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Urbane Guerrilla · 10-18-2006, 03:55 AM

Trying to make implosion spheres out of impure metal? That seems what you're implying, and it sounds like a great way not to arrive at the yield you want. You really want to do it with plutonium, with an enthusiastic (and rather short half-life -- 3 to 5 years) neutron emitter nestled within at the center of a few plutonium-metal shells. I'd have to hunt around to come up with the transuranic metal they used for these "pits." (I believe this method of spark-plugging nuclear weapons is long obsolete -- too tricky to maintain and it irradiated the bomb innards a lot.) Plutonium critical mass is a 32-lb sphere IIRC, which object is about the size of a grapefruit at room temp. An implosion squeeze mashes this down to about half that diameter, for greater efficiency in catching neutrons and thus very much speeding the chain reaction. This is even more efficiently done if the critical mass is made of two or more nested hollow spheres, allowing the plutonium to accelerate before being compressed into a critical mass -- it allows a fission reaction from what is a subcritical mass at ordinary temperature and pressure.

"Time remains to avert conflict?" Sorry, the conflict's already on, and has been going for at least two years. Avert, quotha.

10-18-2006, 03:55 AM	#24
Urbane Guerrilla Person who doesn't update the user title Join Date: Jul 2002 Location: Southern California Posts: 6,674	Trying to make implosion spheres out of impure metal? That seems what you're implying, and it sounds like a great way not to arrive at the yield you want. You really want to do it with plutonium, with an enthusiastic (and rather short half-life -- 3 to 5 years) neutron emitter nestled within at the center of a few plutonium-metal shells. I'd have to hunt around to come up with the transuranic metal they used for these "pits." (I believe this method of spark-plugging nuclear weapons is long obsolete -- too tricky to maintain and it irradiated the bomb innards a lot.) Plutonium critical mass is a 32-lb sphere IIRC, which object is about the size of a grapefruit at room temp. An implosion squeeze mashes this down to about half that diameter, for greater efficiency in catching neutrons and thus very much speeding the chain reaction. This is even more efficiently done if the critical mass is made of two or more nested hollow spheres, allowing the plutonium to accelerate before being compressed into a critical mass -- it allows a fission reaction from what is a subcritical mass at ordinary temperature and pressure. "Time remains to avert conflict?" Sorry, the conflict's already on, and has been going for at least two years. Avert, quotha. __________________ Wanna stop school shootings? End Gun-Free Zones, of course.