[Southack]

"1) Would the presence of oxygen change the energy dependence of the neutron capture cross section, affecting the yield? 1a) Or the difference from that is too small? 2) Would the plutonium "rust" change important factors like density, shape, etc. so that the "implosion" of a "Fat man" would not achieve the desired density, or not achieve it quickly enough, resulting in a lowered yield?"

Uranium Oxide (i.e. rust, commonly seen in nature or after rudimentary refining as yellowcake) is typically a neutron absorber...certainly the critical chain reaction speed is changed going from Uranium to Uranium Oxide...not a good thing for a precisely calculated boom.

[grey_whiskers]

Thank you for the courteous reply.

Cheers!