Plutonium

Definition

Plutonium is a rare transuranic radioactive constituent. It is an actinide metal of silvery-white look that tarnish when uncovered to air, forming a dull covering when oxidized. The element usually exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and silicon. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that can impulsively ignite.

Application

The isotope Pu-239 is a key fissile part in nuclear weapons, due to its effortlessness of fission and accessibility. Encasing the bomb's sphere of plutonium in a tamper decrease the quantity of plutonium needed to arrive at critical mass by reflecting escaping neutrons back into the plutonium core. This reduce the quantity of plutonium needed to reach criticality from 16 kg to 10 kg, which is a sphere with a diameter of about 10 centimetres (4 in).