The "Natural" Nuclear Reactor
Have you heard of any natural nuclear reactors, other than stars? In Oxygen , Nick Lane talks about the one in Gabon (Africa), and how that came to be. But first, remember how fission bomb works? Uranium’s isotope, U-235 decays and emits a few neutrons. Slow down those neutrons using hard water, and you’ve increased the odds of those neutrons hitting the next U-235 atom. The process starts to repeat itself. If this process can continue long enough, you have a nuclear explosion. The key, of course, is to get enough concentration of that U-235 in the first place. So how did all this happen naturally on earth? The solubility of uranium in water depends on the oxygen level. As the oxygen level started rising about 2 billion years back, “oxidized uranium salts leached out of uraninite ores in the rocks and washed away in streams”. Of course, it was very dilute, fewer than a few parts per million. Many such streams converged in Gabon’s shallow lakes. As it turned out, t...