High-resolution Gamma Spectrometry Research Articles

Field-based soil-plant uptake measurements of natural radionuclides for key vegetables and ghaf leaves in Abu Dhabi

With the thriving fossil fuel and nuclear based industries in the nation, radioecology has become necessary for the radiation safety and emergency-preparedness for the United Arab Emirates (UAE). Environmental radiation transport modelling in the UAE and the Arabian Peninsula are severely limited, as we discuss in this paper, due to lack of experiments specific to arid desert climates. To fill the missing gaps in the baseline arid region radioecological database, especially for the soil-plant uptake studies, rigorous field works have been conducted for the first time on the soil and plant in the farms and open fields of the UAE. We present Abu Dhabi based measurements of activity concentrations of radionuclides of natural origins, in soils, key vegetables (cucumber, tomato, and bell pepper), and leaves of ghaf - a prominent native tree. The empirical data are utilized to get the first published estimates of UAE-specific plant-soil concentration ratios (CR), measuring root uptake of radionuclides in nonleafy vegetables and native trees. Such systematic studies are very rare for arid sandy soils. For the 27 samples analyzed, the activity concentrations' (unit Bq kg−1) ranges are: 169–1746 for 40K, 12–19.5 for 226Ra, and 2.7–23.1 for 228Ra. Likewise, wide variability is seen in the averages of concentration ratios also, ranging in 1.05–4.94 for 40K, 0.14–1.82 for 226Ra, and 0.53–2.78 for 228Ra. A net bioaccumulation (concentration ratio >1) of some of these natural radionuclides is found in many samples, but no significant doses or hazard indices are found due to these three radionuclides in the UAE's soils and vegetations. The paper discusses the careful work through tens of field sampling exercises, well controlled sample processing, high resolution gamma spectrometry, and treatment of data from gamma counting rates to accumulated dose rate estimations.

Longitudinal Gradient and Historical Trends of Arsenic and Metals in a Tropical Reservoir

This study aimed to establish the longitudinal gradient and historical trends of arsenic and metals in a tropical reservoir. Water and sediment samples were collected along the Rio Bonito reservoir (Espírito Santo, Brazil), and a sediment core was obtained from the lacustrine zone. Plasma spectrometric techniques were employed to determine concentrations of As, Cd, Co, Cu, Fe, Mn, Ni, and Pb in water and sediment samples, and the sediment samples were dated using high-resolution gamma spectrometry. Higher concentrations of elements were observed in surface water samples from the riverine zone and bottom water samples from the transition zone. Concerning surface sediment samples, elevated concentrations were noted in the transition and lacustrine zones, where deposition is more intense. The sediment core was dated to 1940, before the reservoir dam construction, utilizing 210Pb dating. Certain elements exhibited progressively increasing concentrations over time. Enrichment factor, pollution load, and ecological risk indexes indicated the need for continuous monitoring of this reservoir

Characterization study of NaI(Tl) γ-summing spectrometer

The accurate information regarding the β-decay half-life, feeding pattern from the neutron-rich nuclei have utmost importance in the field of nuclear waste management from the fission reactors as well as correct understanding about the r-process nucleosynthesis in stellar sites. The low capture cross-section measurements are also considered as major task by experimental nuclear astrophysicists. These kinds of measurements are really difficult with conventional high-resolution gamma spectroscopy techniques due to less efficiency of the detectors. For this purpose, we have an almost 4π γ-summing NaI(Tl) spectrometer at SINP, Kolkata. It is basically a cylindrical shaped detector with six sectors of NaI(Tl) crystals read by 6 photomultiplier tubes (PMT) at one end. The detailed characterization of the spectrometer via experiment using laboratory standard sources and GEANT4 simulation model to interpret all the interesting properties will be presented here in this paper.

A new fast screening method for estimating building materials hazard indices with correlated inputs

In this work we investigate a new fast screening method for estimation of chosen hazard indices (HI) using correlated inputs dedicated for small 3.00 g samples using a novel μDOSE. The system detects α and β particles separately, along with 220Rn/216Po, 219Rn/215Po, 212Bi/212Po and 214Bi/214Po decay pairs. Four separate decay pairs along with α and β particle count rates are used to quantify decay chains. The excess β count rates is used to quantify the 40K radioactivity. This provides radionuclide estimates that are correlated—and this correlation is taken into account in calculating hazard indices with their corresponding uncertainties. Calculated hazard indices are verified against state-of-the-art High Resolution Gamma Spectrometry (HRGS) equipped with a High Purity Germanium (HPGe) detector manufactured by Canberra. This research shows that results obtained with the μDOSE system correspond to the results obtained with HRGS and when the activity correlation is taken into account the HI uncertainties are similar in value for both methods.

