So designing a ship from scratch with a reactor that doesn't exist that would cost at minimum well over double what existing entire ships cost which uses high e

So designing a ship from scratch with a reactor that doesn't exist that would cost at minimum well over double what existing entire ships cost which uses high enriched fuel that almost as much in raw natural Uranium as existing (filthy) bunker fuel and then sending that high enriched Uranium (which will have a high percentage of chemically separable plutonium unless you refuel yearly at enormous expense and downtime) all over the world, without security or oversight, managed by an industry that cuts costs and breaks laws constantly is a better plan than... Changing some emissions control equipment, enlarging the fuel tank a little and giving them ammonia when they dock?