[Pink Ling]

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Firstly, no one need to be worried about the subject matter being discussed here; anyone with access to fissile material doubtless has access to far more in-depth discussion than would be seen in this thread. My training as a researcher is in the humanities, specifically history, not physics. However I do prefer to embrace the facts when writing of the social history of technology. Thus any open-source material that may be discussed herein may be of use.

My question relates to compact nuclear weapons. As I understand the two principal means of assembling a super-critical mass of fissile material are ‘gun assembly’ and ‘implosion assembly.’ It is also my understanding that the former requires quite a large, and therefore bulky, amount of very highly enriched uranium.

I also understand that the implosion method generally requires a large quantity of explosives to compress a sphere of fissile material into a supercritical state (with an initiator present at the centre). In this second half of this article: http://nuclearweaponarchive.org/News/DoSuitcaseNukesExist.html Carey Sublette appears to be discussing a subtype of this assembly method, involving a larger mass of fissile material that due to size constraints of the device (i.e. no bulky explosive lenses, pusher/tamper etc) is not so much ‘imploded’ but rather brought into a supercritical state without a great increase in density.

Is what is happening here in this ‘two point linear implosion assembly’ that a football-shaped mass of fissile material is essentially brought into a supercritical state by altering its shape to make it spherical? If it were already critical, or close to it, would it not be releasing a dangerous amount of radioactivity during manufacture? Is it the case that when the explosives are detonated at each end, the converging shockwaves also trigger an ‘initiator’, thus helping bring k>1?

Thanks for your time and input