Activation cross section measurement of alpha-particle induced nuclear reactions on tantalum

Activation cross sections induced by 50 MeV alpha-particle beam on natural tantalum were measured at the AVF cyclotron of the Nishina Center of RIKEN. The well-established stacked target technique and activation method were applied followed by high-resolution gamma spectrometry to determine the reaction cross sections. The experiment aimed to determine activation cross sections for the longer-lived reaction product. Accordingly, activation cross sections were deduced for the formation of 181, 182m, 182g, 183, 184m, 184gRe and 178g, 182gTa.

Gamma-emitting radionuclides in therapeutic muds of the Euganean Thermal District (Padua, Italy)

Mud therapy is a therapeutic tool which uses natural materials available in the environment for healing purposes (clays and thermal water). The use of natural remedies increases the compliance to the cure, and their success is increasing in the last decades, all over the world. As natural matters, also muds have a wide range of composition, so, their use for healing requires appropriate knowledge.One of the most important world reference area for mud therapy has been accessed for sampling in different thermal centers (28) and also the exploiting site of raw clay has been studied. High resolution gamma spectrometry measurements have been acquired, compared with previous published data and discussed considering other compositional parameters.A clear increase of radionuclides of the 238U series characterize therapeutic muds respect to raw materials, 226Ra in particular. The scavenging of Ra from thermal waters is considered to occur after the precipitation of sulfate minerals (gypsum, barite) into the mud matrix, and several lines of evidence suggest that the repeated contact with thermal water (mud recycling) enhance the enrichment of Ra. A different scenario can be drawn for workers and for patients, as their contact with the mud is different for type and time. The dose arising from working in the area of therapeutic muds preparation and the dose to the skin of patients have been calculated.Even if Euganean therapeutic muds are richer in 226Ra respect to other similar materials, no radiological hazards emerged for workers who manage the preparation area, even in the most cautionary scenario. Also for patients, the contribution of Euganean mud therapy to the annual equivalent dose to skin is negligible, according to the cautionary elaboration done. Also considering literature data on the transcutaneous passage of chemical elements with geochemical affinity with Ra, no radiological hazard is detectable.

Gamma Spectrometry Analysis of Natural and Man-Made Radioactivity and Assessment of Radiological Risk in Soils Around Steel Industry

"In this paper low background high-resolution gamma spectrometry was used for the determination of the activity concentrations of the natural and man-made radionuclides in topsoil samples collected in the vicinity of a large steel plant in Galati, Romania. Their values (mean ± standard deviation) for 238U, 226Ra, 232Th, 235U, 210Pb, 40K and 137Cs were: 38.1 ± 6.2; 35.9 ± 5.4; 35.5 ± 3.0; 1.8 ± 0.4; 47.3 ± 8.6; 504.5 ± 38.9 and 7.2 ± 4.7 Bq·kg–1, respectively. 60Co and 241Am had activities below the detection limit: 0.6–1.3 and 2.2–4.7 Bq·kg–1, respectively. The results indicate inputs of natural radionuclides in the sites close to the slag dump, raw materials transportation facility, ore and coal processing factories, blast furnaces, and iron scrap deposit. The evaluation of the associated radiological impact was performed based on selected hazard parameters: absorbed gamma dose rate, total external gamma dose rate, radium equivalent activity index, external hazard index, representative level index, annual effective dose, excess lifetime cancer risk, and annual gonadal dose."

Examining the residual radiological footprint of a former colliery: An industrial nuclear archaeology investigation

Nuclear industrial archaeology utilises radiation mapping and characterisation technologies to gain an insight into the radiological footprint of industrial heritage sites. Increased concentrations of naturally occurring radioactive materials at legacy mine sites are the result of elemental enrichment during coal mining and subsequent combustion. Public safety is of concern around these sites, and therefore, an increased understanding of their associated hazard is essential. Using coincident laser scanning and gamma detection technologies, this study sought to assess the radiological legacy of a coal mine located in Bristol, UK. From this, we can increase our understanding of the residual footprints associated with the local coal mining industry. Samples taken from inside the site were characterised using high resolution gamma spectrometry, wherein the radionuclide content and activities of samples were then quantified. An area of elevated low-level radioactivity was observed at and around buildings believed to belong to the colliery, while Th, U, and K are confirmed at the site from photopeak's of daughter radionuclides. Activities of the radionuclides K-40, U-238, and Th-232 were further quantified during subsequent laboratory analysis. Results highlight an enrichment of naturally occurring radionuclides when compared with global averages for unburned coal. Employing these techniques at further legacy sites would enable an increased understanding of the lasting traces of the coal mining industry, with a focus on NORM enrichment in residual fly ash.

