Intercomparison experiments of systems for the measurement of xenon radionuclides in the atmosphere

Radioactive xenon monitoring is one of the main technologies used for the detection of underground nuclear explosions. Precise and reliable measurements of 131mXe, 133gXe, 133mXe, and 135gXe are required as part of the International Monitoring System for compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). For the first time, simultaneous testing of four highly sensitive and automated fieldable radioxenon measurement systems has been performed and compared to established laboratory techniques. In addition to an intercomparison of radioxenon monitoring equipment of different design, this paper also presents a set of more than 2000 measurements of activity concentrations of radioactive xenon made in the city of Freiburg, Germany in 2000. The intercomparison experiment showed, that the results from the newly developed systems agree with each other and the equipment fulfills the fundamental requirements for their use in the verification regime of the CTBT. For 24-h measurements, concentrations as low as 0.1 mBq m−3 were measured for atmospheric samples ranging in size from 10 to 80 m3. The 133Xe activity concentrations detected in the ambient air ranged from below 1 mBq m−3 to above 100 mBq m−3.