As an add on to that - if nuclear energy did start becoming mass produced in the developed world where some modicum of safety/regulation around waste can be assumed, once all of the necessary reactors are built out to supply first world energy needs, at best, those same private developers/contractors will start lobbying efforts in more questionable parts of the world to build these things. Then it be framed as an equity issue - why is the first world preventing the rest of the world from catching up - even though its actually just a plain "it's not safe to build it in a country in the middle of a civil war".

The more likely scenario I would envision is that - under the guise of business "joint venture partnerships in next generation energy" - the technological know how and access to a steady stream of the requisite raw materials to build weapons will leak to more questionable parts of the world.