METHOD OF RECOVERING KRYPTON AND XENON NUCLIDES FROM WASTE GASES

1406379 Removing radioactive gases BERGWERKSVERBAND GmbH 5 March 1973 [3 March 1972] 10594/73 Heading B1L [Also in Division G6] Krypton and xenon nuclides are separated from waste radioactive gas by passing the gas through an adsorbent, e.g. activated charcoal, until Kr breakthrough occurs, and then regenerating the adsorbent by (a) evacuating to a pressure of 10-300 Torr, (b) flushing with an inert gas at 10-400 Torr to dbtain a gas enriched in Kr and Xe, and (c) restoring the original pressure by introduction of an inert gas. The process may be carried out at raised pressure or reduced temperature. The gas used in stage (b) may be helium, nitrogen, or air, or an easily condensible gas e.g. H 2 O, CO 2 , NH 3 or Freon (RTM). As shown in Fig 2, waste gas flows from valve 21 through adsorbers 20a, 20b, the adsorbers are evacuated by pump 27, and are then flushed, first together and then separately, by CO 2 from evaporator/condenser units 34, 39. The CO 2 is frozen out and Kr and Xe enriched gases are obtained separately from ducts 43, 44 respectively.