Radon is the most important source of natural radiation to human beings and the second major causative agent of lung cancer other than smoking. In recent years, the hazards of human exposure to thoron (Rn-220), anothe...Radon is the most important source of natural radiation to human beings and the second major causative agent of lung cancer other than smoking. In recent years, the hazards of human exposure to thoron (Rn-220), another isotope of radon, and its progeny have gained consensus. To accurately evaluate the dose level and hazards of Rn-220 and its progeny, a standard Rn-220 chamber with strong regulation ability for Rn-220 and its progeny needs to be established for the scale or calibration of measurement instruments. This paper describes the hazards, sources, behavioral characteristics of Rn-220 and its progeny, and some representative Rn-220 chambers established in various countries.展开更多
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 S...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 1NST, Vietnam. Finally, calibration factor calculated is 0.21 （tracks-cm2/Bq·m3·h） and constructed curve between integrated Tn-220 concentration and tracks density with factor R2 = 0.975.展开更多
文摘Radon is the most important source of natural radiation to human beings and the second major causative agent of lung cancer other than smoking. In recent years, the hazards of human exposure to thoron (Rn-220), another isotope of radon, and its progeny have gained consensus. To accurately evaluate the dose level and hazards of Rn-220 and its progeny, a standard Rn-220 chamber with strong regulation ability for Rn-220 and its progeny needs to be established for the scale or calibration of measurement instruments. This paper describes the hazards, sources, behavioral characteristics of Rn-220 and its progeny, and some representative Rn-220 chambers established in various countries.
文摘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 1NST, Vietnam. Finally, calibration factor calculated is 0.21 （tracks-cm2/Bq·m3·h） and constructed curve between integrated Tn-220 concentration and tracks density with factor R2 = 0.975.
