A massive influx of jellyfish forced Électricité de France (EDF) to shut down three reactors at the Gravelines nuclear power plant on Tuesday [1], [2].
The incident highlights the vulnerability of critical energy infrastructure to biological disruptions. As the largest nuclear power plant in Western Europe [4], any reduction in capacity at Gravelines can impact regional power stability.
The disruption occurred on Aug. 11 [2], [5] when tons of jellyfish entered the seawater intake system [1]. The marine life clogged the cooling water filters, which triggered automatic safety shutdowns to prevent equipment overheating [1], [2].
Reports on the scale of the impact vary. While several sources state that three reactors were stopped [2], [3], [6], one report from Nord Littoral indicated that four reactors were affected [7].
EDF operators at the coastal site in Nord, France, managed the shutdown as the jellyfish swarms entered the intake from the English Channel [1], [6]. The plant relies on this seawater to maintain the temperature of its reactors, a process that is easily interrupted by dense biological matter.
There is conflicting information regarding the current status of the facility. Some reports indicate that all affected reactors have been restarted, while others say the units remained shut down pending further safety checks [2], [6].
This is not the first time marine life has interfered with the site's operations. The plant's location on the English Channel makes it susceptible to seasonal blooms of jellyfish, which can occur in massive quantities during specific weather patterns [1].
“Jellyfish entered the seawater intake system, clogging the cooling water filters”
The Gravelines incident underscores a growing challenge for coastal power plants facing 'biological fouling.' As ocean temperatures shift, the frequency and density of jellyfish blooms may increase, potentially leading to more frequent unplanned outages for plants that rely on open-cycle seawater cooling systems.
