The UK鈥檚 40-year-old fusion reactor achieved a world record for energy output in its final runs before being shut down for good, scientists have announced.
The Joint European Torus (JET) in Oxfordshire began operating in 1983. When running, it was temporarily the hottest point in the solar system, reaching 150 million掳C.
The reactor鈥檚 previous record was a reaction lasting for 5 seconds in 2021, producing 59 megajoules of heat energy. But in its final tests in late 2023, it surpassed this by sustaining a reaction for 5.2 seconds while also reaching 69 megajoules of output, using just 0.2 milligrams of fuel.
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This equates to a power output of 12.5 megawatts 鈥� enough to power 12,000 homes, said Mikhail Maslov of the UK Atomic Energy Authority at a press conference on 8 February.
Today鈥檚 nuclear power plants rely on聽fission reactions, where atoms are smashed apart to release energy and smaller particles. Fusion works in reverse, squeezing smaller particles together into larger atoms.
Fusion can create more energy with none of the resulting radioactive waste created by fission, but we don鈥檛 yet have a practical way to harness this process in a power plant.
JET forged together atoms of deuterium and tritium 鈥� two stable isotopes of hydrogen 鈥� in plasma to create helium, while also releasing a vast amount of energy. This is the same reaction that powers our sun. It was a type of fusion reactor known as a tokamak, which contains plasma in a donut shape using rings of electromagnets.
快猫短视频s ran the last experiments with deuterium-tritium fuel at JET in October last year and other experiments continued until December. But the machine has now been shut down for good and it is being decommissioned over the next 16 years.
at the University of Manchester, UK, says JET will reveal many secrets as it is dismantled, such as how the lining of the reactor deteriorated through contact with plasma and where valuable tritium 鈥� worth around 拢30,000 a gram 鈥� has embedded in the machinery and can be recovered. This will be vital information for future research and commercial reactors.
鈥淚t鈥檚 great that it鈥檚 gone out with a little flourish,鈥� says Matthews. 鈥淚t鈥檚 got a noble history. It鈥檚 served its time and they鈥檙e going to squeeze a bit more information out of it during its decommissioning period as well. So it鈥檚 not something to be sad about; it鈥檚 something to be celebrated.鈥�
A larger and more modern replacement for JET, the International Thermonuclear Experimental Reactor (ITER) in France, is nearing completion聽and its first experiments are due to start in 2025.
Tim Luce, deputy head of the ITER construction project, told the press conference that ITER will scale up the energy output to 500 megawatts, or possibly even 700.
鈥淭hese are what I usually call power plant scale,鈥� he said. 鈥淭hey鈥檙e at the lower end of what you would need for an electricity generating facility. In addition, we need to extend the timescale to at least 300 seconds for the high fusion power and gain but perhaps as long as 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.鈥�
Another reactor using the same design, the Korea Superconducting Tokamak Advanced Research (KSTAR) device, recently managed to sustain a聽reaction for 30 seconds at temperatures in excess of 100 million掳C.
There are other approaches to creating a working fusion reactor being pursued around the world as well, such as the National Ignition Facility at the Lawrence Livermore National Laboratory in California. This bombards capsules of fuel with immensely powerful lasers, a process called inertial confinement fusion, and has managed to unleash almost twice the energy that was put into it.
