Heatwaves Force French Nuclear Plants to Cut Output, Straining European Power Grid
Record-high river temperatures have forced French nuclear reactors to reduce output by up to nine gigawatts, prompting temporary drops in electricity exports.
During the June-July 2026 heat wave, French nuclear plants faced high river temperatures and reduced water flow, leading operators to limit output by eight to nine gigawatts, roughly one-fifth of normal summer capacity. Despite the cuts, grid operators reported sufficient reserves for France to continue exporting electricity, though exports fell to around three gigawatts from the usual 10-12 gigawatts. The reductions stem from legal limits on water temperature to protect aquatic life, prompting temporary throttling rather than emergency shutdowns.
Similar challenges have affected Hungary's Paks plant, where low Danube levels threatened a full shutdown. France plans to improve heat resilience through new coastal reactors and cooling-tower designs, but such upgrades will require significant investment and land. The episode underscores the growing influence of climate-related water scarcity on nuclear power and European energy stability.
Why it matters
Heat-driven limits on nuclear output can tighten electricity supplies and raise prices across Europe.
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