Why can't we use an affordable safe/competent reactor design from 30-40 years ago, and stamp that out at scale, rather than building a "new" model that results in failure?
You can't examine the differences in project management and execution while the project is still on paper. You have to commit years and billions of dollars to determine if a project is going to adhere to the original plan or blow out on time and/or money.
Right now South Korea has the best track record of rapidly, affordably building reactors. Some American nuclear proponents think that we should just have South Koreans build Korean reactor designs here, to bypass the apparently irremediable problems in the domestic nuclear industry.
But even the smooth progress of South Korean reactor builders is not assured when they are building outside of Korea.
The Barakah Nuclear Power Plant, built by Koreans with Korean reactors, just powered up its first reactor days ago.
https://en.wikipedia.org/wiki/Barakah_nuclear_power_plant
The timeline from construction start to operation was originally 5 years. It has actually taken 8 years. It's 60% over the time originally scheduled, even though it is using a standard reactor design built by the most competent reactor builders currently available.
(In addition to what pjc50 said.)
edit: Never mind. The system inherits elements from a design used in the Palo Verde NPP near Phoenix, AZ
Probably know how to handle the heat...
However, they're also the main type of reactor that actually got built and works.