
Natural nuclear fission reactor - goldenkey
https://en.wikipedia.org/wiki/Natural_nuclear_fission_reactor
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ryanmercer
Yeah, there's even a nuclear company designing a compact fast reactor named
after Oklo, Oklo Inc.

There was a SciShow about the natural one
[https://www.youtube.com/watch?v=yS53AA_WaUk](https://www.youtube.com/watch?v=yS53AA_WaUk)

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agumonkey
I remember binge watching most of his channel. His presentation and tone are
superb.

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saagarjha
Wow, this is quite a theory:

> Published in 2010, a controversial hypothesis about the origin of the Moon
> proposes that the Moon may have been formed from the explosion of a
> georeactor located along the core-mantle boundary at the equatorial plane of
> the then-rapidly rotating Earth, 4.5 billion years ago.

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m_mueller
interesting, but wouldn't this be way less likely than a planetary collision?
It's hard for me to imagine how a natural reactor could achieve the many many
Gigatons of TNT needed to do this, considering the critical mass of natural
metallic radioactive isotopes being on the order of kilograms. How could
random chance set up such a huge bomb?

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Retric
Even if it could there would not be enough angular momentum to from a large
stable moon. So, it's not a viable theory.

PS: Calculate how fast the earth would need to rotate for this to work out.

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SiempreViernes
I'm sure that with a convoluted enough sequence of runaway fission it could be
done, like if the newly formed clump ends up with reactors venting superheated
gas along conveniently located fissures that provides the necessary torque.

Surely this doesn't make the theory significantly less plausible than the
premise of a natural reactor being somehow inert enough to become a bomb
before it burns itself apart?

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Retric
The moon is fairly close to the earths size on a log scale. Try a rough order
of magnitude for how much gas at what speed that would take.

It might be possible to carefully design multiple precisely timed detonations
to get a second moon to show up. But, a single detonation is not going to work
and your talking about a lot more complexity and energy than a few 'vents'.

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graydsl
I never heard about such a phenomenon before. But yesterday I read about it in
The Long Earth by Terry Pratchet and Stephen Baxter. Life is weird
sometimes...

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Tsiklon
I've encountered this a few times - Frequency Illusion, also known as the
Baader-Meinhof phenomenon. Where something appears with improbable frequency
shortly after discovery. It's a pretty weird phenomenon isn't it?

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simonh
Also given hundreds of people reading this article on HN, what are the chances
that none of them would also recently have read about a related phenomenon?

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garyclarke27
Earth’s core probably has a large fission reactor. Heaviest elements such as
Uranium would naturally gravitate to the center during planet formation, high
pressure and temperatures there provide ideal conditions for natural fission.
Explains heat source for volcanoes etc. Would be impossible for such
tremendous heat to last 4 billion years from formation, without some kind of
additional powerful energy source.

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Symmetry
Not much in the way of neutron moderators so far below the Earth's surface, so
I'd be skeptical. Now, natural radioactive decay of Uranium, etc, are a huge
factor in keeping the Earth's core warm. It's just that nuclear chain
reactions where one atom's decay sets off the next that isn't believed to be a
factor.

