Reliable, accurate information about the detector geometry specifications are required to determine the detector full energy peak efficiency, using the general Monte Carlo simulation code (MC). Due to the incomplete detector geometry specifications given by the manufacturer a CT scanner (X-ray Computed Tomography) has been used to illustrate the physical dimensions, housing and placement of the detector crystal. Also, HPGe detector has been scanned using a collimated reference source (137Cs) to estimate the dead-layer as well as inner hole of the crystal. Obtained information and available manufacturer data are used to generate MCNP5 input file. Estimated dead-layer was a round 0.6 mm for the front facet and about 0.4 mm for the side. To validate MCNP5 model activity of reference point source (137Cs, 60Co and 133Ba) has been estimated. Calculated activity was in agreement with the reference value within relative difference less than 2%. Mass of 235U contents in a reference volume sources has been estimated with relative different less 1%.

Uranium is the most common element in the nuclear fuel cycle. Different techniques have been used for analyzing the isotopic composition of uranium. Precise determination of uranium isotopic ratios for an efficient control of nuclear material was carried out through the modification of the used chromatographic method of uranium. Alpha spectrometry was utilized to identify different types of natural, depleted and enriched samples for safeguard purposes. Uranium element was extracted from other interfering radionuclides, purified, electrodeposited on a stainless-steel disc, and measured using alpha-spectrometer, then isotopic ratios were calculated. For comparison purposes, the samples were also measured using a hyper pure germanium (HPGe) spectrometer and the uranium isotopic ratios were obtained. The results obtained by both techniques were in agreement within difference ranged from-8.7 to 12%. It was concluded that alpha spectrometric measurements of uranium isotopes preceded by efficient radiochemical separation using extraction chromatography is a fast and reliable technique for safeguard purposes.