Yes and france depends on other countries for its incapability to quickly vary production. In other words the nuclear fleet of France has a significantly higher

Yes and france depends on other countries for its incapability to quickly vary production. In other words the nuclear fleet of France has a significantly higher capacity factor than the average demand of the french grid because it can push power to other countries. If that did not exist the french nuclear power would be a lot more expensive (uranium is not free!) Power demands fluctuate as do power generation capabilities. If your generation is inflexible, as nuclear and solar both are at this time (economically speaking right now in this year). You need quick reaction power (e.g. gas peakers) or e.g. pumped hydro. The funny thing is a wholly nuclear grid needs storage as much as a full solar+wind grid does. Of course in a mixed grid both techs can play to their strengths. For example in Lazard's 10.0 LCOE analysis solar plus battery is 92 USD per Mwh, while Nuclear starts at $97. That is smack in the middle of LCOE coal costs! But the solar, will have a lot less of regulatory and construction uncertainty! And a much smaller financial risk. As 3 years from project start to completion is normal. With most projects being set up in independent financial contracts of about 100mw nameplate to allow cancellation if performance or market do not materialize.