Electricite de France has shut down the Golfech-2 nuclear reactor in southern France, citing "Environmental Issues" as the cause, the company said on Thursday.
According to the utility's site notices and operational disclosures, the planned outage is scheduled from July 29 until August 8.
The planning and duration of the shutdown remain subject to reassessment depending on upcoming weather and hydrological forecasts, it added.
Many of France's nuclear facilities rely on river water for cooling systems before discharging the warmed water back into local waterways. A severe heat wave has pushed temperatures higher across parts of Europe.
Strict environmental regulations limit these thermal discharges when river temperatures are already elevated, forcing operators to reduce output or halt reactors entirely to protect aquatic ecosystems.