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Ba, Vu Ngoc,Thien, Bui Ngoc,Loan, Truong Thi Hong Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1
In this work, self-absorption correction factor related to the variation of the composition and the density of soil samples were evaluated using the p-type HPGe detector. The validated MCNP5 simulation model of this detector was used to evaluate its Full Energy Peak Efficiency (FEPE) under the variation of the composition and the density of the analysed samples. The results indicates that FEPE calculation of low gamma ray is affected by the composition and the density of soil samples. The self-absorption correction factors for different gamma-ray energies which was fitted as a function of FEPEs via density and energy and fitting parameters as polynomial function for the logarithm neper of gamma ray energy help to calculate quickly the detection efficiency of detector. Factor Analysis for the influence of the element composition in analysed samples on the FEPE indicates the FEPE distribution changes from non-metal to metal groups when the gamma ray energy increases from 92 keV to 238 keV. At energies above 238 keV, the FEPE primarily depends only on the metal elements and is significantly affected by aluminium and silicon composition in soil samples.
Truong Thi Hong Loan,Vu Ngoc Ba,Bui Ngoc Thien 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4
In this study, natural radioactivity concentrations and dosimetric values of fly ash samples were evaluated for the landfill area of the coal-fired power plant (CFPP) complex at Binh Thuan, Vietnam. Theaverage activity concentrations of 238U, 226Ra, 232Th and 40K were 93, 77, 92 and 938 Bq kg 1, respectively. The average results for radon dose, indoor external, internal, and total effective dose equivalent (TEDE)were 5.27, 1.22, 0.16, and 6.65 mSv y 1, respectively. The average emanation fraction for fly ash were0.028. The excess lifetime cancer risks (ELCR) were recorded as 20.30 10 3, 4.26 10 3, 0.62 10 3, and25.61 10 3 for radon, indoor, outdoor exposures, and total ELCR, respectively. The results indicated thatthe cover of shielding materials above the landfill area significantly decreased the gamma radiation fromthe ash and slag in the ascending order: Zeolite < PVC < Soil < Concrete. Total dose of all radionuclides inthe landfill site reached its peak at 19.8 years. The obtained data are useful for evaluation of radiationsafety when fly ash is used for building material as well as the radiation risk and the overload of thelandfill area from operation of these plants for population and workers.
Huynh Truc Phuong,Vu Ngoc Ba,Bui Ngoc Thien,Loan Truong Thi Hong Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7
In the process of growth and development, plants not only absorb essential nutritional elements, but also absorb radioactive and non-essential elements from the environment, and their distribution varies in different parts of the plant. In this study, neutron activation analysis and gamma spectrometry were performed on stems, roots, and leaves of vegetables. The results indicate that the accumulation of radionuclides and multi-elements depends on the plant type and plant parts. Activity concentrations of <sup>226</sup>Ra and <sup>232</sup>Th in plants were accumulated in the following order: Roots > Stems > Leaves. The highest concentrations of <sup>40</sup>K and <sup>210</sup>Pb were observed in the stems and leaves of plants, respectively. Essential nutrient requirements of plants are in the following order: K > Ca > Mg > Fe > Zn > Mn. Among the nonessential metals, the concentration of Na in the vegetable sample was much greater than those of the other elements. The K/Na ratio in the plant depends on the type of plant and the translocation within the plant.