Don't ask me, go do your own research if you really want to learn about this. It's a complex topic.
I agree that nuclear should have it's place in a modern energy grid for the time being, but the skepticism towards renewables from nuclear proponents is also not right. It may have been justified twenty years ago, but the world is different now.
The thing is that there's isn't one answer to how to smooth out renewable production, making it harder to mentally model than a simple "just build nuclear".
I'm going to just give a few ones that you need to take together:
* You don't need pumped hydro. There's a massive yearly 650 TWh of hydro in Europe, which can serve as a "virtual battery" by using it only when other renewable sources are low. The same, to a lesser extent, is true for bio-methane.
* Electricity is just about 10% of primary energy. The other 90% contain many sources of demand that are extremely amenable to load shifting. Cars, heating, to name two massive ones.
* Short term variations in renewable output (i.e, anything shorter than seasonal) can be smoothed by batteries, eventually. Not today, but, like PV, battery cost is on a staggering exponential decline.
* The EU has an integrated grid, nuclear will continue to be used in all European countries at least indirectly through imports.
From a high level economic perspective: The low and declining cost of a kWh PV provides a massive economic incentive to solve this.