The main objective of this work was to study how the
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-standardisation method of neutron activation analysis performs when applied to Moroccan medicinal plant samples. Irradiation was carried out ...at the Moroccan Triga Mark II research reactor at CNESTEN. Standard references material from NIST and WEPAL were used for internal quality control, mainly to ensure accuracy and precision measurement. More than twenty elements were determined in eight medicinal plants analysed. Mg, K, Ca, Cl, Na were observed as major in high concentrations while rare earth elements and toxic elements were found as traces elements. The results obtained in this study allowed these plants to be classified according to their composition of trace elements, macro-elements, rare earth elements and toxic elements.
Over the past years, the cross-sections reaction data has been re-evaluated several times, in order to approximate the nuclear model measurements with the predictions with great reliability. In our ...work, uncertainty analysis caused by the data on the neutron factor (Keff) and the reactivity temperature coefficient (RTC), in addition to nuclear data adjustment related to the nuclear reactor physics have been done for KRITZ-2:13 reactor, with ENDF/B - VII.1, ENDF/B - VIII.0 and JENDL - 4.0 evaluations by the nuclear code MCNP6.1. Our analysis detects that the greatest uncertainty on Keff and RTC in the studied libraries comes from the capture and fission reaction contributions respectively, for U-238 and U-235. The previous reactions and their covariances were adjusted using the generalized least squares method (GLLSM), in order to contribute to improve the data needed for neutron simulation of experiments and to ensure the installations safety, where Keff and RTC represent neutron parameters reflecting the modification effects in the data.
This paper presents a new procedure to optimize the geometric parameters of a n-type coaxial HPGe detector. It is based on a statistical technique called “Design of Experiments” (DoE). This technique ...aims to identify the most influential parameters and to determine the optimal configuration. In this work, The effects of each parameter on the detector responses have been investigated by a fractional factorial design. Only the most influential factors contributing to the detector response have been selected. Precise modeling of these factors was then performed using a full factorial design. Based on the results obtained from this design, the full energy peak efficiencies according to the geometric parameters were modeled by a multiple-linear regression. These models have been statistically validated by analysis of variance (ANOVA). The optimal combination of the geometric parameters has been identified using the desirability function approach, which is a useful tool to optimize multi-response problems. A verification test was performed to validate the results obtained. It was observed that the relative deviation found between experimental and simulated values was less than 5%.
•Optimization of geometrical dimensions of an HPGe detector.•Application of Monte Carlo simulation and “Design of Experiments” technique.•Investigating influence of each detector parameter on the FEPE.•Achieving good agreement between the measured and the simulated results.
The Sidi Moussa lagoon, located in western coastal Morocco and ranked as a wetland of biological and ecological importance (Ramsar site), is contaminated due to its proximity to the industrial ...phosphate plants and other anthropogenic activities around it. This study was carried out to assess the current environmental state of the lagoon as well as historical inputs of pollutants over several decades. Three sediment cores were collected and analyzed for the determination radionuclide activities (210Pb, 226Ra, 238U and 137Cs) by gamma spectrometry and element concentrations by Inductively Coupled Plasma – Mass Spectrometry. Age-depth relationships were established in two cores using 210Pb and 137Cs as chronometer and time-marker, respectively, and Constant Rate of Supply as radiometric dating model. 210Pb and 238U were present in sediment in activities much higher than those reported for non-contaminated coastal systems. Sediment accumulation rates showed a slight increase over time with a depth-averaged value of 0.16 g cm−2 y−1.
Enrichment Factors and practically derived sediment quality guidelines were used to assess sediment contamination/pollution and toxicological effects linked with the measured concentrations of sediment-bound elements. The profiles of Cr, Co, Cu, As and Ni displayed maximums at depths matching the start of the phosphate industrial plants, and decreasing concentrations in the sections above the maximums, revealing the positive effects of the environmental management system adopted by the phosphate company since early 2000s.
•The Sidi Moussa lagoon, located near the biggest phosphate processing plants in the world, is contaminated by some metals and radionuclides.•The agricultural activities and North-West African upwelling contribute to sediment contamination.•Results have revealed the positive effects of the environmental management system adopted by The Moroccan Phosphate Company.
The uncertainties in nuclear data give inaccurate values of reaction rates in shielding benchmarks. Consequently, the inclusion of the shielding benchmarks in the validation of the nuclear data would ...contribute to the production of general-purpose nuclear data evaluations. The validation of nuclear data goes through an essential step of sensitivity and uncertainty analysis. During this step, the evaluator determines which nuclear data necessitate adjustment. In this work, sensitivity and uncertainty analysis of reaction rates due to two primordial cross sections elastic and capture uncertainties of important isotopes in PCA-REPLICA benchmark are carried out. The reaction rates and their sensitivities are calculated by MCNP6.1 code. The weight window and energy cut-offs are two variance reduction techniques used in this calculation. The covariance matrices of the studied cross sections are processed by NJOY99 software. The sensitivities and uncertainties of the estimated reaction rates are calculated in four energy groups for three detectors 103Rh (n,n’)103Rhm, 115In (n,n’)115Inm and 32S (n,p)32P. The obtained results show that the elastic cross sections of 56Fe, 16O and 1H give large uncertainties on reaction rates, whereas the captures of these isotopes have small uncertainties on reaction rates. The analysis of the sensitivities and the uncertainties of the reaction rates due to elastic and capture cross sections of the 56Fe, 1H and 16O indicate that the elastic cross section of 56Fe needs improvement in the energy range 0.1 MeV–19.60 MeV and the elastic cross sections of 1H and 16O need adjustments in the energy range 1.35 MeV–19.60 MeV.
