Isotopic composition determination codes: current state-of-the-art, recent developments and future challenges

International audienceDetermination of actinide isotopic composition is one of the most important tasks accomplished under IAEA safeguards treaties for verification and inspection activities. Spectrometers based on HPGe detectors have traditionally been the detectors of choice for such systems with a large array of various data analysis codes developed specifically to suit the performance of these detectors. Over the past decade in this domain there has been interest in using medium resolution room temperature detectors based on CdZnTe and LaBr$_3$(Ce) crystals. Moreover, progress in analytical tools that could be applied to analyze worsened statistical quality spectral data has opened a wide range of possible applications where such compact detectors and absence of cryogenics are advantageous. In this paper we aim to provide a review on the recent advances in the domain of isotopic composition determination systems used as with traditional HPGe detectors as well as with medium resolution ones. We limit ourselves to the achievements in the European Union and divide our review in three parts. First, we provide an update on the current status of the French code IGA aimed at applications with traditional HPGe systems. Second, we present the recent results in the domain of isotopic composition determination codes development for medium resolution detectors, namely the codes MCSIGMA and CAMILA developed in the framework of a PhD project in Belgium. Third, we give an outlook on the current research activities conducted at CEA List Saclay in the domain of isotopic composition determination algorithms applied to medium resolution detectors

sIGAle, a new code for automatically determining radionuclide activities using CdZnTe spectrometry

2009 1st International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications (ANIMMA)International audienceThe sIGAle code is developed by CEA LIST at the request of CEA DEN to analyse spectra measured with CdZnTe detectors. sIGAle is a specific automatic analysis software which allows a complete analysis of the spectrum, with automatic calibration, identification of radionuclides present in the spectrum, determination of fluence rates for each significant peak and, if the transfer function is known, calculation of activity for each radionuclide. The sIGAle code takes into account the asymmetric peaks with tails specific to spectra measured with CdZnTe detector and provides a reproducible evaluation of the peak areas, which was the major requirement of CEA DEN. The sIGAle code has been tested by CEA DEN in the field and in laboratories. This paper presents a detailed description of the general principle of the sIGAle code and experimental results

sIGAle, a New Code for Automatically Determining Radionuclide Activities Using CdZnTe Spectrometry

International audienceThe sIGAle code is developed by CEA LIST at the request of CEA DEN to analyse spectra measured with CdZnTe detectors. sIGAle is a specific automatic analysis software which allows a complete analysis of the spectrum, with automatic calibration, identification of radionuclides present in the spectrum, determination of fluence rates for each significant peak and, if the transfer function is known, calculation of activity for each radionuclide. The sIGAle code takes into account the asymmetric peaks with tails specific to spectra measured with CdZnTe detector and provides a reproducible evaluation of the peak areas, which was the major requirement of CEA DEN. The sIGAle code has been tested by CEA DEN in the field and in laboratories. This paper presents a detailed description of the general principle of the sIGAle code and experimental results

EasyMSI: a competitive software tool for the interpretation of Mass Spectrometry Imaging datasets

International audienceEasyMSI is a software tool for spatial and spectral visualization and processing of mass spectrometry imaging, with several modules providing user assistance for the interpretation of data. It has been developed by CEA-LIST during the Computis European project (2006-2009) and the Masda-Eye ANR project (2010-2012). EasyMSI can read MALDI and SIMS datasets in Analyze format (Applied Biosystems), GRD format (IonTof) and the imzML standard format for mass spectrometry imaging based on mzML. EasyMSI provides basic functionalities for data display and exploration (spectrum and image display, peak and pixel picking, zooming on spectra and images, ROI selection), and some more specialized treatments such as denoising spectra or structure analysis. EasyMSI offers the advantage to display MALDI data without binning. The user can choose tobin or not SIMS data, and the associated binning rate. As assistance to the interpretation of data, EasyMSI computes several indicators. The relative variance spectrum enhances peaks that have a highly contrasted space distribution. The Moranindex is an autocorrelation indicator adapted to detect thin local structures such as membranes, in images. The correlation spectrum associated to a given m/z brings out correlated m/z, often co-localised or complementary with the given m/z.EasyMSI is able to extract the peak list of the total spectrum, with parameterized criteria of extraction, to best adapt to the dataset peak shapes versus noise. Peak list can be used for molecule identification through the interrogation of biological databases. EasyMSI also includes clustering tools to perform spatial (i.e. pixel-based) classification or spectral (i.e. m/z-based) classification on peak lists or binned data. The K-means clustering is one of the simplest and fastest classification methods. The time for running a K-means clustering usually lasts only some seconds. The hierarchical clustering enables to performclustering inside a zone defined by a preceding clustering. The diffusion map method consists in reducing dimensionality by embedding data in a space in which data are more easily synthesized, and to do a clustering analysis in the reduced data

