The tasks of separating Xe/Kr and Ar/O 2 /N 2 mixtures are encountered during the industrial production of pure Xe, Kr, and Ar by isolating them from air. Cryogenic distillation plants that (primarily) produce pure O 2 and N 2 from air also produce impure or mixed byproduct streams highly enriched with noble gases -a Xe/Kr stream and an Ar stream contaminated with O 2 and N 2 . These streams are then subject to further cryogenic separations to obtain pure Xe, Kr, and Ar for their many uses. [ ] The task of capturing dilute Xe and/or Kr from air is encountered in (i) the reprocessing and recycling of spent nuclear fuel (SNF) and (ii) the detection of nuclear explosions from (banned) nuclear weapons tests . Expanding on (i), reprocessing and recycling the large US inventory of SNF [ ] would recover unused fissile material for new fuel assemblies and reduce the volume of radioactive waste to sequester . However, radioactive isotopes of xenon (Xe) and krypton (Kr) (fission products) evolve from the SNF during reprocessing (" ppm 127 Xe, " ppm 85 Kr in the off-gases), which must be captured and (particularly, 85 Kr) sequestered as opposed to released into the atmosphere [ ].