Nuclear fission

In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into two or more smaller, lighter nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay.

This process is used to create electricity in nuclear power stations.

A natural nuclear fission reactor is a uranium deposit where self-sustaining nuclear chain reactions have occurred. The phenomenon was discovered in 1972 in Oklo, Gabon, and this is still the only known location for this in the world. It consists of 16 sites with patches of centimeter-sized ore layers. Here self-sustaining nuclear fission reactions are thought to have taken place approximately 1.7 billion years ago, and ran for a few hundred thousand years, averaging probably less than 100 kW of thermal power during that time.