But then, after decades of trying to perfect safe and easy nuclear power, scientists discovered that a fully operational nuclear reactor had been safely chugging away under the West African dirt, long before humans came along. This sounds like something that would turn up in an outlandish documentary about stuff built by aliens, but the most remarkable thing about it is that the Oklo mine reactor in Gabon is completely natural.
Back in the 1970s, the French were mining uranium out of Gabon when they came upon the strange discovery that what they were digging up was depleted uranium (the waste from a nuclear plant) and even plutonium (which doesn't exist in nature -- ordinarily). After ruling out a secret West African nuclear program, scientists were forced to conclude that a kind of natural nuclear reactor had assembled itself in the uranium deposit and provided power for meerkat cities for millennia.
"Don't make us angry. You wouldn't like us when we're angry."
This reactor, assembled by nature due to random chance, generated the equivalent of about 100 kilowatts of electricity, got hot enough to boil off nearby groundwater, and consumed more than five tons of uranium before it shut itself down millions of years ago. Somehow, all of the elements just fell together to form a natural, self-regulating nuclear plant, and it kept running for 150,000 years.