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The world's first nuclear reactor is prehistoric
史前核反應堆
It's not easy to create a controlled nuclear reaction in power plants, but the nature had created the world's first nuclear reactor two billion years before humankind, beneath the surface of Oklo in Gabon, Africa. This natural reactor formed when a uranium-rich mineral deposit came in contact with groundwater, which slowed the neutrons ejected from the uranium so that they could interact with and split other atoms. Heat was produced, turning the water to steam, thus temporarily slowing the chain reaction. The environment cooled, water returned, and the process repeated. Scientists estimate that this prehistoric reactor ran for a hundreds of thousands of years, producing the various isotopes expected from such reactions.
在發電廠要控制好核反應可不是件容易的事，但是自然的鬼斧神工在人類出現的兩百萬年前就已經制造出了世界上第一次的核反應堆，位于非洲加蓬的奧克洛地區的地下。這一地區富含鈾礦，當鈾元素與地下水接觸后，就會減緩鈾釋放出中子，這樣它們就可以相互作用并分裂出原子從而產生熱量，使水變成蒸汽，暫時放慢連鎖反應的速度。當溫度下降后，蒸汽又變成了水，這一過程重復進行。科學家預計這一史前核反應持續了上百萬年，并從中釋放出了大量同位素。
