Messung der Krypton-85-Aktivität der atmosphärischen Luft / A Method for Measurement of the Krypton-85-content in the Atmosphere

To measure the Kr-85 content in the atmosphere we developed a simple method. Within a time internal of five to ten days (depending on the moisture of the air) five to ten m of air (NTP) are pumped through activated carbon (pressure 300 torr, temperature 77 °K). When sampling time is over, the carbon is heated to 470 °K. This gives a gas sample of 4 1 with more than 90% of the atmospherical krypton in 3 hours. With a further step of enrichment, the volume of the sample is reduced to 100 ml. The final separation of krypton from O , N , CO, CO and Xe is made by gaschromatography at room temperature with methane as eluent gas (duration 25 min). The Kr-fraction is transported to a proportional counter (200 ml). The overall yield is 90%. The overall error of the Kr-85 content is near 1%. Data are given for the time of 15. 6. 1973 to 29. 12. 1974.