Year
2008
Abstract
The 235U isotopic abundance determination using portable gamma-ray spectroscopy systems is widely used for nuclear material quantification and verification in the field. In nuclear safeguards, this technique constitutes a powerful tool for achieving immediate conclusions during inspections at nuclear facilities. The performance of some commercially available portable systems is being investigated by the Brazilian Safeguards Laboratory: a low resolution system composed by a 2”x2” NaI(Tl) crystal and a portable mini-multichannel analyzer model GBS-166; a low resolution compact system model Canberra Inspector-1000 with a 1.5”x 1.5” NaI(Tl) non-stabilized crystal model IPRON-1; and a high resolution system composed by a HPGe detector model Canberra GL1015R and a portable mini-multichannel analyzer model GBS-166. For data analysis, the spectra acquired with low resolution systems were analyzed by the NaIGEM® version 1.52a code. For the high resolution system, the MGAU® version 4.0 code was used. The purpose was to evaluate the performance of the systems in regards to the precision and biases for 235U isotopic determination of typical nuclear material items found in nuclear facilities. In this study, the data acquisition and analysis was focused on measurements of low enriched 30B type UF6 cylinders that are routinely handled in a fuel fabrication plant. The performance results from each system were compared. Finally, the performance of each system for nuclear material verification activities in the field was discussed and compared to international performance standards.