A huge nuclear power station in France has temporarily shut down after a "massive and unpredictable" swarm of jellyfish swam into the cooling system.

Late Sunday, a jellyfish swarm clogged the cooling-water filters at Gravelines, a six-reactor plant on France’s North Sea coast. Four units shut down automatically. It was a bad timing, as two other reactors were already offline for maintenance,

Jellyfish swarms forced a shutdown of France's largest nuclear facility at Gravelines, impacting 900-megawatt reactors but posing no safety risks to staff.