DEVELOPMENT AND APPLICATION OF THE CYCLIC DELAYED NEUTRON COUNTING TECHNIQUE AT ES-SALAM RESEARCH REACTOR

Uranium content in samples can be generally determined by neutron activation followed by counting delayed neutrons; this technique is called delayed neutron counting (DNC). It is fast, non-destructive and free of interferences, but its sensitivity is insufficient to determine low uranium concentrations. The cyclic delayed neutron counting (CDNC) technique was developed to improve the detectable limit of the delayed neutron counting (DNC) device, which allows the uranium analysis of low concentration in samples. By using twenty cycle activation and delayed neutron counting, it has been demonstrated that a limit of 0.02 μg of uranium can be achieved. This later is 4 times lower than the value determined by the (DNC) technique, which was 0.08 μg of uranium. It confirms the theoretical predictions. An expression was deduced to represent the decrease of this parameter with the number of cycles. This new technique has been applied for the analysis of several standard samples. The obtained concentrations are in agreement with the corresponding certified reference values (CRV). The precision and the accuracy achieved are better than those determined by the classical (DNC) technique.