Gravelines nuclear plant shuts reactors due to jellyfish swarm

The Gravelines nuclear power plant, the largest in Western Europe, has been forced to shut down or reduce the power of several reactors due to a massive influx of jellyfish. The operator, EDF, reported that more than 200 tons of jellyfish clogged the seawater pumping station's filtration systems.

As of late August 2026, multiple units have been affected. Specifically, reactors 3 and 6 were shut down preventatively to ensure plant safety, while reactors 1 and 2 are operating at reduced capacity. Other units remain offline due to previous jellyfish-related incidents earlier in the month or scheduled maintenance.

To manage the situation, EDF has deployed seven boats to collect the jellyfish and release them further out at sea, with support from the organization France Pêche Durable. While the phenomenon has occurred in previous years, experts suggest that increasing concentrations may be linked to climate change and warming waters. EDF has stated there is no risk to the electrical grid or overall plant safety.