EDF shuts Nogent and Bugey reactors as heatwave pushes cooling rivers above legal limits
4 GW goes offline, 6% of French nuclear capacity, as Seine and Rhone temperatures breach discharge thresholds; RTE grid stress warning already in force
Summary
EDF shut two nuclear generating units on June 25 as the Omega heatwave drove cooling-river temperatures above legally permitted discharge limits. Nogent-sur-Seine, on the Seine about 110 km south of Paris, and Bugey, on the Rhone near Lyon, were taken offline, removing 4 GW of baseload, roughly 6% of France's installed nuclear capacity. Grid operator RTE had already issued a supply-stress warning covering the June 25 peak demand window. France sends around 15% of its electricity production to neighbouring grids, particularly Belgium, Italy and Germany.
Why it matters
France is the largest nuclear exporter in Europe and the marginal baseload supplier to Belgium, Italy and Germany during heat events. Losing 6% of nuclear capacity at peak demand forces RTE to absorb the gap with gas-fired peakers and curtail cross-border exports, directly pushing up TTF spot prices and tightening the margin between supply and demand for the continental EU Grid.
What to watch
- Whether Bugey and Nogent return to service before the forecast heat-dome break this weekend, when demand eases but river temperatures lag.
- TTF day-ahead and intraday price moves Thursday evening and Friday.
- Whether a second-tier EDF plant along the Loire or Rhone breaches discharge thresholds as the heat lingers.