Four reactors at France’s Gravelines nuclear plant will return to operation throughout the week, slightly later than initially planned, EDF data indicates after they were forced offline by a swarm of jellyfish in the cooling systems.
The plant in northern France is one of the largest in the country and is cooled from a canal connected to the North Sea.
Its six units produce 900 megawatts of power each, or 5.4 gigawatts in total.
The first reactor, unit 6, is expected to restart on Tuesday, and then one reactor is expected to come back online each day until all four have returned to service on Friday, EDF data suggested.
The original plan was for all four to restart on Tuesday.
EDF did not give a reason for the delay, although France is in the midst of a heatwave that is creating challenges for many nuclear cooling systems.
Its data showed the first reactor had still not restarted by midday on Tuesday.
The whole Gravelines plant was temporarily halted on Monday after a “massive and unpredictable” swarm of jellyfish got into the cooling systems, EDF said.
Four reactors were taken offline while the other two were already undergoing planned maintenance.
They were English Barrel jellyfish, a native, non-stinging species that can grow up to 90 centimetres across, said citizen scientist Aäron Fabrice de Kisangani.
The current would have pushed the jellyfish from the harbour and into the canal towards the nuclear plant, and then they would not have been able to escape the suction of the water coolant system, pulling them into the filters, Aaron said.
Higher average sea temperatures this year could cause larger jellyfish blooms, he added, noting that jellyfish were staying longer in the North Sea due to mild autumns and winters.
This is not the first time that jellyfish have disrupted nuclear plants.
Scotland’s Torness faced similar problems in 2011 while Gravelines itself was disrupted in 1993.
https://thewest.com.au/news/disaster-and-emergency/jellyfish-hit-french-nuclear-site-faces-delayed-restart-c-19663672
