Comment by quotemstr
Submarine reactors run on super high enriched fuel instantly one could instantly repurpose into a bomb. Lots of gen 4 and 5 reactor designs that combine low cost, compact footprint, and running on less expensive and carefully controlled fuel.
French have some LEU submarines. They seem to be pretty good on paper. Needs refueling every ten years.
https://en.wikipedia.org/wiki/Suffren-class_submarine