Discharges of 131I coming from hospitals and outpatients in the sanitary sewage system of Bogotá

An integral sampling methodology was applied to the sewerage network of Bogotá by inspecting wells that carry sanitary water from institutions that use 131I in nuclear medicine treatments to determine the areas of the city with activity of this radioisotope, which may reach the Salitre wastewater treatment plant and are subsequently discharged into the Bogotá river. The areas evaluated included the location of authorized institutions that use 131I in nuclear medicine and their patients. A total of 13 wells were sampled in the city, each with three samples, and the characterization of the samples was performed using the technique of high-resolution gamma spectrometry with Ge-HP detector and covered the relevant aspects that must be considered to make a complete characterization of the presence of the isotope studied. Among these factors are the season of the year with precipitation, pipe flow, location of the nuclear medicine facilities, existence of decay systems, number of rooms for treatment with 131I and water trajectory through the sewage system.Based on the results obtained, it was possible to identify potential sources of radioisotope 131I that are exceeding the discharge limits established by Colombian regulations (i.e., 19 Bq/L at the discharge point). From the 13 wells sampled, radioisotope 131I was detected in 11 of them. From the assessed wells, 3 were connected to facilities in which activity was found to be above the discharges limit allowed in Colombia for the sanitary sewer.This research complements the study on traceability of 131I in Bogotá-Colombia that begins with its importation by radiopharmacies who distribute it to hospital patients and outpatients, continuing its trajectory through management systems or homes to the sewage system of Bogotá, field that had not been studied. It allows inferring the degree of compliance with Colombian regulations and serves as a basis for evaluating regulatory changes in the levels of 131I dispensing in water networks. Further studies are required to assess the potential impacts of these materials on the local population.

High-Resolution Gamma-Ray Spectrometry of Pebble Bed Reactor Fuel Using Adaptive Digital Pulse Processing

In this work, an investigation was performed to assess the feasibility of passive gamma-ray spectrometry using adaptive digital pulse processing for online interrogation of pebble bed reactor (PBR) fuel. This work incorporates the physics of the radiation emission phenomenon with advanced pulse processing techniques to develop a high-resolution gamma-spectrometry system capable of handling ultrahigh count rates in various applications of nuclear science and technology. Computational modeling was used to simulate the irradiation of PBR fuel and to design the adaptive digital pulse processing–based gamma-ray spectrometry system. Monte Carlo simulations were performed to study the gamma-ray spectra of the PBR fuel and to perform coupled photon-electron transport analysis to calculate the pulse-height spectrum of PBR fuel. A Monte Carlo computer routine was used to predict the effect of pulse pileup at high-count-rate conditions. This code utilizes the random interval distribution function based on Poisson statistics to simulate the pileup behavior. Combined with pileup logic, a recursive trapezoid filter with adaptive shaping parameters was implemented to simulate the pileup behavior of a digital gamma-ray spectrometry system. The adaptive shaping algorithm selects the rise time of the trapezoid shaping filter based on the separation between the input pulses for each incoming signal. The simulation results using the proposed adaptive digital pulse processing demonstrated that with the improved energy resolution, the burnup information can be more accurately determined on a pebble-by-pebble basis as compared to fixed shaping, and tasks related to in-core fuel management, safeguards, and waste management become feasible to perform efficiently and accurately.

Radioanalytical models applied to the investigation of caesium signatures in sugar samples

The presence of anthropogenic radioisotopes in the environment may be due to inappropriate discards, nuclear tests and accidents, which requires and justifies constant monitoring to ensure the safety of nuclear applications. The radiometric analysis is a necessary condition for exporting sugar for world consumption. The investigation of 134Cs and 137Cs in a sugar matrix is required to predict radiometric anomalies. This work aimed to standardise a semi-empirical radiometric model to characterise and quantify caesium isotopes in sugar. The research was carried out with high-resolution gamma spectrometry, a non-destructive method. The results were applied to the analysis of different types of sugar for export. The models allowed us to determine with excellent resolution the minimum quantifiable activities of 0.74 Bq kg−1 and 0.48 Bq kg−1 for 134Cs and 137Cs, respectively, which are lower than 600 Bq kg−1, reference values adopted by the EU for isotopes in food.

Set up and test of an anticoincidence system for the detection of radioactive xenon by gamma spectrometry system

