Jellyfish Swarm Shuts Down Reactors at Europe's Largest Nuclear Plant

France's Gravelines nuclear power plant, the largest in Western Europe, has been forced to shut down three of its reactors due to an overwhelming invasion of jellyfish. The massive influx of marine life into the seawater pumping stations led operator EDF to halt reactors No. 2, 3, and 4 on Monday. Additionally, the power output of unit No. 1 was reduced to 50%. Only reactor No. 6 is currently operating at full capacity, while reactor No. 5 is undergoing scheduled maintenance.

This incident marks the second consecutive year the Gravelines plant, situated on the North Sea coast, has experienced such a disruption. Last year, a similar jellyfish swarm caused four reactors to automatically shut down, with the gradual reconnection of the final reactor to the national grid taking about ten days.

EDF has assured the public that the current situation poses no threat to the safety of the installations, personnel, or the environment. However, the recurring nature of the problem highlights potential vulnerabilities in nuclear operations. The proliferation of jellyfish in the northern French coastal waters is a regular, seasonal occurrence, but experts note that large swales appearing each summer are becoming more frequent.

Climate change is cited as a significant factor contributing to the global increase in jellyfish populations, primarily due to rising ocean temperatures. This event at Gravelines occurs as France's nuclear power sector faces unprecedented challenges. The national nuclear fleet has already recorded record unavailability rates due to drought and heatwaves, with 15.6% of its power capacity missing on Sunday, according to calculations based on EDF data since 2015. This signifies a historic level of nuclear power loss attributed to rising water temperatures and reduced river flows, impacting the cooling systems essential for nuclear reactors.