THE MEASUREMENT OF LOW CONCENTRATIONS OF KR-85 IN ATMOSPHERIC AIR SAMPLES

Krypton-85 atmospheric contamination produced by the nuclear industry has been investigated on the basis of regular measurements. Kr-85 concentrations observed in ground-level air of Prague between 1983 and 1993 are presented and their time-related changes analyzed. The long-term trend of Kr-85 air activity increased steadily over the monitored period with the growth rate of 38 mBq.m(-3) (STP)/yr and reached about 1.2 Bq.m(-3) (STP) in 1992. Short-term variations of the baseline level with the average amplitude of 12% show a seasonal periodicity. Occasionally detected extreme values of up to 2.5 Bq.m(-3) (STP) indicate undispersed emissions from distant nuclear fuel reprocessing plants.