The restrictions are more to do with the size of the ship, not it's propulsion mechanism.
Routinely, US Submarines and Aircraft Carriers (all powered by nuclear reactors) sail into normal civilian ports around the world for various reasons.
[1] https://news.usni.org/2016/09/27/n-z-chief-navy-u-s-nuclear-...
The restrictions are more to do with the size of the ship, not it's propulsion mechanism.
Routinely, US Submarines and Aircraft Carriers (all powered by nuclear reactors) sail into normal civilian ports around the world for various reasons.