Effect of the Radon Background Fluctuation on the Low Activity Measurement of the 214 Pb, 214 Bi and 226 Ra

In this study, radon background fluctuation effect on the measurement of 214 Pb, 214 Bi and 226 Ra low level activity concentrations were investigated in ventilated laboratory. For this purpose, detectors which had 150% and 20% efficiencies were used. In spite of the air ventilation, radon background fluctuation effect on the low level activity measurement was observed. 20% efficiency detector measured activity discrepancies were 5.7% for 214 Pb, 8.7% for 214 Bi and 5.8% for 226 Ra. 150% efficiency detector measured activity discrepancies were 13.8% for 214 Pb, 11.5% for 214 Bi and 12.7% for 226 Ra.