科研之友
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摘要
The physical verifications, that the national and international inspectors carry out in order to perform a credibility control, often consist in the measurement of physical quantities, related to the declared nuclear material properties, by Non-destructive Assay (NDA). Analysis of ores and its purified constituent's samples has been carried out in this work using non-destructive gamma assay technique. The spectrometer based on HpGe detector and its electronics was calibrated using standard IAEA multi-lines gamma sources. The efficiency calibration curve was plotted for broad gamma energies; 50-2600 keV. The gamma transition of U-235 (143.7, 163.3, 185.7, and 205.3 keV) and U-238 (63, 766.3, and 1001.03 keV) were used for qualitative and quantitative assay of the samples. The specific activities of the samples were calculated based on the determined efficiency, branching ratio (emission probability per disintegration), mass of sample and count rate of the characteristics gamma transitions of uranium isotopes at fixed geometrical conditions. A simplified equation was derived for calculation of U-235 atom ratios. The results of calculation show natural origin of the analyzed samples; around 0.72%. Where, the anthropogenic U-236 was not detected at all in the spectra. The uranium activity ratios (U-235/U-238) were calculated based on the measured activity. The uranium isotopic mass and total uranium content of the investigated samples were also calculated. The results obtained are depicted, tabulated and discussed in comparison with recent published national and international works.
- 出版日期2018-6-3
