Peak uranium is a problem that will occur eventually with nuclear fission based power, just as with the current discussion of the problem of peak oil. Indeed, this problem occurs with any fuel, regardless of its apparent availability - even with nuclear fusion, there is only a finite amount of tritium and deuterium available for it. A time will come when the supply of economically viable reserves of fissionable material will drop below the demand, driving the price sky-high, and creating yet another piece in the energy crisis puzzle.
 When will it happen?
The concept is mentioned on peak oil sites, with the implicit assertion that this event will happen in the near future. Simple calculations tend to support this view. However, they do not take into account that most of Earth's geography has not been explored for uranium yet, and that reserves are defined in terms of the market price of uranium - when uranium prices rise, reserves expand, because it's now economical to extract lower grade deposits and exploration intensifies. Experts from MIT say that the reserves of uranium are so large that uranium availability is not going to be a problem in the next century, even if many new reactors are built around the world.
Current nuclear power reactors can utilize less than 1% of the energy contained in uranium (heavy-water reactors such as the CANDU extract roughly 0.7% of the uranium's energy-content and the light-water reactors more commonplace in Europe, Asia, and America extract roughly half a percent, mainly because they all use solid fuel pellets which allow highly neutron-absorptive fission-products to accumulate until their neutron absorption exceeds the number of new neutrons introduced by fuel fission). Alternative designs, such as breeder reactors and the molten salt reactor, can utilize a greater percentage of this energy. Breeder reactors can utilize nearly 100% of this energy, by optimizing the transmutation of uranium-238 into plutonium. Some breeder reactors can also utilize thorium by transmuting it into uranium-233; thorium is roughly three times as abundant on Earth as uranium. Several fully functional prototypes of various breeder reactors were built. If these technologies are widely adopted, the problem of peak uranium will be delayed for many thousands of years, by increasing the available amount of nuclear fuel by two orders of magnitude.
The peak can also be significantly delayed by reprocessing spent nuclear fuel to recycle remaining fissionables (which form up to 90% of spent fuel by weight and volume). This not only reduces waste, but also hugely reduces the volume of high-level nuclear waste which must be handled and stored, and slightly reduces the risk of storing it (as spontaneous and induced fission no longer contributes to the heat of the waste). The mixed-oxide fuels that result can also incorporate significant amounts of weapons-grade plutonium — a practical way of reducing the planet's inventory of this unpleasant material and the accompanying nuclear security concerns.
 Unintended side-effects
As peak uranium approaches, the price of uranium for both nuclear and thermonuclear weapons will also increase. While this could be offset by other fissionable materials, the eventual peak will still occur, causing nations to choose between weapons of mass destruction and energy for their people (and/or military).
- PeakOil.org - Is there enough uranium to run a nuclear industry big enough to take over from fossil fuels?
- Note: this article doesn't get all the facts right, for example "complete decommissioning of old reactors has scarcely begun" - Connecticut Yankee is an example of a reactor that was successfully decommissioned.
- Power for U.S. From Russia’s Old Nuclear Weapons
- ↑ Or, for that matter, any mined resource. The Hubbert curve, though usually cited in connection with oil, has also been invoked for copper, iron, and phosphates, as well as many other metals whose depletion is less threatening to technological human society. It is intuitively obvious that harvesting any resource in excess of its renewal rate (which is effectively zero for most mined resources) will produce a Hubbert curve; the question is whether available data enable meaningful predictions of future supply trends.
- ↑ MIT releases major report: The Future of the Nuclear Fuel Cycle
- ↑ WNA: Supply of uranium