Extreme weather, jellyfish knock one-fifth of France's nuclear capacity offline

France on Wednesday recorded a more than 20 percent shortfall in nuclear power production capacity, a record deficit caused by environmentally related outages linked to drought, extreme heat and a jellyfish invasion.

France uses nuclear power to generate around 70 percent of its electricity. The country has seen nuclear power production disrupted by multiple heatwaves and droughts this year.

According to AFP calculations based on data published by energy group EDF since 2015, 20.4 percent of generating capacity was unavailable.

Between 9:45 a.m. and 10:00 a.m., EDF's nuclear fleet recorded a new peak in outages due to "environmental constraints" or "external environmental causes," both in terms of the number of reactors shut down or operating at reduced output and in terms of lost generating capacity.

In total, 13 of the 57 reactors in EDF's nuclear fleet were affected. Eight reactors were completely shut down while five were operating at reduced power.

Much of the lost nuclear generating capacity was due to full or partial shutdowns at five of the six reactors at the Gravelines nuclear power plant after a swarm of jellyfish clogged pumps used to cool the units.

Experts say overfishing, plastic pollution and warming seas due to climate change have created conditions allowing jellyfish to thrive and reproduce.

Outside the Gravelines plant, the largest in Western Europe, the shutdowns or production reductions affecting other reactors are linked to extreme heat and droughts, depriving the plants of the water they need for cooling.