Two units at EDF's Gravelines nuclear power plant shut down due to jellyfish influx

en.Wedoany.com Reported - On August 27, Électricité de France (EDF) confirmed that the Gravelines nuclear power plant in northern France once again experienced a massive jellyfish influx. Since the night of August 26, more than 200 tonnes of jellyfish entered the seawater pump station filtration system area, prompting EDF to proactively shut down Units 3 and 6 and reduce power output at two other units. The remaining two units were already offline for maintenance and other reasons, meaning none of the plant's six units were operating at full capacity at the time.

The Gravelines nuclear power plant is located between Calais and Dunkirk in northern France, comprising six pressurized water reactor units with a single-unit capacity of 900 megawatts each, for a total installed capacity of 5.4 gigawatts. The plant draws water from a canal connected to the North Sea to supply seawater for the unit cooling systems. When large numbers of jellyfish enter the water intake area, they can accumulate at the filtration equipment of the seawater pump station, disrupting cooling water circulation, prompting the operator to take shutdown and power reduction measures.

This is the second time this month that the plant has adjusted unit operations due to jellyfish accumulation. On August 10, large numbers of jellyfish entered the seawater intake circuits of Units 3 and 4, causing continuous clogging of filtration equipment and failure of cooling water circulation pumps. Units 4 and 3 automatically tripped at 19:38 and 19:56 that day, respectively. The incident did not affect facility safety, personnel health, or the surrounding environment. EDF reported the event to the French Nuclear Safety and Radiation Protection Authority on August 14 as a Level 0 event on the International Nuclear Event Scale.

Among them, Unit 3 was reconnected to the grid on August 18 but was subsequently shut down again due to a new wave of jellyfish accumulation; Unit 4 also experienced an automatic trip during its restart on August 22 due to abnormal temperatures in equipment related to the turbogenerator set.

EDF has deployed monitoring systems around the water intake channels and filtration equipment, and has arranged for seven fishing vessels to continuously harvest jellyfish near the plant, transferring them to offshore areas away from the facility. EDF stated that this round of unit operation adjustments poses no risk to the supply of France's power system.