All civilian nuclear plants (hither-to) are rube-goldberg systems that are best thought of as one-off designs. There's a mile of red-tape and oversight because...well...Electricity generation in the USA is a private enterprise, and capitalism is a bottom-dollar-on-investment activity which results in Home Corporate cutting corners wherever they think they can get away with it.

A monument of why there are so many protections and oversight now in place....is in Blair, Nebraska. That plant is shutting down and closing its doors...

https://en.wikipedia.org/wiki/Fort_Calhoun_Nuclear_Generating_Station

They discovered that those calculations from the 60′s had errors ... also some of them are missing, and then some of them are just plain incomplete. But Omaha Public Power District admits ... that there were "incorrect and incomplete or missing calculations. There were inconsistencies between the calculations and the drawings. There were incomplete considerations of all load combinations and there were simple numerical errors."

That kind of crap is why things have become how they are. Fortunately, in spite of the screwups, nothing terrible and exciting and BREAKING NEWS worthy has ever happened as a result.

Funding is another problem....before operation can begin, the owners need all of the money needed for decommissioning. Why? So that taxpayers don't get caught holding the check when Home Corporate tries to dissolve itself and reverse-incorporate their way out of paying.