I’m now back in Montreal after a weekend in Fredericton, New Brunswick. Eventually I’ll write about the trip a bit, I think. For now I just needed a few minutes off from my String Theory midterm cram session. (Only 22 hours to go.)
In the meantime, here’s the one tidbit that came up not even in one of the talks at the physics conference, but over lunch at a little greek place off King Street — There are naturally occuring nuclear reactors. And I’m not talking about the Sun, although that technically is also a natural nuclear reactor.
Apparently the little bacteria who are responsible for concentrating uranium in the ground were being so productive in west Africa a little over a million years ago that they increased the concentration of uranium-235 in the soil to such levels that, combined with the water in the surrounding soil needed to slow down the radiated neutrons, a sustained nuclear reaction was possible.
They estimate it ran at about a kilowatt or so, and when it got too hot the water would just vapourize, causing the reaction to stop until the bacteria went back to their bacterial ways and enriched the soil again so it could start all over. Not only was the reaction self-regulating, but all the nuclear waste was self-contained, not moving more than 10 metres since it was created.
Read about the Oklo natural nuclear reactors here, and try google for more sources as well.