What you'll see there is as you'd expect if you understand how fission power plants work and how economics works for electricity supply. The nuclear plants may not be running at what is notionally 100% nameplate power output but they are not in fact being used as a "buffer option" very much.
That big yellow-green splodge on the "Origin 24 hours" chart? That's nuclear power. Varying, maybe +/- 2GW , but nowhere close to enough to offset France's varying power requirements over the course of a day.
France's (much fewer) gas turbines are much more able to spin up and down quickly to benefit from transient utilization and so they, together with the interconnects possible due to France's relatively central location (the UK to the West, Germany to the East, Spain to the South) allow it to manage well on most days without tinkering with the power efficiency of the fission generators.
I am glad I will able to put to rest this common misconception about nuclear power ramping up speed. While it's a common rebuttal argument against nuclear, it's rather incorrect since nuclear power is actually able to ramp up fast enough. Moreover, French nuclear stations are typically older than they should and newer ones could move even faster. But better than Germany's
Anyway, enough empty talk and here is a real world use case from West Europe the 19th of march 2019, lots of wind a sunday. I should translate the whole thing for everyone one day.
All I see there is consumption %s. I think your thoughts about marginal power usage seem reductive.
Of course, immediately your marginal power will be by gas turbine. However if power increases overall, wouldn't sustained power usage force an increase nuclear baseload? The overall GW output of nuclear has varied YoY substantially.
The section you apparently didn't scroll down to, "Origin of electricity in the last 24 hours" shows you exactly what I described.
The chart you've offered is denominated in TWh, thus energy not power, because it is cumulative over an entire year rather than showing marginal power. So you end up concluding that if a nuclear power station is closed for two months for repairs, or a new one is brought online those somehow constitute energy "flexibility".
https://www.electricitymap.org/zone/FR
What you'll see there is as you'd expect if you understand how fission power plants work and how economics works for electricity supply. The nuclear plants may not be running at what is notionally 100% nameplate power output but they are not in fact being used as a "buffer option" very much.
That big yellow-green splodge on the "Origin 24 hours" chart? That's nuclear power. Varying, maybe +/- 2GW , but nowhere close to enough to offset France's varying power requirements over the course of a day.
France's (much fewer) gas turbines are much more able to spin up and down quickly to benefit from transient utilization and so they, together with the interconnects possible due to France's relatively central location (the UK to the West, Germany to the East, Spain to the South) allow it to manage well on most days without tinkering with the power efficiency of the fission generators.