Determination of low level 85Kr and 133Xe concentrations in the environment

This study was performed under the joint TRMC/INER program for the determination of low level 85Kr and 133Xe concentrations in the environmental air samples. Based on cryogenic adsorption of krypton and xenon on charcoal followed by chromatographic separation from other gases, the 85Kr and 133Xe recovered from 200 liters of atmospheric air can be determined either on-line gas flow proportional counter or liquid scintillation counting. The recovery yields of krypton and xenon examined by using 85Kr and 133Xe tracers were nearly 100%. The minimum detectable activity of 85Kr and 133Xe by gas flow proportional counting is about 7.40 Bq. The method is satisfactory for environmental monitoring applications under abnormal conditions of nuclear facilities. However, for lower level environmental 85Kr and 133Xe measurements, the liquid scintillation counting method can be applied due to their extremely low detection limits (i.e. 0.107 Bq and 0.093 Bq for 85Kr and 133Xe, respectively). Using this method, the measurable limits of concentrations are 0.535 Bq/m3 and 0.466 Bq/m3 for 85Kr and 133Xe, respectively. (author). 15 refs., 3 figs., 1 tab