At some date in the future, we may decide to reprocess the waste to extract valuable materials.
I bet 100 years in the future or somthing, we may decide to dig up Yucca mountain for cheap fuel, putting the (mostly) uranium waste into breeder reactors.
On a side note: Thorium, a common radioactive metal found in such things as camping lantern mantles, can be put in a special breeder reactor and converted into very fissionable U-233. Thorium is three times as common as uranium, so energy from such a plentiful fuel is very attractive. The East Indians already have a small test thorium breeder reactor.
Also: Regular uranium breeder reactors.
One of the main costs of nuclear energy production currently is getting the fuel. Uranium, a metal that is cheaper than silver, is mined out of the ground. Now, over 99% of naturally occuring uranium is U-238, a non-fissionable isotope worthless as a fuel. Only a fraction of 1% is U-235, a fissionable isotope. To make a fissionable fuel, you have to increase the U-235 content to around 5%.
So they have to seperate two isotopes of the same element, which is difficult. A common way of doing this is to vapourize the uranium, and enlessly use centrifuges to increase the U-235 concentrations.
However, there is a better way: If you have a reactor core surrounded by U-238, neutrons from the reactor core can transmute it to Plutonium-239! However, only fast neutrons can jostle the uranium enough to turn it into Pu-239. So fast breeders have no boron rods to slow the neutrons, as in ordinary reactors. Paradoxily, fast neutrons aren't very good at sustaining a nuclear reaction. So, to keep the reaction going, you need a high concentration of U-235, around 15-30%. However, the plutonium produced in these fast breeder reactors can be used to fuel them, thereby eliminating the need to use expensive concentrated U-235 fuel. Fast breeders usualy use liquid sodium or water as a coolant.
The french already have had a large liquid sodium fast breeder in service since 1984. It's the Super-Phenix
, a reactor that produces 20% more fuel than it uses.(That link also has other info on fast breeders) The French hope to build even more breeder reactors.
If regular reactors were replaced by breeder reactors, the need to mine uranium would be almost non-existent.
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