Depends if nuclear includes decommissioning and clean-up costs.
Do you really want lakes full of residual waste for the next few tens of millennia?
The UK currently has no idea what to do with a lot of its waste. So it's simply left to rust and ferment in water - not a good outcome.
Sustainable intermittency turns out to be something of a myth anyway. Intermittency effects across Europe turn out to be negligible.
So instead of building nukes, you can spend the money on mixed-mode sustainables and a hugely improved distribution grid and get a cleaner and more reliable outcome overall.
You can also make sustainables distributed, and run them on a domestic scale as well as an industrial one.
PV roof installations have worked well in Germany and are starting to work well in the UK, even though neither location is known for being sunny.
You'd get much better results in the sunnier parts of the US.
UPower is a fast reactor. 99% of nuclear waste, and almost all long-term waste, is transuranics, which fast reactors use as fuel. What remains is the fission products, which go back to the radioactivity of the original ore in a couple centuries. Encase them in glass and bury them, and you're good.
Helion is a fusion reactor. Its "waste" is helium, and it uses a reaction that produces only 6% of its energy as neutron radiation.
In both cases the reactor itself may become somewhat radioactive, but that's another short-term problem.
