Rapid identification of low activity of depleted uranium using portable γ -spectrometer

Objective To explore the feasibility of using portable γ spectrometer to rapidly identify the low activity of depleted uranium and the underlying conditions. Methods Firstly, high purity germanium (Ge) γ spectrometer was used to analyze energy spectrum of DU samples (5 g) and calculate nuclide percentage of 235U in an attempt to ascertain the properties of these DU samples. The portable γ spectrometer was used to provide the evidences for identification of DU samples. Secondly, portable γ spectrometer was also used to identify DU samples of same group. These samples contain 1 g DU powder and 0-5 g environmental clay powder, which were sealed with double layer pocket, and then detected with a distance of 1-5 cm during the longest detection time of 10 min. According to the detection of nuclide activity of 238U and 235U in the samples and the subsequent calculation of specific activity, the nuclide percentage composition was calculated and the existence of DU was confirmed if this value of 235U was less than 0.718%. Results The activity of 238U was detected using portable γ spectrometer under all test conditions, while the activity of 235U was detectable only under certain test conditions (MA≥1 g, DN≤1 cm). Under the condition that the 238U and 235U was both detected, the nuclide percentage of 235U was all less than 0.718%, which suggested that the DU was confirmed. Conclusions The energy spectrum of low activity of DU and the type of nuclide could rapidly be identified and evaluated by using portable γ spectrometer. This is same as the conclusions obtained with high purity Ge γ spectrometer, α spectrometer and ICP-MS. Key words: Portable γ spectrometer; Depleted uranium; Identification