Nobody said it would be as cheap as solar. But "renewables" can't fulfill ALL power needs ALL the time.
When you actually need to generate electricity rather than gather it, what's better than nuclear?
When you actually need to generate electricity rather than gather it, what's better than nuclear?
So you can build expensive nuclear plants for that small fraction of the time, or you can continue to use existing fossil fuel plants for free. The difference to the carbon bottom line is small.