> as there are no containerized nuclear reactions that I know of.

Even if you built one, as some people have proposed designs, it doesn't get you nuclear reactors you can just stack up on a ship or something. Containerized reactors could be convenient for getting a reactor to a remote site where it's needed but once there you'll have to provide substantial shielding for it; usually the way this is meant to be done in these proposals is digging a big hole and/or putting up earthen berms around it. And those earthen berms will be subjected to a lot of neutron radiation, so you need a plan to deal with the site after you run this reactor for any substantial amount of time; the whole site will be radioactive.

There's really no getting around this, and most of the people pitching container-sized nuclear reactors are hoping investors don't realize it. The amount of shielding that you could ever hope to place in an ISO container isn't anywhere near enough.

You can use the reactor in the open ocean where shielding is not a big deal, and switch to conventional fuels when needed.

Nuclear submarines and aircraft carriers already exist in pretty good numbers.