Krypton and Xenon Radionuclides Monitoring in the Northwest Region of Russia

摘要

Monitoring of Xe and Kr radionuclides was conducted from August 2006 to 30 July 2008 within the framework of ISTC Project #2133. Cherepovets City in Vologda Province and St. Petersburg were chosen as monitoring locations. Kr–Xe concentrate samples were obtained as a result of processing of several thousand m3 of atmospheric air. New results of 85Kr monitoring show, that for last 15 years, the 85Kr volumetric activity in the atmospheric air of the northwest region of Russia has increased approximately 50% and has achieved a level of 1.5 Bq/m3. This value correlates well with similar data for Western Europe and Japan. The xenon fraction (80–160 cm3 under STP) is adsorbed on charcoal in the ampoule, which is measured in the well of HPGe gamma detector. Minimum detectable concentration (MDC) of 133Xe for this technique is 0.008 mBq/m3, and it is the most sensitive method used today. The 133Xe concentration in the atmospheric air of Cherepovets City varied in the monitoring period ranging from 0.09 to 2.5 mBq/m3. During the period of March 2007–30 July 2008, 133Xe activity concentration in the atmospheric air of St. Petersburg changed from background values (0.2–0.3 mBq/m3) to 185 mBq/m3 and for approximately 20% of the samples 135Xe was also measured with the 135Xe/133Xe activity ratio varied within the range of 0.03–3.5.