An approach to discriminatively determine thoron and radon emanation rates for a granular material with a scintillation cell |
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| Institution: | 1. Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, 1550 Kamisaibara, Kagamino-cho, Tomata-gun, Okayama 708-0698, Japan;2. Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany;1. University of Nottingham, School of Biosciences, Sutton Bonington Campus, Leicestershire, LE12 5RD, UK;2. Loughborough University, Department of Chemistry, Ashby Road, Loughborough, Leicestershire, LE11 3TU, UK;1. Federal University of Technology – Paraná (UTFPR), Avenida Sete de Setembro, 3165, Curitiba 80230901, Brazil;2. Pelé Pequeno Príncipe Research Institute (IPPPP), Avenida Silva Jardim, 1632, Curitiba 80250200, Brazil;3. National Science Center “Kharkov Institute of Physics and Technology” (NSC KIPT), Street Akademicheskaya, 1, Kharkiv 61108, Ukraine;1. Department of Diagnostic Imaging, Fox Chase Cancer Center, 333 Cottman Ave, Philadelphia, PA 19111, USA;2. Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran;1. CEA, LIST, Laboratoire National Henri Becquerel (LNE-LNHB), Bât. 602 PC111 CEA Saclay, F-91191 Gif-sur-Yvette, France;2. BIPM, Pavillon de Breteuil, 12, bis Grande Rue, 92312 Sèvres Cedex, France;3. Ionizing Radiation Division, National Institute of Metrology, No. 18, Bei San Huan Dong Lu, Beijing Zip Code: 100013, PR China;1. Ural Federal University, Ekaterinburg, Russia;2. Institute of Industrial Ecology UB RAS, Ekaterinburg, Russia |
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| Abstract: | A powder sandwich technique was applied to determine thoron (220Rn) and radon (222Rn) emanation rates for a granular material. The feature of this technique is the sample preparation, in which a granular material is put and fixed between two membrane filters. Airflow is directly given to this sandwich sample, will include thoron and radon emanated from the material, and then is transferred to the detector. This method makes sure that thoron and radon emanated are not retained in pore space within the sample volume, which is crucial for the appropriate emanation test. This technique was first introduced by Kanse et al. (2013) with the intention to measure the emanation of thoron - but not of radon - from materials having much higher 224Ra activity than 226Ra. In the present study, the methodology for the discriminative determination of thoron and radon emanation rates from a granular material has been examined using a flow-through scintillation cell and sandwich sample. The mathematical model was developed to differentiate total alpha counts into thoron- and radon-associated counts. With a sample of uranium ore, this model was experimentally validated by comparison between the scintillation cell and a reference detector that can discriminatively measure thoron and radon concentrations. Furthermore, the detection limits and uncertainties were evaluated to discuss the characteristics of this method. Key parameters for improving the determination of thoron and radon emanations were found to be the background radon concentration and the leakage of radon from the measurement system, respectively. It was concluded that the present method is advantageous to a sample that has much higher 226Ra activity than 224Ra. |
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| Keywords: | Thoron Radon Emanation Sandwich technique Granular material Scintillation cell |
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