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1.
Environ Monit Assess ; 191(11): 660, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31646407

RESUMO

This study makes a first attempt at a detailed estimation of the background radioactivity level and its distribution at the Sinop nuclear power plant site. The activity concentration levels of 226Ra, 232Th, 40K and 137Cs radionuclides in soil samples collected from 88 locations around Sinop Province, Turkey, in November 2016, were measured using gamma spectrometry. The distributions of radionuclide levels obtained from the results were evaluated using a geostatistical method, and the estimated radiation levels were determined using the ordinary kriging (OK) method, which is the best linear unbiased estimator (BLUE) for unmeasured points. Estimates of distribution results were evaluated using cross-validation diagrams, and it was shown that the OK method could predict radiological distributions for appropriate criteria. Finally, using the kriging parameters, distributions of radiation levels for the entire work area were mapped at a spatial resolution of 100 × 100 m2. These maps show that the natural radionuclides (226Ra, 232Th and 40K) are distributed at higher levels to the southeast of Sinop than in the other regions, and the activity of an artificial radionuclide (137Cs) is high in the interior and northern sections.


Assuntos
Elementos Radioativos/análise , Centrais Nucleares/estatística & dados numéricos , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Análise Espacial , Radiação de Fundo , Radioisótopos de Césio/análise , Radioisótopos de Potássio/análise , Rádio (Elemento)/análise , Espectrometria gama/métodos , Tório/análise , Turquia
2.
Radiat Prot Dosimetry ; 184(3-4): 290-293, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31297520

RESUMO

Elevated levels of natural background radiation due to scattered patches of monazite sand around the beaches of Mangalore, India, have been reported earlier. A comparative study of gamma dose rates was performed in both normal background and high natural background radiation areas around Mangalore using different types of portable gamma dosimeters. In addition to this, gamma-ray energy spectra were acquired, in situ, using a NaI(Tl) based portable gamma spectrometer. Soil and sand samples were collected for laboratory analysis with HPGe detectors. Measurements were carried out during the years 2016-18 revealed that in majority of the locations the gamma dose rates were similar to the normal background regions, whereas, in certain locations the dose rates were higher with values up to 530 nSv/h.


Assuntos
Radiação de Fundo , Raios gama , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Humanos , Índia , Metais Terras Raras , Doses de Radiação
3.
Appl Radiat Isot ; 151: 30-38, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31158703

RESUMO

Sources of background and background variation in a BEGe type HPGe detector located in a surface laboratory were identified. Different strategies for background reduction were applied. A cosmic veto was installed, and optimised using a digital acquisition system in list-mode with time-stamped data. This resulted in the reduction of total background by a factor of 1.4. Thermal and fast neutron fluxes were also calculated. The radon induced background component and its variation were significantly reduced.


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação/métodos , Radônio/análise , Espectrometria gama/métodos
4.
Appl Radiat Isot ; 151: 207-216, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31203051

RESUMO

In this study, average radon flux distribution in the Rize province (Turkey) was estimated by the artificial neural networks (ANN) method. For this purpose, terrestrial gamma dose rate (TGDR), which is defined as an important proxy in determining radon flux distribution, was used. Input parameters that were used for ANN were the natural radionuclide (238U, 232Th and 40K) activity values in soil samples taken from 64 stations in Rize Province, data from ambient gamma dose rates (AGDR) directly affecting the distribution of radon flux and data of geographical coordinates. Randomly chosen 42 stations were used for ANN training and data from 22 stations were used for testing the ANN model. Performance test results gave a Pearson's r value of 0.60 (p < 0.001) and RMSE of 0.296. The area that was used for the model was divided into grids of 100 m by 100 m and a spatial distribution map was composed by using ANN predicted radon flux rates at grid nodes, whereby natural radionuclide values and Ordinary Kriging predicted values of external gamma dose rates were used for composing the map.


