Jellyfish Invasion Forces Shutdown of Three Reactors at Gravelines Nuclear Plant

Electricité de France (EDF) has shuttered three reactors at the Gravelines nuclear power plant in northern France after a massive influx of jellyfish choked the facility’s seawater pumping stations. Reactors 2, 3, and 4 were stopped completely, while the production capacity of unit 1 was slashed by 50%.

A Partial Shutdown of Western Europe’s Largest Plant

Only reactor 6 remains fully operational at 100% capacity. In a statement published on its website, EDF clarified that the situation does not impact the safety of the plants, the personnel, or the environment.

As the largest nuclear power plant in Western Europe, Gravelines relies on seawater for cooling; when jellyfish flood the pumping systems, they obstruct the water flow essential for reactor operations.

A Recurring Seasonal Crisis

This is not an isolated event. A similar incident struck the same plant one year ago, when four reactors were forced to shut down automatically due to a jellyfish influx. Recovery then was a slow process, with the final reactor returning to the national power grid approximately 10 days later.

While jellyfish along the northern French coast are a regular seasonal occurrence, the scale is shifting. An expert cited by Il Messaggero last year noted that reports of large swarms in this specific area every summer are becoming more frequent.

The Toll of Rising Ocean Temperatures

The proliferation of these swarms is tied to global environmental shifts. Il Messaggero attributes the increase to factors including rising ocean temperatures driven by climate change.

Compounding Failures in the French Grid

The jellyfish invasion arrives as French nuclear energy faces a broader trend of operational instability. Calculations based on EDF data published since 2015 show that France experienced a nuclear energy deficit of 15.6% on a recent Sunday, triggered by droughts and heatwaves.

According to Il Messaggero, France has never seen such a significant loss of nuclear energy caused by reduced flow rates and rising river temperatures.