EDF Holds 1.9 GW Offline as Rhone Restrictions Outlast the Heat
Three percent of France's nuclear fleet remained curtailed on 2 July despite cooler air, with river temperatures on the Rhone keeping environmental limits in force.
EDF curtailed around 1.9 GW of French nuclear generation capacity on Thursday (2026-07-02) morning, or roughly 3% of the country's fleet, even as air temperatures receded from extreme highs seen in late June, Montel reported, citing the utility's Remit transparency data.3
River cooling constraints, not ambient heat, are now driving the shortfall. The 1.3 GW St Alban 2 reactor on the Rhone was running 115 MW below full capacity under environmental restrictions set to lift at 00:11 CET on Friday (2026-07-03). The 910 MW Bugey 3 unit, also sited on the Rhone, remained offline. Both plants face the same regulatory logic: French law requires EDF to reduce output when river temperatures exceed thresholds designed to protect downstream ecosystems, regardless of grid conditions or dispatch economics.3
The lag matters because it extends the supply gap beyond what weather alone would predict. River temperatures recover more slowly than air temperatures after a heatwave, meaning restrictions at Rhone-sited plants can persist for days after conditions feel manageable at weather stations. Getting from the peak curtailments recorded in late June down to 1.9 GW is progress; reaching zero requires the Rhone itself to cool.3
The market read-through is visible in gas. ICE Endex TTF front-month was trading at €43.73 on Thursday (2026-07-02) morning, up 1.77% on the session. The move partly reflects gas generation continuing to fill residual demand that French nuclear would normally cover at low marginal cost. France is a large net exporter of baseload power; when nuclear availability falls, neighbouring markets must absorb the shortfall through gas-fired generation, lifting European hub prices in the process.3
ICE EUA Dec-rolling held at €79.54 on Thursday (2026-07-02) morning. The carbon market's response to the nuclear shortfall has been modest, partly because the heatwave simultaneously suppressed industrial activity and lifted cooling demand, leaving the net impact on gas-fired generation — and thus EUA demand — less clear-cut than a straightforward nuclear outage might imply.3
EDF's Remit data as of Thursday (2026-07-02) showed St Alban 2's restriction ending at 00:11 CET on Friday (2026-07-03); Bugey 3's return date was not specified in the available data. Weather forecasters in May (2026-05-21) had anticipated that France would see frequent cooling rainfall after thunderstorms this summer, which they said could reduce the risk of sustained nuclear output disruption. Whether that pattern materialises through early July is the variable the grid is now waiting on.3,1
EDF's 2025 annual results, published in the first half of 2026, highlighted strong operational performance and positive cash flow, reducing net financial debt. Thermal stress events nonetheless complicate availability forecasts for a fleet whose reactors are concentrated along rivers that warm quickly in sustained heat.2
River temperature data for the Rhone at Bugey and St Alban is the immediate signal to track. If readings drop fast enough to clear the regulatory thresholds before the Friday (2026-07-03) deadline, St Alban 2 could return to full output on schedule and Bugey 3 could receive earlier clearance than current Remit data implies. If Rhone temperatures stay elevated into the weekend, the St Alban 2 restriction may be extended and Bugey 3's return could slip further, keeping French nuclear availability below seasonal norms and TTF's gas-burn support in place into next week (week of 2026-07-06).3