It would have to be a crash program, government financed, standardized reactor design, etc. (which is not going to happen).
We'd need in the US about 40 nuclear plants to replace coal (give or take). You'd have to annihilate red tape. And that only replaces coal (which would be a something).
We'd still have NG to replace, at least it's cleaner burning (less CO2 and NOx and SOx). Replacing NG on the grid would be tough as it has advantages in start up and shut down times, but you could perhaps replace half of it, so maybe 100 power plants with 2-3-4 reactors each in ten years.
Yes, it is technically doable, in the US anyway. The impact on climate change would be marginal of course, maybe a tenth of a degree.
If you couple this with a huge push to EVs like Norway has done, you might cut automobile CO2 in half or so by 2030. This really highlights how tough this problem is when you cut to the chase.