Measurement and on line control of radioactive contamination of the air using ASS-500 stations

The method of continuous monitoring of artificial radionuclides in the ground-level atmosphere, used for early warning system in care of nuclear emergencies, is presented. The system consist of the scintillation spectrometer AS-01 mounted in the ASS-500 station cabinet. The results of calibrations and operational tests are given. For continuous operation mode the lower activity concentration limit is 0.44 Bq/m3 for 131I and 0.79 Bq/m3 for 137Cs. The activity concentration in the air of 10 Bq/m3 for artificial radionuclides is used as the alarm threshold value. The ASS-500 station equipped with AS-01 spectrometer allows obtaining of the immediate information on the presence of artificial radionuclides in the air. The sampling process is not disturbed by AS-01 spectrometer. Therefore, the determination of the activity concentration in the air on the level of few μBq/m3 by means of HPGe spectrometers is possible (author)