A swarm of jellyfish forced a nuclear power plant to shut down four reactors after the animals were found in the plant’s cooling systems.
It was called a “massive and unpredictable presence of jellyfish,” The New York Times reported.
The Gravelines plant in northern France is the country’s largest nuclear power plant and pulls water from a canal to the North Sea, Reuters reported.
It has six units in total that produce 5.4 gigawatts. All six were down Monday —four because of the jellyfish and the other two for planned maintenance.
A source told Reuters that sea creatures did no damage, but the filter pumps need to be cleaned.
The filter drums were in a non-nuclear part of the facility, the Times reported.
A marine biology consultant with the U.S. National Oceanic and Atmospheric Administration said that jellyfish reproduce quickly when the water is warm.
“Jellyfish breed faster when water is warmer, and because areas like the North Sea are becoming warmer, the reproductive window is getting wider and wider,” Derek Wright said.
They can also enter a ship’s ballast tank, hitching a ride until the water is pumped out.
One invasive species, the Asian Moon jellyfish, was first seen in the North Sea in 2020 but is native to the Pacific Northwest.
They cause issues with plants in China, Japan and India, Reuters reported.
Jellyfish also shut down plants in Israel, Scotland and Sweden, the Times reported.
The company that runs the plant, EDF, said it did not know the species of jellyfish that is causing the trouble, according to Reuters.
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