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> Previously in the article they mentioned that this 10kg of Uranium believed to be for sale on the black market is a fifth of what you would need for a Hiroshi

> Previously in the article they mentioned that this 10kg of Uranium believed to be for sale on the black market is a fifth of what you would need for a Hiroshima-type weapon but it's just about enough for a well designed implosion nuke. With 60kg of HEU I could build Little Boy by myself in my garage with parts I can get at Home Depot and Cabela's. With 10kg of HEU I could build Fat Man with a breeder reactor, a couple hundred thousand in precision machine tools, several tens of thousands in specialty electronics, and a small team of specialists. Both are possible, but one is far more feasible to do than the other for a terrorist group. That said, 10kg in a Little Boy type device would still cause a pretty big boom. The damage from the radiological hysteria that would follow its use would be far greater than the explosive damage, though.

gh02t 11y ago
That estimate for an implosion weapon is a little low by my reckoning, for it to be even remotely in that ballpark it'd require extensive reflection and other trickery. Without doing the math, I'd guesstimate a more realistic number to be about 1/3rd to 1/2 that neededfor a realistic implosion weapon. But an implosion weapon is infinitely more complicated, even if I hand you all the material it just isn't going to happen that someone would be able to build it in their garage. The concept is pretty simple, but there are a lot of little gotchas and also the machining and electrical tolerances are impossibly difficult without very specialized tools even if you had detailed plans. The design for the initiator in particular was notoriously a major problem during the Manhattan project and they really weren't sure if any of the ideas they had would work. Gun-assembled weapons are simpler but still pretty complicated. I'm not sure there would be much benefit to using only 10kg of U-235, which is way subcritical. You'd get a tiny bit of extra boom and some nasty isotopes from the fissions, but strapping some Co-60 to a bomb would probably be more effective. For comparison, Little Boy used around 64 kg, though that was more than the minimum needed.
excuse-me-sir 11y ago
Welcome to the list.
- rbanffy 11y ago
  There is enough information floating around for almost any reasonably competent engineer with a knack for physics (or vice versa) to build an implosion device. The list is long.
  - gh02t 11y ago
    I'm going to have to dispute that one... an implosion weapon is very complicated. Even if you had detailed plans, you simply can't build them without access to very high precision tools. The tolerances necessary to make them work are extremely severe, especially in the construction of the initiator (the thing that initially injects neutrons to kick off the reaction) and in the triggering for the explosives. The basic concept is really easy to grasp, but the nitty-gritty engineering details are much harder than is readily apparent. Gun-assembled weapons are simpler, but still complicated. The big issue with them is that they tend to go critical as the target and projectile are coming together and blow themselves apart before the bang really gets going. Getting them to come fully together and stay confined long enough to get good yield is not as easy.

gh02t 11y ago

That estimate for an implosion weapon is a little low by my reckoning, for it to be even remotely in that ballpark it'd require extensive reflection and other trickery. Without doing the math, I'd guesstimate a more realistic number to be about 1/3rd to 1/2 that neededfor a realistic implosion weapon. But an implosion weapon is infinitely more complicated, even if I hand you all the material it just isn't going to happen that someone would be able to build it in their garage. The concept is pretty simple, but there are a lot of little gotchas and also the machining and electrical tolerances are impossibly difficult without very specialized tools even if you had detailed plans. The design for the initiator in particular was notoriously a major problem during the Manhattan project and they really weren't sure if any of the ideas they had would work. Gun-assembled weapons are simpler but still pretty complicated. I'm not sure there would be much benefit to using only 10kg of U-235, which is way subcritical. You'd get a tiny bit of extra boom and some nasty isotopes from the fissions, but strapping some Co-60 to a bomb would probably be more effective. For comparison, Little Boy used around 64 kg, though that was more than the minimum needed.

excuse-me-sir 11y ago

Welcome to the list.

rbanffy 11y ago
There is enough information floating around for almost any reasonably competent engineer with a knack for physics (or vice versa) to build an implosion device. The list is long.
- gh02t 11y ago
  I'm going to have to dispute that one... an implosion weapon is very complicated. Even if you had detailed plans, you simply can't build them without access to very high precision tools. The tolerances necessary to make them work are extremely severe, especially in the construction of the initiator (the thing that initially injects neutrons to kick off the reaction) and in the triggering for the explosives. The basic concept is really easy to grasp, but the nitty-gritty engineering details are much harder than is readily apparent. Gun-assembled weapons are simpler, but still complicated. The big issue with them is that they tend to go critical as the target and projectile are coming together and blow themselves apart before the bang really gets going. Getting them to come fully together and stay confined long enough to get good yield is not as easy.