The UK’s 40-year-old fusion reactor achieved a world record for energy output in its final operations before being shut down permanently, scientists announced.
The Joint European Torus (JET) in Oxfordshire began operating in 1983. While in operation, it was temporarily the hottest spot in the solar system, reaching 150 million°C.
The reactor’s previous record was a reaction that lasted 5 seconds in 2021 and produced 59 megajoules of thermal energy. But in its final tests in late 2023, it surpassed it by sustaining a reaction for 5.2 seconds while achieving 69 megajoules of output, using just 0.2 milligrams of fuel.
This is equivalent to an energy output of 12.5 megawatts, enough to power 12,000 homes, Mikhail Maslov of the UK Atomic Energy Authority said at a press conference on February 8.
Today’s nuclear power plants rely on fission reactions, in which atoms break apart to release energy and smaller particles. Fusion works in reverse, joining smaller particles to form larger atoms.
Fusion can create more energy without the resulting radioactive waste created by fission, but we still don’t have a practical way to harness this process in a power plant.
JET forged atoms of deuterium and tritium (two stable isotopes of hydrogen) into plasma to create helium, while releasing a large amount of energy. This is the same reaction that drives our sun. It was a type of fusion reactor known as a tokamak, which contains donut-shaped plasma using rings of electromagnets.
Scientists conducted the last experiments with deuterium-tritium fuel on JET in October last year and other experiments continued until December. But now the machine has been permanently stopped and will be out of service for the next 16 years.
Juan Matthews of the University of Manchester, UK, says JET will reveal many secrets as it is dismantled, such as how the reactor’s coating deteriorated from contact with plasma and where valuable tritium, valued at about 30,000 pounds per gram, in the reactor. machinery and can be recovered. This will be vital information for future research and commercial reactors.
“It’s great that it came out with a little flourish,” Matthews says. “It has a noble history. He has already served his sentence and they are also going to extract a little more information from him during his dismantling period. So it’s not something to be sad about; It is something that should be celebrated.”
A larger, more modern replacement for JET, the International Thermonuclear Experimental Reactor (ITER) in France, is nearing completion and its first experiments will begin in 2025.
Tim Luce, ITER’s deputy construction project manager, said at the news conference that ITER will increase power output to 500 megawatts, or possibly even 700.
“These are what I normally call scale power plants,” he said. “They are at the lower end of what would be needed for an electricity generation facility. Additionally, we need to extend the time scale to at least 300 seconds for high fusion power and gain perhaps up to an hour in terms of energy production. So what JET has done is exactly a scale model of what we have to do in the ITER project.”
Another reactor using the same design, the Korea Superconducting Tokamak Advanced Research (KSTAR) device, recently managed to sustain a reaction for 30 seconds at temperatures above 100 million°C.
Other approaches to creating a functional fusion reactor are also being pursued around the world, such as the National Ignition Facility at Lawrence Livermore National Laboratory in California. It bombards fuel capsules with immensely powerful lasers, a process called inertial confinement fusion, and has managed to release almost twice as much energy as was put into it.