Three reactors at the French nuclear power plant “Gravelines“ were shut down late on Monday due to a massive accumulation of jellyfish, operator EDF said, quoted by Reuters, BTA reported.
Reactors 2, 3 and 4 were shut down due to the invasion, and the power of reactor 1 was limited to 50 percent as a preventive measure. Reactor 5 has already been shut down for scheduled maintenance, while reactor 6 continues to operate at full capacity.
The plant in northern France is one of the largest in the country and is cooled by a canal connected to the North Sea. Its six reactors have a capacity of 900 megawatts each, or 5.4 gigawatts in total.
The measures were introduced after the entire plant was shut down last year due to a similar incident. Since then, EDF has introduced new monitoring systems and methods for catching jellyfish to prevent or limit such incidents.
The company has installed fixed cameras at the inlet channels and filter drums to detect possible blockages as early as possible, an engineer told Reuters.
EDF is also working with a French fishing organization and a marine rescue service, which monitor jellyfish swarms and can signal targeted operations to catch them before they reach the plant.
Fishing boats were dispatched on Saturday after an initial alert, which limited the impact of the swarm. The jellyfish that have already reached the plant are being removed with vacuum machines.
According to EDF, no new jellyfish are arriving and the cleanup is nearing completion, which should allow the shutdown reactors to resume operations quickly.
The situation does not affect the safety of the plant, personnel or the environment, the company said.
Scientists warn that such incidents could become more frequent due to factors such as global warming, the introduction of invasive species, the loss of habitat for natural predators and overfishing.
EDF is also facing restrictions on the operation of other nuclear reactors due to high temperatures, while France expects the fifth heat wave of the year to intensify this week and further limit nuclear power production.