https://www.nytimes.com/2009/02/18/us/18nuke.html
> "The rule, approved by the commission in a 4-to-0 vote, requires that new reactors be designed so their containment structure would remain intact after a plane crash, cooling systems would continue to operate and spent fuel pools would be protected."
You can't risk a failure in the primary cooling system, and since reactors need active cooling in the event of a regional grid power failure just to avoid core meltdown, you need onsight power generation capable of running the cooling loop 24-7 (failure in this system led to the Fukushima explosions). These systems (from cooling loops to steam generators) are under constant stress and have relatively high maintenance costs (a major factor in the closure of California's San Onofre reactor).
Then you have to add in the cost of the uranium fuel rods, which is a complex supply chain issue in many countries (the recent coup in Niger has shut down 1/3 of France's uranium ore supply chain for their reactors, say news reports). Uranium supplies are limited and historically uranium prices get volatile when it seems a reactor boom is coming (look at right before Fukushima). Then you have the long-term costs of spent fuel treatment and secure storage, and eventual reactor decommissioning.
I really don't see anyway to reduce these costs such that nuclear will be anywhere near cost-competitive with today's solar/wind/storage complexes, that are entirely capable of producing reliable 24/7 grid power at costs well below that of a comparable nuclear power plant in most locations.