Four units of the Gravelines NPP in France have been closed down because of a “massive and unpredictable presence of jellyfish” in the water pumping stations used to cool the reactors, EDF said. The six-unit Gravelines plant is the largest NPP in Western Europe.
Jellyfish were found in the filters of the pumping stations that suck in the seawater intended to control the temperature of the reactors of the power plant. Gravelines is cooled using water pumped into a channel connected to the North Sea. Its six 900 MWe pressurised water reactors produce 5.5 GWe.
The North Sea has several species of jellyfish that often approach the coast when water temperatures rise. Their gelatinous character enable them to pass through the first filters of the pumping stations where they block the filter drums, equipped with a very fine mesh in order to allow only seawater to pass through. Resuming operation “will be done in stages”, according to the plant’s communication department.
“The plant’s teams are mobilised and are currently carrying out the necessary diagnostics and interventions to be able to restart the production units in complete safety,” EDF said in its press release. The automatic shutdowns of units 2, 3, 4 & 6 “did not have any consequence on the safety of the installations, the safety of the personnel or on the environment,” EDF stated. However, the power plant is completely shut down, because units 1&5 are closed for maintenance.
