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

Four reactors at France’s Gravelines nuclear power plant, located along the English Channel, were temporarily shut down over the weekend after a swarm of jellyfish threatened to clog critical water intake systems.

France's EDF power company restarted one reactor at the Gravelines nuclear power in northern France on Wednesday after a je