Gamma-ray Spectrometric Analysis Research Articles

Gamma ray spectrometric analysis and assessment of radiation hazards in soils of Mbeere North region, Kenya.

This study used gamma ray spectrometry to determine the radiological safety of construction soil sampled randomly from Mbeere North region, Kenya. The mean activity concentration of 232Th, 238U, and 40K was 149.7±2.8 Bqkg-1, 88.3±2.4 Bqkg-1, and 490±35 Bqkg-1, respectively. These averages exceed the world average for all the radionuclides. The radionuclides were non-uniformly distributed, with higher concentrations along the slopes and on the feet of the hills. The mean absorbed dose rate, indoor and outdoor annual effective dose, radium equivalent, external hazard index, and internal hazard index were 157.9±4.4 nGh-1, 0.58±0.02 mSvy-1, 0.39±0.01 mSvy-1, 340.7±9.2 Bqkg-1, 0.92±0.02 and 1.14±0.03, respectively. Among the radiation safety indicators, only the average internal hazard index exceeded slightly the acceptable safe limit. Therefore, soils of Mbeere North region are radiologically safe for use in brick making and construction of human habitats.

Gamma-ray spectrometric analysis of bore-well rock samples from agricultural area of Tamil Nadu

Natural gamma radiation exposure to humans can possess significant health risks when exposed either externally or internally. Though risks are not established at low doses, the exposure levels are set based on conservative approach. In this work, 22 bore-well rock samples were collected from the agricultural area of Dharmapuri district, Tamil Nadu to evaluate the radiation exposure to humans living in that area using a gamma-ray spectrometer. The results shows that, the activity concentration of 238U ranges from MDA to 87±2 Bq kg−1 with an average value of 25 Bq kg−1, and for 232Th it ranges from MDA to 10±2 Bq kg−1, and for the 40K it ranges from 167±9 to 669±10 Bq kg−1 with the mean value of 310 Bq kg−1. The various radiological parameters are calculated and compared with the world-recommended limit to assess the radiation hazards. To identify the relation among the natural radioisotopes, Pearson correlation analysis was performed between the radiological variables. It reveales that radionuclides 238U and 232Th strongly correlated with each other and radiological parameters. This implies that 238U and 232Th originated from the same source and 40K was derived from different sources.

Analysis for the secondary gamma-ray emission for glasses irradiated with various doses of fast neutron: Case study borate and silicate glasses

Are borate and silicate glasses suitable for working as shieling materials against fast neutrons?To correctly answer the above question, some silicate, and borate-based glasses were fabricated and irradiated with various doses of fast neutrons varied between 1.73 and 12.10 MGy. The color and hardness of the fabricated glasses were affected by the fast neutron fluence where the transparent glasses turned colored as well as the hardness of the fabricated glasses was decreased. The gamma-ray spectrometric analysis shows a high activity concentration produced in the barium borate glasses due to the formation of radioisotopes Ba-131 and Ba-133 reaches to 5.92E+05 Bq and 4.25E+03 Bq, respectively for sample Cd-5 Batch 3. Additionally, the gamma-ray spectrometric analysis for the sodium silicate glasses shows low activity concentrations emitted from isotopes formed due to the activation of Y2O3-associated impurities. These activities are low compared to that emitted by barium borate-based glasses.

Natural radioactivity assessment of surface soil collected from Poovar village of Kerala, India

Making use of gamma ray spectrometric analysis method, the activities of soil-borne radio-nuclides viz. 226Ra, 232Th and 40K in the surface soil samples from a specific village in coastal county has been determined. The surface soil of living environment in the Poovar village was used for the study. The activity concentration is used for evaluating various radiologically vital parameters such as levels of radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), absorbed gamma dose rate (D), outdoor and indoor annual effective dose (AED), representative gamma radioactivity level index (Iγ) and alpha index (Iα) in the region. The estimated radioactivity concentrations of 226Ra, 232Th and 40K was observed to fluctuate from below detectable level (BDL) of the instrument to 9 Bqkg−1, 21 Bqkg−1 to 36 Bqkg−1 and 453 Bqkg−1 to 585 Bqkg−1, respectively. Since all of the samples investigated in the study are within the advised limit, there are no radiation threats to the human beings in the region. The obtained information in this research can be used for future radiological mapping and impact assessments.

