US conducts limited nuclear test

[hunter]

6. Plutonium is tricky stuff.

Our military leaders want to see how well the cores of our nuclear weapons are holding up, to reassure themselves old bombs still work.

Plutonium normally has six allotropes and forms a seventh (zeta, ζ ) at high temperature within a limited pressure range. These allotropes, which are different structural modifications or forms of an element, have very similar internal energies but significantly varying densities and crystal structures. This makes plutonium very sensitive to changes in temperature, pressure, or chemistry, and allows for dramatic volume changes following phase transitions from one allotropic form to another. Densities of the different allotropes vary from 16.00 g/cm3 to 19.86 g/cm3.



http://en.wikipedia.org/wiki/Plutonium

If the density and geometry of the plutonium core has changed too much since the bomb was manufactured then the bomb fails; instead of incinerating everything for miles around it simply contaminates the area with radioactive waste. The bomb scientists conducting these tests are trying to figure out how much spontaneous recrystallization of these plutonium bomb cores is acceptable so they can develop timetables for refurbishing or remanufacturing bombs.

Too bad we don't simply dismantle all the bombs and use them to make nuclear fuel for electric power plants. So long as this weapons grade plutonium exists (and there are hundreds of tons of it) somebody will be making bombs.