Jellyfish Cause Partial Shutdown at France's Gravelines Nuclear Plant

Jellyfish Influx Forces Partial Shutdown at French Nuclear Plant

Two reactors at France’s Gravelines nuclear power station were taken offline this week due to a large influx of jellyfish clogging the facility’s seawater filtration system. The shutdowns mark the second time in a year that marine life has disrupted operations at the plant.

Électricité de France (EDF), the plant’s operator, confirmed that units three and four were shut down on Wednesday and Thursday, respectively, after jellyfish obstructed the cooling system. A third reactor, unit six, has been offline since August 10 for the same reason. Unit five remains closed for a scheduled inspection.

Gravelines, one of France’s largest nuclear facilities, is located between Dunkirk and Calais in the Hauts-de-France region. The plant relies on a canal connected to the North Sea for cooling. Each of its six reactors produces 900 megawatts of electricity.

This is not the first time jellyfish have affected the plant. In August 2023, a similar influx forced temporary closures. EDF stated that after the latest shutdowns, only units one and two remain operational, though they are running at reduced capacity as a precaution.

Jellyfish populations tend to increase in warmer months, as rising sea temperatures boost plankton levels, attracting the marine creatures closer to shore. Several species are native to the region and commonly appear along the French coast during summer.

To mitigate the issue, EDF has implemented preventive measures, including collaboration with local fishermen who capture jellyfish and release them farther offshore. Similar incidents have occurred at other nuclear plants, such as Scotland’s Torness facility in 2011 and Sweden’s Oskarshamn plant in 2013, though such disruptions remain uncommon.

EDF has not provided a timeline for when the affected reactors will resume full operation. The company continues to monitor the situation and assess the effectiveness of its countermeasures.