE. "We call that a Q value." Essentially, a Q value of one stands for every kilowatt (kW) energy you put in and get per kW hour.

The crew hopes that the Q value of the reactions in ITER in France will be between Q five and 10. The first plasma (the first time the machine is powered on) of which is currently scheduled to occur in late 2025 or early 2026. That's quite soon.

Interchangeable robot hands do all the maintenance work at the fusion plant

This fusion machine becomes the hottest place in the solar system when turned on
Maintenance of the fusion energy machine is carried out by 'superhero robots'

D' Arras demonstrated to IE the gigantic robots with interchangeable hands to suit the tools needed for any maintenance job of the fusion machine. "For example, if one of the tiles on the internal walls of the vessel needs changing, we can put on [a suitable] device to the end of the arm."

"Robot operators sit in a chair remotely where they have these little arms that come down. They can manipulate the robot live," explains D' Arras. There are numerous cameras on the robot's arms so operators can see exactly where they are in the vessel.

Since the robots are "quite expensive," a lot of training is needed before anyone can operate a MASCOT (the robot's name). Each MASCOT has two arms with grippers that can operate over 900 bespoke tools. The MASCOTs are deployed on the end of an articulated 12-meter boom, driven by a remote handing team from a control room fitted out with live camera feeds and VR screens for additional precision views.

D'Arras tells IE that prospective engineers must first play a game of Jenga- just next door to the training vessel- using a MASCOT to prove their competency.

MASCOTs keep humans safe in a toxic, challenging environment. Keeping humans out also avoids contamination

The fusion plant is a challenging environment- at least for humans. Beryllium is just one of the toxic materials making up the fusion machine's wall tiles. Because of this, most of the vessel's maintenance work must be carried out with MASCOT(s) and other various robots.

Anyway, "you wouldn't really be able to get in there while it was running," clarifies D' Arras, who further explains that from the oil on your fingerprints, human presence would cause impurities in the plasma. One impact of contamination is that the reactor would cool down, and there would be some damage to the device. It would be the same issue even if humans went inside while the vessel was not running.

"It is a really pristine environment in there, which is quite juxtaposed to the outside of the vessel where there are miles and miles of pipework and wires etc.," describes D' Arras.

'Magnets prevent [the plasma] from coming into contact with walls and doing any damage to our machine'

During the New Scientist Live event, the U.K. team commonly received the question: If you're storing plasma at 150 million degrees Celsius, why doesn't your machine melt? D'Arras explains this is because the plasma never comes into contact with the vessel. The use of large magnetic fields confines the plasma.

"Colloidal magnets confine the plasma one way while toroidal magnets confine the plasma in another direction. And they sort of squeeze/push the plasma together," explains D' Arras. In this way, the forces densify the plasma in the center and prevent it from coming into contact with the machine walls and causing any damage.

The team hopes that the STEP program's environmentally friendly and sustainable approach to energy production will gain a positive response and encourage people to get on board.

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