How Swarming Jellyfish Overran Three French Nuclear Power Reactors
A "massive influx" of jellyfish forced Electricite de France SA to shut three units at its Gravelines nuclear power plant this week and reduce output at a fourth, reports Bloomberg. Just as summer temperatures surged, 3.2 gigawatts went offline — and the power utility was already facing cuts other nuclear sites as high temperatures reduced the river water available for cooling. More details from…
Electricite de France SA shut down three reactors at its Gravelines nuclear power plant and reduced output at a fourth due to a massive influx of jellyfish this week. The summer heatwave increased temperatures, causing a scarcity of river water for cooling, already leading to cuts at other nuclear sites. Gravelines spent hundreds of thousands of euros in 2025 to prevent this from happening again, only for it to occur again a year later.
Higher water temperatures create more plankton and animals that jellyfish feed on, speeding up their life cycles and extending breeding seasons. This is not the only instance of wildlife disrupting energy infrastructure; last year, a raccoon caused more than a thousand power outages in Connecticut by infiltrating a substation.
To combat the jellyfish swarm, EDF installed fixed cameras at intake canals and filter drum screens to promptly identify any blockages. They also partnered with fishing and sea rescue organizations to monitor swarms and launch trawling operations to reduce their density before reaching the plant. Vacuum trucks were used to remove existing jellyfish on-site, with cleanup expected to finish quickly and allow the units to restart.
Scientists predict these events may become more frequent due to global warming, invasive species, habitat loss of predators, and overfishing.
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