Nuclear isn't uncompetitive due to some inherent technological reason. It's uncompetitive due to overregulation and gold plating.
Solar used to be completely uncompetitive, but improvements in technology and increases in scale made the economics work. Nuclear got kneecapped before that could have a chance of happening.
Compare a nuclear project to a solar panel. Solar is cheap, simple, commoditised, flexible, and is riding on almost miraculous learning curves. If dispatchable energy can be solved, beyond just gas/coal plants, ideally with long-duration storage based on the conversion of electricity, then this is going to be an infinitely better option. It's also just not clear what role nuclear plants have given that renewables need highly dispatchable power to ramp up and down according to their variable output, not baseload nuclear power.
Is there a study that identifies which regulations are unnecessary and how much removing them would save?
This is an oft repeated point by pro nuclear folk, but it’s not true. There are many regulatory regimes all over the world, and new nuclear is competitive in effectively none of them. Even in single party state china with few regulations , nukes are a declining share of total power every year.
They’re just giant big complex pieces of machinery. With huge ongoing security, insurance and deferred decommissioning costs.
That's the go-to nuclear apologist argument, but it doesn't hold water. Nuclear is struggling globally, even in China. That points to inherent problems. Regulation also doesn't explain why costs have been so widely underestimated. That's a function of dishonesty of the cost projections, not of regulation.
I'll add that regulation is the price you pay for implicit subsidy like government insurance against accidents. You don't get the latter without the former.