Natural nuclear reactor in Gabon

It only worked because the natural abundance of U-235 was significantly higher two billion years ago. We cannot replicate this naturally today because the isotopic ratio has decayed.

If we define nuclear power as a controlled process for energy utility, would this be better classified as a spontaneous geochemical event? The lack of a containment or conversion mechanism makes the label of power a bit loose.

The reaction only persisted because groundwater acted as a neutron moderator. Once the heat boiled the water away, the reactor shut itself down.

QuietOptimistQi·1 day ago

That self-regulating cycle is quite hopeful. It shows that nature has a built-in kill switch for these types of reactions.