And the technology is incredibly mature, submarine reactors were some of the first reactors, period.
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.
And they are heavily guarded.
In the current political climate I prefer energy sources that don’t cause severe damage if sabotaged.
Did you hear the worries in Ukraine that Russia could hit a wind turbine with a rocket?