Jellyfish shut down French nuclear power plant

French utility EDF announced that production units 2, 3, and 4 of the Gravelines nuclear power plant shut down automatically on Sunday due to disruptions caused by jellyfish.

The incident ocurred on Sunday 10 August between 11.00pm and midnight, when a "massive and unpredictable presence of jellyfish" was detected in the filter drums of the pumping stations.

According to the EDF statement, the reactors shut down in accordance with the plant's safety protection systems, and ultimately had no impact on the safety of the facility or the workers.

On Monday 11 August, at 6:20am, unit 6 also shut down automatically.

EDF has mobilised teams to carry out diagnostics and ensure the units can restart safely.

The Gravelines plant consists of six nuclear reactors with a nameplate capacity of 900MW each. It's located about 20km from Dunkerque and Calais and its cooling water comes from the North Sea.

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Incidents such as these are not uncommon. In 2021, the Torness nuclear power plant in Scotland shut down in an emergency procedure when jellyfish clogged the sea water-cooling intake pipes at the plant.

In 2013, the invertebrates forced the closure of the Oskarshamn nuclear power plant in Sweden, which contains the world’s largest boiling-water reactor.

Recent research has shown that jellyfish blooms occur more frequently near nuclear power plants, with a relationship between thermal discharges from the plants and the blooms been hypothesised. However, further research is required to further understand the dynamics planktonic ecosystems and to confirm the link.