Uranium Enrichment Measurement Using Enrichment-Meter Approach

2018 ◽  
Author(s):  
K. Abd El Gawad ◽  
Yushou Song
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Wall Thickness ◽  
Measurement Accuracy ◽  
Gamma Spectroscopy ◽  
Nuclear Safeguards ◽  
Measurement Bias ◽  
Nuclear Materials ◽  
Container Wall ◽  
235U Enrichment

The 235U enrichment is one of the most important characteristics of nuclear materials for nuclear safeguards purposes. The multi-group γ-ray analysis method for uranium (MGAU) is an important non-destructive gamma spectroscopy method for 235U enrichment determination. Using that method, the typical measurement bias is below 3% for uranium material with abundance from 0.3 to 93 %. However, it is not applicable for the samples with thick container or without isotopic decay equilibrium. In this work, the enrichment meter method was studied with two uranium dioxide samples (235U abundance 0.71 % and 3.167 %). The nuclear materials spectra were measured using a planar high-purity germanium detector. Based on the specific gamma peak (185.71 keV) of relative high intensity, this traditional enrichment meter approach gives measurement bias more than 10 %. Thus, this work represents two objects: (1) an alternative approach which was investigated, where the calibration is performed through Monte Carlo simulation (MCNP5) instead of experiment in advance, as the measurement bias was reduced to be around 5 %. Thus, to use this approach, one should have the sample details, such as dimensions, chemical composition and container. (2) The influence of the container wall thickness on the measurement accuracy by Monte Carlo simulation. So, if the container wall thickness is not modeled correctly the measurement accuracy is influenced, which is investigated by simulation.

scholarly journals Neutron Induced Capture Gamma Spectroscopy Sonde Design and Response Analysis Based on Monte Carlo Simulation

2015 ◽  
Vol 18 (3) ◽  
pp. 154-161 ◽  
Author(s):  
Byeongho Won ◽  
Seho Hwang ◽  
Jehyun Shin ◽  
Jongman Kim ◽  
Ki-Seog Kim ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Gamma Spectroscopy ◽  
Response Analysis

A new method for calculating bulk density in pulsed neutron-gamma density logging

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. D219-D232
Author(s):  
Hu Wang ◽  
Wensheng Wu ◽  
Tianzhi Tang ◽  
Ruigang Wang ◽  
Aizhong Yue ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Pair Production ◽  
Bulk Density ◽  
Density Estimation ◽  
Measurement Accuracy ◽  
Gamma Ray ◽  
Estimation Algorithm ◽  
Gamma Density ◽  
Pulsed Neutron

Formation density is one of the most important parameters in formation evaluation. Radioisotope chemical sources are used widely in conventional gamma-gamma density (GGD) logging. Considering security and environmental risks, there has been growing interest in pulsed neutron generators in place of the radioactive-chemical source in using bulk-density measurements. However, there still is the requirement of high accuracy of the neutron-gamma density (NGD) calculation. Pair production is one of the factors influencing the accuracy of the results, which should be considered. We have adopted a method, based on the difference between the inelastic gamma-ray response of high- and low-energy windows, to reduce the impact of pair production upon calculating the bulk density. A new density estimation algorithm is derived based on the coupled-field theory and gamma-ray attenuation law in NGD logging. We analyze the NGD measurement accuracy with different mineral types, porosity, and pore fluid and determine the influence of the borehole environment on NGD logging. The Monte Carlo simulation results indicate that the improved processing algorithm limits the influence of the mineral type, porosity, or pore fluid. The NGD measurement accuracy is ±0.025 g/cm3 in shale-free formations, which is close to the GGD measurement (±0.015 g/cm3). Our results also show that the borehole environment has a significant impact on NGD measurement. Therefore, it is necessary to take the influence of the borehole parameters into account in NGD measurements. Combined with Monte Carlo simulation cases, we evaluate the application results of the new density estimation algorithm in various model wells.

Study on Variation of HPGE Detector Dead Layer Thickness and its Effect on the Measurements of the Detector Response and Samples Characterization Using Monte Carlo Simulation

2018 ◽  
Author(s):  
K. Abd El Gawad ◽  
Yushou Song
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Layer Thickness ◽  
Hpge Detector ◽  
Dead Layer ◽  
Nuclear Safeguards ◽  
Detector Response ◽  
Dead Layer Thickness ◽  
235U Enrichment ◽  
Good Agreement

