A swarm of jellyfish have succeeded in shutting down Sweden’s biggest nuclear power plant.

E.ON SE were forced to take action after the creatures got into a cooling water inlet at the reactor on the Baltic coast.

The 1,400 MW Oskarshamn-3 units accounts for 5 per cent of Sweden’s power supply.

Anders Oesterberg, a spokesman for EON, said by e-mail, “The last time this happened was in August 2005, when we had to shut down Oskarshamn-1 because of a jellyfish invasion.”

The jellyfish are part of the genus Aurelia otherwise known as moon jellyfish and may grow as large as 40 centimetres in diameter.

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