France has been doing fine with nuclear and hydro for decades (at least when scheduled maintenance doesn’t all happen at the same time). You can use dams as big batteries by pumping water back up when you have excess and nuclear production is actually fairly scalable up and down which ensures the peaks are never that big.
And yet, in France, RTE, the grid supervisor, itself subcompany of EDF who owns the nuclear plants, keeps publishing reports saying that if France does not up their solar generation there is no way the grid works in the future with increased demand volatility.
You can use dams to store renewable energy too.
That's the point. Some people says that renewable is intrinsically flawed because of intermittence. But at the grid level, we will need flexibility, aka storage, no matter what, which means that the intermittence problem is strongly reduced.
And, yes, nuclear plant can scale up and down, but: 1) they need to be designed to do so efficiently and some existing don't. Building a "flexible" nuclear to provide flat generation is uselessly expensive, building a "flat" nuclear to provide flexible generation is uselessly expensive. 2) nuclear, intrinsically, is good to provide flat generation, and scaling the generation up and down cost more money than building storage.
So, it is more efficient to build storage in case of a nuclear heavy grid. Sure, you have different way to solve the problem of flexible grid with nuclear, but you insist on one solution JUST because the other solution is not convenient for you because it is also positive for a grid containing renewable.