# Did Japan have an Atomic Bomb? **URL:** \ **Category:** Factual Questions\ **Created:** [February 14, 2014, 6:42pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354 "2014-02-14T18:42:45Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [February 15, 2014, 7:13pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/61 "2014-02-15T19:13:43Z")
I don’t think you can participate meaningfully in an extended discussion about the bomb without reading Rhodes’s book, unless you’ve somehow read all the equivalent material elsewhere. It and to a slightly lesser degree the follow-up _Dark Sun_ are one of the finest, most complete and most insightful modern histories I’ve ever read. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [February 15, 2014, 7:20pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/62 "2014-02-15T19:20:58Z")
> [@The\_Second\_Stone](#): > > think more of the difference between a piston engine and a jet engine. No, I understand that different engineering processes are used to get the final result, but it is exactly the same final process and result - quickly creating a critical mass that then releases some very large part of its energy. You could compare various forms of IC engine or various forms of jet engine, but the difference between those two is much greater than the difference between the two bomb techniques. IMVHO. A piston compressing a fuel mixture and a Wankel rotor compressing a fuel mixture is very close to an exact analogue… again IMHO. ---
**Author:** ![Darth\_Sensitive](https://avatars.discourse-cdn.com/v4/letter/d/58956e/32.png) [@Darth\_Sensitive](https://boards.straightdope.com/u/Darth_Sensitive)\ **Post date:** [February 15, 2014, 7:31pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/63 "2014-02-15T19:31:44Z")
> [@watchwolf49](#): > > Hitler needed the war over very soon, so the German program was underfunded. Their scientists wouldn’t have been able to get a working bomb in time. The Imperial Japanese detonating a bomb … c’mon … wherever they did would still be dangerously radioactive. I just can’t imagine a hundred square miles of Korea fenced off without anyone noticing. Might want to inform the people of Hiroshima that they should move. ---
**Author:** ![handsomeharry](https://avatars.discourse-cdn.com/v4/letter/h/e9c0ed/32.png) [@handsomeharry](https://boards.straightdope.com/u/handsomeharry)\ **Post date:** [February 15, 2014, 10:52pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/64 "2014-02-15T22:52:23Z")
> [@Chronos](#): > > They had two, for certain values of “had”. Though they didn’t keep either very long, though. Hmmm…not bad!😃 ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [February 15, 2014, 10:56pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/65 "2014-02-15T22:56:13Z")
> [@Darth\_Sensitive](#): > > Might want to inform the people of Hiroshima that they should move. Well, given History Channel’s penchant for fabulification, I expect the next one to claim that the Nazis had the bomb and tested it and that’s why all the people in the concentration camps were sick and dying. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [February 16, 2014, 12:20am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/66 "2014-02-16T00:20:22Z")
> [@Darth\_Sensitive](#): > > Might want to inform the people of Hiroshima that they should move. People seem to not notice that Hiroshima and Nagasaki are healthy large inhabited cities and not radioactive wastelands from science fiction. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [February 16, 2014, 12:37am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/67 "2014-02-16T00:37:17Z")
> [@FluffyBob](#): > > People seem to not notice that Hiroshima and Nagasaki are healthy large inhabited cities and not radioactive wastelands from science fiction. And any seven-foot, three-eyed denizen of those cities will be happy to give you a taste of his bottom-left tentacle should you imply it! ---
**Author:** ![Mr.Miskatonic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mr.miskatonic/32/310_2.png) [@Mr.Miskatonic](https://boards.straightdope.com/u/Mr.Miskatonic)\ **Post date:** [February 16, 2014, 1:50am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/68 "2014-02-16T01:50:41Z")
> [@Sailboat](#): > > Plutonium, [actually](http://en.wikipedia.org/wiki/Tickling_the_dragon%27s_tail). And it was two guys, in two separate but roughly similar incidents. But that was just “criticality,” releasing a burst of radiation, and no explosive power. A far cry from sufficient to destroy a city. There was an [incident with Uranium](http://en.wikipedia.org/wiki/Arnold_Kramish), however. Mind you it was equipment failure and not anything like a critical mass situation. ---
**Author:** ![j\_sum1](https://avatars.discourse-cdn.com/v4/letter/j/8baadc/32.png) [@j\_sum1](https://boards.straightdope.com/u/j_sum1)\ **Post date:** [February 16, 2014, 2:01am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/69 "2014-02-16T02:01:02Z")
Fight my ignorance here. How is the mechanism for fissioning uranium different from the fissioning of plutonium? You can answer for controlled fission (aka reactor) as well as uncontrolled (aka bomb). ---
**Author:** ![The\_Hamster\_King](https://avatars.discourse-cdn.com/v4/letter/t/8edcca/32.png) [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)\ **Post date:** [February 16, 2014, 2:17am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/70 "2014-02-16T02:17:18Z")
> [@j\_sum1](#): > > Fight my ignorance here. How is the mechanism for fissioning uranium different from the fissioning of plutonium? When atoms split they give off stray neutrons. Those neutrons then hit other atoms causing them to split as well. If you put enough radioactive material – a critical mass – in one place you get an out of control chain reaction that produces a big explosion. An atom bomb consists of separate pieces of radioactive material that can be brought together to form a critical mass. This has to happen quickly because once the chain reaction starts the increasing heat and pressure blows the pieces apart. If the assembly of the pieces happens too slowly the result is a fizzle – a small explosion that blows the core apart before very much fission happens. Uranium bombs work like cannons. You set off a normal explosion to fire a “bullet” of uranium into a “target” of uranium. This creates a critical mass quickly enough to avoid a fizzle. Plutonium is so reactive that even a cannon isn’t fast enough to get the pieces together in time. Plutonium bombs work through implosion. A hollow sphere of plutonium is surrounded by a spherical jacket of explosives. When the explosives detonate it creates a spherical shock wave that compresses the plutonium into a critical mass. Designing an explosive jacket that will produce a perfectly spherical implosion is very, very hard. ---
**Author:** ![j\_sum1](https://avatars.discourse-cdn.com/v4/letter/j/8baadc/32.png) [@j\_sum1](https://boards.straightdope.com/u/j_sum1)\ **Post date:** [February 16, 2014, 2:22am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/71 "2014-02-16T02:22:17Z")
Thanx **Hamster**. Got that. I knew the basic principle of critical mass and that Pu is more reactive. (And not naturally available.) I didn’t know the implications for bomb design or that the spherical implosion was so difficult to achieve. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [February 16, 2014, 2:31am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/72 "2014-02-16T02:31:07Z")
> [@The\_Second\_Stone](#): > > The H bomb is even more complex, requiring (and again, I don’t know) at least one plutonium bomb (and probably a minimum of two) to explode in such a way as to force tritium (a kind of heavy hydrogen) to smush together at incredible speed and force. The first such device was the size of a house. And there were a very limited number of Wicked Witches left to drop those houses on. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [February 16, 2014, 2:34am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/73 "2014-02-16T02:34:45Z")
> [@FluffyBob](#): > > People seem to not notice that Hiroshima and Nagasaki are healthy large inhabited cities and not radioactive wastelands from science fiction. That’s an interesting point—never even occurred to me before. Is there any measurable radiation at all left over from the blasts? ---
**Author:** ![Mr.Kobayashi](https://avatars.discourse-cdn.com/v4/letter/m/4af34b/32.png) [@Mr.Kobayashi](https://boards.straightdope.com/u/Mr.Kobayashi)\ **Post date:** [February 16, 2014, 2:47am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/74 "2014-02-16T02:47:53Z")
> [@Washoe](#): > > That’s an interesting point—never even occurred to me before. Is there any measurable radiation at all left over from the blasts? [The master speaks](http://www.straightdope.com/columns/read/2466/if-nuclear-fallout-lasts-thousands-of-years-how-did-hiroshima-and-nagasaki-recover-so-quickly). ---
**Author:** ![Ranchoth](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranchoth/32/1066_2.png) [@Ranchoth](https://boards.straightdope.com/u/Ranchoth)\ **Post date:** [February 16, 2014, 3:13am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/75 "2014-02-16T03:13:15Z")
> [@The\_Hamster\_King](#): > > Uranium bombs work like cannons. You set off a normal explosion to fire a “bullet” of uranium into a “target” of uranium. This creates a critical mass quickly enough to avoid a fizzle. As an interesting sidenote, there actually _have_ been a couple of Uranium-implosion bomb designs—the bomb used in the [Ivy King test](http://en.wikipedia.org/wiki/Ivy_King) and the [first Chinese atomic bomb](http://en.wikipedia.org/wiki/596_%28nuclear_test%29), for example. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [February 16, 2014, 3:17am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/76 "2014-02-16T03:17:12Z")
> [@The\_Hamster\_King](#): > > When atoms split they give off stray neutrons. Those neutrons then hit other atoms causing them to split as well. If you put enough radioactive material – a critical mass – in one place you get an out of control chain reaction that produces a big explosion. > > An atom bomb consists of separate pieces of radioactive material that can be brought together to form a critical mass. This has to happen quickly because once the chain reaction starts the increasing heat and pressure blows the pieces apart. If the assembly of the pieces happens too slowly the result is a fizzle – a small explosion that blows the core apart before very much fission happens. > > Uranium bombs work like cannons. You set off a normal explosion to fire a “bullet” of uranium into a “target” of uranium. This creates a critical mass quickly enough to avoid a fizzle. > > Plutonium is so reactive that even a cannon isn’t fast enough to get the pieces together in time. Plutonium bombs work through implosion. A hollow sphere of plutonium is surrounded by a spherical jacket of explosives. When the explosives detonate it creates a spherical shock wave that compresses the plutonium into a critical mass. > > Designing an explosive jacket that will produce a perfectly spherical implosion is very, very hard. just to nitpick - the Plutonium pit is not, strictly speaking, hollow. There is a small, spherical “spark plug” that resides at the center of the pit, but that is only there to provide enough free Neutrons at the moment of maximum compression to initiate the reaction. Interestingly, the Manhattan- era design of this initiator is considered one of the top secrets of the bomb, and AFAIK, it’s design is still classified 70-odd years later. If this initiator was not necessary, a perfectly round, solid sphere of PU-239 could be used. In other words, it’s not the “crushing” of a hollow sphere that makes the mass go critical, it’s the actual change in density caused by the compression of the explosive force. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [February 16, 2014, 9:22am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/77 "2014-02-16T09:22:44Z")
