Three reactors at France’s Gravelines nuclear plant shut down after a massive jellyfish swarm overwhelmed seawater filtration systems. The northern French facility took reactors 2, 3, and 4 offline as a precaution. Reactor 1 reduced output by half, while reactor 5 remained under maintenance. Only reactor 6 continued operating normally, cutting roughly 3.2 gigawatts of capacity during a summer heatwave.
Gravelines use seawater for cooling, the filtration systems protecting its intake pipes. Several dozen tons of jellyfish overwhelmed those systems on August 10. The plant experienced a similar shutdown in August 2025. EDF later introduced fishing vessels and thermal imaging to monitor jellyfish blooms.
The latest incident highlights growing challenges for France’s nuclear fleet. Heatwaves and drought have already disrupted several reactors this summer. Experts link expanding jellyfish populations to warming seas, overfishing, and plastic pollution. Similar incidents have affected nuclear plants across Europe and Asia.
EDF said the shutdown posed no threat to workers, facilities, or the environment.
