Models showing the fission of uranium 235.

This is a model illustrating the fission of uranium 235. When atoms of uranium 235 are bombarded with neutrons, they break up into two parts, releasing energy and secondary neutrons. If a sufficient number of atoms is bombarded, enough neutrons escape to cause a self-sustaining chain reaction generating huge amounts of energy. Rapid fission allowed the development of the atomic bomb, while fission in controlled circumstances enabled the production of nuclear power. This 'ball-and-stick' model was made over forty years ago in the Museum's own workshop. It was used for exhibition to illustrate the fission process.