A new theoretical approach was developed for computing the FEP efficiency of HPGe and scintillation detectors using the concept of probability function. Thus integral expressions for the FEP ...efficiency were developed using three probability functions. Starting from the integral expression of the FEP efficiency and using integral means and Chebyshev functional, new expressions of the FEP efficiency, detector response, and self-attenuation factors were obtained. Also, the new approach provides new insights useful for gamma spectrometry measurements. Two practical applications of this approach are described.
•A new theoretical approach for computing the FEP efficiency is described.•Integral expressions of the FEP efficiency were developed.•New expressions of the FEP efficiency were obtained using integral means.•New expressions were developed for self-attenuation factors.•Two practical applications of the new approach are described.
In this work, a classical approach was used for calibrating the GESPECOR detector model for computing the full-energy peak efficiency of p-type coaxial HPGe detectors that is based on the use of ...linear least squares optimization. The key element of the work is the multiplicative model developed for approximating the values of the full-energy peak efficiency provided by GESPECOR code. It was linearized using the logarithmic transformation to allow an easy use of the linear least squares optimization. A procedure was also developed to estimate the optimal values of the parameters, describing the p-type coaxial HPGe detectors. Its application to a Canberra detector GC3018 showed that it is possible to determine accurate values of the full-energy peak efficiency computed by GESPECOR code using the optimized parameter values.
A novel virtual point detector model was developed for cylindrical high purity germanium detectors that are widely used in gamma-ray spectrometry. According to this model, the full energy peak ...efficiency response of these detectors can be computed by replacing the detector with a virtual point detector located at the center of the detector crystal. In fact, the novel model makes the transfer of the FEP efficiency response from a reference point source to a given point source, both sources being located on a line that passes through the virtual point detector. The model was tested and provided accurate results.
•A novel virtual point detector model is described in this paper.•The FEP efficiency response is approximated by a power function model.•The novel model has a solid theoretical basis.•Two computational ways were developed to apply in practice the model.•This model may provide accurate values of the FEP efficiency response.
This paper provides guidance for determining the neutron activation profile of core drill samples taken from the biological shield of nuclear reactors using gamma spectrometry measurements. Thus, it ...provides guidance for selecting a model of the right form to fit data and using least squares methods for model fitting. The activity profiles of two core samples taken from the biological shield of a nuclear reactor were determined. The effective activation depth and the total activity of core samples along with their uncertainties were computed by Monte Carlo simulation.
•The paper provides guidance for determining the activity profile of core drill samples.•Effective activation depth and total activity are computed by Monte Carlo simulation.•Exponential fit is the simplest way for evaluating the activity profile of core samples.
The assessment of uncertainty in free release measurements by integral gamma scanning method is described and applied to the measurement of homogeneous and heterogeneous waste drums. It is based on ...the propagation of distributions using the Monte Carlo method. In addition, two techniques for the uncertainty reduction are also described. The first technique makes use of containers constructed from two concentric cylinders and the second technique is based on the measurement of a group of waste drums. It is proved that the uncertainty of clearance measurements can be reduced using both techniques.
•Uncertainty assessment in free release measurements is described.•Uncertainty assessment is based on the propagation of distributions.•Two techniques for uncertainty reduction are also described.•It is proved that the uncertainty can be reduced using both techniques.
This paper presents complex studies on establishment of derived emission limits for potential radionuclides emitted as gaseous and liquid effluents, during the decommissioning activities (2nd and 3rd ...phases) of a nuclear research reactor, cooled and moderated with distilled water, type VVR-S, owned by the IFIN-HH. In the present paper there are described: the analysis methods and equipment used, the methodologies for calculating doses and the Derived Emission Limits (DEL), the experimentally measured activities of the representative radionuclides found in gaseous and liquid effluents resulted from decommissioning activities, as well as the effective derived limits of liquid and gaseous effluents, applying the calculation methodologies, specific to critical categories of exposed subjects. A constraint effective dose limit for a person from the critical group of 50 μSv/year was considered in calculations. From the comparison of the two series of values, measured released activities and DELs, there has been concluded that for the gaseous effluents they comply with the DELs, while in the case of liquid effluents they are higher and consequently they must be treated as liquid radioactive wastes.
•The DELs for gaseous and liquid effluents in decommissioning were studied.•The impact on the environment and critical group was assessed.•Gamma-ray spectrometry was used to determine the radionuclide composition.•Based on the dosimetry models, the values of conservative DELs were calculated.•The DELs are compliant for gases, not for liquids; require the treatment as rad-waste.
Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for ...several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The action outputs (input files and efficiency calculation results, including practical recommendations for new users) are made available on a dedicated webpage.
•Examples of the use of Monte Carlo simulation using different software.•Simple cases with two types of germanium detectors and four kinds of sources.•Calculation of full-energy peak and total efficiencies for 5 energies.•Input files and efficiency calculation results available on a dedicated webpage.
Two dedicated software packages -LabSOCS and GESPECOR- for efficiency evaluation in gamma-ray spectrometry, were compared for equivalence. The detection efficiency and the coincidence-summing ...corrections coefficients were calculated for a specific HPGe detector, for different sample parameters and energies typically encountered in environmental radioactivity measurements. The discrepancy between the results obtained with the two codes were acceptable for most of the applications. Furthermore, the deviations between the values of the standard sources/ reference materials activities from the certificate and the values obtained after Monte Carlo simulation were less than 8% for LabSOCS and 9% for GESPECOR.
•LabSOCS and GESPECOR were compared for equivalence.•Detector characterization is absolutely necessary for simulation with LabSOCS.•Detection efficiencies were evaluated both with LabSOCS and GESPECOR for volume sources.•Coincidence summing effects were evaluated for multi-energetic radionuclides.•Results demonstrate precision and accuracy of both software.
The paper presents a new approach in the integral gamma scanning of rotating waste drums based on solving a first-kind Fredholm integral equation using a small number of measurements. Both numerical ...experiments and experimental results show that the nuclide inventory of waste drums can be determined accurately using the new approach especially when the waste drums contain multi-gamma emitters.
► A new approach in the integral gamma scanning of rotating waste drums is presented. ► Approach is based on solving a Fredholm integral equation using several measurements. ► Extensive numerical experiments were performed for testing the new approach. ► The accuracy of the gamma scanning is improved especially for multi-gamma emitters. ► Accuracy better than 16% was obtained in the measurement of a waste drum with 152Eu.
An internal consistency test of the calculation of coincidence-summing correction factors FC for volume sources is presented. The test is based on exact equations relating the values of FC calculated ...for three ideal measurement configurations. The test is applied to a number of 33 sets of FC values sent by 21 teams. Most sets passed the test, but not the results obtained using the quasi-point source approximation; in the latter case the test qualitatively indicated the magnitude of the bias of FC.
•A self-consistency test of coincidence summing calculations is presented.•It is based on equations relating FC values for 3 ideal volume geometries.•Can be easily applied in any laboratory for checking the quality of FC software.•33 sets of FC values (various computations) for 60Co, 133Ba, 134Cs, 152Eu evaluated.•Inconsistency and bias of FC based on quasi-point source approximation revealed.
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