Billion-year-old Nuclear Reactors

From the Astronomy Picture of the Day, it’s the remnants of a two-billion-year-old nuclear reactor discovered in 1972 in a mine in Oklo, Gabon. Apparently in the old days there was enough uranium-235 in the Earth’s crust that, under the right conditions, nuclear fission could occur naturally. Over time the fuel was used up, and … Continue reading Billion-year-old Nuclear Reactors