K.J.Healey said:
How many reactors would have to be built to replace 100% of our (USA's) consumption of oil as a power source (non auto)?
To give you an idea, France went "totally nuclear" in about 20 years time: they started mid-seventies, and they were about finished mid nineties. They now have about 58 PWR running, and that's good for about 80% of the total electricity consumption (and a lot of spare power to help the Germans when they have problems

).
Now, taking that the PER CAPITA economic muscle of the US right now is certainly not less than France's was in the 80-ies, it should take the US about the same or less time to do the full conversion.
Given that in the US about ~100 reactors (most of them rather old!) generate 20% of the electricity consumption, 5 times more should do the thing, and the PER CAPITA effort - which didn't ruin France at all - shouldn't be unbearable. Of course, there might be some delay in getting the industry capable of such an output up and running.
Economically, the US has without the slightest bit of doubt the muscle to do a total nuclear conversion. Hell, your Irak war would already have bought you about 500 reactors! And the price of the reactor is about the total price: on the life time of a reactor, the fuel cost is about 5% of the total cost...
As others pointed out, there will be a shortage of fresh uranium ore in about 50-100 years, which is about exactly the time scale needed to have a large deployment of breeders, which can extract about 100 times more energy from the "waste" than has already been extracted. The technology exists already since about 50 years, btw, the very first US power reactor WAS a fast breeder. But one has to improve upon the total security, cost and reliability of these systems, and 40 years of research/devellopment is largely sufficient.
So this is about the next best thing after renewables: reuse your waste and be happy for a few 1000 years. No more geopolitical bickering to get to the ressources, you have them already in your waste bins!
In France, they want to have their first prototype fast breeder (after Superphenix, shot down by the Green boys in the 90ies) up and running beginning of the 2020ies, to be able to switch to large scale production around 2040.