RTE (Reseau de Transport d'Electricite)
France's national electricity transmission operator, ensuring grid balance during nuclear heatwave curtailment.
Last refreshed: 20 July 2026
Why did France's grid operator insist two Bugey reactors keep running through the heatwave?
Timeline for RTE (Reseau de Transport d'Electricite)
Required minimum Bugey 4 and 5 output as a public necessity for grid security
European Energy Markets: France cheaper on a waiver ending todayBackground
RTE, France's electricity transmission system operator, told the nuclear regulator ASNR it needed minimum output from Bugey reactors 4 and 5 to keep the grid secure through the July 2026 heatwave. That justification, recorded in ASNR's own derogation order as a "necessite publique", is what allowed the reactors to keep running under a relaxed Rhone thermal-discharge limit from 10 to 20 July.
RTE was carved out of EDF in July 2000 to meet EU rules requiring transmission to be legally separated from generation, becoming a standalone limited company through further legal acts in 2004 and 2005. It remains majority owned by the EDF Group and the Caisse des depots, and operates roughly 100,000 kilometres of high-voltage lines, the largest transmission network in Europe.
The Bugey call is one of many RTE makes each summer when heatwaves push cooling-water limits and demand into conflict at the same time. Golfech 2, Bugey 3 and Chooz 2 shut fully in the same mid-July window on river-cooling limits, with several other units curtailed to reduced power, underlining how much of France's nuclear fleet RTE has to actively manage rather than simply dispatch.