Year
2009
Abstract
The reference NDA technique used in nuclear safeguards to measure the fissile mass in nuclear material samples is the neutron coincidence counting. Nowadays, most of the neutron coincidence counting systems are based on an analogue-logical technology. The analogue signal from the He-3 tubes is processed by amplifiers producing a train of logical TTL pulses that are fed into a neutron analyser performing the time correlation analysis using specific software. The common analogue configuration does not allow us to go back on a result using other electronics parameters (predelay, gate-width, etc). With digital signal processing, it is possible to record the signal as a file containing the pulses detected in a chronological order. This feature is achieved through the MEDAS dating card (Multi Events Datation System). In the first part, a comparison between the results obtained with an analogue electronic device (2150) and the MEDAS dating card is presented. The second part of the paper provides the presentation of the software called TRIDEN (Dating Impulse Treatment for Neutron Emitters). This software has been developed by IRSN to scan the file and give a diagnosis on the quality of the result. Each measure provides a binary file that is analyzed by TRIDEN and gives for each acquisition a Rossi-alpha curve and all the inherent characteristics of the neutron cell. The benefit brought by this technique has improved the diagnostic information gathered by the inspectors during their site inspections.