Sadly enough the first thing I thought of was what if pirates take control of one these ships? Now a bunch of armed bandits are holding a nuclear reactor hostage at sea. There is even some incentive to never return it but disassemble it and sell it to terrorist organizations.
I agree with you, I don't like the prospect of pirates getting their hands on a nuclear reactor.
I'm aware however that even if they did, a terrorist (or terrorist organization) can't make a bomb out of a reactor. Heck, they'd most likely get themselves killed if they tried to fiddle with the core of a reactor. But let's say they kidnap a super-genius scientist/engineer and hold a gun to their hands and ask them to make a bomb. Even then, the genius scientist wouldn't be able to make one. The uranium in a reactor is low enriched; the minimum enrichment to make a nuclear bomb is 20%, and this design limits uses uranium enriched to at most 17.25%. One can claim that a terrorist can further enrich the uranium, but if they can do that, they can start from natural uranium, why would they wait to get their hands on reactor uranium? The other possibility is to try and refine the Plutonium-239. But in a reactor, the Pu-239 gets mixed with Pu-240, and making a bomb out of such a mix is not impossible if you are the US military, but is very likely out of reach for a terrorist organization.
The more worrisome scenario is if Iran hijacks some of these ships.
This will (hopefully) never happen. The Egyptians will surely not let a 100 nuclear reactors sail through their country every day. But maybe they will and the next Evergiven will be the Everradiant.
