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Technical Procedure Determination of Thoron Indoor Concentration by LR-115 Type II



Author(s)

Nguyen Thi Thu Ha, Trinh Van Giap and Le Dinh Cuong

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DOI:10.17265/2162-5263/2016.03.001

Thoron (Rn-220) is an invisible, odorless radioactive gas and nine times heavier than air. Purpose of project is to set up procedure to determine Rn-220 concentration which has been carried out in laboratory using Solid State Nuclear Track Detector (SSNTD) based passive detector technique. In this study, technical procedure has been applied in Karlsruhe diffusion chamber and LR-115, Type II strippable (Kodak Pathe, France) detector. The results have investigated how LR-115 work for Rn-220 by using Monazite ore to simultaneously measure Rn-222 and Rn-220. To carry out experiment, Karlsruhe diffusion chamber is used to with and without Poly-Ethylene (PE) membrane. Karlsruhe diffusion chamber with PE membrane only detect Rn-222, without PE membrane detect total Rn-222 and Rn-220. Precision evaluation by duplicate measure at 8 cm detector-source distance with relative standard deviation is less than 2.54%. Testing technical procedure, detectors have been sent to National Institute of Radiological Science (NIRS) for Rn-220 calibration exposure. After detectors have been calibration exposure at NIRS, it carried out all the following steps of procedure which set up at laboratory in INST, Vietnam. Finally, calibration factor calculated is 0.21 (tracks•cm-2/Bq•m-3•h) and constructed curve between integrated Tn-220 concentration and tracks density with factor R² = 0.975.

LR-115, type-II (SSNTDs), Rn-220, spark counter