Plutonium

AP

Cost: Roughly $4,000/g

What do you do with it: Make nuclear things. There are two kinds of plutonium, according to the World Nuclear Association, weapons grade and reactor grade.

The first is recovered as a by-product of typical used fuel from a nuclear reactor, after the fuel has been irradiated ('burned') for about three years. The second is made specially for the military purpose, and is recovered from uranium fuel that has been irradiated for only 2-3 months in a plutonium production reactor. The two kinds differ in their isotopic composition but must both be regarded as a potential proliferation risk, and managed accordingly.