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A method to improve radioactive waste drum activity estimation in Segmented Gamma Scanning (SGS) systems was developed for homogenous content. We describe a method to quantify the activity of spatially distributed gamma-emitting isotopes (‘hot spots’) in homogenous content waste drums without the use of a collimator. Instead of averaging all the detector's readings we treat it as many different spatial samples as if we have multiple detectors surrounding the waste drum ("virtual detectors"). From these readings, we form a general linear model. Next, we derive the Maximum Likelihood Estimator (MLE) for the multiple sources position and activity. We solve this hyper-dimensional search problem using an Alternating Projections (AP) technique which transforms the problem into a simpler one-dimensional maximization problem. We tested this method using a mathematical simulation with a various number of sources, at random activities and positions for several energy bands. The preliminary results are consistent and show large improvement of the accuracy with comparison to industrial SGS systems and the same accuracy as new methods which exploits the spatial samples. Furthermore, since this method eliminates the need for heavy led collimator, none of the sources is blocked for the whole measurement period, which provides increased count rates and decreases the total measurement time.

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Gamma spectrum analysis tool providing enhanced identification capabilities aimed for the use in homeland security applications is presented. The diversities of the radiation sensors in use and of the measurement terms require constant effort and generic approach in adaptation of the existing spectrum analyzing solutions.In order to approach these operational requirements, the S p ecldentijier -new software application -was developed. Specldentijier's main program is divided into two main parts: a generic database and a spectrum processing module. In this novel development several peak search and spectrum processing algorithms are implemented in the processing module.Preliminary tests of isotope identification performance according to the standards for Homeland Security (HLS) applications were performed and are presented in this work. The main software blocks, algorithm modules and functionalities are described and their essentiality is discussed.