If we can operate submarines and aircraft carriers with nuclear, there is no reason why container ships and other cargo ships can't be nuclear powered. We could decarbonize the seas very effectively. It's not done simply because it is more profitable to use oil. 
Titanic but it irradiates the entire coastline from Madagascar to Singapore
With the proper reactors, it shouldn't be that bad. The Soviets had a bunch of nuclear sub accidents but they never caused a major ecological disaster.
I don't trust companies to not cut corners.
Yeah I'd want these to be nationalized too