That like-for-like, accounting for negative externalities in all alternatives, nuclear isn't that much more expensive.
Nah, wind and solar are much cheaper, they just aren’t great for providing base load, without some other storage. Nuclear is very good at base load but makes a bad peaker (and is expensive). Gas is also “cheaper” when you ignore externalities, which most places do.
Well, sure, oranges are cheaper than apples, but that doesn't help me much when I want to make apple pie.
I strongly advise against putting fissible materials in your apple pie.
If you wish to make an apple pie from scratch, you must first invent the universe.