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.