[adrianN]

With nuclear you have the option of running the reactors at 50% peak and produce energy at approximately twice the cost per kWh.

[ta1243]

That's it. If you need to have nuclear capacity for a grid for say 30GW, despite average usage being just 10GW, your price is now $300/MWh rather than $100/MWh if you can run them 24/7