Jellyfish swarm halves output at France's Paluel nuclear plant for second time in a month
Filters at Normandy pumping station clogged by jellyfish reduce Paluel's generation by 2.4 GW; EDF crews working to restore full capacity
A swarm of jellyfish forced France's Paluel nuclear power plant in Normandy to cut output on Sunday, marking the second disruption to the country's nuclear fleet linked to jellyfish in a month.
France's national energy firm EDF said the marine animals entered the filters of the plant's pumping station, affecting the non-nuclear part of the site and prompting operators at 21:00 local time (19:00 GMT) to take measures that reduced generation by about 2.4 gigawatts. Paluel has an installed capacity of roughly 5.2 gigawatts across four reactors; one unit was shut down and a second had output reduced as a protective measure, a near halving of the plant's normal production.
EDF said its teams were carrying out work to clear the filters and restore full operation. The company described the intervention as a precaution to protect equipment and ensure safe operations while staff remove the biological debris from intake systems.
This is the second such incident this month after a separate "massive and unpredictable" swarm of jellyfish in August forced temporary cessation of operations at the Gravelines plant on France's northern coast. Operators at both sites said the interruptions affected the non-nuclear cooling and water intake systems rather than the reactors themselves.
Nuclear power accounts for a major share of France's electricity generation. The World Nuclear Association estimates nuclear provides about 70% of the country's energy consumption, making the reliability of intake and cooling systems critical to grid supply and plant availability. Paluel is one of France's largest nuclear complexes, with each of its four units generating more than 1,300 megawatts under normal operation.
Operators and grid managers have in recent years taken a range of measures to respond to sea-related blockages of intake systems, including temporary shutdowns or output reductions when filters are overwhelmed, and deploying crews to clear debris. EDF said actions at Paluel were taken to protect plant systems and personnel while crews completed clearing operations.
Authorities and the operator did not report any radiological or safety issues affecting the reactors. EDF's statements emphasized that the affected equipment was part of the plant's auxiliary, non-nuclear systems and that standard safety protocols guided the decision to reduce generation.
The incidents at Paluel and Gravelines highlight an operational vulnerability of coastal power plants to marine life entering cooling water systems. EDF said it would continue work to restore full generation at Paluel and monitor intake filters to reduce the risk of further interruptions.
Grid operators were alerted to the output reduction and have been adjusting distribution to maintain supply, EDF said. Further updates on restoration of capacity at Paluel were expected as crews completed the cleaning and testing necessary to return the affected units to full service.