Oklo, the Two Billion Year Old Nuclear Reactor

Scientists discovered that the Oklo mine in Gabon, Central Africa, had less Uranium-235 than expected, leading to the realization that it was the site of a natural nuclear reactor from 2 billion years ago. This reactor operated under specific conditions, with Uranium-235 and neutrons present, and groundwater acting as a moderator to control the reaction. The cycle of reaction and cooling continued for hundreds of thousands of years until the uranium was depleted, leaving behind evidence of this ancient natural phenomenon.

What was the concentration of Uranium-235 that the French scientists expected to find in the ore from the Oklo mine?

What conditions did the uranium deposits at the Oklo mine fulfill that allowed for a natural nuclear reactor to exist?

How did groundwater contribute to the control of the nuclear reaction at Oklo?

What was the average ongoing power output of the natural nuclear reactor in the Oklo area?

What ultimately caused the natural nuclear reaction at Oklo to stop?