French nuclear output cut by heatwave

European Union — Europe's fifth heatwave this summer is expected to limit French nuclear power production by about 15% of the nuclear fleet's total capacity on Friday, with six reactors expected to be fully offline, according to operator Électricité de France. Total nuclear curtailments are expected to reach 9.4 gigawatts at the peak on Friday across nine reactors. The heat-related outages, combined with regular maintenance, technical issues, and fuel saving, are expected to put some 27.7 GW of nuclear power offline on Friday, the lowest level of nuclear availability since August 2023, according to London Stock Exchange Group Power Research. Low nuclear production paired with limited wind output lifted power prices, with the French day-ahead contract for Friday the highest since June 23, up 4.4% at €154.50 per megawatt hour, according to London Stock Exchange Group data. The nuclear shortfall also ripples across borders, forcing countries like Britain and Germany to turn on coal and gas plants to replace reduced exported nuclear power. France relies on nuclear power for about 70% of its annual electricity production. French rules limit how much heat plants can discharge into rivers for environmental protection, forcing reactors to cut output when water temperatures rise during heatwaves. Thursday is expected to be the peak of the current heatwave, with temperatures between 35 and 40 degrees Celsius in most regions, according to France — Météo-France. Despite the continued outages, nuclear power production in France increased in June and July compared to the previous year as Électricité de France has reworked its nuclear fleet maintenance schedule. Two of the jellyfish-hit nuclear reactors at the Gravelines plant are expected to remain offline for several more days.