Nuclear Bomb Chain Reaction
The video below shows the reaction that occurs to create a nuclear explosion, or in more controlled circumstances, to create nuclear power for an electricity generating power plant.
The isotope used in the video below is Uranium 235, it has a half-life of 700 million years and can be found reasonably abundantly in nature, as opposed to other radioactive isotopes that have to be made by undergoing nuclear fission.
Some nuclear bombs have a smaller bomb inside them, the purpose of this smaller bomb is to decrease the volume taken up by the uranium, this ensures that the uranium is at critical mass by compacting the original material into a smaller space, when the uranium has reached critical mass, the chain reaction can begin.
Depleted uranium is used extensively by the military in weaponry, it is a very dense material, several times more dense than lead, and as a result is very good as an armour piercing ammunition, usually tank piercing.
Naturally formed Uranium must be enriched by isotope separation – it usually contains a majority of Uranium 238 and only a small percentage of Uranium 235, Uranium 238 is not fissile so this percentage needs to be increased before the Uranium is pure enough for nuclear fuel or a nuclear weapon.
The Uranium 238 that is left over after the enrichment process is the depleted Uranium mentioned above, it is considerably less radioactive but still very hazardous in granular form.
The international atomic energy agency tries to control and monitor any enrichment of Uranium, as it may be used for either power generation or a weapon. Below is a video showing the reaction process involved in a nuclear detonation –