I recently learned about the existence of a natural nuclear reactor in Oklo (Gabon – see Image), from a physics podcast and was amazed to learn that this reactor was active until about 1.5 billion years ago. It was discovered in 1972 by French physicist Francis Perrin.
“It came as a great surprise to most, therefore, when, in 1972, French physicist Francis Perrin declared that nature had beaten humans to the punch by creating the world’s first nuclear reactors. Indeed, he argued, nature had a two-billion-year head start. Fifteen natural fission reactors have been found in three different ore deposits at the Oklo mine in Gabon, West Africa. These are collectively known as the Oklo Fossil Reactors.”
U.S. Department of Energy
Office of Civilian Radioactive Waste Management
Yucca Mountain Project