[en] The discharge rates, isotopic composition, and major in-plant pathways for radioactive krypton and xenon in effluent gases at commercially operated nuclear power stations in the United States are reported. Specific information was obtained in the course of radiological surveillance studies at two BWR and two PWR stations, and periodic average discharge rates are reported by station operators. Techniques for radiochemically analyzing these radioactive gases are described: in-plant samples at relatively high concentrations are analyzed directly by gamma-ray spectrometry; low-level samples, especially those collected in the environment, are first concentrated, and may also be treated to separate krypton and xenon from each other and from other gases. Also discussed is the measurement of radionuclide concentrations in air by radiation dosimetry