When the Sea Strikes Back: Jellyfish Halt France’s Nuclear Giant

France’s Gravelines nuclear power station, a sprawling 5.4-gigawatt complex on the North Sea coast, faced an unlikely adversary: jellyfish.
Dense bloom swept into the plant’s cooling water intake, clogging filters and triggering an automatic shutdown of four reactors. The remaining two units were already offline for maintenance. In a single night, the country’s largest nuclear facility went from full power to complete silence.
Scientists believe warming waters and shifting ecosystems are fueling these massive swarms. Longer reproductive seasons, the spread of invasive species like the Asian Moon jellyfish, and the loss of natural predators have made blooms both more frequent and more intense. What was once a rare ecological quirk is now a recurring operational hazard.
EDF, which operates Gravelines, initially aimed to restart the affected units on Tuesday. That schedule has now slipped, with a phased return planned through Friday, starting with unit six. The company insists there was never any danger to staff, the public, or the environment, just an unexpected standoff between high technology and soft-bodied drifters.
It’s not the first time marine life has disrupted power generation, but this episode underscores a growing reality: infrastructure built for a stable climate is facing new, unpredictable pressures. And in this case, it wasn’t a storm or a technical fault that brought down a nuclear giant, just a silent tide of translucent creatures, drifting on currents that are changing faster than the systems we’ve built to control them.