A French nuclear plant has temporarily shut down due to a “massive and unpredictable presence of jellyfish” in its filters, its operator said. The swarm clogged up the cooling system and caused four units at the Gravelines nuclear power plant to automatically switch off, energy group EDF said. The site in northern France was shut after the incident, with its remaining two units already down for maintenance.
EDF said there had been “no impact on the safety of the facilities, the safety of personnel, or the environment”. It added that the jellyfish were found “in the non-nuclear part of the facilities”. “The plant teams are mobilised and are currently carrying out the necessary diagnostics and interventions to be able to restart the production units safely,” EDF said in a statement.
The Gravelines nuclear power plant is one of France’s largest, with six units each producing 900 megawatts of power. It is cooled from a canal connected to the North Sea, where several species of jellyfish are native and can be seen around the coast when the waters are warm. According to nuclear engineer Ronan Tanguy, the marine animals managed to slip through systems designed to keep them out because of their “gelatinous” bodies.
“They were able to evade the first set of filters then get caught in the secondary drum system,” he told Ireport. Tanguy said this will have created a blockage which reduced the amount of water being drawn in, prompting the units to shut down automatically as a precaution. He stressed that the incident was a “non-nuclear event” and more a “nuisance” for the on-site team to clean up.
For local people, there would be no impact on their safety or how much energy they could access: “They wouldn’t perceive it as any different to any other shut-down of the system for maintenance.” Jellyfish have caused similar problems at power stations in the past, including at the Torness nuclear plant in 2011 and Sweden’s Oskarshamn plant in 2013, but cases of this kind are rare.
About 70% of France’s electricity comes from nuclear energy, according to the World Nuclear Association (WNA). The shutdown of the Gravelines nuclear power plant may have a temporary impact on energy production, but it is unlikely to affect the overall energy supply in France. The plant’s shutdown is a precautionary measure to ensure the safety of the facility and its personnel.
The incident highlights the potential vulnerability of nuclear power plants to external factors such as jellyfish swarms. While rare, such incidents can have significant consequences for energy production and highlight the need for power plants to be designed and operated with resilience and adaptability in mind.