Jellyfish Influx Forces Partial Shutdown of French Nuclear Plant

Jellyfish Clog Cooling System at Gravelines Nuclear Plant

A massive influx of jellyfish has led to the partial shutdown of a nuclear reactor in northern France, according to Électricité de France (EDF), the state-owned utility that operates the facility. The Gravelines nuclear power station, located between Dunkirk and Calais in the Hauts-de-France region, has had multiple units taken offline because of jellyfish blocking the seawater filtration system used for cooling.

EDF said that two of the plant's six units were shut down on Wednesday and Thursday due to the presence of jellyfish in the system. A third unit has been shut down since 10 August for the same reason, while a fourth unit has been closed for inspection. In total, EDF confirmed that units three, four, and six were now shut.

The disruption follows a similar event earlier in the month. Unit three had only been reconnected to the grid on 18 August after the first wave of jellyfish appeared, the company said. Units one and two were also operating at reduced power as a preventative measure.

The Gravelines station, one of the country's biggest nuclear power plants, has six units each producing 900 megawatts of power. The station is cooled from a canal connected to the North Sea, making it vulnerable to marine organisms.

Why Jellyfish Appear

Several species of jellyfish are native to the region and can be seen around the coast when the waters are warm. Experts say that hot weather increases plankton levels at the water's surface, drawing jellyfish up and increasing their numbers near the intake points.

This is not the first time jellyfish have caused problems at Gravelines. The plant was also closed last August because of jellyfish in its filters. To mitigate the issue, measures have been implemented, including a partnership with fishermen who capture and release the jellyfish further offshore, according to French outlet Ici.

Similar Incidents Elsewhere

Such incidents are rare but not unprecedented. Similar issues have occurred at other nuclear stations, including at the Torness plant in Scotland in 2011 and Sweden's Oskarshamn plant in 2013. However, these cases remain uncommon.

EDF has not provided a timeline for when the affected units might return to full operation, but the company is actively working to clear the filters and implement preventive measures.