This stuff is easy to find. Wiki is a simple start.
This was one of the keys I used to unlock myself from the PO panic. When you spend time researching this, checking it, crossreferencing it, finding the experts and talking to them, you realise that PO, even if it's now ( it ain't ) isn't a desperate problem.wiki wrote: The IAEA estimates that using only known reserves at the current rate of demand and assuming a once-through nuclear cycle that there is enough uranium for at least 100 years. However, if all primary known reserves, secondary reserves, undiscovered and unconventional sources of uranium are used, uranium will be depleted in 47,000 years.  
The OECD estimates that with 2002 world nuclear electricity generating rates, with LWR, once-through fuel cycle, there are enough conventional resources to last 270 years. With breeders, this is extended to 8,500 years.
If one is willing to pay $300/KgU uranium, there is a vast quantity available in the ocean.
* Kenneth S. Deffeyes
Deffeyes estimates that if one can accept ore one tenth as rich then the supply of available uranium increased 300 times. His paper shows that uranium is log-normal distributed. There is relatively little high-grade uranium and a nearly inexhaustibly large supply of very low grade uranium.
* Huber and Mills
Huber and Mills believe the energy supply is (effectively) infinite and the problem is merely how we go about extracting the energy.
* Bernard Cohen
In 1983, physicist Bernard Cohen proposed that uranium is effectively inexhaustible, and could therefore be considered a renewable source of energy. He claims that fast breeder reactors, fueled by naturally-replenished uranium extracted from seawater, could supply energy at least as long as the sun's expected remaining lifespan of five billion years. - whilst uranium is a finite resource mineral resource within the earth, the hydrogen in the sun is finite too - thus, if the resource of nuclear fuel can last over such time scales, as Cohen contends, then nuclear energy is every bit as sustainable as solar power or any other source of energy, in terms of sustainability over the finite realistic time scale of life surviving on this planet.
We thus conclude that all the world’s energy requirements for the remaining 5×109 yr of existence of life on Earth could be provided by breeder reactors without the cost of electricity rising by as much as 1% due to fuel costs. This is consistent with the definition of a “renewable” energy source in the sense in which that term is generally used.
* Ernest Moniz
But the basic premise of reuse is open to question, said Ernest J. Moniz, a professor at the Massachusetts Institute of Technology and a former deputy United States Secretary of Energy.
He told the group that most of the thinking on reusing the fuel dated from decades ago, when uranium was thought to be scarce. But now, “roughly speaking, we’ve got uranium coming out of our ears, for a long, long time,” Professor Moniz said