The design of a radon chamber for the calibration of radon monitors at the Centre for Applied Radiation Science and Technology, Mafikeng, South Africa

Abstract

The radon chamber was designed at CARST. The purpose of the radon chamber design was solely for the calibration of radon monitors in this study. The radon chamber, rectangular in shape was manufactured with a Perspex material of thickness 6 x 10⁻³ m and of volume of 0.5 m³. Accommodation of radon monitors and radon sources fits the 0.5 m³ radon chamber. A sealable door of the chamber is valuable in allowing the movement of radon monitors in and out of the chamber. The Tudor - shaft soil samples were used as radon sources. Experimentally; radon concentration, humidity, temperature and pressure were measured with the AlphaGUARDs. The HPGe detector was used for nuclide activity measurement of the source soil sample. The ²²⁶Ra activity in the Tudor-shaft radon source was measured through the activity of its progenies ²¹⁴Pb and ²¹⁴Bi gamma energy line and computed to be 1394.676 ±11.737 Bq. The radon ingrowth was computed through the ²²⁶Ra activity to determine secular equilibrium. The computed radon ingrowth activities were used as a standard for calibrating the experimentally obtained radon activities from radon monitors (AlphaGUARDs). The calibration factors for the study is the change in difference between the radon monitors and the computed radon ingrowth activities determined as 223.97Bq and 339.83Bq. A hyperbolic relationship between the computed radon ingrowth activities and the two radon monitors was observed.