Jellyfish at the Gravelines nuclear power plant: first reactor restarts

Production should gradually resume. This Wednesday morning, at 7:30 a.m., one of the reactors at the Gravelines nuclear power plant (Nord), number 6, was able to restart, according to EDF.

It had automatically shut down on Monday due to a "massive and unpredictable" cluster of jellyfish in the pumping stations for the water used to cool the reactors. Production units 2, 3 and 4 had shut down on Sunday evening for the same reason.

They are still down this Wednesday. Work is "in progress" and they are expected to restart "in the coming days," according to a spokesperson for the operator.

According to the operator, the incident had "no impact on the safety of the facilities, the safety of personnel or the environment."

The plant - the largest in Western Europe in terms of the number of reactors and its production capacity - was completely paralyzed, as the other two units were undergoing maintenance. However, an EDF spokesperson assured on Monday that this shutdown did not pose any "risk of shortage" for the French electricity grid.

It is "quite rare" for jellyfish to paralyze the operation of nuclear reactors, but the operator already experienced a similar situation in the 1990s. This type of incident has also occurred in the United States, Scotland, Sweden and Japan.

The proliferation of jellyfish around the world is due to several factors, including the warming of the oceans with that of the climate, but also overfishing, which eliminates some of their direct predators such as tuna.