The design, construction and validation of a radon chamber for the calibration of radon monitors at the North-West University, South Africa.

Abstract

Radon is a radioactive gas that emits alpha particles, hence it has high radiological risk if inhaled. The concentration of radon in air, particularly indoor, must be monitored using well calibrated devices to ensure it does not exceed reference levels. The aim of this study was to design and construct a radon chamber for the calibration of radon monitors at the Centre for Applied Radiation Science and Technology (CARST). It is made of perspex sheet material of thickness 6 x 10-3 m and of volume 0.5 m3. The radon chamber housed Alphapump, two Alphaguards, an Airthing Wave Plus monitor, an EB85 liquid radium standard solution and electrical wires. The two Alphaguards and Airthing Wave Plus monitors were exposed to a radon atmosphere and found not to be in proximity to the calibration curve computed using EB85 liquid radium standard solution values over a period of 40 days. To align to the calibration curve, calibration factors were obtained for AG2260 and AG2261 as 1.55 kBq/m3 and 1.42 kBq/m3, respectively. The temperature observed during the experiment ranged from 19.8 °C to 27.68 °C and relative humidity ranged from 49.63% to 84.75%. The designed chamber was operated without an Alphapump mechanism, the results were found to be in agreement with the US National Radon Safety Board criteria.