Μεταβολές της συγκέντρωσης του ραδονίου και των θυγατρικών του στον υπαίθριο επιφανειακό αέρα

Abstract

Measurement of the radioactivity in the air near the ground is widely used in the control of natural radiation and as an early warning system for nuclear emergencies in the case of artificial radioactivity in the air from human activities. Monitoring of the concentration of radionuclides, originating from radon (Rn-222) and its progeny, in the lower layers of air has been found to correlate with meteorological parameters, resulting in an intense diurnal and seasonal variation. In this sense, measurements of gross alpha radioactivity in the air near the ground and the gamma radioactivity emitted from the ground were carried out in the Nuclear Technology Laboratory of Democritus University of Thrace, in the city of Xanthi in North-eastern Greece. The air alpha radioactivity during typical days reached a peak in the morning, followed by a rapid decrease to a minimum value in the afternoon rising again to the peak of the following morning. The diurnal and seasonal dependence of the alpha radioactivity variation on the temperature and the humidity of air was confirmed through the statistical treatment of the measurements. The variation of ground level gamma radiation was found to follow the variation of alpha radioactivity. The periodic variation is due to the meteorological parameters that influence the concentration of aerosols, where attached are radon progeny radionuclides. A mathematical function was developed to describe the typical diurnal variation of gross .# radioactivity in the air. The function variables are the relative humidity and temperature in the air and the ground level ### radioactivity. An evaluation model for the measurements is proposed through the application of the function. This is based on the normalisation of the alpha radioactivity in air to a desired flat response preferably at a zero value and any deviations outside the statistically permissible limits.