- Nuclear waste is the material that nuclear fuel becomes after it is used in a reactor. It looks exactly like the fuel that was loaded into the reactor -- assemblies of metal rods enclosing stacked-up ceramic pellets. But since nuclear reactions have occurred, the contents aren’t quite the same. Before producing power, the fuel was mostly Uranium (or Thorium), oxygen and steel. Afterwards, many Uranium atoms have split into various isotopes of almost all of the transition metals on your periodic table of the elements.
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| Thorium |
- The waste, sometimes called spent fuel, is dangerously radioactive, and remains so for thousands of years. When it first comes out of the reactor, it is so toxic that if you stood within a few meters of it while it was unshielded, you would receive a lethal radioactive dose within a few seconds and would die of acute radiation sickness within a few days. Hence all the worry about it.
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| Used Nuclear Waste Pool |
- In practice, the spent fuel is never unshielded. It is kept underwater (water is an excellent shield) for a few years until the radiation decays to levels that can be shielded by concrete in large storage casks. The final disposal of this spent fuel is a hot topic, and is often an argument against the use of nuclear reactors. Options include deep geologic storage and recycling. The sun would consume it nicely if we could get into space, but since rockets are so unreliable, we can’t afford to risk atmospheric dispersal on lift-off.
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| Picture of Reactor Cooling Tower |
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