Radiological hazard levels of construction rocks excavated from quarries in Kericho county, Kenya

The study determined the natural activity concentration levels of 40K, 232Th and 238U in rocks used for construction from the 15 selected quarries in Kericho County, Kenya through Gamma-ray Spectrometric analysis at the Physical Sciences department of South Eastern Kenya University (SEKU). IAEA procedures were followed from sample collection, preparation and measurement. Samples were collected, crushed, oven dried at 105 , weighed and packed in sealed containers and kept for four weeks in order for secular equilibrium to be achieved between 226Ra and 232Th. The average activity concentration of 232Th, 238U and 40K were 101 ± 5 Bq/kg, 56 ± 3 Bq/kg and 1100 ± 55 Bq/kg and ranged from 41 ± 2 to 138 ± 7 Bq/kg, 26 ± 1 to 116 ± 6 Bq/kg and 512 ± 26 to 1919 Bq/kg ± 96 Bq/kg respectively. The average external and internal hazard indices were 0.8 mSv/y and 0.9 mSv/y respectively. Radium equivalent ranged from 222 ± 11 Bq/kg to 366 ± 18 Bq/kg with an average value of 285 ± 14 Bq/kg which was below the permissible limit of 370 Bq/kg; therefore, the excavated rocks for construction from the selected quarries in Kericho county poses insignificant health risk to the general population and quarry workers.

Gamma Ray Spectrometric Analysis of Sand Samples from Selected Beaches along Kenyan Coastline.

In this study, the activity concentration levels of 238U, 232Th, and 40K in sand samples collected from Shanzu, Nyali, Kenyatta, Tiwi, Shelly, and Diani beaches selected along the Kenyan coastline were determined using a gamma ray spectrometer with a NaI(Tl) detector. The average activity concentrations of 238U, 232Th, and 40K in sand samples were analyzed as 87 ± 4, 98 ± 4, and 1254 ± 62 Bq/kg, respectively. Also, radium equivalent (Raeq) activity and internal (Hin) and external (Hex) hazard index were calculated to assess the radiological hazards associated with the use of sand samples as building materials. The average values of Raeq, Hin, and Hex were found as 327 ± 16 Bq/kg, 0.98, and 0.72, respectively. The average values of outdoor and indoor annual effective dose rates were estimated as of 0.23 and 0.63 mSv/y, respectively, which are below maximum recommended limit of 1 mSv/y. Generally, these results indicate no significant radiological health hazards for the studied beaches.

ASSESSMENT OF RADIONUCLIDES IN SOME NIGERIAN MADE CEREALS AND TEA PRODUCTS

This study investigated the presence of the radionuclides 226Ra, 232Th, 40K and 137Cs in some cereals and tea products commonly available in Nigerian markets. Fifteen cereal samples and ten tea samples were purchased from different markets in Lagos, Nigeria. Gamma-ray spectrometric analyses of the samples were done using a High Purity Germanium (HPGe) detector to obtain the activity concentrations of the radionuclides with 137Cs being below the detection limit in all the samples analyzed. The mean activity concentrations (in Bqkg-1) of 226Ra, 232Th and 40K in the cereal samples were (0.839 ± 0.713), (1.153 ± 1.084) and (22.514 ± 8.897) respectively; while the values for the tea samples were (1.145 ± 0.765), (0.94 ± 0.601) and (19.212 ± 9.533) respectively. The associated hazard indices for the cereals ranged from 0.0065 to 0.0368 while that for the tea products varied from 0.0044 to 0.0292. These values are well below the world recommended limit of 1.0. The calculated annual effective doses due to the ingestion of the investigated samples ranged from 0.068 mSvy-1 (for age groups from 1 y) to 0.189 mSvy-1 (for age group 17 y). For the tea samples, the highest value was found in the age group 12 – 17 y, while the lowest was found in the age group 1 – 2 y. These values are below the allowable level of 1 mSv per annum for members of the general public as recommended by the International Commission on Radiological Protection. This indicates that the consumption of these cereals and teas do not pose as health hazards to both children and adults in the populace.
 

