As heat wave hits France, four nuclear reactors are shut down by mass of jellyfish

Electricite de France SA was forced to shut four atomic reactors after a swarm of jellyfish clogged up filter drums at its Gravelines power plant.

The “massive and unforeseen” presence of jellyfish in the filter drums of pumping stations closed four out of six reactors at Gravelines on the north coast of France, EDF said in a statement on Monday. Pumping stations for coastal nuclear plants usually draw in sea water for cooling, sometimes exposing them to marine life.

A marine heat wave is intensifying off the west coast of France, with unusually warm waters in the English Channel near Gravelines, data from Copernicus Marine Service show. Jellyfish populations can “bloom” at such times, and France has closed several beaches in recent weeks due to invasions of the eight-legged molluscs, according reports compiled by the beach information app Meduseo.

The 3.6 gigawatts of generating capacity will be returned to service later this week, according to EDF, which has already flagged potential curbs to its nuclear output as a result of the heat wave baking Europe. The utility has said high temperatures in the Garonne and Rhone rivers are likely to compromise cooling procedures at some atomic sites. Temperatures in southwest France could top 109 degrees over the next two days.

Fish clogged up filters at another French nuclear site in 2021 and EDF’s Torness station in Britain has been halted several times due to excessive amounts of seaweed.