IV. Eurasian conference on nuclear science and its application : presentations, 31 October- 3 November 2006. Baku, Azerbaijan.

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Browsing IV. Eurasian conference on nuclear science and its application : presentations, 31 October- 3 November 2006. Baku, Azerbaijan. by All Authors "3905"

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    Uranium isotopic analysis of depleted uranium in presence of other radioactive materials by using coaxial and planar Ge detectors
    (Azerbaijan National Academy of Sciences Institute of Radiation Problems ve Turkish Atomic Energy Authority, 2006) Yücel, Haluk; Yeltepe, Emin; Dikmen, Hasan; Vural, Mustafa; 3905; TAEK-ANAEM
    This paper deals with the determination of isotopic abundance of depleted uranium (DU) employing two different γ-ray spectrometric methods. One is the multi-group y-ray analysis (MGA) method using the low energy region (< 300 keV) with a planar Ge detector intrinsically calibrated with γ- and X-rays of uranium without use of standards. The MGA method is quicker and more practical for situ applications, however, it has been previously demonstrated by author [1] that relative abundances of DU obtained by MGA method are not consistent with the declared values for the DU samples in the presence of the actinides such as Th, Np, Pa and Am. The main reason for these erroneous results has already been proposed to be the interference of the γ- and X-rays of uranium with those emissions of the other actinides in the 80-130 keV region. The latter method is the absolute γ-ray analysis method (AGA), which uses the γ-rays of energies in the range of 130-1001 keV region for uranium but it requires an accurate absolute efficiency calibration with use of radionuclide standards. For the application of the AGA method, a high efficient coaxial Ge detector was calibrated by using the multi-radionuclide standards. It is emphasized that less intense but cleaner gamma peaks at 163.3 keV (5.08 %) and 205 keV (5.01%) of 235U are preferably used for the determination of 235U abundance in the AGA method, although there are more intense peaks of 235U observed in the γ-ray spectra such as 143.8 keV (10.76%) and 185.7 keV (57.2%) of 235U. Because both 143.8 keV and 185.7 keV peaks affected seriously due to interferences with 143.3 keV (0.44%) of 237Np and with 186.2 keV(3.51%) of 226Ra. Additionaly, in the higher energy region (above 130 keV) of the spectra, it was chosen the analytical peaks: 258.2 keV (0.076%), 742.8 keV (0.106%), 766.3 keV (0.294%) and 1001 keV (0.837%) y-rays of 234mPa (238U) for the determination of 238U. However, the 1001 keV peak among them is preferably chosen for the isotopic abundance analysis of 238U. On the other hand, in the low energy region, the most intense peak of 234Th (~>HU), 63.3 keV (4.8%) has not been considered for the analysis because it has a fully multiplet (62.86 keV + 63.29 keV) and includes the interferenc peaks of the 62.70 keV (1.5%) of 234Pa, the 63.81 keV (0.263%) of 232Th and the 63.90 keV (0.011%) of 237Np, when the presence of other radioactive materials along with DU. It is clear that the AGA method needs more tedious and laborious work, however, it results in more accurate results for 235U isotopic analysis of DU samples. The results for the abundances measured from the AGA method are compared with those of MGA method when DU samples measured along with other radioactive materials.