A simple technique for measuring the activity size distribution of radon and thoron progeny aerosols. (April 2021)

• Record Type: Journal Article
• Authors: Kranrod, Chutima; Chanyotha, Supitcha; Tokonami, Shinji; Ishikawa, Tetsuo
• Is Part Of: Journal of environmental radioactivity. Volume 229/230(2021)
• Publication Date: 2021-04
• Subjects: Radon -- Thoron -- Progeny -- Activity size distribution; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2020.106506
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: In this study, a portable cascade impactor was developed to more efficiently determine the activity size distribution of attached radon and thoron progeny in a natural environment. The developed impactor consisted of four stages with a backup filter stage for collection of the aerosol samples. The aerosol cut points were set for 10, 2.5, 1, and 0.5 μm at a sampling rate of 4 L min −1 . Five CR-39 chips were used as alpha detectors for each stage. To separate the alpha particles emitted from radon and thoron progeny, the CR-39 detectors were covered with aluminium-vaporized Mylar films. The thickness of each film was adjusted to allow alpha particles emitted from radon and thoron progeny to reach the surface of the CR-39 detectors. The particle cut-off characteristics of each stage were determined by mono-dispersive aerosols with particle sizes ranging from 0.1 to 1.23 μm from the collection efficiency curve. The test results showed that the respective cut-off size of stages 3 and 4 were close to the designed cut-points. Validation of the technique by comparison with two commercial devices confirmed that the developed technique could provide the necessary information to estimate the activity size distribution of attached radon and thoron progeny for dose assessment, especially, in a field survey where direct electric power is not available. Highlights: Significant information on the activity size distribution of radon and thoron progeny in the environment can be measured. The impactor can work anywhere without AC supply. Solid-state nuclear track detectors are used as the impaction plate though they face a backup filter at the last stage. The dose conversion factor for radon and thoron progeny can be specified based on the measured activity size distribution.