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Comment by _yb2s | Hacker News Reader

This is such an interesting and weird phenomenon, in the context of the complexity of human made nuclear reactors.

I once read a horrifying fiction story about a pre-industrial culture that used nuclear reactions in open piles of uranium ore tended by slaves as a heat source, but cannot remember the name or author.

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That anecdote is present in the Manifold series by Stephen Baxter

Thanks! That makes sense, I have read that series, but didn't remember that was where this was from.

Manifold Space specifically (unless it’s also present in his other Manifold books)

It seems less odd when one realizes how common uranium actually is. Today, it is about as common as tin. Knowing that, there were probably lots of undiscovered places where the density got high enough to fission. Much of the earth's internal heat comes from fission. We only get interested when it happens near the surface.

Uranium is one of the elements that are greatly enriched in the continental crust of the Earth (like also thorium and the rare-earth metals).

So in the continental crust the abundance of uranium is more than one hundred times greater than the average abundance of uranium in the entire Earth or in the Solar System.

Otherwise uranium would have been almost the least abundant chemical element, as it is on average in the entire Solar System.

Tin is among the metals that are depleted in the crust of the Earth. Elsewhere tin is a few hundred times more abundant than uranium.

A continental crust like on Earth can appear only on planets that have been melted, so that the light and heavy minerals have combined and separated by density, with the continental crust floating over the molten magma and then solidifying. Most of the Earth has been melted by the collision that has formed the Moon, but possibly also by other smaller collisions.

In most other places in the Solar System it will be unlikely to find so easily accessible and abundant uranium as here on Earth.

> Knowing that, there were probably lots of undiscovered places where the density got high enough to fission.

Density of U235, specifically… you could crystallize pure uranium in the Earth’s crust today, and it would not be enriched enough for a nuclear reactor.

I remember it having a time travel aspect as well as moderation of reaction via chared tree trunks thrust into the heap.

> I once read a horrifying fiction story about a pre-industrial culture that used nuclear reactions in open piles of uranium ore

The real world was worse than this fiction. It's easy to find pictures of old advertisements for radioactive products, in the years following the discovery of radioactivity. Radioactive pills "to boost your energy", radioactive cosmetics, radioactive false teeth... Now imagine what happened to the people that used these.

https://en.wikipedia.org/wiki/Santa_Susana_Field_Laboratory#...

https://en.wikipedia.org/wiki/Jackass_Flats

https://coloradosun.com/2020/12/29/grand-junction-cold-war-n...

https://en.wikipedia.org/wiki/Radioactive_contamination_from...

https://en.wikipedia.org/wiki/Windscale_fire

https://en.wikipedia.org/wiki/Kyshtym_disaster

https://www.gw2ru.com/history/3317-kyshtym-accident-radiatio...

https://en.wikipedia.org/wiki/Andreev_Bay_nuclear_accident#A...

A Time-Lapse Map of Every Nuclear Explosion Since 1945 - by Isao Hashimoto

https://www.youtube.com/watch?v=LLCF7vPanrY

or https://www.arcgis.com/apps/Time/index.html?appid=b8540a8a25...

Those real world early uses of nuclear technology were indeed awful- nuclear testing at Bikini Atoll comes to mind, which did intentional treatment vs. non-treatment experiments on the Marshall Islanders.

Even that is nothing close to the fiction I am talking about, having a class of slaves that operate a fully open nuclear reactor with hand tools.

I dont think that is worse.

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