The main objective of this work is to produce an optimal modeling for our aged Planar-HPGe detector using Monte Carlo method (MC). That optimization included the analysis of the germanium dead (inactive) layer thickness for our old detection system (planar-HPGe detector). DL is one of the important parameters needed in order to obtain the smallest discrepancy between simulated and experimental measurements of detector efficiency. Also, precise determination of 235U enrichment for UO2 samples which is necessary for purposes of nuclear materials verification in the field of nuclear safeguards. The thickness of Germanium dead layer (DL) can be vary by time as it is not well known due to the existence of a transition zone where photons are strongly attenuated and absorbed, that cannot contribute to the total photon energy absorption which causes a significant decrease in efficiency. Therefore, using data provided by manufacturers since long years (manufacture date) in the detector simulation model is not convenient. As a result, some strong discrepancies appear between measured and simulated efficiency, in addition to that non-accurate results for 235U enrichment determination. The Monte Carlo method applied to overcome this difficulty was to vary the thickness of dead layer step by step in simulation, a good agreement (minimum deviation) between estimated and experimental efficiency was reached when a suitable germanium dead layer thickness was chosen. Calculations and measurements were performed for radioactive nuclear material samples in the form of UO2 powder with different sizes and enrichments at different locations, under different gamma-lines emitted after a-decay of the 235U nuclei. Results indicated that a good agreement between simulated and measured efficiencies is obtained using a value for the germanium dead layer thickness approximately (2.45 mm) six in comparison with (0.389 mm) provided by the detector manufacturer.

scholarly journals Gamma Spectrometry in the Presence of Fast Neutrons

2019 ◽  
Author(s):  
Iran Hassanzadeh ◽  
Armin Allahverdy ◽  
Okhtay Jahanbakhsh ◽  
Alireza Khorrami Moghaddam
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Gamma Spectroscopy ◽  
Point Sources ◽  
Fast Neutrons ◽  
Gamma Photon ◽  
Gamma Source ◽  
Experimental Conditions ◽  
Low Efficiency ◽  
Detector Materials

Purpose: In some gamma spectroscopy experiments, neutrons may also be present, so depending on experimental conditions, Gamma spectroscopy can be influenced by the presence of neutrons. Materials and Methods: In this study, a NaI(Tl)(63 mm×63 mm) detector is used to investigate the effects of fast neutrons on the spectrum of gamma photons. The radiation source used in these experiments is made up of two point sources: an AmBe (50 mCi) neutron source and a 137Cs(10 mCi) gamma source. Results: Results were determined through both measurements and Monte Carlo simulation (MCNPX) under two different experimental conditions and were compared. When the detector is placed under an angle to the source, gamma photon energy peaks resulting from inelastic interactions of the fast neutrons with the detector materials and surrounding materials in the energy range of 0.1-0.9(MeV) are pretty visible in the gamma main spectrum. These results can be used to optimize industrial tomography experiments carried out with NaI(Tl) scintillators. Conclusion: Also, the results show that the detection of fast neutrons with a NaI(Tl) scintillator is possible with low efficiency.  

Measurement Sensitivity Matrices Kalman Filter with Measurement Bias

2014 ◽  
Vol 668-669 ◽  
pp. 928-931
Author(s):  
Jin Pan ◽  
Wei Tao Lou ◽  
Tai Shan Lou
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Kalman Filter ◽  
Measurement Bias ◽  
Measurement Sensitivity ◽  
Optimal State

Based on the measurement sensitivity matrices, a new Kalman filter is proposed to obtain the optimal state estimates by mitigating the influence of the measurement bias, when the observations have the measurement bias. Its effectiveness is verified by the Monte Carlo simulation.

Electron Scattering in Solids

1990 ◽  
Vol 48 (2) ◽  
pp. 4-5
Author(s):  
Ryuichi Shimizu ◽  
Ze-Jun Ding
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Angular Distribution ◽  
Elastic Scattering ◽  
Electron Scattering ◽  
Cross Sections ◽  
Expansion Method ◽  
Electron Excitation ◽  
Partial Wave Expansion ◽  
Backscattered Electrons

Monte Carlo simulation has been becoming most powerful tool to describe the electron scattering in solids, leading to more comprehensive understanding of the complicated mechanism of generation of various types of signals for microbeam analysis.The present paper proposes a practical model for the Monte Carlo simulation of scattering processes of a penetrating electron and the generation of the slow secondaries in solids. The model is based on the combined use of Gryzinski’s inner-shell electron excitation function and the dielectric function for taking into account the valence electron contribution in inelastic scattering processes, while the cross-sections derived by partial wave expansion method are used for describing elastic scattering processes. An improvement of the use of this elastic scattering cross-section can be seen in the success to describe the anisotropy of angular distribution of elastically backscattered electrons from Au in low energy region, shown in Fig.l. Fig.l(a) shows the elastic cross-sections of 600 eV electron for single Au-atom, clearly indicating that the angular distribution is no more smooth as expected from Rutherford scattering formula, but has the socalled lobes appearing at the large scattering angle.

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