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Nuclear weapons: Difference between revisions

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* <sup>232</sup>Th - <sup>233</sup>U - <sup>235</sup>U - <sup>238</sup>U - <sup>249</sup>Pu - <sup>240</sup>Pu - minor actinides - transuranics - fissile, fissionable, fertile
* <sup>232</sup>Th - <sup>233</sup>U - <sup>235</sup>U - <sup>238</sup>U - <sup>249</sup>Pu - <sup>240</sup>Pu - minor actinides - transuranics - fissile, fissionable, fertile
* Fission chain reactions release thermal (slow) neutrons. Thermal neutrons affect materials differently:
* Fission chain reactions release thermal (slow) neutrons. Thermal neutrons affect materials differently:
** <sup>233</sup>U is fissile, and can be bred from <sup>232</sup>Th. Without subsequent physical enrichment, however, it'll be contaminated to some degree by <sup>232</sup>U (n + <sup>233</sup>U -> <sup>232</sup>U + 2n, <sup>232</sup> β− -> <sup>232</sup>U), a retarded younger brother noted by a meager lifespan and γ-rich decay chain.
** <sup>233</sup>U is fissile, and can be bred from <sup>232</sup>Th. Without subsequent physical enrichment, however, it'll be contaminated to some degree by:
*** <sup>232</sup>U (n + <sup>233</sup>U -> <sup>232</sup>U + 2n, <sup>232</sup> β− -> <sup>232</sup>U), a retarded younger brother notable for meager lifespan and γ-rich decay chain (though note that Georgia Tech researchers have fashioned <sup>232</sup>UBe<sub>13</sub> (uranium beryllide) [http://smartech.gatech.edu/handle/1853/14650 neutron initiators], so it has that).
** <sup>235</sup>U is fissile, but requires enrichment infrastructure (no plausible breeding path). Given sufficient mass of highly-enriched uranium, it's a real dream to work with, and criticality is about as difficult as lighting a Sparkler. With a 700+ million year half-life, it's not going anywhere, either. Modern cores employ <sup>239</sup> for three reasons: (a) smaller critical mass (b) beancounting and (c) style.
** <sup>235</sup>U is fissile, but requires enrichment infrastructure (no plausible breeding path). Given sufficient mass of highly-enriched uranium, it's a real dream to work with, and criticality is about as difficult as lighting a Sparkler. With a 700+ million year half-life, it's not going anywhere, either. Modern cores employ <sup>239</sup> for three reasons: (a) smaller critical mass (b) beancounting and (c) style.
** <sup>239</sup>Pu is fissile, and can be chemically extracted from neutron-activated actinides. Without subsequent physical enrichment, however, it'll be contaminated to some degree by:
** <sup>239</sup>Pu is fissile, and can be chemically extracted from neutron-activated actinides. Without subsequent physical enrichment, however, it'll be contaminated to some degree by: