[berkes]

They can be slowed down. True.

But that takes minutes or hours to do. And on anything but 100% power, the fuel innefficiency is bad. That latter is mostly a problem with coal, but even nuclear is burning fuel and costing wear.

Plants can be optimized to react really fast, or run efficient on lower capacity, or run efficient on max capacity. Choose one.

[lightgreen]

There’s no need to change power output rapidly. Power demand can predicted very well. Sorry, I didn’t understand your argument.

[Lyrex]

You're right that power consumption is predictable. But looking at some great-parent posts I'd assume we're still talking about using nuclear as backup for renewable sources. In this case, often the renewable power production is the bigger variable factor in my opinion, and it's less predictable than usage patterns.