EDF kept Bugey 3 (900 MW), Golfech 2 (1,300 MW) and Chooz 2 (1,450 MW), 3.65 GW in all, offline through 14-16 July and slipped their restart dates to 19, 22 and 25 July 1. All three now fall past the 20 July Bugey heat exemption the desk flagged when the units first came down on 12 July . EDF is France's state-owned nuclear operator, Europe's largest, and these reactors sit on rivers whose water it uses for cooling.
French law caps the temperature of water discharged back into rivers at 28C to protect aquatic life, and in a heat dome the intake is already too warm to run a reactor at full load without breaching it. EDF is running a further seven units at reduced output under the same limit. No amount of demand can override the rule; the reactors stay down until the rivers cool or a temporary exemption is granted, and this time the exemption dates arrived after the restarts.
That matters because French nuclear normally sets the cheap leg of the Continental clearing price. With 3.65 GW frozen out and more curtailed, the fleet that usually exports into Germany is instead leaning on its own margin, which is what turns the cross-border spread erratic in the next event.
