They're run exclusively by militaries, which have notoriously liberal budgets and conservative operational safety. Shipping merchants reverse both tendencies. Nuclear isn't safe by its nature, nuclear is safe in the right hands and horribly catastrophic otherwise.
It's a big difference whether the boat the reactor is on has guns and is run by a military or whether it's a random private enterprise without guns. You don't want enriched uranium like it's used in nuclear submarines to fall into the wrong hands.
The kind of fissile stuff being proposed for most forward-deployed reactor designs is not useful for weapons. The biggest danger is blowing up the reactor itself, causing it to be a type of dirty-but-conventional bomb, a non-nuclear (fission/fusion) blast.
This is true on average, but of the available nuclear technologies, reactors used on ships and subs have the highest enriched uranium (making them inherently more dangerous just as a target of non nuclear nations). I believe they are also responsible for a large number of accidents, although when those occur, the affected personnel are usually limited to the crew.
That statistic is extremely misleading because it completely ignore systemic risk. And it does not account for environmental damage.
Additionally, it is not based on nuclear reactors on rusty cargo ships run by cash-strapped companies. Those companies are notoriously hiring the cheapest workforce they can find and dodging regulations in any way they can.
And you would trust them never to leak some radioactive coolant in the ocean?
Security is not much of a concern. An attempt to seize the ship means you can failsafe the reactor and drop it to the bottom of the ocean. Pirates and lesser nation-states won't have the resources to recover it.
You've got to be kidding. Low paid commercial crews are subject to bribery, and often don't even keep a close watch for security threats. Plus no nation state will allow a nuclear powered merchant vessel into port if there's a risk of a damaged reactor getting dumped into their waters.
It's just totally unrealistic, the kind of thing that only a programmer with zero time on the water would propose.
Unless you're actually boarded, why would you drop the reactor? The point is that a hypothetical commercial shipping reactor would have to be a self-contained, intrinsically safe design with no user-servicing - this is the sort of design pebble-bed reactors the general modular reactor concept points towards.
The idea is that the reactor is mounted at the bottom of the hull, basically only provides electricity out as a "black box". It's not reachable by the crew from inside the ship, and gets a set of failsafe charges which cut it loose from the ship if it becomes unhappy about it's situation - i.e. if its GPS signal is cut for too long, if it strays from it's geofence boundary, or if someone tries to breach it's location in the ship.
Even if you paid off the crew, they don't have control over the powerplant. Fairly obviously you wouldn't want to leave a reactor on the seafloor, but if it drops itself then like a blackbox it triggers a sonar beacon and whoever commissioned it (presumably a well-regulated US firm) would respond to collect it.
But in the scheme of things, that’s fine. There are several nuclear subs and munitions at the bottom and there aren’t reports of terrible radiological effects.
Nah, we all know that there are dozens of entities out there who would _love_ to publish the "Sunk US sub causing elevated radiation levels!" article. The incentive is high. So the absence of the report does mean something.
The right metric is deaths/TWH. Nuclear is the safest by a wide margin, 1000x safer than coal. [1]
[1] https://ourworldindata.org/safest-sources-of-energy