2019 Fiscal Year Annual Research Report
The Mechanism Study of Radioactive Microparticles in the Body by Respiration and the Risk Assessment of Internal Exposure by using an Improved Model
| Project/Area Number |
19J14291
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| Research Institution | Hirosaki University |
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Principal Investigator |
HU JUN 弘前大学, 保健学研究科, 特別研究員(DC2)
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| Project Period (FY) |
2019-04-25 – 2021-03-31
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| Keywords | radon / internal exposure |
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| Outline of Annual Research Achievements |
To test the mechanism of the radioactive microparticles intaking to the human body,a stable radioactive microparticles generation and exposure system are necessary, therefore a test experiment was carried out in Hirosaki University's radon and thoron exposure chambers. A novel direct 222Rn/220Rn progeny monitor was developed, which can measure the accumulative progeny concentration during the whole exposure period, and be used to estimate the activity concentration of the deposition progeny. The natural uranium rock and aerosol Generator were responsible to generate the aerosol particles and mixed with radon gas in the chamber to form the radioactive microparticles.A theoretical model of the direct progeny monitor was developed based on the experiment data.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
The theoretical model of the mechanism of the direct progeny monitor was developed based on the experiment data. A parameter sensitivity analysis of the theoretical model of the direct progeny monitor was carried out to test its influential factors. The results show both the attachment process and the deposition process of 222Rn and 220Rn progeny are important to the performance of the progeny monitor. Moreover, dosimetry software package IMBA was applied to analyze the influential factors of inhalation dose, which can be competent to implement to evaluate the effective dose coefficient with the experimental data. These interim results are the basement to improve the method of internal exposure causing by the inhalation of radioactive microparticles.
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| Strategy for Future Research Activity |
The radon exposure experimental system will generate mixed aerosol and radon gas to form stable radioactive microparticles in the exposure chamber. The activity will be measured with the controlled aerosol size by progeny monitor. Then the influence of the mechanism of the coagulation, condensation and decay processes of the radioactive microparticles will be simulated by the theoretical model and validate with the experimental data. The validate theoretical model will be used to improve the input parameters of IMBA. The aerosol distribution, number of condensation nuclei and radon concentration will be measured in typical houses in Aomori, and China. And then, the risk assessment of the internal exposure in these areas will be evaluated by using the improved IMBA model.
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