Abstract: Disclosed is a method for selectively removing and recovering the noble gas and other gaseous components typically emitted during nuclear process operations. The method is adaptable and useful for treating dissolver off-gas effluents released during reprocessing of spent nuclear fuels whereby to permit radioactive contaminant recovery prior to releasing the remaining off-gases to the atmosphere. Briefly, the method sequentially comprises treating the off-gas stream to preliminarily remove NO.sub.

Abstract: A method is disclosed herein for treating the gaseous effluents emitted from a nuclear reactor, said method being adaptable for treating either gaseous effluents produced during normal reactor operations or combustible and fission product gases released as the result of a nuclear reactor system failure. The treatment comprises sequential direction of the gaseous mixture through a multiplicity of adsorbent beds, each of said beds being preferentially adsorptive towards at least one component of said gaseous mixture, whereby to effect the desired separation by substantially either thermal-swing, cryogenic, or rapid cycle adsorption techniques.

Abstract: Noxious nitrogen oxides in a waste gas stream such as the stack gas from a fossil-fuel-fired power generation plant or other industrial plant off-gas stream is catalytically reduced to elemental nitrogen and/or innocuous nitrogen oxides employing ammonia as reductant in the presence of a zeolite catalyst in the hydrogen or sodium form having pore openings of about 3 to 10 A.