Realization of radioactive equilibrium in the KRISS radon chamber

• The activity concentrations of radon decay products are evaluated by the Modified Tsivoglou Method.
• Mosquito-repellent incense is used to produce aerosol particles in the radon chamber.
• The radioactive equilibrium in the chamber was achieved within 2 days and confirmed by the Bateman equation.

The maintenance of radioactive equilibrium between radon and its decay products in a radon chamber is necessary to calibrate radon decay product monitors. In this study, the activity concentrations of radon decay products have been measured, and mosquito-repellent incense has been used to produce aerosol particles in the chamber. Filter papers with 8 μm pore size were used to collect aerosol in the chamber. The activity concentrations of radon decay products have been evaluated by the Modified Tsivoglou Method. The correction factors due to the differences in counting time requirements of the Modified Tsivoglou Method and the time delay between consecutive measurements have been determined. Finally, the radioactive equilibrium has been confirmed by applying the Bateman equation.