On August 10, 2025, four reactors at the Gravelines nuclear power plant in northern France were shut down due to a swarm of jellyfish clogging the cooling systems, as reported by operator EDF.

EDF assured that these shutdowns did not compromise the safety of the installations, the security of personnel, or the environment, although the plant was already offline for maintenance on two other units.

Gravelines is the largest nuclear power plant in Western Europe, featuring six pressurized water reactors, each with a capacity of 900 megawatts, and is preparing to host two next-generation reactors with a capacity of 1600 megawatts by 2040.

The specific jellyfish species causing the blockage is currently under investigation, and while it remains unclear when the reactors will restart, a gradual return to operation is anticipated.

This incident raises concerns about the impact of marine life on nuclear energy operations, especially in the context of climate change.

Although the incident did not pose a threat to safety or the environment, it highlights the unintended consequences of heat pollution associated with nuclear energy.

The jellyfish overwhelmed the filtration systems designed to keep debris out of sensitive equipment, triggering safety protocols to prevent damage.

EDF expects the affected units to restart by August 14, 2025, and reassured that there is no risk of a power shortage, as other energy sources remain operational.

Despite the shutdown, EDF emphasized that the incident does not impact electricity supply, as other plants can compensate for the loss, particularly during the lower summer electricity demand.

The increase in jellyfish populations has been attributed to warming waters and invasive species, such as the Asian Moon jellyfish, first observed in the North Sea in 2020.

While jellyfish do not pose a danger to humans, they represent an additional challenge for coastal infrastructure in a warming climate.

The plant is located near beaches that have become popular among migrants attempting to cross into Britain, but the jellyfish species involved are not harmful to humans.