Assuntos
Redes Neurais de Computação , Radônio/análise , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Turquia
5.
Appl Radiat Isot ; 151: 129-139, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31177070

RESUMO

Ramlet Homayyer area is located in the southwestern part of Sinai Peninsula, Egypt, to the east of Abu-Zeneima city, located on the eastern coast of Gulf of Suez, Red Sea. The Paleozoic succession in the study area (up to 300 m thick) overlies the basement complex and is covered by basaltic sheets. The lithologic nature of the Paleozoic rocks played a very important role in the localization of various mineralizations (e.g. Mn, Fe, Cu, REEs, Th … etc.) In the present study of Ramlet Homayyer area, ground spectral gamma-ray survey was conducted along N-S profiles, equally-spaced, with lengths of about 2.5 km, and the total area equals about 10 km2. The measurements were conducted using a portable gamma-ray spectrometer, model GS-512. The examination of the total-count (T.C.) radiometric contour map shows that the radioactivity values vary widely from 3.4 Ur to 101.3 Ur. The potassium (K) content in Ramlet Homayyer area ranges from 1.2% to 16.0%. The equivalent thorium (eTh) content in the study area has a maximum value reaching about 68.9 ppm. The equivalent uranium (eU) content attains its maximum value reaching about 84.0 ppm. Factor analysis technique, which provides a way of thinking about radiospectrometric elements and ratio interrelationships alltogether was carried out. The application of factor analysis technique, helped to delineate the zones of high concentrations of eU, eTh and K separately, where the first factor (F1) can delineate high eU zones, (F2) high eTh zones and (F3) high K zones. The radiometric lithologic mapping was conducted for the whole area, by testing the homogeneity of all measurements recorded indicates that the distribution of the radioactivity all over the area is not homogeneous. This indicates that the lithological cover of the study area cannot be considered as one lithologic unit, but contains different types of rock units. Each Interpreted radiometric lithologic units (IRLU) is corresponding to one geomorphological mass or features. As a result of the ground radiometric survey of the study area, chemical analyses for some selected samples were taken and conducted from the anomalous zones at G. Homayyer, G. Ghorabi and Khameila areas. These analyses showed presence of concentrations of uranium up to 147 ppm, 58 ppm, 52 ppm in addition to trace elements with high concentrations of some elements as: Y, Cr, W, Sr and Ag, which gives 6819,768,314,561 and15 ppm respectively.


Assuntos
Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Egito , Seguimentos , Imagens de Satélites , Inquéritos e Questionários
6.
Appl Radiat Isot ; 149: 142-151, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31063963

RESUMO

Gamma-ray spectrometry is applied to estimate equivalent uranium (eU), equivalent thorium (eTh), and K% of 748 rock samples collected from Syrian territory. The spectrometry results are used to evaluate and map the radioactive heat production (HP) of Syria. A new approach involving the multifractal technique with the concentration-number model (CN) and log-log plots was originally proposed and hence applied in this paper to map the distribution of uranium concentration and HP of Syria. This approach helps us to differentiate different eU and HP ranges related to different litho-types. The advantages of proposing and applying the fractal technique are that the boundaries of the distinguished radioactive ranges of eU and HP coincide well with the lithological boundaries, which gives this technique superiority over other traditional statistical methods. The fractal CN model with the use of log-log plots proves its efficacy in differentiating between several eU and HP populations that are related directly to the geology of Syrian territory. The fractal model shows four threshold break points corresponding to uranium concentrations of 3.1, 7.38, 16.6, and 28.8 ppm and an HP of 0.715, 1.86, 3.63, and 6.26 µW/m3, respectively. The highest HP ranges are mainly related to the phosphatic deposits, characterized by the highest uranium content.


Assuntos
Temperatura Alta , Monitoramento de Radiação/métodos , Geologia , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Síria , Tório/análise , Urânio/análise
7.
Health Phys ; 117(4): 449-456, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31124830

RESUMO

Timely achievement of uranium series' secular equilibrium is not always feasible. Our objective is to mathematically justify methods for early uranium series gamma spectroscopy measurements that can accurately predict naturally occurring radioactive material equilibrium activities long before equilibrium is established. It was believed that, regardless of prior Rn escape, after sealing a sample for a few hours the activities of Rn, Ra, and U could theoretically be determined with a single measurement of both Pb and Bi. However, when accounting for error, this theory did not work as expected (CV = 14.0 in Ra simulation). A similar approach published by Li et al. in 2015 proved to be much more reliable with the error considered, using Pb activities measured at two different times gave significantly improved results when tested the same way (CV = 0.29 in Ra simulation). Because both Pb and Bi activities are typically available when using gamma spectrometry, we combine these approaches and further increased the accuracy of the calculated activities (CV = 0.21 in Ra simulation).


