Age determination of Pu-bearing samples using gamma spectrometry for safeguards and nuclear forensics applications

Abstract

Age dating of plutonium (Pu), i.e. determination of the elapsed time since the last chemical purification of the material, is one of characteristics or signatures important to deduce the history of Pumaterial in nuclear safeguards and forensics applications. This work describes a method to determine the age of some Pu-bearing samples using non–destructive gamma spectrometry. The presented method is relatively fast in comparison with destructive methods, does not require any reference materials, and could be applied to measure Pu-material in any physical and chemical forms. The Pu age is estimated from the 241Am/241Pu activity ratio. The 241Am and 241Pu activities are measured using the In Situ Object Counting System (ISOCS). The determined ages are compared to those obtained using the “Multi-Group Analysis (MGA)” Code. A maximum deviation of about 11% between the two methods is found for the investigated samples. The estimated Pu purification age of the samples is of an average value of51.914±0.02% years.