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Interlaboratory comparison of three methods for the determination of the radon exhalation rate of building materials.

Abstract：

:In this study three methods for the determination of the radon (222Rn) exhalation rate of building materials are compared. All three are so-called purge-and-trap methods in which the sample is enclosed in a container from which the exhaled radon is continuously purged by a constant flow of nitrogen gas. The outflowing radon is directed through a trapping agent, and the radon exhalation rate is subsequently calculated from the trapped activity. The main differences between the three methods are the trapping agent (silica gel, charcoal), trapping temperature (liquid nitrogen, room temperature), trapping period (30 min to 10 d), analytical method to determine the trapped activity (liquid scintillation counting, gamma ray spectrometry, total gamma counting) and the sample counting times (1 to 16 h). The repeatability and intralaboratory reproducibility are determined for one of the methods and amount to 3.1% and 4.3%, respectively. The intralaboratory reproducibility, derived from five samples with a radon release rate up to 450 microBq s(-1), was found to be 5.6% on average (range 3 to 8%). These figures are close to the combined standard uncertainty of the individual results that vary between 3 to 6%, depending on the method and method variables such as trapping period and the uncertainty of the calibration source. Furthermore, another 10 commercially available building materials were analyzed to investigate the correlation between the applied methods. Using linear regression analysis, it was found that the slope deviated not more than 10% from the one to one correspondence line. The results show that measurements of the exhalation rate can be carried out with a large degree of accuracy provided sufficient care is taken for a well-documented standard method.

journal_name

Health Phys

journal_title

Health physics

authors

de Jong P,van Dijk W,de Vries W,van der Graaf ER,Roelofs LM

doi

10.1097/01.hp.0000144573.53642.d9

keywords:

subject

Has Abstract

pub_date

2005-01-01 00:00:00

pages

59-64

issue

eissn

0017-9078

issn

1538-5159

pii

00004032-200501000-00006

journal_volume

pub_type

杂志文章

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Interlaboratory comparison of three methods for the determination of the radon exhalation rate of building materials.