Nuclear Power Plants in Times of Climate Change: Four French Nuclear Reactors Shut Down Due to Jellyfish Infestation

Paris (France) - At France’s largest nuclear power site, Gravelines, all active reactors were unexpectedly shut down automatically over the past weekend. The cause was a massive influx of jellyfish, which clogged the cooling water pump filters and triggered safety shutdowns.

According to the state energy provider EDF, reactors 2, 3, and 4 were shut down on Sunday evening, followed by reactor 6 on Monday morning. Units 1 and 5 were already offline for maintenance. This temporarily brought the entire six-pressurized-water-reactor plant to a standstill.

With a gross capacity of around 5,460 MW, Gravelines is France’s most powerful nuclear site—almost as much as the total gross capacity of the active UK nuclear power plants (approx. 5,883 MW).

EDF assured that the shutdowns had no impact on the safety of the plant, personnel, or the environment. Technicians are working on resolving the issue and preparing for a safe restart.

The incident highlights the increasing challenges nuclear power plants face due to climate change and rising sea temperatures. Coastal facilities, in particular, are vulnerable to environmental phenomena such as jellyfish blooms, which can suddenly and unexpectedly disrupt operations.

Source: IWR Online, 13 Aug 2025