Determination of Actinide Isotopic Composition: Performances of the IGA Code on Plutonium Spectra According to the Experimental Setup

International audienceThe IGA code (a French acronym standing for actinides gamma isotopy) is a tool developed by the CEA LIST to determine the isotopic composition of plutonium and uranium, based on the automatic analysis of the γ/X spectrum emitted by a nuclear sample. Its main feature is its generic approach of the problem. As a consequence, the IGA code is a very flexible tool, because no particular experimental setup is imposed to the user for the acquisitions, in terms of energy range, gain, channel number or detector resolution. However, these experimental conditions can have an impact on the quality of the results. So, a study has been carried out to evaluate the effect of different experimental parameters on the IGA performances for plutonium spectra and quantify these performances. The study has been led according to three different approaches: analysis of IGA results on a whole spectrum database coming from French laboratories, analysis on artificially modified spectra and finally analysis of results on new real spectra acquired in the laboratory on certified samples

Determination of actinide isotopic composition: Performances of the IGA code on plutonium spectra according to the experimental setup

International audienceThe IGA code (a French acronym standing for actinides gamma isotopy) is a tool developed by the CEA LIST to determine the isotopic composition of plutonium and uranium, based on the automatic analysis of the γ/X spectrum emitted by a nuclear sample. Its main feature is its generic approach of the problem. As a consequence, the IGA code is a very flexible tool, because no particular experimental setup is imposed to the user for the acquisitions, in terms of energy range, gain, channel number or detector resolution. However, these experimental conditions can have an impact on the quality of the results. So, a study has been carried out to evaluate the effect of different experimental parameters on the IGA performances for plutonium spectra and quantify these performances. The study has been led according to three different approaches: analysis of IGA results on a whole spectrum database coming from French laboratories, analysis on artificially modified spectra, and finally analysis of results on new real spectra acquired in the laboratory on certified samples

MAGIX, a new software for the analysis of complex gamma spectra

International audienceThe MAGIX code (a French acronym standing for Automatic Gamma and X-ray Measurement) is a software developed to analyze γ/X spectra on the topic of severe accident diagnosis. Indeed, the gamma spectra obtained after a severe reactor core accident are complex because they are composed of hundreds of lines of short-lived fission products and Fukushima accident demonstrated a lack in robustness of data interpretation during a crisis. MAGIX allows a complete and entirely automatic analysis of the spectra, with identification of radionuclides and calculation of activities. It can analyze spectra measured by detectors with excellent resolution such as HPGe detectors as well as detectors with medium resolution (e.g. CZT and LaBr3). For most detectors, the analysis of the spectra can be done without a detection efficiency curve because its process can include the calculation of a relative detection efficiency. MAGIX accepts spectra corresponding to any experimental setup (energy slope, energy range, resolution, absorber, etc.). However, these experimental conditions can have an impact on the quality of the results. Results on spectra simulated in different configurations showed that the analysis of the HPGe spectrum with the user defined efficiency and with the MAGIX detection efficiency were close. Furthermore, they also showed that the accuracy of activities was similar with increasing energy slopes but decreased with resolution degradation, with fewer correctly identified radionuclides in this case

Results on identification of bacteria aging in complex environmental samples using Raman spectroscopy

International audienceSpontaneous Raman scattering is a reliable technique for fast identification of single bacterial cells, when spectra are acquired in laboratory conditions where bacteria growth and state are controlled. We have developed a multi-modal system combining Raman spectroscopy and darkfield imaging, aiming at analysing environmental samples, typically in the field context of biological pathogens detection. Such samples are heterogeneous, both in terms of phenotype content and environmental matrix, even after a preliminary purification step. In this paper, we report a study on the identification of Bacillus Thuriengensis (BT) mimicing pathogen bacteria, embedded in a real-world matrix: a sample of surface water enriched with environmental bacterial species. The purpose is to evaluate both the detection limit of aging BT over time and the false alarm rate, in the conditions of our experiment