Assuntos
Radiação de Fundo , Monitoramento de Radiação/métodos , Rádio (Elemento)/análise , Espectrometria gama/métodos , Tório/análise , Urânio/análise , Humanos
8.
Health Phys ; 117(3): 278-282, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31124835

RESUMO

Military historical artifacts found in museum displays and storage locations were analyzed for their Ra and Rn progeny activities to determine the fraction of Rn lost to the environment. Gamma-ray spectroscopy using high-purity germanium detectors was used to determine Ra activity and infer Rn activity based on Pb and Bi. Analyses were conducted without affecting the structural integrity of the artifacts. Ra was measured directly after correction for solid angle and finite sample-detector distance. Although Rn can be similarly analyzed, the collection in charcoal of Rn off-gassed from the artifact after the establishment of secular equilibrium was preferable. Rn off-gassing rates vary greatly between the six devices studied, with a maximum off-gassing rate of 1,850 ± 50 Bq h. Large variations in off-gassing rate were also observed between an additional 30 nominally identical dials, with a mean and standard deviation of 7.7 ± 7.1 Bq h. The work is not predictive of airborne Rn activity within museums, where building size and ventilation are significant and unique to each location. However, the significant off-gassing rates and their large variation suggest that Rn activities may be elevated in enclosed locations, such as aircraft cockpits and storage facilities.


Assuntos
Poluentes Radioativos do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Materiais de Construção/análise , Monitoramento de Radiação/métodos , Rádio (Elemento)/análise , Radônio/análise , Espectrometria gama/instrumentação , Artefatos , Humanos , Instalações Militares , Espectrometria gama/métodos , Ventilação
9.
Radiat Prot Dosimetry ; 184(3-4): 453-456, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31038699

RESUMO

Accurate measurement of radon progeny concentration is important for the dose assessment of radon exposure and the study of radon progeny behaviours. For measuring 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity, an alpha-beta spectrometry method was developed and applied in a step-advanced filter radon progeny monitor. The derivation details of this method is given in this paper and the uncertainty is discussed. The comparison experiments are carried out in radon chamber and in field. Results show that the alpha-beta spectrometry method can give 218Po, 214Pb and 214Bi concentration as well as EEC with high sensitivity either for 60 min or for 30 min cycle, which leads to low uncertainty. This method can be used as a reference method for radon chamber and is suitable for portable radon progeny monitor.


Assuntos
Poluentes Radioativos do Ar/análise , Bismuto/análise , Radioisótopos de Chumbo/análise , Polônio/análise , Monitoramento de Radiação/métodos , Produtos de Decaimento de Radônio/análise , Espectrometria gama/métodos , Partículas alfa , Partículas beta
10.
Radiat Prot Dosimetry ; 184(3-4): 413-417, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31038701

RESUMO

An intercomparison experiment of three radon progeny measurement methods, based on alpha spectrometry (Kerr method), alpha-beta spectrometry and liquid scintillation counter (LSC method), was carried out in the standard radon chamber at NIM. Both the consistency and the uncertainty analysis of three different methods were studied in detail. Results show that, at the EEC level of 4000 Bq/m3, the uncertainties of the alpha-beta spectrometry, LSC method and Kerr method were 3.78%, 6.41% and 9.46%, respectively, which are mainly contributed by detection efficiency uncertainty, measuring time uncertainty and counting statistical uncertainty in sequence. The comparison results at different concentration levels show that the measurement values of three methods are consistent within the error range of 3%. The alpha-beta spectrometry can be used as a reference standard method to achieve the simultaneous measurement of RaA, RaB, RaC concentrations and EEC in the radon chamber.


Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação/métodos , Produtos de Decaimento de Radônio/análise , Radônio/análise , Contagem de Cintilação/métodos , Espectrometria gama/métodos , Partículas alfa , Partículas beta
11.
Sci Rep ; 8(1): 14115, 2018 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-30237485

