Three units at the Gravelines nuclear power station in northern France have been shut down due to a massive influx of jellyfish affecting the seawater filtration systems used for cooling.
Two units were taken offline on Wednesday and Thursday, with a third unit already closed since August 10 for the same reason, according to Électricité de France (EDF).
This marks the second consecutive year that jellyfish have disrupted operations at the Gravelines plant, one of France's largest nuclear facilities, located in the Hauts-de-France region between Dunkirk and Calais. The station was also impacted by jellyfish last August.
Unit three had only recently been reconnected to the grid on August 18 after an earlier jellyfish event this month. Units one and two are currently operating at reduced power as a precautionary measure.
The Gravelines plant's six units each generate 900 megawatts of power and are cooled using water from a canal connected to the North Sea.
Experts suggest that warmer weather increases plankton levels near the surface, drawing jellyfish closer to shore and into the plant's intake systems. Several jellyfish species are native to the area and are typically most active during the warmer months.
EDF has implemented measures to mitigate jellyfish infiltration, including a partnership with fishermen who capture and release the marine life further offshore. Similar, though rare, incidents have occurred at other nuclear facilities, including the Torness plant in Scotland in 2011 and Sweden's Oskarshamn plant in 2013.