ESTIMATION OF RADIOLOGICAL HAZARDS DUE TO NATURAL RADIONUCLIDES FROM THE ROSTERMAN GOLD MINE TAILINGS, LURAMBI, KAKAMEGA, KENYA.

Radiological hazards associated with naturally occurring radionuclides in materials from Rosterman gold mine were assessed by analysis of 30 samples. The gamma-ray spectrometric analysis of tailing samples reported an average activity concentration of 263±13, 123±6 and 84±4Bqkg-1 for 40K, 232Th and 226Ra, respectively. The average absorbed dose rate was 124±6 nGy h-1, while the annual effective dose of 0.4±0.02mSv y-1 for indoor and 0.3±0.01mSv y-1 for outdoor were reported. The mean and range of radiological parameters (external and radium equivalent) calculated from the tailing samples were within the permissible limits and hence mining of gold at Rosterman has no significant radiological health implication on the miners and the surrounding population.

Geochemical features of pyrite pseudomorphs according to plant residues from the Upper Jurassic deposits of the Middle Volga river area (Russian Federation)

The study of the mineralogy and geochemistry of biomorphic ore formations has great importance for studying the processes of transformation of plant tissues during the formation of the sedimentary rocks, including ore mineralization. Forms of biogenic mineralization in sedimentary rocks are represented by various processes. The pyritization of organic residues is one of the most common forms. The purpose of this work was to conduct a detailed mineralogical and geochemical study of biomorphic ore formations collected from Mesozoic (Upper Jurassic) deposits of the right bank of the Volga river. The initial conditions for the fossilization of the objects of study were the same. Therefore, the structural and morphological features of the pyrite aggregate developing on them can be caused not only by geochemical conditions but also by the structure of the residues themselves. Samples were examined by optical microscopy, X-ray phase analysis, gamma-ray spectrometric analysis, X-ray computed tomography and X-ray fluorescence analysis. As a result of research, the stages of mineralization of wood were established, which reflect the features of sedimentation.

Variation of natural radionuclides in non-ferrous fayalite slags during a one-month production period

The European Basic Safety Standards (EU-BSS) describes a set of NORM (Naturally Occurring Radioactive Material)-processing industries which produce residues known to be possibly enriched in NORs (Naturally Occurring Radionuclides). These residues can be used as a component in building materials aimed for public usage. The industrial processes, in which the residues are produced, are often complex and total monitoring can be challenging especially when the origin of the used raw materials varies. In this study the NORs present in non-ferrous fayalite slags of a secondary smelter facility, a NORM-processing industry according to the EU-BSS, were monitored daily during a one-month production period. In addition flue dust samples and feedstock samples, known to contain elevated levels of NORs, of the same period were measured. The survey involved the gamma-ray spectrometric analysis of the decay products from the 238U and 232Th decay chains, 235U and 40K using HPGe detectors. Secular equilibrium was observed for the slags, flue dust and feedstock samples in the 232Th decay chain, in contrast to the 238U decay chain. During the month in question the ratios of maximum over minimum activity concentration were 3.1 ± 0.5 for 40K, 4 ± 1 for 238U, 6 ± 1 for 226Ra, 13 ± 7 for 210Pb, 4.5 ± 0.6 for 228Ra and 4.7 ± 0.7 for 228Th for the slags. Even with the activity concentration of the feedstock material ranging up to 2.1 ± 0.3 kBq/kg for 238U, 1.6 ± 0.2 kBq for 226Ra, 22 ± 7 kBq/kg for 210Pb, 2.1 ± 0.2 kBq/kg for 228Ra and 2.0 ± 0.4 kBq/kg for 228Th, none of the slag samples exceeded the exemption/clearance levels of the EU-BSS and RP-122 part II, which can respectively provide guidance under equilibrium and in absence of equilibrium. As each NORM-processing industry has its own complexity and variability, the observed variations point out that one should approach one-time measurements or low frequency monitoring methods cautiously. Low frequency measurements should be optimised depending on the discharge of the batches. A follow up of the industrial process and its output can provide important insights to assure a limited public exposure upon application of these industrial residues.Finally a comparison is made with reported data on other metallurgical slags and the use of the slags in building materials is evaluated using the Activity Concentration Index (ACI) proposed by the EU-BSS.

