EIA figures for 2011:

EIA pictorial data
Note that nuclear electric power is 8% of total
and it costs us about 80 tons of actual fissile fuel and fission product waste in a year. See below
Nuclear power, fourth generation, could supply ALL of the energy the USA uses.

Fissile fuel actually used in PWR reactors

50 million lbs of Uranium Oxide, U3O8 From EIA tables
That's 25 thousand short tons.
For  238U and  16O that has 21,200 tons of actual uranium.


Now the fissile isotope 235U is 0.7% of natural uranium.
So for 1000 tons of uranium, you have 7 tons of the fissile isotope. In 21,200 tons, there's just under 150 tons of fissile uranium!
Notice that the nuclear electric energy from that tiny quantity of resource is more than twice what hydroelectric power produces, and also more than the sum of all the more recently introduced "renewable" sources.

A Pressurized Water Reactor (PWR) runs with uranium "enriched" to 3.6% of   235U
To make the calculation easy, consider how we get 1000 tons of enriched U . Start with 8000 tons of natural uranium, the depleted fraction D will be 7000, enriched E, 1000. To get 3.6% in the enriched fraction (E), we need 36 tons of fissile isotope in fraction E.
E starts with 7 tons, D with 49.
The enrichment process, which centrifuges a gas of uranium hexafluoride, takes 29 tons from the 49 in D, which ends up with 20. The depleted fraction becomes 0.25%   235U.

Besides the fission caused by neutrons, neutron capture by   238U in the reactor creates fissile plutonium,   239Pu, which is also fissile. This is called a breeding reaction. The plutonium behaves like the fissile uranium, providing about a third of the total energy. So that requires about half as much mass as the fissioned   235U. Rounding up 3.6% of 21,200 tons, there's 100 tons total of   235U, so at 50% burnup, 50 tons of uranium is fissioned, and 25 tons of   239Pu joins it.
Burnup at 50% means there cannot be as much as 50 tons of Pu left over.
Estimated total mass fissioned: 75 tons total for 8% of all USA energy. Let's say less than 80.
Actual fission product nuclear waste is the same.
Total plutonium "waste" is less than 50 tons, 30 seems more likely.

All the rest is unused uranium, and it's "richer" in   235U than the natural metal. Uranium and plutonium are chemically similar enough that it should be not too difficult to devise a chemical way to separate part of the uranium with all of the plutonium at a concentration that is far below bomb grade, but useful for reactors of the IFR type.

A breeder reactor, such as the IFR. which was canceled "because it wasn't needed!" in 1994, is designed to recycle, breed, and burn up all the uranium and plutonium. So from the above, for breeder reactors to supply 100% of the total energy EIA reports for 2011, would take 80 times 100/8 tons.
That's 1000 tons, of natural uranium, needing just enough enriched uranium to start the reactors.