At three ore deposits at Oklo in Gabon, sixteen sites (the so-called Oklo Fossil Reactors) have been discovered at which self-sustaining nuclear fission took place approximately 2 billion years ago.
En minas en Oklo (Gabón) descubríronse dezaseis lugares (chamados Oklo Fossil Reactors) no que tiveron lugar fisións nucleares hai aproximadamente dous mil millóns de anos.