RESUMO

In this study, in-situ and laboratory γ-ray spectroscopy techniques were compared to evaluate the activity concentration of natural radionuclides in soil. The activity concentrations of 238U (226Ra), 232Th, and 40K in the soil in 11 sites were simultaneously measured with in-situ portable HPGe and the NaI(Tl) detectors. In parallel, 55 soil samples collected from these sites were analyzed with a laboratory γ-ray spectroscopy technique (HPGe). A strong correlation was observed between the in-situ and laboratory HPGe techniques with a linear correlation coefficient (R2) of 0.99 for 226Ra and 232Th and 0.975 for 40K, respectively. The in-situ HPGe technique shows a strong correlation with the NaI(Tl) detector. γ-Rays cps of 226Ra, 232Th, and 40K of the NaI (Tl) detector were then converted to specific activities (Bq kg-1 unit) in soil using the empirical formulas obtained in this study. The absorbed dose rate in air at 1 m height above ground due to these radionuclides was calculated using the Beck's formula and the results were compared with measured values obtained with an high pressure ionization chamber. The results of the calculated and measured dose rate show a strong correlation of R2 = 0.96. The reliability and precision of analytical spectroscopy techniques of radioactivity and radiation dose were confirmed in this work.


Assuntos
Doses de Radiação , Monitoramento de Radiação/métodos , Radioisótopos/análise , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Radiação de Fundo , Solo/química
12.
Health Phys ; 114(1): 94-106, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-30085973

RESUMO

Gamma ray spectroscopy enables the identification of radioactive sources, and, with proper calibration, their activities. In use since the 1950s, NaI(Tl) spectroscopic systems remain popular due to their affordability and high detection efficiency. The crystals and accompanying electronics may vary, and there are practical choices necessary to produce the best possible spectra for a given application or correctly interpret system performance. An overview of the scintillation mechanism as well as the common features of a gamma ray spectrum are presented in this paper. This includes a discussion of the impacts of the size and shape of detector crystals on the spectrum and counting efficiency. A description of supporting electronics is included along with techniques for arranging and optimizing them. Coaxial cables become part of the circuit and can degrade the detector signal if they have mismatched impedance or excessive length. A discussion is included of tradeoffs involved in selecting combinations of individual electronics components for NaI(Tl) spectroscopic applications. Lastly, a comprehensive energy calibration procedure is provided. This paper thus serves as a tutorial on several practical aspects of a NaI(Tl) gamma ray spectroscopy system.


Assuntos
Raios gama , Iodetos/química , Contagem de Cintilação/métodos , Sódio/química , Espectrometria gama/métodos , Tálio/química , Calibragem , Espectrofotometria , Análise Espectral , Raios X
13.
Phys Med Biol ; 63(18): 185019, 2018 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-30033938

RESUMO

We present a full-scale clinical prototype system for in vivo range verification of proton pencil-beams using the prompt gamma-ray spectroscopy method. The detection system consists of eight LaBr3 scintillators and a tungsten collimator, mounted on a rotating frame. Custom electronics and calibration algorithms have been developed for the measurement of energy- and time-resolved gamma-ray spectra during proton irradiation at a clinical dose rate. Using experimentally determined nuclear reaction cross sections and a GPU-accelerated Monte Carlo simulation, a detailed model of the expected gamma-ray emissions is created for each individual pencil-beam. The absolute range of the proton pencil-beams is determined by minimizing the discrepancy between the measurement and this model, leaving the absolute range of the beam and the elemental concentrations of the irradiated matter as free parameters. The system was characterized in a clinical-like situation by irradiating different phantoms with a scanning pencil-beam. A dose of 0.9 Gy was delivered to a [Formula: see text] cm3 target with a beam current of 2 nA incident on the phantom. Different range shifters and materials were used to test the robustness of the verification method and to calculate the accuracy of the detected range. The absolute proton range was determined for each spot of the distal energy layer with a mean statistical precision of 1.1 mm at a 95% confidence level and a mean systematic deviation of 0.5 mm, when aggregating pencil-beam spots within a cylindrical region of 10 mm radius and 10 mm depth. Small range errors that we introduced were successfully detected and even large differences in the elemental composition do not affect the range verification accuracy. These results show that our system is suitable for range verification during patient treatments in our upcoming clinical study.


Assuntos
Algoritmos , Imagens de Fantasmas , Terapia com Prótons/instrumentação , Terapia com Prótons/métodos , Espectrometria gama/métodos , Calibragem , Humanos , Método de Monte Carlo
14.
Appl Radiat Isot ; 140: 179-184, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30031285

RESUMO

During the last days of September to the first days of October in 2017, a unique detection of 106Ru was observed in air filters sampled at different locations in Sweden via the national air monitoring network. Furthermore, measurements of precipitation also showed the presence of 106Ru. This initiated soil sampling and in situ gamma-ray spectrometry at one of the locations.


