Abstract
The performance of continuous radon monitors (CRMs) is usually evaluated under controlled conditions in a radon chamber during calibrations or intercomparison exercises. The impact of thoron on CRMs response is rarely evaluated; in case the evaluation is performed, it is carried out in a controlled atmosphere with relatively constant, homogeneous, and generally high thoron concentrations and very low radon levels. In a real indoor environment, both radon and thoron concentrations are extremely variable, so the thoron interference evaluations reported in the literature are generally not applicable to CRMs used to measure radon concentration indoors. For this reason, an experimental study was carried out with four different CRMs in an indoor environment (an office room) where medium-to-high concentrations of both radon and thoron were expected. Thoron concentration has been separately evaluated throughout two different active monitors. Three CRMs resulted in overestimations of radon concentration by about 10% due to thoron interference, whereas such interference results were negligible for the fourth CRM. However, the thoron interference can also be used to assess thoron concentration by using CRM not specifically designed to do so. Based on the results of this study, an indirect method to assess thoron concentration is indeed proposed, relying on the combination of two identical monitors (one placed right close to the wall and the other one far enough from there).
Highlights
Continuous radon monitors (CRMs) are being increasingly used in many application fields including the evaluation of short- and long-term effectiveness of remedial actions and the estimation of the actual exposure of workers [1]
Interference due to thoron has been observed to determine an overestimated radon concentration returned by some continuous radon monitors
10% has been observed for AlphaGUARD monitors and the RadonEye Plus monitor, whereas the interference has resulted to be negligible on TERA
Summary
Continuous radon monitors (CRMs) are being increasingly used in many application fields including the evaluation of short- and long-term effectiveness of remedial actions and the estimation of the actual exposure of workers [1]. The performance of any detectors, including the affordable CRMs, needs to be evaluated in terms of accuracy, precision, and response linearity. Such evaluations are carried out throughout calibrations or intercomparison exercises performed in a radon chamber [2,3,4]. The latter realizes when the returned radon (in the following referred to as Rn) concentration is overestimated due to the non-negligible thoron concentration This phenomenon, as expected, has been observed especially close to the walls, where the thoron concentration is generally maximum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
