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Nuclear weapons: Difference between revisions

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** Thorium. For all purposes, entirely <sup>232</sup>Th (look at the half-lives).
** Thorium. For all purposes, entirely <sup>232</sup>Th (look at the half-lives).
* Neutron moderators - fueling - MOX - breeders - feedbacks - inherently safe designs
* Neutron moderators - fueling - MOX - breeders - feedbacks - inherently safe designs
** Moderate to take advantage of upscaled W<sub>fis</sub> function. Keep this in mind for "hydrides" below...
* Recycling - metal oxide fuel - reprocessing - fusion-driven waste fission
* Recycling - metal oxide fuel - reprocessing - fusion-driven waste fission
* Four-factor formula - criticality control - fuel burnup - fission products - fission poisons - <sup>135</sup>Xe - <sup>149</sup>Sm
* Four-factor formula - criticality control - fuel burnup - fission products - fission poisons - <sup>135</sup>Xe - <sup>149</sup>Sm
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** <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>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 ((<sup>233</sup>U,''n'') -> <sup>232</sup>U + ''2n'', (<sup>232</sup>Pa,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> (<sup>232</sup>uranium beryllide) [http://smartech.gatech.edu/handle/1853/14650 neutron initiators], so it has that).
*** <sup>232</sup>U ((<sup>233</sup>U,''n'') -> <sup>232</sup>U + ''2n'', (<sup>232</sup>Pa,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> (<sup>232</sup>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>Pu 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>Pu because (a) smaller critical mass (more energy per fission) (b) neutron flux (more prompt neutrons per fission) and (c) we can.
** <sup>238</sup>U is not fissile, but can be bred into <sup>239</sup>Pu. Furthermore, it ''can'' be fissioned by the 14.7 MeV neutron resulting from D-T fusion, and there's an absolute ton of it.
** <sup>238</sup>U is not fissile, but can be bred into <sup>239</sup>Pu. Furthermore, it ''can'' be fissioned by the 14.7 MeV neutron resulting from D-T fusion, and there's an absolute ton of it.
** <sup>239</sup>Pu is fissile, and can be chemically extracted from activated actinides (primarily <sup>238</sup>U breeding). 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 activated actinides (primarily <sup>238</sup>U breeding). Without subsequent physical enrichment, however, it'll be contaminated to some degree by:
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* High explosives - Taylor-Rayleigh instabilities - assembly geometry - neutron multiplications - Rankine-Hugeniot conditions
* High explosives - Taylor-Rayleigh instabilities - assembly geometry - neutron multiplications - Rankine-Hugeniot conditions
* Hydrides (see the <b>Ruth</b> section from [http://nuclearweaponarchive.org/Usa/Tests/Upshotk.html Upshot-Knothole])
* Hydrides (see the <b>Ruth</b> section from [http://nuclearweaponarchive.org/Usa/Tests/Upshotk.html Upshot-Knothole])
** Slowing the neutrons increases absorption probability, allowing more efficient explosion
** The additional interactions ('''not''' the reduced speed) take too long, though, and containment is lost
* [http://arxiv.org/abs/physics/0510052 "The B61-based Robust Nuclear Earth Penetrator: Clever retrofit or headway towards fourth-generation nuclear weapons?"]. Gsponer 2005-11-19.
* [http://arxiv.org/abs/physics/0510052 "The B61-based Robust Nuclear Earth Penetrator: Clever retrofit or headway towards fourth-generation nuclear weapons?"]. Gsponer 2005-11-19.
==Fusion Weapons and Boosting==
==Fusion Weapons and Boosting==