> [@The\_Second\_Stone](#): > > The first such device was the size of a house. 62 tons, in fact. Meet [Ivy Mike](http://en.wikipedia.org/wiki/Ivy_Mike). > [@The\_Second\_Stone](#): > > The H bomb is even more complex, requiring (and again, I don’t know) at least one plutonium bomb (and probably a minimum of two) to explode in such a way as to force tritium (a kind of heavy hydrogen) to smush together at incredible speed and force. More or less. The [Teller-Ulam design](http://en.wikipedia.org/wiki/Teller-Ulam_design) is used for all modern thermonuclear weapons, and although heavily classified, the basics are assumed to be as described in the Wikipedia article. A “primary” plutonium fission bomb provides heat, x-rays and compression to ignite a “secondary” supply of fusion fuel, and that in turn usually fissions the uranium “tamper” (heavy shell that contained the initial explosions for a few milliseconds to allow fusion to start). It’s a convenient factor that the more common uranium isotope U-238, which does not normally fission, is dense enough to serve as an ideal tamper and also will fission under the neutron flux caused by the fusion explosion. Often, the majority of a bomb’s “yield” is actually caused by this third-stage fissioning of the tamper. It’s diabolically clever and efficient. Elegant…except for being the worst thing ever conceived. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [February 16, 2014, 9:33am UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/78 "2014-02-16T09:33:54Z")
> [@FluffyBob](#): > > People seem to not notice that Hiroshima and Nagasaki are healthy large inhabited cities and not radioactive wastelands from science fiction. Pripyat, OTOH… ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [February 16, 2014, 3:28pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/79 "2014-02-16T15:28:36Z")
> [@watchwolf49](#): > > General Groves was presented with six different methods to produce the Atom Bomb. He was tasked with selecting the one that would be productive first. Instead, he gave the go ahead to _all six_. That’s why the Manhattan Project was so huge and costly. > > Hitler needed the war over very soon, so the German program was underfunded. Their scientists wouldn’t have been able to get a working bomb in time. The Imperial Japanese detonating a bomb … c’mon … wherever they did would still be dangerously radioactive. I just can’t imagine a hundred square miles of Korea fenced off without anyone noticing. What makes you think a few kiloton nuclear bomb being detonated would require fencing off an area a “hundred square miles?” I wouldn’t have wanted to live on top of ground zero in Hiroshima a year after the bombing but lots of people did and the impact was fairly minimal. Especially relative to WWII era norms where governments threw away thousands of lives a day. I think something like 1500 cancers over a 50 year period in which hundreds of thousands of people lived in Hiroshima have been attributed to radiation effects from the bombings. I’m always in shock at how people seem to have all these crazy ideas about what nuclear weapons do and this is one of the most frequent, that any area hit by any type of nuclear weapon becomes “uninhabitable” forever. The radiation levels that can actually kill humans outright dissipate very quickly from a Little Boy type bomb, and the amount left wouldn’t be enough for a war time government to quarantine off the area forever. Maybe in c. 2013 United States or Europe they’d just quarantine it off, because there’s no acceptance for sacrificing a small portion of people to the side effects, but we’re talking the 1940s here and Japanese controlled Korea. ---
**Author:** ![Little\_Nemo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/little_nemo/32/3120_2.png) [@Little\_Nemo](https://boards.straightdope.com/u/Little_Nemo)\ **Post date:** [February 16, 2014, 3:48pm UTC](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354/80 "2014-02-16T15:48:57Z")
> [@Martin\_Hyde](#): > > we’re talking the 1940s here and Japanese controlled Korea. Okay, seriously, this did not happen. There’s no way Japan ever built an atomic bomb. The United States occupied Japan after the war and had full access to all its secrets. There’s no way the Japanese government would have been able to hide a development program much less actual production and use of an atomic bomb. The United States made a big point out of how the Manhattan Project was a response to fears of a German atomic bomb program. Full publicity was given to the German program after the war. Why wouldn’t a more successful Japanese program have also been publicized? America had every reason to portray Hiroshima and Nagasaki as responses to a Japanese bombing if they could have. The Koreans have long complained about Japanese treatment of their country. Why would they not talk about it if Japan had used an atomic bomb in their country? Japanese research in chemical and biological weapons has been publicized. Why would Japanese research in nuclear weapons be concealed? [Previous page](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354.md?page=3) [Next page](https://boards.straightdope.com/t/did-japan-have-an-atomic-bomb/681354.md?page=5)