How can I find a legendary "formula" for an A-Bomb and not be put on a terrorist watch-list in the process?

April 11, 2007 9:32 PM

How can I find a legendary "formula" for an A-Bomb and not be put on a terrorist watch-list in the process?

My grandfather worked in nuclear medicine until retirement after WWII. He often told me stories about the people he worked with, one of whom was apparently very prominent in that field. I can't remember the details of what he had worked on, but I really want to say that he worked in some way with designing nuclear weapons. He often recounted the story where this gentleman showed him a tiny slip of paper on which was written a short formula. "Do you know what this is?" he would ask, "Its the formula for the [Chinese?] A-Bomb." and would promptly put it back in his pocket. According to my grandfather, this colleague shouldn't have had the formula and shouldn't have been showing it to anyone.

At the end of this story, he would talk about how he always wanted a painting of a nuclear explosion with the little nameplate underneath displaying that short formula. So let me cut to the chase: I would make this for him (as a surprise.) I have the painting skills, but I don't have that formula. Is there any way of finding something like this out? Am I going to be put on a terrorist watch list for even asking this? Would such a formula even exist? If I can't get the formula perhaps someone out there could help me fake it convincingly, as I can't imagine my grandfather would remember it very well (if at all.)

posted by Becko to science & nature (13 comments total)

Was it the chemical formula for a nuclear chain reaction?

Something like:

U235(92)+n -> Ba142(56) + KR91(36) +3n
or

U235(92) + n -> Cs140(55) + Rb93(37) + 3n?
posted by vacapinta at 9:46 PM on April 11, 2007

I'm not a nuclear engineer, but the closest thing to a secret formula for a fission bomb is the details of the geometry of the explosive lens for the core of an implosion type fission bomb. At least, every book I've read on the subject has said something along the lines of "it was a very clever bit of design work" and left it at that. That said they never implied that it was impossible to figure out, just that it would be unseemly to print in a book for the public. It reminds me of the way curse words in latin dictionaries were defined in greek and vice versa. I can't think of a way to ask someone (that you don't know already) who would be able to figure it out that wouldn't a) be sketched out and b) probably would if they had any common sense not tell you. It's information that seems to have few justifiable reasons in seeking (your grandfather aside).
posted by frieze at 9:46 PM on April 11, 2007

Something like Vacapinta may very well do the trick. I suppose there's no real way of ever knowing what exactly was on that slip of paper but I don't think it was anything so specific like Frieze suggested. Atleast I hope not. It may just be ignorance on my part (I went to art school, I'm way out of my league here) but I imagine by the 'matter-of-fact' way my grandfather tells it that whatever it was that was on the slip could be considered the bomb, even on the most basic level. The "geometry of the explosive lens for the core of an implosion type fission bomb" could be considered what makes the bomb, the bomb for all I know, but I'd like to think it was the simple little equation that Vacapinta offered. I (and my Grandpa) thank you.
posted by Becko at 10:09 PM on April 11, 2007

Yeah, as frieze says, the secret, technically difficult part of a nuclear bomb is the design, not the formula. You have to get all the fissile material into a supercritical mass/shape very quickly, becuase as soon as you start to get into a critical configuration, the bomb will blow all the fissile material apart, and unless you get that done very quickly, that happens before most of the nuclear material has undergone fission. We're talking a matter of microseconds here, at most.

Asking for the formula of a nuclear bomb is like asking for the formula of a car - you can write down the formulas for the combustion of various hydrocarbons, which are the reactions that ultimately power the car, but that's a) widely known, and b) not the hard part of making a car.
posted by DevilsAdvocate at 10:12 PM on April 11, 2007

The formula has been mentioned above; the construction is pretty-well documented in this Wikipedia article.
posted by Civil_Disobedient at 10:23 PM on April 11, 2007

Of course, you are on the list now, so you can only count this as a half-success.
posted by Bokononist at 12:07 AM on April 12, 2007

As others have already said, the formula vacapinta gives is far from secret and doesn't seem to fit the bill.

It might have been something about the engineering of the bomb, but it could also have been something about the refinement process of the fissile material, but again that doesn't seem like something that could be expressed as a formula.
posted by edd at 2:38 AM on April 12, 2007

Your granddad was probably telling you a bullshit story. At the least, the story doesn't make sense.

If he knew what the formula was or recognized it as being correct, and all he did was work in nuclear medicine and not in weapons design, then whatever was on that paper was not remotely secret.
posted by ROU_Xenophobe at 6:14 AM on April 12, 2007

lol to ROU: "Your family sucks, listen to me".
posted by omidius at 11:22 AM on April 12, 2007

Unless your grandfather retired after Oct. of 1964, the date of their first nuclear test, it could not have been a formula for a Chinese bomb.

More likely it was something about the Hiroshima or Nagasaki bombs-- and they were very different. The Hiroshima bomb was a U235 bomb and the Nagasaki bomb had a core of plutonium (as did the bomb of Trinity, the very first nuclear explosion). The Hiroshima bomb, named Little Boy, shot a hemisphere of U235 down a 'gun barrel' toward another such hemisphere to initiate the nuclear explosion; a hollow sphere of plutonium was imploded in the Nagasaki (named Fat Man) and Trinity devices.

It's interesting that our first use of a nuclear weapon was of a design which had never been tested, with fissionable material which had never been tested in a bomb, when we had another bomb of proven design sitting on the shelf. The linked site says the little boy design was considered more reliable, but could not be tested because it contained all the sufficiently purified U235 in the world, but I think it's permissible to wonder whether dropping the first bomb when you had-- when you had to have-- considerable doubt it would even go off might have been easier to do, sort of like what allows people to pull the trigger in Russian Roullette.

But back to the formula. The fissionable elements are always described as U235 hemispheres and hollow plutonium spheres, but I don't see how either one of them could have been other than alloys of uranium and alloys of plutonium. Both these metals will burn in air, and Google tells me, if I did it right, that 500C for Pu and 170C for U are the appropriate ignition temps in air. And that means you would almost have to alloy them to be able to handle them, and very long and difficult experimentation may have been necessary to come up with a workable alloy in each case; not only does any alloying material have to impart suitable phyical and chemical characteristics, it must not absorb too many neutrons or it could quench the chain reaction.

So I would guess the formula was the alloy specification of the Hiroshima or Nagasaki bomb-- and that could still be pretty sensitive.
posted by jamjam at 12:14 PM on April 12, 2007

Or machine and handle in an inert atmosphere like argon or helium. Seems like it would be a lot easier to have everyone in scuba than all that alloy testing.
posted by Mitheral at 4:24 PM on April 12, 2007

I don't know about U, but Pu is always spoken of being sintered, and sintering in an inert atmosphere is a very common process.
posted by oats at 6:49 PM on April 12, 2007

Good points; my guess was a wild one, to be sure.
posted by jamjam at 8:20 PM on April 12, 2007