EDF Heat Curbs Strip 6.7% of French Nuclear Capacity After St Alban 2 Extension
Heat-driven output cuts deepened at St Alban 2 on Thursday (2026-07-09), extending restrictions beyond their planned window and pushing French nuclear losses to a summer high.
EDF extended and widened a production cut at its St Alban 2 reactor on Thursday (2026-07-09), pushing heat-related nuclear curtailments across France's fleet to 6.7% of total installed capacity, Montel reported.3
The St Alban 2 unit had been running under an 885 MW output restriction due to expire at 15:45 CET. Instead, EDF increased the cut to 1,075 MW and extended the end time to 18:30 the same afternoon, leaving the reactor generating at just 260 MW through the afternoon demand period on Thursday (2026-07-09). Both the depth of the cut and the restoration window shifted in the same move: deeper restrictions and a later end point than the market had been pricing.3
Summer heat forces periodic curtailments at French nuclear stations by constraining cooling water discharge temperatures. Thursday's (2026-07-09) 6.7% figure covers the entire fleet: multiple units operating under simultaneous restrictions, with the St Alban 2 extension adding to an aggregate shortfall that had already built up across several plants.3
EDF also cited its Chooz 2 unit, rated at 1.5 GW, in connection with current production constraints, Montel reported. Together, the St Alban 2 and Chooz 2 restrictions show that Thursday's (2026-07-09) capacity losses are not confined to one reactor.3
When French nuclear supply falls, the gap flows through European power and gas markets. France draws more power imports or burns more gas to cover domestic generation, tightening the continental gas balance in a market already running warm this summer. ICE Endex TTF front-month traded at €50.51 on Monday (2026-07-13), up 11.90% on the day. German day-ahead power reached €107.73, a gain of 3.89%. NBP UK gas front-month rose 2.38% to €47.16, as European power and gas markets priced elevated summer supply risk.
The curtailments come as EDF's long-term capacity plans remain under European Commission scrutiny. The EC opened a formal investigation in May (2026-05-19) into France's proposal to build six new reactors with combined capacity of 10 GW at an estimated cost of EUR 73bn, Montel reported. France's economy and energy ministry said talks with Brussels over the subsidy scheme would last "the coming months."1,2
Whatever the outcome of those negotiations, new reactors are years from delivery. The existing fleet is what EDF must work with this July. The speed with which St Alban 2's restriction deepened from 885 MW to 1,075 MW in a single afternoon, without returning to full output, shows how quickly aggregate losses accumulate when heat is broad.3
The immediate market question is whether these restrictions hold or expand. If St Alban 2 restored output close to the 18:30 CET extended deadline on Thursday (2026-07-09), the loss registers as short-duration. Sustained temperatures through July and August would keep similar constraints in place at additional stations. Chooz 2, at 1.5 GW, is the next unit to watch: how EDF handles its output over the coming week will show whether Thursday's (2026-07-09) 6.7% figure marks the season's ceiling or a point on the way to a larger cut.3