Two billion years ago, a natural nuclear reactor formed in a uranium deposit in Africa.Why is it not possible for such a natural reactor to form somewhere on Earth today? A)It is in fact possible for this to occur. B)Too much uranium has already been mined for this to occur. C)Too much ²³⁵U has now decayed for a critical mass to form naturally. D)The remaining uranium deposits are too far underground for this to occur. E)Uranium in the remaining deposits is mixed with too many other elements for this to occur.

Question

Quizplus · Accepted Answer

Uranium undergoes radioactive decay over time, decreasing its concentration and making it less likely that a critical mass could be formed naturally. This means that it is no longer possible for a natural nuclear reactor to form on Earth today.

Two Billion Years Ago, a Natural Nuclear Reactor Formed in a Uranium