A new computer code for the determination of the isotope composition of actinides by X- and gamma ray spectrometry and its applications

International audienceSince 1998 CEA and COGEMA have been collaborating on new tools for isotope analysis by X- and gamma ray spectrometry with germanium detectors. The research program started with the determination of plutonium isotope composition, knowledge of which is essential in several branches of the nuclear industry. The newly developed application is characterised by an original approach and innovative gamma ray spectrometry techniques featuring: - a generic design (for example, no distinction is made between the analysis of the different isotopes of plutonium); - the systematic and automatic use of an atomic and nuclear database; - an advanced constrained-optimisation algorithm expressing physical knowledge in terms of constraints thus allowing robust analysis of very complex regions of interest; - the simultaneous determination of global efficiency curve and isotope ratios. For a user, this application takes form of an entirely automatic tool that accepts spectra corresponding to any experimental setup (gain, energy range, resolution, screen etc), without any detailed data on the setup being necessary. Moreover the user can control all intermediate results by the way of a user-friendly interface through an Internet browser. As the performance of the application proved satisfactory for plutonium isotopes in terms of robustness and precision, it was decided to extend it first to uranium enrichment, then to uranium and plutonium mixtures, and more generally to any actinide and contaminant mixtures. The development and evolution of the enhanced tool proceeded smoothly due to its initial generic design. In addition, a specific peak-location module was developed. This can recognize isotopes in a spectrum, and orientate the treatment to different classes such as 'plutonium spectrum', 'uranium spectrum', or 'mixture spectrum'. The application, called IGA, can now recognize and analyse a spectrum with actinides such as plutonium, uranium, neptunium and curium, together or alone, and in the presence of contaminants. The same set of algorithms has been also applied to another purpose, the characterisation of waste packages. A dedicated tool, called IGA/Sandra, has been developed for the CEA centre at Fontenay aux Roses. This tool is able to compute not only isotopic ratios and relative efficiency but also absolute activities, by normalisation with measured efficiency. Another domain of application of IGA is spectrum analysis from CdTe, CZT and NaI detectors. The peak location module already gives good results, since it is able to adapt itself to each type of detector and to find peaks in this type of spectrum

Optimization Study of the Monte-Carlo Simulation Model of a CdZnTe Detector for Gamma Spectrometry Based Nuclear Waste Drum Characterization

International audienceNuclear waste management is a major challenge for the nuclear industry. Radiological characterization of nuclear waste packages is an important step of this industrial process as an inaccurate analysis could lead to the over classification of a package and, consequently, to a higher cost of storage. In this context, INNOWTECH and CEA List develop a low-cost and automated nuclear measurement method based on gamma spectrometry carried out with CdZnTe detectors in view of reducing uncertainties on radionuclide activities. In a previous study, we showed that the MCNP6 model of the GR1+ KROMEK CdZnTe detector created by Selivanova et al. (Appl. Radiat. Isot., 2019) contains non-modelled parts and inaccurate parameters that contribute to reducing the validity range of the simulation model. In this paper, we carry out an optimization study of such a Monte-Carlo simulation model using an original approach. First, we assess experimentally the detector’s response according to the angular distribution in metrological conditions at LNHB (Laboratoire National Henri Becquerel, France). Secondly, we conducted a comparative study of different gamma spectrometry softwares and retain the sIGAle code developed by CEA List. Thirdly, we fine-tuned the MCNP6 simulation model. On the one hand, the geometry of the model is adjusted thanks to gamma radiographies of the CdZnTe detector conducted with a pixelated CdTe detector (Widepix system) and an 241 Am source. On the other hand, a tool named SBINI (Simulation-Based Inference for Nuclear Instrumentation) is used to infere physical parameters of the MCNP6 model in order to optimize simulation results according to experimental ones. This new approach based on two complementary tools can be applied to optimize Monte-Carlo simulation models of various particle detectors