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When the US nuked Japan was there any worry about a radiation cloud possibly floating to another country that was not involved? Or is this even possible? (lemmy.world)
submitted 11 months ago by to c/askscience@lemmy.world
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[–] 48 points 11 months ago (11 children)

It was possible, but both bombs - Fat Man and Little Boy were in the kiloton range of size, and not like the modern nuclear arsenal that are in megatons of size, so the nuclear fallout at the time was much more limited.

Also, given the prevailing winds flow from west to east, much of the radioactive material fell into the Pacific just east of Japan. Now the rampant nuclear testing (once the scientific community worked out that a nuclear detnation would NOT set the atmosphere on fire - like some suspected it might..) which happened in the Pacific and in the Southwestern US during the 50's and 60's, was an entirely different animal.

That caused a lot of problems in the US and on the Pacific Islands and atolls downwind.

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  • [–] 19 points 11 months ago* (last edited 11 months ago) (4 children)

    It's back down to kilotons, actually, albeit hundreds. The tens of megatons thing was to make up for the inaccuracy of early delivery methods; now firing more small bombs is preferred. And the Tsar Bomba was undeliverable - purely for show.

    They're also a lot cleaner now, too - Fat Man and Little Boy were quite dirty, so significant fallout did happen. Little Boy was used in an airburst, and so it's mess was distributed pretty globally through the stratosphere, but Fat Man's came right back down in black rain.

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  • [–] 3 points 11 months ago (3 children)

    Undeliverable? They dropped it from a plane.

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  • [–] 3 points 11 months ago* (last edited 11 months ago) (2 children)

    Okay, undeliverable in the same sense their tanks are by air. Sure, you can load a T-34 (which looks like it also comes in at 27 tonnes) on an aircraft, but it's not intended as a scalable way to use them. You'll remember the plane was almost knocked out of the sky by the blast as it flew away. It was also the only model they had that could do it, and it couldn't go very far with such an unusually heavy load.

    The largest nuke that saw actual service was the 25 MT American B41, which had impressive yield for it's size, despite, as you can see in the wiki's picture, still being a very significant device. There was also a project to design bombs of unlimited yields, but the scientists were basically just goofing off, and the army told them to stop it.

    The modern Western (and Chinese?) design is at the other end of the space - being as small as possible while maintaining efficiency. They have just enough of a fusion stage to support full burnup in the fission stage.

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  • [–] 2 points 11 months ago (1 child)

    See, you say "undeliverable" and I picture Castle Bravo, which was the size and shape of a microbrewery.

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  • [–] 3 points 11 months ago

    I'd guess the reason they didn't go the Castle Bravo route is probably just that it's hard to work deep in the arctic, where you as the USSR can test with minimal (but not zero, RIP Severny) impact. There was also the official justification that the extremely clean burn was the point of the test, which would be defeated by contact with and activation of the ground. It seems SHRIMP from Castle Bravo weighed 10 tonnes, so picture adding a nose and tailfins and maybe some electronics to it and you'd still have a more practical weapon.

    Here's the aerodynamic casing for the Tsar Bomba (empty, which is how it can sit on that dolly):

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  • [–] 13 points 11 months ago

    Yeah, it's important to remember how tiny these bombs were, considering what came after them. Which is especially crazy if you consider they were large enough to obliterate entire cities and kill hundreds of thousands of people.

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  • [–] 30 points 11 months ago* (3 children)

    I always love that bit .... scientists wondering if the first test would set the entire planet's atmosphere on fire ...

    Scientist getting ready to pull the trigger on the first bomb: .... if we don't fuck around .... how are we ever gonna find out?

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  • [–] 28 points 11 months ago (2 children)

    It wasn’t a real concern. Calculations showed very minimal chance. But I guess it’s not zero until you try it

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  • [–] 6 points 11 months ago*

    Fallout is not necessarily proportional to yield. In fact, small bombs like this can be much “dirtier” than the fusion boosted fission designs.

    The detonation height also plays a counterintuitive role; lower is worse. Though I’m not sure how this applies to the Fat Man and Little Boy fireballs, I remember their detonation heights being kinda low.

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