[moonshot925]

Yes. The upfront costs of nuclear power are enormous and the returns are very slow. But it leaves room for future upgrades like rail guns and laser CIWS.

[tanknetter]

But it leaves room for future upgrades like rail guns and laser CIWS.

Not necessarily. Nuclear reactors don't produce electricity (exception being spacecraft nuke plants, which produce very limited amounts of energy through atomic decay). They produce steam, which is used to spin turbines, which can be jacked into generators to produce electricity.

The ship, therefore, needs to be designed with a nuke plant big enough to create enough steam to both propel the ship (either through turbines hooked into the shafts/propellors through reduction gear, or into big electric engines in a turbo-electric setup) and to create enough electricity to power all the electronics, electricity-based weaponry, EM catapults, etc.

The more electric goodies you start tacking on to a design, the larger the electrical generation plant must be, which causes a cascading increase in the size of the steam-generating nuke plant. In a 65,000 tonne hull, that's going to create issues. Heck, it's creating issues in the older Nimitz-class ships as they get upgraded during RCOH (mid-life refueling overhaul), and one of the reasons why the EM catapults going into the Ford won't be backfitted onto the earlier ships. The existing nuke plants can't produce enough steam for everything ...