EDF shuts three Gravelines reactors, cutting 3.2 GW after jellyfish swarm
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Electricité de France shut three reactors at the Gravelines nuclear plant on Monday after a massive influx of jellyfish clogged cooling water intakes, cutting 3.2 gigawatts of capacity. The disruptions occurred as France endures a heat wave, with temperatures expected to approach 40 degrees Celsius in some regions.
The Gravelines Shutdowns
Two reactors were halted on Monday, with a third shut on Tuesday, according to regulatory filings by EDF. A fourth unit is operating at reduced output. Together, the outages have removed 3.2 GW from the grid. The 5.7 GW Gravelines plant on France’s northern coast draws seawater for cooling, making it vulnerable to marine life. Two of the reactors are scheduled to resume by Wednesday night, while the other two—totaling 1.8 GW—may stay offline until the end of the week.
Jellyfish Bloom
Unusually high water temperatures off the French coast have triggered a proliferation of jellyfish. The swarms clogged filter drums at the plant’s pumping station, similar to an incident last year. Warmer seas are known to spur jellyfish blooms, which can overwhelm intake systems at coastal power stations. EDF has not commented on the exact size of the swarm but described the event as a ‘massive influx.’
Heat Wave Pressures
France is in the grip of another summer heat wave, the fifth this year, pushing temperatures toward 40C and raising electricity demand for cooling. The heat also strains inland nuclear plants, which must limit output to avoid discharging overly warm water that could harm river ecosystems. EDF has already curtailed generation at several river-based nuclear sites, compounding the supply tightness caused by the Gravelines outages.
What's Next
EDF expects two of the four affected Gravelines reactors to restart by late Wednesday, but the remaining 1.8 GW could be offline through the week. It remains unclear whether further jellyfish incursions will force additional shutdowns as heat persists along the coast.
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EDF shuts three Gravelines reactors, cutting 3.2 GW after jellyfish swarm
