A nuclear power plant in northern France hit by a jellyfish invasion was getting back online on Wednesday, operator EDF said, with service restored at the first of four closed reactors.

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

Located on the Channel coast near Dunkirk, Gravelines is the largest nuclear power plant in western Europe, with six 900 megawatt reactors.