Oklo ഖനികൾ in ഗബോണ്: ഒരു സ്വാഭാവിക nuclear chain reaction

First time when humans launched a nuclear chain reaction was in 1942, in Chicago. But there is one place on Earth where nature itself launched a natural ആണവ reactor ചില 1.8 - 1.7 billion years ago - Oklo ഖനികൾ in ഗബോണ്, ആഫ്രിക്ക.