PARIS: France's main energy provider said on Sunday (Jul 12) that three nuclear reactors had been temporarily shut down and eight others were operating at reduced power, due to the heatwave sweeping the country.

"Due to the weather conditions and to comply with regulations on (cooling water) discharges, and thus to protect the environment," reactors at the Golfech, Bugey and Chooz plants, located on the banks of the Garonne, Rhone and Meuse rivers respectively, have been shut down, energy group EDF said.

The measure is an environmental protection requirement to avoid discharging too much hot water into rivers already warming from the heatwave.

Power plants critical to the country's electricity production use river water to cool their reactors, which heats the water that is then released back into the river.

SECOND SHUTDOWN IN WEEKS

The economy ministry on Saturday issued an exemption to the temperature limits for the heating of the Rhone around the Bugey plant "to ensure the security of the power grid", valid until Jul 20.

The shutdowns are the second time in recent weeks that EDF has had to stop nuclear reactors due to extreme heat, after a record-breaking heatwave hit France in June.

On Sunday, the third heatwave to sweep the country since May saw more than a third of France under the national weather service's highest heat alert.

More than 25 million people were experiencing temperatures that forecasters said could reach up to 41 degrees Celsius (105.8 degrees Fahrenheit), according to an AFP tally based on population data.

The heatwave has forced tourist hotspots to shut early, led to event cancellations and shortened a stage on the Tour de France. Wildfires have proliferated and deaths by drowning have spiked amid the heat.

Since the end of May, France has been hit hard by repeated episodes of intense heat, which have caused excess mortality and exposed problems with infrastructure maladapted to extreme weather, the increasing frequency of which scientists have linked to man-made climate change.