The AP1000 was a new design when Vogtle 3 and 4 were planned. It was certified by the NRC in 2005. NuScale had its small modular reactor design certified by the NRC just a couple of years ago:
If you mean that the NRC holds back designs that are more exotic than plain old light water reactors, maybe so, but that isn't relevant to the "looming power crisis" mentioned by bpodgursky up-thread. Light water reactors are the most affordable and fastest to build everywhere in the world. Pressurized heavy water reactors (like CANDU) are also mature designs. Everything else is slower and more expensive to build, with very limited operational history compared to the dominant water based reactor designs.
https://www.energy.gov/ne/articles/nrc-certifies-first-us-sm...
If you mean that the NRC holds back designs that are more exotic than plain old light water reactors, maybe so, but that isn't relevant to the "looming power crisis" mentioned by bpodgursky up-thread. Light water reactors are the most affordable and fastest to build everywhere in the world. Pressurized heavy water reactors (like CANDU) are also mature designs. Everything else is slower and more expensive to build, with very limited operational history compared to the dominant water based reactor designs.