Activity measurements of radon from construction materials

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• 作者：L. Fior^a ; J. Nicolosi Corrê ; a^a ; S.A. Paschuk^a ; ^{spaschuk@gmail.com} ; V.V. Denyak^a ; H.R. Schelin^a ; ^b ; B.R. Soreanu Pecequilo^c ; J. Kappke^a
• 关键词：NORM ; Rn-222 ; Construction materials ; Track detectors ; Alpha particles
• 刊名：Applied Radiation and Isotopes
• 出版年：2012
• 期刊代码：6_09698043
• 类别：ce
• 出版时间：July, 2012
• 卷：70
• 期：7
• 页码：1407-1410
• 文件大小：387 K

摘要

This work presents the results of radon concentration measurements of construction materials used in the Brazilian industry, such as clay (red) bricks and concrete blocks. The measurements focused on the detection of indoor radon activity during different construction stages and the analysis of radionuclides present in the construction materials. For this purpose, sealed chambers with internal dimensions of approximately 60脳60脳60 cm³ were built within a protected and isolated laboratory environment, and stable air humidity and temperature levels were maintained. These chambers were also used for radon emanation reduction tests. The chambers were built in four major stages: (1) assembly of the walls using clay (red) bricks, concrete blocks, and mortar; (2) installation of plaster; (3) finishing of wall surface using lime; and (4) insulation of wall surface and finishing using paint. Radon measurements were performed using polycarbonate etched track detectors. By comparing the three layers applied to the masonry walls, it was concluded that only the last step (wall painting using acrylic varnish) reduced the radon emanation, by a factor of approximately 2. Samples of the construction materials (clay bricks and concrete blocks) were ground, homogenized, and subjected to gamma-ray spectrometry analysis to evaluate the activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K. The values for the index of the activity concentration (I), radium equivalent activity (Ra_eq), and external hazard index (H_ext) showed that these construction materials could be used without restrictions or concern about the equivalent dose limit (1 mSv/year).