Estimation of radon emanation power: a comparison of different methods

Abstract

Radon emanation power was estimated by applying three different methods. The first was based on measuring radon exhalation rates by closed-loop accumulation method employing RAD7 device. Radon leakage rate was determined by applying two models of fitting the experimental data. Specific activities of 226Ra in soil samples were measured by coaxial HPGe detector (GEM30-70, ORTEC). The second method was indirect gamma-ray spectrometry method which included two separate measurements of counts under the photopeaks of 351.9 keV (214Pb) and 609.3 keV (214Bi). The influence of sample moisture content on radon emanation was demonstrated byboth methods. Radon emanation power of the sample with the highest radon exhalation rate was also estimated by two-month exposure of two radon diffusion chambers equipped with CR-39 detectors. A good agreement among the results was obtained; coefficient of variation was below 10% for the samples employed in the study. Assuming zero volumetric fraction of 218Po in air provided more consistent results.