Chooz
French nuclear power plant on the Meuse River, subject to river-cooling curtailment during 2026 summer heatwaves.
Chooz's two 1,500 MW reactors on the Meuse went offline on 12 July 2026 when river-cooling water breached EDF's discharge limit, one of the sites behind EDF's fleet-wide curtailment reaching 7.6 GW by 3 August.
Last refreshed: 3 August 2026 · Appears in 1 active topic
Could summer heat force France to throttle down its Meuse nuclear reactors?
Timeline for Chooz
Mentioned in: River heat cuts 7.6 GW off EDF's fleet
European Energy MarketsFrance cheaper on a waiver ending today
European Energy MarketsStayed offline; restart slipped to 25 July
European Energy Markets: EDF slips three reactor restarts to late JulyFrench heat flips the FR-DE spread
European Energy MarketsEDF adds Chooz to the curtailment list
European Energy MarketsBackground
Chooz is a French nuclear power station on the Meuse, in the Ardennes near the Belgian border, run by EDF. Its two operating reactors, Chooz B1 and B2, are 1,500 MW pressurised water units of the N4 design, the immediate precursor to the EPR, commissioned in 1996 and 1997.
The site replaced Chooz A, France's first pressurised water reactor at 305 MW, run jointly with Belgian utility SENA from 1967 until its 1991 shutdown; decommissioning of its reactor vessel began in 2016.
As a river-cooled plant, Chooz sits alongside Blayais, Bugey, Golfech and Saint-Alban on EDF's list of sites exposed to summer heat, a vulnerability formalised when EDF added Chooz to its curtailment warning list on 9 July 2026. French nuclear baseload, long treated as weather-proof, is becoming a variable that can tighten repeatedly as river temperatures rise.
Heat curtailment keeps taking it offline
EDF took both Chooz reactors offline on 12 July 2026, alongside Golfech and Bugey, after Meuse cooling water breached the plant's discharge limit during the summer's second heat dome. The station had been added to EDF's curtailment warning list only three days earlier, on 9 July.
Chooz's restart then slipped to late July, part of a wider delay across three reactors confirmed on 14 July. By 3 August, EDF's fleet-wide river-heat curtailment reached 7.6 GW, its steepest cut of the heatwave, with an easing forecast from 4 August.
Reference
What is Chooz nuclear power station?
Where is Chooz nuclear power station located?
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Why did EDF add Chooz to its heat-curtailment list?