Assuntos
Poluentes Radioativos/análise , Radioisótopos de Rutênio/análise , Filtros de Ar , Poluentes Radioativos do Ar/análise , Humanos , Monitoramento de Radiação/métodos , Monitoramento de Radiação/estatística & dados numéricos , Chuva/química , Estações do Ano , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos , Suécia
15.
J Environ Radioact ; 192: 105-116, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29909224

RESUMO

Proximal gamma-ray spectroscopy recently emerged as a promising technique for non-stop monitoring of soil water content with possible applications in the field of precision farming. The potentialities of the method are investigated by means of Monte Carlo simulations applied to the reconstruction of gamma-ray spectra collected by a NaI scintillation detector permanently installed at an agricultural experimental site. A two steps simulation strategy based on a geometrical translational invariance is developed. The strengths of this approach are the reduction of computational time with respect to a direct source-detector simulation, the reconstruction of 40K, 232Th and 238U fundamental spectra, the customization in relation to different experimental scenarios and the investigation of effects due to individual variables for sensitivity studies. The reliability of the simulation is effectively validated against an experimental measurement with known soil water content and radionuclides abundances. The relation between soil water content and gamma signal is theoretically derived and applied to a Monte Carlo synthetic calibration performed with the specific soil composition of the experimental site. Ready to use general formulae and simulated coefficients for the estimation of soil water content are also provided adopting standard soil compositions. Linear regressions between input and output soil water contents, inferred from simulated 40K and 208Tl gamma signals, provide excellent results demonstrating the capability of the proposed method in estimating soil water content with an average uncertainty <1%.


Assuntos
Monitoramento de Radiação/métodos , Solo/química , Espectrometria gama/métodos , Água/química , Simulação por Computador , Método de Monte Carlo , Reprodutibilidade dos Testes
16.
Phys Med Biol ; 63(11): 115014, 2018 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-29726411

RESUMO

Activation of detectors and phantoms used for commissioning and quality assurance of clinical proton beams may lead to radiation protection issues. Good understanding of the activation nuclide vectors involved is necessary to assess radiation risk for the personnel working with these devices on a daily basis or to fulfill legal requirements regarding transport of radioactive material and its release to the public. 11 devices and material samples were irradiated with a 220 MeV proton pencil beam (PBS, Proton Therapy Center, Prague). This study focuses on devices manufactured by IBA Dosimetry GmbH: MatriXX PT, PPC05, Stingray, Zebra, Lynx, a Blue Phantom rail and samples of RW3, PMMA, titanium, copper and carbon fibre plastic. Monitor units (MU) were monitored during delivery. Gamma spectrometry was then performed for each item using a HPGe detector, with a focus on longer lived gamma emitting radionuclides. Activities were quantified for all found isotopes and compared to relevant legal limits for exemption and clearance of radioactive objects. Activation was found to be significant after long irradiation sessions, as done during commissioning of a proton therapy room. Some of the investigated devices may also cumulate activity in time, depending on the scenario of periodic irradiation in routine clinical practice. However, the levels of activity and resulting beta/gamma doses are more comparable to internationally recommended concentration limits for exemption than to dose limits for radiation workers. Results of this study will help to determine nuclide inventories required by some legal authorities for radiation protection purposes.


Assuntos
Terapia com Prótons/instrumentação , Prótons , Espectrometria gama/instrumentação , Humanos , Imagens de Fantasmas , Terapia com Prótons/métodos , Radiometria/instrumentação , Espectrometria gama/métodos
17.
Appl Radiat Isot ; 139: 114-120, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29751324

RESUMO

A gamma spectrometric method is presented for in situ radiation monitoring of bottom sediments with contaminated layer of unknown thickness to be determined. The method, based on the processing of experimental spectra using the results of their simulation by the Monte Carlo method, is proposed and tested in practice. A model for the transport of gamma radiation from deposited radionuclides 137Cs and 134Cs to a scintillation detection unit located on the upper surface of the contaminated layer of sediments is considered. The relationship between the effective radius of the contaminated site and the thickness of the layer has been studied. The thickness of the contaminated layer is determined by special analysis of experimental and thickness-dependent simulated spectra. The technique and algorithm developed are verified as a result of full-scale studies performed with the submersible gamma-spectrometer.


