DEPLETED, NATURAL AND LOW ENRICHED URANIUM VERIFICATION BY RECENT PORTABLE PASSIVE NON-DESTRUCTIVE ASSAY TOOLS

Employment and use of recent methods for verification of nuclear materials are milestone and key point for effective domestic and international safeguards.Modern non-destructive assay (NDA) techniques based on CdZnTe, NaI and HpGe have been used in this work to verify depleted, natural and low enriched uranium. The 235U activity of the samples was calculated based on the count rate of the 185.7 keV photopeak and compared with the certified values. The γ-lines 143.8 and 163.4 keV showed good correlation with the 235U activity in the investigated samples. The 238U and 234U activity were also measured and calculated. The 235U enrichment percentages (%E) of these samples were then calculated and found to be 0.58%, 0.72% and 1.57% respectively. The 235U/238U activity ratios of the depleted and low enriched samples were found to be sharply correlated with %E. Traces of the anthropogenic origin 236U was identified by measurement in two of the verified samples. In spite of the 234U/238U ratio was almost one in the case of depleted and natural uranium, disequilibrium between 238U and its daughter 234Th was observed.