No abstract

Evaluating measurement uncertainty of a physical quantity is a mandatory requirement for laboratories within the recognition ISO/IEC 17025 certification to access reliability of measured results. In this work, the uncertainty of ionizing radiation measurements such as air-kerma, personal dose equivalent Hp(d) was evaluated based on GUM method and Monte Carlo method. An uncertainty propagation software has been developed for evaluation of the measurement uncertainty more convenient.

In this study, ARGOS software was used to simulate the atmospheric radioactive emissions from Fangchenggang nuclear power plant to Viet Nam. The simulated cases are hypothetical accidents with hypothetical source terms equivalent to level 6 of the International Nuclear and radiological Event Scale (INES). The results show the possibility of using ARGOS in simulating atmospheric dispersion, assessing radiation dose to humans from the Fangchenggang nuclear power plant accident to Viet Nam in some accident situations. Furthermore, the obtained results contribute to forecasting and supporting emergency response when an accident occurs in nuclear power plants.

FLEXPART software simulates atmospheric emissions based on wind-field movements and random disturbances. To simulate random processes, FLEXPART uses a certain number of simulation particles. Changing the number of simulation particles causes a change in the simulated results of the dispersion concentration of the radionuclides. The larger number of simulated particles results in the more accurate simulated results. However, increasing the number of simulated particles results in the increasing of the computational cost. The report presents an assessment of the uncertainty in theconcentration of radionuclides in simulating dispersion of 137Cs and 131I nuclides using FLEXPART software according to the number of simulation particles. The number of simulation particles used in this study are 100, 1000, 5000, 7500, 10000, 15000, 20000, 25000 and 30000 particles / hour. Using the image processing software OpenCV to evaluate the uncertainties of simulated results according to the number of simulated particles used. Evaluation results show that the simulated results are acceptable with the number of simulated particles being of 20000 particles/hour.

In this study, aerosol samples at Hanoi, Vietnam from February 2017 to January 2018collected on the glass fiber filter were analyzed for 210Pb by using HPGe spectrometry. 210Pb weekly activity concentrations were in the range of 0.12 mBq.m-3 to 2.87 mBq.m-3 with an average value of 0.92 mBq.m-3 and 210Pb monthly activity concentrations were in the range of 0.99 mBq.m-3 to 9.24 mBq.m-3 with an average value of 4.01 mBq.m-3. The analysis of monthly averaged 210Pb activity concentrations revealed a dominant seasonal variability: high activity concentrations of 210Pb in winter and lower values in summer. The correlation between the activity concentrations of 210Pb in aerosoland the meteorological parameters (average temperature, precipitation and relative humidity) were observed and the obtained correlation coefficients are -0.95, -0.58 and -0.71, respectively.