Natural nuclear fission reactor | Hacker News Reader

Natural nuclear fission reactor

en.wikipedia.org

71 pointsgoldenkey18 comments

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

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

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.

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?

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.

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?

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'.

Yeah, that's my point. It seems rather improbable.

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...

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?

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?

I learned about this from the "Science of Discworld" books, I believe the first one, which I cannot recommend enough if you like Sir Terry.

It’s in Isamov’s Robot series, but I won’t give any spoilers.

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.

Here: https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget

Natural fission is not thought by experts to play a substantive role in energy generated inside the Earth.

> Earth’s core probably has a large fission reactor.

I'm pretty sure you've got "fission reactor" mixed up with "alpha decay heat". While you do technically get two different nuclei as the products of an alpha decay, fission is a different reaction.

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.

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