Assuntos
Sedimentos Geológicos/química , Monitoramento de Radiação/métodos , Espectrometria gama/métodos , Poluentes Radioativos da Água/análise , Algoritmos , Radioisótopos de Césio/análise , Simulação por Computador , Humanos , Método de Monte Carlo , Monitoramento de Radiação/estatística & dados numéricos , Espectrometria gama/estatística & dados numéricos
18.
Isotopes Environ Health Stud ; 54(5): 522-534, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29847152

RESUMO

The Jos Plateau has been reported to have elevated levels of natural background radiation. A few earlier studies have measured the levels of natural radioactivity for specific locations in the area. Our interest is to investigate how geology of the study area influences the activity concentrations of natural radionuclides. Thus, the activity concentrations of terrestrial radionuclides in soil samples collected across the geological formations of the Jos Plateau were determined by gamma spectrometry technique. The mean activity concentrations of 226Ra, 232Th and 40K were found to exceed their corresponding world reference values of 35, 40 and 400 Bq kg-1, respectively. Data were compared using statistical methods, analysis of variance (ANOVA) and post hoc tests. The results revealed in some instances significant influences of geological types on the activity concentrations in the area. The spatial distribution maps of activity concentrations of 226Ra, 232Th and 40K were geostatistically interpolated by ordinary Kriging method using ArcGIS software.


Assuntos
Geologia/estatística & dados numéricos , Radioisótopos de Potássio/análise , Rádio (Elemento)/análise , Solo/química , Tório/análise , Radiação de Fundo , Geologia/métodos , Nigéria , Doses de Radiação , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/análise , Espectrometria gama/métodos
19.
J Environ Radioact ; 189: 197-201, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29689484

RESUMO

The analysis of natural radium-in-water activity concentrations is for two reasons of general interest: (1) radium in natural waters may pose a problem with regard to radiation protection and (2) radium isotopes in natural waters can be used as environmental tracers in hydrological studies. A state-of-the-art method for radium extraction from (generally large) water sample volumes is radium adsorption onto MnO2 coated acrylic fibers. In our study we comparatively evaluated four methodical approaches for post-extraction preparation of the fiber to allow gamma spectrometric measurements. The methods included (1) straightforward measurement of the loose fiber, (2) compressing the fiber after mixing it with an adhesive, (3) combustion of the fiber and embedding the ash in candlewax, and (4) leaching of the fiber and embedding the resulting precipitate in candlewax. The aim of the study was to compare the advantages and disadvantages of the four preparation approaches with respect to their individual practicability. Even though the methodical fiber preparation approaches have been suggested in the literature before (as cited in this paper), results of their direct practical comparison have not been presented yet. Our study revealed that balancing practical sample preparation effort against data reproducibility suggests a measurement of the compressed fiber applying an adhesive to be the preferable approach.


Assuntos
Compostos de Manganês/química , Óxidos/química , Rádio (Elemento)/análise , Espectrometria gama/métodos , Poluentes Radioativos da Água/análise , Reprodutibilidade dos Testes
20.
J Environ Radioact ; 189: 109-119, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29653355

RESUMO

The combination of gamma-ray spectrometry, the development of related Monte Carlo method and the GEANT4 (GEometry ANd Tracking) toolkit have been developed for gamma spectrometry simulation. The main objective was to validate simulation models of broad energy germanium (BEGe) detector geometry built in our laboratory (BE6530 model). Monte Carlo simulation of the geometry of BE6530 detector for efficiency calibration was carried out with GEANT4 toolkit. The simulated efficiencies curves using MC were compared with experimental results. Measurement uncertainties for both simulation and experimental estimations of the efficiency were assessed in order to see whether the consequences of the realistic measurement fall inside adequate cut-off points. The validation of the simulation was carried out by experimentally estimating the activity concentration in a reference sample and the comparison showed good correlation between experimental and simulation. Therefore, from the outcomes of this study, it can be concluded that Monte-Carlo simulation is a helpful, reasonable option that additionally gives more prominent adaptability, greater flexibility, precision and accuracy, and gained time when determining the detector response and efficiency in routine of environmental radioactivity monitoring.


Assuntos
Espectrometria gama/métodos , Algoritmos , Calibragem , Simulação por Computador , Germânio , Método de Monte Carlo , Monitoramento de Radiação/instrumentação , Monitoramento de Radiação/métodos , Software , Espectrometria gama/instrumentação
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