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Determination of the uranium enrichment is an important safeguards verification task, routinely carried out using non-destructive assay methods. The enrichment-meter method is one of the most widely used passive non-destructive X- and gamma-ray based methods used for such tasks. Among its advantages is the highly constrained physical nature of its underlying formalism, allowing it to be used with high-resolution HPGe detectors, as well as with low-resolution NaI detectors. Due to attractive features and spectroscopic performance, CdZnTe and LaBr 3 (Ce) detectors raised interest in their application to such tasks as well. However, their spectroscopic performance is different to that of the traditional detectors in many ways. Application of the enrichment-meter method requires determination of the net peak areas corresponding to 235 U signature photopeaks. The latter requires an adequate algorithm to select the region-of-interest boundaries, which may be sensitive to asymmetrical photopeaks of CZT detectors. In this paper we conduct a performance assessment of a 500 mm 3 CZT detector of a quasi-hemispherical design and a 2 × 2 inch LaBr 3 (Ce) scintillator with the enrichment-meter method using a set of certified uranium standards with enrichment degrees from 0.31% to 4.46% of 235 U atomic abundance. We investigate the impact of different methods used for net peak area determination, statistical quality of acquired spectra and size of region-of-interest boundaries on accuracy and uncertainty. We propose an algorithm for symmetrical/asymmetrical region-of-interest boundaries determination and make recommendations on the best combinations of the region-of-interest size and method used for the net peak area determination for each of the detectors. The underlying routines of the algorithm and analysis procedures are described in detail and results are presented., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Room temperature semiconductor detectors of CdZnTe type have been proposed as possible alternatives to spectrometers based on HPGe and NaI detectors. Attractive spectroscopic performance and portability, as well as continuous improvements in their design and availability in different sizes make them especially competitive in various radiation measurement applications where absence of cooling, small size and significantly better resolution compared to other room temperature detectors are an asset. Among these applications are nuclear safeguards that include uranium and plutonium isotopic composition determination tasks. This paper focuses on the investigation of possibilities and limits of a net peak area based methodology used for the determination of the uranium enrichment without use of calibration standards. Tests are conducted on a room temperature medium resolution spectrometer based on a 500 mm 3 CdZnTe sensor of a quasi-hemispherical design using which spectra of different statistical quality are obtained from certified uranium standards. Gamma-ray peaks in the 143-1001 keV energy range are used as uranium gamma-ray signatures. Performance assessment of an intrinsic calibration of the counting efficiency curve is conducted. A hybrid methodology based on a combination of the peak ratios method with Monte Carlo simulations of the counting efficiency curve is proposed for poor quality spectra. Implemented algorithms and analysis routines are described in detail and presented., (Copyright © 2018 Elsevier Ltd. All rights reserved.)