Earlier quoted context omitted.
Powering the world (all energy, not just the grid, and not just the grid in the US) with PWRs won't work, because we run out of cheap uranium too quickly. Breeding is needed for sustainable use of nuclear.
Incorrect, we have plenty of uranium both terrestrially and through seawater extraction: https://www.forbes.com/sites/jamesconca/2016/07/01/uranium-s... Sure seawater extraction is more expensive. But procuring raw uranium is a tiny fraction of nuclear's cost. You'll see statistics saying nuclear fuel is a significant cost, but most of that expense is from enrichment not extracting raw uranium.
Uranium is a small fraction of nuclear's cost at current uranium prices. But eventually that runs out, and the price of uranium would increase dramatically. This has always been the motivation for breeders.