[Yo-Yo]

A fleet of such cargo ships would DOMINATE the world shipping lanes, because per-unit shipping costs would be sharply lower, and speed of transport could be conceivably somewhat quicker, as turnaround at the port is limited only by loading and unloading capabilities - no refueling time for YEARS.

And would be targets of terrorists for decades who wanted to get ahold of nuclear material for dirty bombs. Or just make the cargo ship a dirty bomb and blow the reactor while unloading in Long Beach, CA.

[hoagy62]

In 1962, the US did actually try a nuclear-powered cargo ship....

Why Did The NS Savannah Fail?

(They didn't really even worry about terrorists using the Savannah for nefarious purposes back then. AFAIK, only the Russians use nuclear power in any capacity for civilian ships, and I believe it's exclusively with icebreakers.)