•Reaction rates calculation in PCA-REPLICA using variance reduction techniques.•56Fe, 1H, 16O cross sections analysis using Rh-103 (n,n’)Rh-103m detector.•56Fe, 1H, 16O cross sections analysis using In-115 (n,n’)In-115m detector.•56Fe, 1H, 16O cross sections analysis using S-32 (n,p)P-32 detector.
Personal and environmental radiation monitoring services are widely used through luminescent techniques. In this paper, we practiced performance testing on thermoluminescent and optically stimulated ...luminescent dosimeters by assessing their homogeneity, linearity, energy, and angular dependence tests. The IEC and ICRP requirements were used to compare the performance response of dosimeters. Based on the experimental results, we realized that both detectors comply with the international criteria. The homogeneity percentage was 8.9% and 13.7% for TL and OSL detectors, respectively. The percentage deviation of the linearity test does not exceed 10% for both dosimeters except for the TL dosimeters at low irradiation dose. For the angular dependence, deviations were less than 2% for TLDs and 5% for OSLDs. These detectors display mean values of the relative energy response of −15.29% and −6.51% for OSL and TL detectors. Generally, TL materials manifested low sensitivity to radiation dose levels. On the other hand, the OSLDs demonstrated a more pronounced under-response to energy beam qualities than TLDs. Regarding COV tests, TL and OSL dosimeters have passed the c2 test.
•TL and OSL dosimeters characteristics were tested.•Nine radiation qualities and eleven angles of incidence were used to test homogeneity, non-linearity, energy, and angular dependence.•The Hp(10) measurement accuracy was evaluated by both the ICRP trumpet curve analysis and IEC 62387 covariance test.
The present work aims to calculate Hp(3) conversion coefficients from air Kerma for mono energetic photons (from 10 to 10 MeV) using EGSnrc and MCNP6 Monte Carlo codes. Absorbed dose and Kerma are ...calculated into a cylindrical phantom corresponding to that applied in the ORAMED Project. MCNP6 results are found in a good agreement with the reference data (ORAMED Project) with a local difference about 0.7%. On the other hand, the results obtained by EGSnrc/DOSRZnrc are close to the reference data with a local difference less than 1% for angles of incidence from 0° to 180°-degrees, except at 90° and 120° angles the difference is increased due to the complex geometry of the phantom. We are validated DOSRZnrc based EGSnrc code for calculating Hp(3) conversion coefficients for mono-energetic photons.
•Comparison between MCNP and EGSnrc radiation protection calculation.•A new DOSRZnrc/EGSnrc phantom has been developed and validated.•Must protect the eye Lens from photons incident per angles < 75° and that have energy < 1 MeV.
This work aims to establish some X-ray qualities recommended by the International Standard Organization (ISO) using the half-value layer (HVL) and Hp(10) dosimetry approaches. The HVL values of the ...following qualities N-60, N-80, N-100, N-150 and N-250 were determined using various attenuation layers. The obtained results were compared to those of reference X-ray beam qualities and a good agreement was found (difference less than 5% for all qualities). The GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations) radiation transport Monte Carlo toolkit was employed to simulate the production of X-ray spectra. The characteristics HVLs, mean energy and the spectral resolution of simulated spectra have been calculated and turned out to be conform to the ISO reference ones (difference less than the limit allowed by ISO). Furthermore, the conversion coefficients from air kerma to personal dose equivalent for simulated and measured spectra were fairly similar (the maximum difference less than 4.2%).
In order to study the sensitivity and the uncertainty of the Moroccan research reactor TRIGA Mark II, a model of this reactor has been developed in our ERSN laboratory for use with the N-Particle ...MCNP Monte Carlo transport codes (version 6). In this article, the sensitivities of the effective multiplication factor of this reactor are evaluated using the ENDF/B-VII.0, ENDF/B-VII.1 and JENDL-4.0 libraries and in 44 energy groups, for the cross sections of the fuel (U-235 and U-238) and the moderator (H-1 and O-16). However, the quantification of the uncertainty of the nuclear data is performed using the nuclear code NJOY99 for the generation and processing of covariance matrices. On the one hand, the highest uncertainty deviations, calculated using the ENDFB-VII.1 and JENDL4.0 evaluations, are 2275, 386 and 330 pcm respectively for the reactions U235(n, f), U235(nν¯) and H1(n, γ). On the other hand, these differences are very small for the neutron reactions of O-16 and U-238. Regarding the neutron spectra, in CT-mid plane, they are very close for the three evaluations (ENDF/B-VII.0, ENDF/B-VII.1 and JENDL-4.0). These spectra present two peaks (thermal and fission) around the energies 0.05 eV and 1 MeV.
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