Partial shutdown of units at France's Gravelines nuclear power plant due to jellyfish influx

French utility EDF announced on August 27 that the Gravelines nuclear power plant in northern France has taken emergency measures to shut down or reduce power output at some reactor units following a massive influx of jellyfish.

An EDF spokesperson stated that since the night of August 26, more than 200 tonnes of jellyfish have accumulated near the filtration system of the plant's seawater pumping station. To ensure facility safety, the plant took preventive measures by completely shutting down 2 of its 6 reactor units.

Meanwhile, 2 other units were operated at reduced power, and the remaining 2 units were already offline for maintenance and inspection reasons. This means that no unit at the Gravelines nuclear power plant is currently generating at full capacity.

Located along the coast, the Gravelines nuclear power plant is France's largest nuclear facility in terms of installed capacity, with a total installed capacity of 5.4 gigawatts. EDF stated that the incident poses no risk to grid operations. The plant is collaborating with multiple partners to further analyze the causes of the large-scale jellyfish accumulation, though no definitive conclusions have been reached yet.

It is understood that the Gravelines nuclear power plant has installed monitoring systems to detect and respond to large jellyfish swarms at an early stage. Seven local fishing vessels have been operating around the plant day and night, catching jellyfish and relocating them to offshore waters away from the plant for release.

In mid-August this year and in August last year, the Gravelines nuclear power plant also experienced operational interruptions due to jellyfish invasions. Experts believe that overfishing, plastic pollution, and seawater warming caused by climate change may have created conditions for the massive reproduction and growth of jellyfish.

About 70% of France's electricity comes from nuclear energy. Since the beginning of this year, French nuclear power production has been constrained multiple times due to heatwaves and drought.