Three units at France's Gravelines nuclear power plant automatically shut down due to jellyfish intrusion

French utility EDF recently stated on its website that three units at the Gravelines nuclear power plant in northern France automatically shut down after a large influx of jellyfish clogged the filtration system, triggering safety measures.

The statement indicated that the incident occurred on August 10, 2026. Due to the jellyfish intrusion, three units at the Gravelines plant automatically shut down, while a fourth unit reduced its power output. The plant has a total of six reactors, of which the fifth reactor had already been shut down for planned maintenance, and the sixth reactor remained in operation.

The Gravelines plant experienced a similar situation a year earlier, when a large number of jellyfish entered the relevant water intake and filtration systems, causing four reactors to automatically shut down.

Data shows that the massive proliferation of jellyfish in coastal waters during summer is linked to factors such as rising seawater temperatures and overfishing. This incident comes at a time when France's nuclear power generation is being affected by high temperatures and drought. Nuclear power plants typically rely on water sources such as rivers to cool equipment, and excessively high water temperatures or falling water levels can limit the generating capacity of units.

On August 9, 15.6% of France's nuclear power capacity was unavailable, the highest level since EDF began publishing such data in 2015.