In its final experiments before being shut down for good last year, the UK's JET reactor set a world record for the energy output of a fusion reaction

The UK’s 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°C.

The reactor’s 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.

This equates to a power output of 12.5 megawatts – enough to power 12,000 homes, said Mikhail Maslov of the UK Atomic Energy Authority at a press conference on 8 February.