The cost of building a plant with old technology is high. That's because it's been over-regulated and because it's old tech.

Newer plant designs will be cheaper to build and simpler. They will need to be regulated differently as a matter of course because they're fundamentally different designs.

What you're saying here is that building a 1960s nuclear power plant design with modern regulation is expensive, which is true, but that's like saying that driving a 1955 Ford Thunderbird is expensive when compared to a Tesla S. That's true, but you're comparing apples and rocks, here.