Q. Oklo natural nuclear fission reactor is located in which country?
Answer: Gabon
Notes: Gabon has the world's only site known to have self-sustaining natural nuclear fission, at the Oklo reactor zones near the town of Franceville in the Haut-Ogooué province. The site was discovered in 1972, during French mining for uranium to supply nuclear reactors. Geologists noticed an unusually low concentration of uranium-235, leading to the current theory that the site was a natural nuclear reactor two billion years ago. Although the original Oklo Mine's resources are now depleted, 17 other sites have been found in the same region that once sustained nuclear fission. Half of the reactor zones lack carbonaceous material and in these locations, caesium, rubidium, strontium and boron escaped and were lost. However, in others, uraninite is encased in solidified two billion-year-old bitumen. Some geologists have suggested that this natural bitumen encasement could be a way of storing human-produced nuclear waste in permanent geologic disposal sites.