It takes about five years, lots of concrete = lots of CO2 emissions, to build a 1GW reactor. You'd need to complete about one per week for the next 35 years to replace ONE-SEVENTH of the energy we now get from fossil fuels. (Pascala and Socolow, Science pdf
2004) (Stanford pdf
on implementing sustainable energy.) Finish one reactor per week. Good luck with that.
And if you managed that, you'd run out of fuel for those reactors within a couple of decades. (Don't start with the but-but thorium!
, or fusion, or god-knows-what-all. The testing and permitting on new tech would take us way past peak oil.)
You'd have to take care of the expected waste, plus the unexpected waste from accidents, for ever.
Meanwhile, Germany is implementing soloar and energy efficiency and is AHEAD of its targets.
The more time, effort, and money we waste chasing nukes, the less we have for a real solution.