Nuclear Power Plant Shut Down by a ‘Massive’ Swarm of Jellyfish

A bizarre marine invasion has brought one of France’s biggest nuclear power plants to a screeching halt — and it’s all thanks to jellyfish.

Officials say a massive swarm of the gelatinous creatures clogged critical cooling pipes at the Gravelines Nuclear Power Station in northern France late Sunday night, forcing an emergency shutdown of multiple reactors.

The sprawling facility — located on the coast between Calais and Dunkirk — relies on seawater from a canal connected to the North Sea to keep its six reactors cool. But when the jellyfish flooded the intake system, the plant’s automated safety protocols kicked in.

“We were faced with a massive and unpredictable bloom,” a spokesperson for state-run energy giant Électricité de France (EDF) told French media. “Our filter drums were overwhelmed within hours.”

By midnight, reactors 2, 3, and 4 had gone offline. Reactor 6 followed soon after. The remaining two reactors were already down for maintenance, leaving the plant completely out of service.

Gravelines isn’t just any power plant — each reactor produces 900 megawatts of electricity, meaning the sudden shutdown yanked 5.4 gigawatts from France’s power grid at the height of summer energy demand. That’s enough to supply several million homes.

EDF has insisted there is “no risk to the safety of the plant, its staff, or the environment,” but energy experts say the incident highlights a growing vulnerability in coastal nuclear facilities.

Marine biologist Dr. Sophie Lemaitre told Le Parisien the phenomenon isn’t new — but the size of this bloom was staggering. “Warmer seas mean jellyfish populations can explode overnight,” she said. “If they hit an intake pipe, they can bring an entire nuclear station to its knees.”

Jellyfish blooms are a seasonal hazard in the North Sea, but EDF described this swarm as unusually dense. The company has not announced when the reactors will be restarted.

Meanwhile, energy analysts warn that losing one of Europe’s largest nuclear plants, even temporarily, could put pressure on electricity supplies across the continent.

“This is a reminder that even high-tech energy systems can be brought down by something as simple as jellyfish,” said Paris-based energy consultant Marc Delcourt. “It’s nature reminding us who’s really in charge.”