Nuclear fleet modulation: volumes doubled between 2019 and 2024
Published on 16 February 2026, EDF's report documents modulation rising from around 15 TWh to more than 30 TWh, now also during the day.
On 16 February 2026, EDF shared the main findings of a study devoted to the modulation of its generation fleet, designed to assess its industrial, organisational and social impacts.
Modulation refers to the ability of a generation asset to vary its output in order to contribute to balancing the power system. It is built into the design of EDF's assets, particularly nuclear ones, in order to allow flexible operation.
Volumes have risen sharply: between 2019 and 2024, nuclear modulation doubled, from around 15 TWh to more than 30 TWh. In 2025, the nuclear fleet modulated by 33 TWh.
The change also concerns timing. Historically, reactor output reductions occurred mainly at night and at weekends. They now also occur during the day, during periods of high solar generation. More frequently, modulation can lead to reactor shutdowns.
This trend directly illuminates the economic value of demand-side flexibility: every megawatt hour of consumption shifted towards hours of abundant generation correspondingly reduces the need to modulate decarbonised generation assets.