There is absolutely no reason that nuclear propulsion can’t work for most ships and even trains. The current size of submarine propulsion could be made to fit them. It’s been done for decades. After that, how about semi tractors?
“There is absolutely no reason that nuclear propulsion can’t work for most ships and even trains.”
Countries don’t allow them into their ports.
I guess the rub is ensuring they survive a crash without hurting a lot more people.