[SteveGregory]

Nuclear is the only technology that sufficiently solves the heat problem.

Lots of our energy is spent on heat, whether residential or industrial.

Nuclear produces heat. If only we used this for district heating, container ships, and electricity

[pjc50]

I'm not sure I'd trust lowest bidder flag of convenience ships operating beyond national law to operate a reactor safely without ever dumping radioactive material in the only ocean we have.

[dredmorbius]

To say nothing of the 200 or so ships lost at sea every decade. Not evenly distributed across the oceans, but concentrated in sea lanes, especially near ports and land, especially choke points such as straits, capes, and canals.

The scale of operations, with ~80,000 registered commercial large ships, regulation of an international activity dominated by lowest-cost, least-regulated, flag-of-convenience registries (as you note), very often minimally-trained, and very disempowered crews (authoritarian / high-gradient socio-economic-political power discrepencies play a role in numerous accident dynamics), training, and scrapping practices all put a distinct chill in that notion.

[pjc50]

I'm reminded of https://en.wikipedia.org/wiki/SS_Richard_Montgomery : 1,400 tonnes of explosives sunk in the Thames estuary. At least it's safeish as long as nobody touches it. The couple of nuclear reactors in subs that have already sunk are I believe in deep distant water, losing one inshore would be a serious problem.

[dredmorbius]

Nuclear submarines tend not to congregate in and/or near shipping lanes, as a general rule.

Their role in commerce is limited.

[dredmorbius]

... the point being, for nuclear-powered merchant traffic, that that does congregate near shipping lanes. Increasing consequent risk.

[i_am_proteus]

Biofuels are a much simpler carbon-free option for ships. Cargo ships are built and scrapped, made to last only a few decades. Powering them with nuclear would be insanely cumbersome and expensive.