A record 20.4 percent of generating capacity is unavailable due to environmental constraints, including a jellyfish invasion that clogged pumps at Western Europe's largest nuclear power plant.
On August 12, 2026, France recorded a shortfall of more than 20 percent in its nuclear power generating capacity, a record deficit caused by environmental disruptions linked to drought, extreme heat, and a jellyfish invasion. According to calculations by the AFP news agency based on data from the energy group EDF, as much as 20.4 percent of generating capacity was unavailable, the highest level since 2015.
Between 9:45 and 10:00 a.m. local time, EDF's nuclear fleet saw a new peak in outages due to "environmental constraints" or "external environmental causes." In total, 13 of the 57 reactors in France's nuclear fleet were affected, with eight reactors completely shut down and five operating at reduced power.
A large portion of the lost capacity is attributed to full or partial shutdowns at five of the six reactors at the Gravelines nuclear power plant, the largest in Western Europe. There, a swarm of jellyfish clogged the pumps used to cool the reactors. Experts point out that overfishing, plastic pollution, and rising sea temperatures due to climate change have created conditions favorable to the proliferation and blooming of jellyfish populations.
Outside Gravelines, outages or production cuts at other reactors are linked to extreme heat and droughts that deprive plants of the water needed for cooling. In 2026, France has faced multiple heatwaves and dry spells that have continuously disrupted nuclear power generation, on which the country heavily relies-nuclear energy covers about 70 percent of total electricity production.
This development highlights the growing vulnerability of France's nuclear sector to the impacts of climate change, as the very plants meant to be key to the low-carbon transition are increasingly exposed to extreme weather conditions that hamper their operation.
