That’s not why they don’t do it, it’s because it’s way too expensive. That fact alone precludes it from being used on cargo ships.

Now ask yourself this: do I want vessels flagged in the countries with the least regulations and the most corruption to be run by a for profit maritime shipping company that skimps on maintenance budgets and crew costs to be running nuclear reactors with highly enriched uranium (weapons grade) anywhere they want around the world, even through pirate territory?

Fuck No I don’t. I barely trust the nukes running them in the USN!