Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation

Publication Type:

Journal Article

Source:

Journal of environmental Radioactivity, Volume 157, p.52-59 (2016)

Abstract:

Measuring radium-226 concentration in liquid samples using radon-222 emanation remains competitive<br/>with techniques such as liquid scintillation, alpha or mass spectrometry. Indeed, we show that high-<br/>precision can be obtained without air circulation, using an optimal air to liquid volume ratio and<br/>moderate heating. Cost-effective and efficient measurement of radon concentration is achieved byscintillationflasks and suffi<br/>ciently long counting times for signal and background. More than 400 such<br/>measurements were performed, including 39 dilution experiments, a successful blind measurement of<br/>six reference test solutions, and more than 110 repeated measurements. Under optimal conditions,<br/>uncertainties reach 5% for an activity concentration of 100 mBq L-1<br/>and 10% for 10 mBq L-1. While thetheoretical detection limit predicted by Monte Carlo simulation is around 3 mBq L-1, a conservative<br/>experimental estimate is rather 5 mBq L-1, corresponding to 0.14 fg g<br/>-1. The method was applied to 47natural waters, 51 commercial waters, and 17 wine samples, illustrating that it could be an option for<br/>liquids that cannot be easily measured by other methods. Counting of scintillationflasks can be done in<br/>remote locations in absence of electricity supply, using a solar panel. Thus, this portable method, which<br/>has demonstrated sufficient accuracy for numerous natural liquids, could be useful in geological and<br/>environmental problems, with the additional benefit that it can be applied in isolated locations and in circumstances when samples cannot be transported.<br/>