GRAVELINES, France – Four reactors at France’s Gravelines nuclear power plant, located along the English Channel, were temporarily shut down over the weekend after a swarm of jellyfish threatened to clog critical water intake systems.
According to the plant’s operator, several of the facility’s production units went offline after jellyfish were detected in the filter drums of the plant’s pumping stations.
The French multinational electric utility company said the pumping stations, located in the non-nuclear section of the site, supply cooling water essential for the facility’s operation.
“They had no impact on the safety of the facilities, the safety of personnel, or the environment,” EDF said in a statement.
Jellyfish lay on the shore near the Gravelines nuclear power plant in Gravelines, northern France on August 12, 2025. Four units at the Gravelines nuclear power plant (Nord) were shut down on August 11, 2025 due to the “massive and unforeseeable presence of jellyfish” in the pumping stations for the water used to cool the reactors, EDF announced. These automatic shutdowns of units 2, 3, 4, and 5 “had no impact on the safety of the facilities, the safety of personnel, or the environment,” EDF assured on its website. The plant is thus temporarily completely shut down, as its two other production units, 1 and 5, are currently undergoing maintenance.
(Photo by SAMEER AL-DOUMY/AFP via Getty Images / Getty Images)
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The Gravelines nuclear power plant is one of the largest nuclear facilities in Western Europe and has been connected to the grid since the 1980s.
The impacts of jellyfish on coastal power plants is not without precedent, as there have been similar incidents reported around the globe during the summer months.
Along the English Channel, jellyfish sightings are frequent and can occasionally result in beach closures due to safety concerns for swimmers.
Much of the North Sea and Mediterranean Sea have experienced above-average water temperatures this year, fueling extensive heat waves and creating more favorable conditions for jellyfish.
Previous studies have suggested warmer seas can also accelerate jellyfish breeding cycles, increasing the likelihood of large swarms.
In June, several French nuclear reactors reduced output to limit the amount of discharge into waterways because of record-breaking sea surface temperatures.
The country’s regulations require operators to avoid releasing waste, as overheated water can harm aquatic life.
Warm water is known to place additional stress on marine species, lower oxygen levels and disrupt sensitive ecosystems.
GRAVELINES, FRANCE – AUGUST 12: A jellyfish is washed up on the beach in front of the Gravelines nuclear power station, operated by Electricite de France SA (EDF) on August 12, 2025 in Gravelines, France. It has been reported that EDF has been forced to shut down the nuclear power plant at Gravelines in France due to a swarm of jellyfish entering the water intake system that cools the reactors.
(Photo by Dan Kitwood/Getty Images / Getty Images)
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Despite the recent interruptions at the Gravelines plant, France has not reported issues meeting the demand for electricity.
According to the World Nuclear Association, the country generates about 70% of its electricity from nuclear energy and frequently exports surplus power to neighboring nations.
EDF said plant teams remain mobilized and are conducting diagnostics and technical interventions to clear the intake systems and safely restart the affected units.
The utility did not say when it expects to have the reactors back online to generate power for the grid.