A review of the evaluation of TENORM levels at the produced water lagoon of the Minagish oil field using high-resolution gamma-ray spectrometry

An evaluation of the specific activity concentrations associated with technologically enhanced naturally occurring radioactive materials (TENORM) and anthropogenic radionuclides has been undertaken as part of a systematic study to provide a radiological map of the outer boundary of the produced water lagoon located in the Minagish oil field in the south west of the State of Kuwait. The lagoon contains material from the discharge of produced water which is a by-product of oil production in the region. The lagoon samples were prepared and placed into sealed, marinelli beakers for a full gamma-ray spectrometric analysis using a high-resolution, low-background, high-purity germanium detection systems at the University of Surrey Environmental Radioactivity Laboratory. Of particular interest are the calculation of the activity concentrations associated with members of the decay chains following decays of the primordial radionuclides of the 238U chain (226Ra, 214Pb, 214Bi) and the 232Th chain (228Ra, 228Ac, 212Pb, 212Bi, 208Tl), and the enhanced concentrations of radium isotopes. This conference paper presents an overview summary of the experimental samples which have been measured and the analysis techniques applied, including isotopic correlation plots across the sample region. The result shows the expected significant increase in 226Ra (and progeny) concentrations compared to the NORM values previously reported by our group for the overall terrain in Kuwait.

Gamma Spectrometric Analysis of Iron Ore Samples of Arak, Iran

Introduction Iron ore is one of the most important natural raw materials that is widely used for manufacturing iron and steel. This type of ore contains various amounts of radionuclides; thus, exposing workers handling their extraction, transportation, and processing to radiation. Materials and Methods In this study, 12 ore samples (each mass weighing about 2 kg) were collected from the iron ore mining areas of Arak region, Iran. The specific activities of 226Ra, 232Th, and 40K were determined usinggamma-ray spectrometry method employing high-purity germanium (HPGe) detector. Results The specific activities of 226Ra, 232Th, and 40K in samples were 9.39-271.70 Bq/kg, -3 Sv/y) suggested in International Commission of Radiological Protection (ICRP) Publication 82. Conclusion The gamma ray spectrometric analysis showed that the specific activities of natural radionuclides in samples, except for limonite ore, were within the worldwide range. The effective dose received by workers was much lower than the maximum acceptable value (1000 μSv/y); therefore, the level of radiations in this mine had no adverse consequences for public health.

Determination of levels of naturally occurring radioactive materials in lagoon samples containing produced water from the Minagish oil field in the state of Kuwait

An evaluation of the activity concentration (Ac) associated with naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a radiological map of the ground materials from a produced wastewater lagoon located in the Minagish oil field in the south west of the State of Kuwait. This lagoon contains material from the discharge of produced water which is a by-product of oil production in the region. Samples of surface materials have been collected, prepared and placed into sealed, Marinelli beakers for a full gamma-ray spectrometric analysis using a high-resolution, low-background, high-purity germanium detection system. This short conference paper presents a summary of results for an initial selection of sixteen surface samples from the edges of the Minagish oil lagoon which have been analysed to obtain Ac values for members of the 226Ra (214Bi and 214Pb) and 232Th (228Ac, 212Pb and 208Tl) decay chains and for 40K. These are compared with other studies for the same geographical region.

