In August 2025, an unexpected marine invasion brought one of Western Europe’s most significant energy assets to a standstill. At France’s Gravelines nuclear power station—a colossal facility with six reactors, each generating about 900 MW—a sudden swarm of jellyfish infiltrated the plant’s cooling systems.
A Bizarre Blockage
Over the weekend, plant operators spotted jellyfish clogging the filter drums of the water intake systems. These filters prevent debris from entering the cooling pumps that regulate reactor temperatures. When the gelatinous creatures overwhelmed the system, safety protocols automatically shut down reactors 2, 3, and 4 late Sunday night, followed by reactor 6 early Monday morning.
Meanwhile, workers had already taken the other two reactors offline for scheduled maintenance, which left the entire plant inactive.
Safety First
EDF, the operator, assured the public that the shutdown posed no risk to personnel, the environment, or national safety. Engineers confirmed that the issue stayed confined to non-nuclear parts of the plant. Although the filters suffered no damage, crews needed to clean them before restarting the reactors.
A Growing Threat
Jellyfish have long challenged coastal power facilities. Experts point to warming sea temperatures, reduced predators due to overfishing, and marine pollution as factors accelerating jellyfish reproduction. Gravelines itself has faced similar outbreaks in the 1990s, and power plants in Sweden, Scotland, Japan, and the US have also endured jellyfish-related shutdowns.
Restart Underway
By August 14, engineers restarted Reactor 6 at 7:30 am, and teams continued working to bring the remaining reactors back online in the following days.
