Plutonium

Plutonium (pronounced /pluːˈtoʊniəm/) is a rare radioactive, metallic and toxic chemical element. It has the symbol Pu and the atomic number 94. It is a fissile element used in most modern nuclear weapons. The most significant isotope of plutonium is 239Pu, with a half-life of 24,100 years. It can be made from natural uranium. The most stable isotope is 244Pu, with a half-life of about 80 million years, long enough to be found in extremely small quantities in nature, making 244Pu the nucleon-richest atom that naturally occurs in the Earth's crust, albeit in small traces.[1]

The isotope 239Pu is a key fissile component in nuclear weapons, due to its ease of fissioning and availability. The critical mass for an unreflected sphere of plutonium is 16 kg, but through the use of a neutron-reflecting tamper the pit of plutonium in a fission bomb is reduced to 10 kg, which is a sphere with a diameter of 10 cm. The Manhattan Project "Fat Man" type plutonium bombs, using explosive compression of Pu to significantly higher densities than normal, were able to function with plutonium cores of only 6.2 kg.[7] Complete detonation may be achieved through the use of an additional neutron source (often from a small amount of fusion fuel). The Fat Man bomb had an explosive yield of 21 kilotons.

The UNSC uses Plutonium in fission reactors, and in a number of nuclear weapons, ranging from the small Fury Tactical Nuclear Weapon, to the devastating NOVA Bomb, as well as in their warship reactors.