Main results of the second AIRP international radon-in-field intercomparison for passive measurement devices

Thoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron interference. Rates of thoron infiltration (as thoron interference) into the diffusion chamber of the monitor were evaluated. The temporal variation was obtained based on measurements of the underfloor space of a Japanese wooden dwelling using a diffusion-type radon monitor, a reference radon monitor which was not affected by thoron interference, and a thoron monitor. The thoron infiltration rate for the diffusion-type monitor varied from 0% to 20%. In particular, it appeared to increase when ventilation of the underfloor space air was forced. The variable thoron infiltration rate, with respect to ventilation strength, implied that not only a diffusive process, but also an advective process, played a major role in air exchange between the diffusion chamber of the monitor and the outer air. When an exposure room is characterized by the frequent variation in air ventilation, a variable thoron response is considered to occur in radon–thoron discriminative detectors, in which only diffusive entry is employed as a mechanism for the discrimination of radon and thoron.

Section: Introductionmentioning

confidence: 77%

Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air

Omori

Shimo

Janik

et al. 2020

“…However, the real scenarios, dwellings, and working places, where the radon monitors or passive detectors are laid can differ from the stable conditions usually performed to test them. Accordingly, some intercomparisons have been carried out in field environments in order reproduce such situations, which should be periodically conducted [4][5][6][7]. The exercise presented in this article is the comparison of indoor radon gas measurements under field conditions performed with passive detectors, giving an integrated measurement over time, and active monitors, continuously monitoring radon concentration, within the European MetroRADON project (http://metroradon.eu/).…”

Section: Site Descriptionmentioning

confidence: 99%

“…A total of 23 groups of passive detectors and 22 active monitors were exposed in Room1 (see Figure 2). The statistical criteria employed to select the number of exposed and transit detectors were based on the usual international intercomparison requirements [6,7,12] and with enough of a number that assured obtaining a representative average with a low uncertainty. order to decide when to remove the passive detectors of every exposure period.…”

Section: Radon Exposures Devices and Logistic Arragementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Intercomparison of Indoor Radon Measurements Under Field Conditions In the Framework of MetroRADON European Project

Rábago

Merino

Celaya

et al. 2020

Interlaboratory comparisons are a basic part of the regular quality controls of laboratories to warranty the adequate performance of test and measurements. The exercise presented in this article is the comparison of indoor radon gas measurements under field conditions performed with passive detectors and active monitors carried out in the Laboratory of Natural Radiation (LNR). The aim is to provide a direct comparison between different methodologies and to identify physical reasons for possible inconsistencies, particularly related to sampling and measurement techniques. The variation of radon concentration during the comparison showed a big range of values, with levels from approximately 0.5 to 30 kBq/m3. The reference values for the two exposure periods have been derived from a weighted average of participants’ results applying an iterative algorithm. The indexes used to analyze the participants’ results were the relative percentage difference D(%), the Zeta score ( ζ ), and the z-score ( z ). Over 80% of the results for radon in air exposure are within the interval defined by the reference value and 20% and 10% for the first and the second exposure, respectively. Most deviations were detected with the overestimating of the exposure using passive detectors due to the related degassing time of detector holder materials.

“…Similarly, detectors capable of performing alpha spectrometry have been reported to evidence thoron interference due to energy resolution and algorithm used to calculate the radon concentration [ 4 ]. Specific correction algorithms have been conceived to avoid overestimation of radon concentration due to thoron in measurements performed by CRMs operating energy discrimination [ 1 ] or not [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Thoron Interference on Performance of Continuous Radon Monitors: An Experimental Study on Four Devices and a Proposal of an Indirect Method to Estimate Thoron Concentration

Carlo

Ampollini

Antignani

et al. 2022

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).