VZTAH MEZI PŘIROZENOU RADIOAKTIVITOU HORNIN A PŮD NA NICH VYTVOŘENÝCH – ZÁKLADNÍ PROBLÉM INTERPRETACE DAT ZÍSKANÝCH LETECKOU A TERÉNNÍ GAMASPEKTROMETRIÍ

The objective of this study was to assess the amount of natural radionuclides in fresh parent rocks and their effect on natural radioactivity of soils developed from them. Forty-five fresh rocks consisting mainly of granitoids, syenitoids, acid to basic metavolcanites, mica schists, gneisses, quartzites, serpentinites, sandstones, graywackes, and limestones and their corresponding overlying soils were sampled for laboratory gamma-ray spectrometric analysis. Contents of potassium, uranium and thorium were converted to mass activity of 226Ra equivalent (am) and terrestrial gamma radiation dose rate (D). Data are tabled and discussed. The highest am values occured in syenitoids (386–441 Bq·kg-1) followed by granitoids, mica schists, greywackes and gneisses, whereas the lowest am values were found in quartzose sandstones (15–36 Bq·kg-1) followed by limestones (less than 15 Bq·kg-1) and serpentinites (less than 6 Bq·kg-1). The natural radioactivity of soils is usually slightly lower than that of parent rocks due to the lower content of potassium, uranium and thorium in soils. This is typical for granitoids, syenitoids and rocks of similar mineralogical composition. In soils developed on granitoids and syenitoids were found increased concentrations of all three elements in the grain size fraction below 0.063 mm. Soils developed on rocks with low natural radioactivity (such as limestones and serpentinites) tend to have significantly higher natural radioactivity than their parent rocks. This may complicate the interpretation of data obtained by airborne gamma-ray spectrometry.

Calculation of the decision thresholds for radionuclides identified in gamma-ray spectra by post-processing peak analysis results

A method for calculating the decision thresholds for gamma-ray emitters, identified in gamma-ray spectrometric analyses, is described. The method is suitable for application in computerized spectra-analyzing procedures. In the calculation, the number of counts and the uncertainty in the number of counts for the peaks associated with the emitter are used. The method makes possible to calculate decision thresholds from peaks on a curved background and overlapping peaks. The uncertainty in the number of counts used in the calculation was computed using Canberra׳s Standard Peak Search Program (Canberra, 1986, Peak Search Algorithm Manual 07-0064). For isolated peaks, the decision threshold exceeds the value calculated from the channel contents in an energy region that is 2.5 FWHM wide, covering the background in the immediate vicinity of the peak. The decision thresholds vary by approximately 20% over a dynamic range of peak areas of about 1000. In the case of overlapping peaks, the decision threshold increases considerably. For multi-gamma-ray emitters, a common decision threshold is calculated from the decision thresholds obtained from individual gamma-ray emissions, being smaller than the smallest of the individual decision thresholds.

Analysis of 7Be behaviour in the air by using a multilayer perceptron neural network

A multilayer perceptron artificial neural network (ANN) model for the prediction of the 7Be behaviour in the air as the function of meteorological parameters was developed. The model was optimized and tested using 7Be activity concentrations obtained by standard gamma-ray spectrometric analysis of air samples collected in Belgrade (Serbia) during 2009–2011 and meteorological data for the same period. Good correlation (r = 0.91) between experimental values of 7Be activity concentrations and those predicted by ANN was obtained. The good performance of the model in prediction of 7Be activity concentrations could provide basis for construction of models which would forecast behaviour of other airborne radionuclides.

Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detectors.

Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disposal. Gamma-ray spectrometric analyses were carried out with High Purity Germanium (HPGe) and Lanthanum bromide (LaBr3:Ce) scintillation detectors. HPGe is the most used detector for its high energy resolution although it is more suitable for use in a laboratory. The use of LaBr3:Ce can be considered a viable option, particularly in realizing a portable spectrometric system to perform "on-site" measurements and a fast dose rate evaluation before the disposal of activated parts. Due to a high activity of target assembly components replaced after a typical irradiation cycle (about 5000 μAh integrated beam current), gamma-ray spectrometric measurements were performed at a large distance from the detector, even more than 100 cm, or by using a purposely realized Lead-walled collimator. The identification of some key-radionuclides allows to evaluate through simple formulations the dose rate behavior for each component as function of decay time from the last irradiation. The knowledge of the dose rate behavior is a significant piece of information to health physicists for waste handling with safety at work. For an Havar™ foil, the dose rate will be reduced to about 1/1,000 of the starting value after a decay period of approximately 4 y (about 1,500 d), with a relatively safety at product disposal work. For a longer time, only long-lived radionuclides (57)Co, (60)Co, and (54)Mn contribute to dose rate.

A radiometric and petrographic interpretation of discrepancies on uranium content in samples collected at Alte Madonie Mounts region (Sicily, Italy)

The main goal of this work is to evaluate a correlation between anomalous Uranium (U) content and petrographic features of some soil and rock samples collected at Alte Madonie Mounts region (North-central Sicily, Italy). A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in “Marinelli” beakers for 20 days before the measurement to ensure that radioactive equilibrium between 226Ra and 214Bi was reached. Gamma-ray spectrometric analysis was used to quantify radioactivity concentrations. Mineralogical and chemical features of the samples were determined by X-ray Fluorescence (XRF), X-ray Diffractometry (XRD), Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) and Scanning Electron Microscope – Energy Dispersive Spectrometry (SEM-EDS) analyses.The average values of concentrations of 226Ra, 228Ac and 40K were respectively 30, 17 and 227 Bq kg−1 while the greatest values were 134, 59 and 748 Bq kg−1. Linear relationships were observed between 226Ra, 228Ac and 40K concentrations: the activities of 226Ra and 228Ac were comparable, while those of 40K were about 10 times greater. An exception was highlighted for a group of samples where 226Ra activities were much higher than expectations. Chemical compositions and mineralogical features of the samples have made it possible to justify these anomalies.

An experimental approach to efficiency calibration for gamma-ray spectrometric analysis of large air particulate filters

A full-energy-peak efficiency (FEPE) calibration procedure for gamma-ray spectrometric analysis of air particulate samples collected on large filters is described herein. The experimental results are obtained for an unconventional measurement geometry, termed a “packet-sample”. The sample is obtained from a large cellulose filter (45cm×45cm) used to collect air particulate samples that is resized to dimensions suitable for spectrometric measurements (6cm×6cm×0.7cm). To determine the FEPEs, many standards were created, i.e., some filters containing a small amount of ThO2 and others containing a known amount of KCl.Efficiency curves obtained through best fits to experimental data for three high-purity germanium (HPGe) detectors, one of them for X-ray measurement, cover the energy range from 40keV to 2600keV. To validate the efficiency calibration procedure two experimental tests with the use of calibrated sources were conducted and, as application example, airborne concentrations of 131I (particulate matter), 134Cs and 137Cs at Palermo (Italy) in the days following the Fukushima accident in Japan were evaluated.

7Be in ground level air in Daejeon, Korea

(7)Be concentrations in the ground level air in Daejeon, Korea were determined during the period of January 1998 to December 2009 by gamma-ray spectrometric analysis of particulate samples collected on filter paper with a high-volume air sampler. The monthly concentrations of (7)Be in the ground level air were in the range of 1.3-7.7 mBq m(-3) with strong seasonal trends of low values in the summer and high values in the spring and autumn. The annual mean values of (7)Be concentrations showed weak reverse correlation with the annual average sunspot number.