The aim of this work is based on the optimisation of a gamma spectrometry system in anticoincidence for the detection of noble gases, in particular the radioactive isotopes of xenon. These four radionuclides are of particular interest for the Comprehensive Nuclear Test-Ban Treaty (CTBT). The Laboratory of the ENEA Research Centre of Brasimone, where the experimental apparatus has been set up to carry out the measurements of 131mXe, 133Xe, 133mXe and 135Xe, is able to provide, if necessary, data and analysis on noble gases. The apparatus provides for the sampling of outdoor air, the passage through filters and in activated carbons maintained at cryogenic temperatures to allow xenon absorption. Finally, gas extraction and xenon volumes are analyzed by means of gas chromatography and a thermal conductivity detector. At the end of the extraction an aluminium cylinder containing radioxenon is analyzed by high resolution gamma spectroscopy using a High Purity Germanium Detector P-type. The signals produced by the interaction of cosmic rays with the crystal have been recognized as the main cause of the increase of the detector background because they give rise to the Compton continuum and, as a result, they affect the value of the minimum detectable activity (MDA). In order to overcome this effect, a system in anticoincidence has been developed using two plastic scintillators, placed over the shielding of the HPGe detector, which send pulses recording within a time delay window located in the germanium multichannel analyzer: at the time the signal arrives from the scintillator, the gate blocks data acquisition to avoid recording pulses generated by cosmic radiation. For both configurations of the system (with and without the anticoincidence apparatus operating) the energy, and efficiency calibrations have been carried out using a certified multigamma-ray calibration source to assess the performance.

Cluster- and PCA-based gamma-ray spectrometry data processing algorithm for hydrothermal alteration haloes mapping

In the present paper a high-resolution gamma-spectrometry data processing algorithm aimed at locating hydrothermal alteration haloes is discussed. On the first stage a cluster model of spatial variation of radioactive background is created using information on natural radioactive elements (NRE) concentrations and numerical geomorphological characteristics. This model allows for good terrain differentiation in terms of its lithological and landscape variability. Mathematical procedure for removal of NRE distribution variance, related to variability of lithology and elementary landscapes, improved radiometry data for mapping zones of hydrothermal alterations. On the second stage we integrated the “corrected” gamma-ray spectrometry data using principal component analysis (PCA). Comparing the acquired factor model with a priori radioactive models of hydrothermal alterations allowed us to differentiate quartz-hydromica and quartz-pyrite-sericite alteration haloes.

The MICADO Integrated Gamma Station for Radioactive Waste Packages radiological characterization

The MICADO (Measurement and Instrumentation for Cleaning And Decommissioning Operations) Project of the H2020 Research and Innovation Programme aims to propose a cost-effective solution for non-destructive characterization of nuclear waste, implementing a digitization process that could become a referenced standard facilitating and harmonizing the methodology used for the in-field Waste Management and Dismantling & Decommissioning operations. It employs instruments based on different technologies: an active and passive neutron measurement system, a photo-fission facility, and the ‘Integrated Gamma Station’. Within the MICADO Project, an entire work package has been dedicated to the design and realization of the ‘Integrated Gamma Station’ obtained by combining different gamma detection technologies supporting each other to a comprehensive and effective non-destructive gamma characterization, able to accommodate Radioactive Waste Packages of different sizes. The techniques implemented are i) dosimetry measurements, count rate inspection and raw spectroscopy with the CAEN RadHAND, ii) gamma imaging in open geometry with the CEA Nanopix gamma camera, iii) high resolution gamma spectrometry with the ENEA Tomographic Gamma Scanner (TGS). The latter able to carry out different characterization methodologies, i.e., Open Geometry, Segmented Gamma Scanning, Angular Scanning, and Tomography. This paper describes the layout of the Integrated Gamma Station conceived, its features and detection capabilities, and part of the measurement campaign realized during the MICADO Project.

Spatial trends in the distribution of natural radioisotopes in the bottom sediments of Santos Basin (Brazil)

Activities related to the marine exploration of oil and gas reservoirs tend to cause a concentration of natural radionuclides in related materials. As such, knowledge regarding the distribution of radionuclides in sedimentary basins with current oil operations is essential for modeling radiological hazards and possible risks of site contamination. This study investigated the distribution of 226Ra and 228Ra, radioisotopes from the 232U and 232Th decay chains in bottom sediment of the Santos basin. Sediment samples were collected from sites in a sampling grid based on depth contours and were analyzed through high-resolution gamma spectrometry. A distribution model of the spatial variation of these isotopes, the frst of its kind for the Basin, supported the interpretation of similar tendencies in their distribution. From studying the spatial trends of the mean levels of the isotopes with descriptive statistics and variance analysis, latitudinal and bathymetric diferences in the content of radionuclides emerged. These diferences are probably derived from the distinct sources of these elements, as 226Ra originates in the deep ocean from the decay of parent 230Th and from the patterns of sedimentation driven by open ocean circulation, while 228Ra is supplied by terrigenous materials transported by the northward-fowing Brazilian Coastal Current.

Complex Dose Rate Calculations in Luminescence Dating of Lacustrine and Palustrine Sediments from Niederweningen, Northern Switzerland

This study focusses on dose rate determination in complex settings in two drill cores from the site of Niederweningen, northern Switzerland. A crosscheck with a certified standard material and neutron activation analyses (NAA) reveals an overall good performance of high-resolution gamma spectrometry (HR-GS) when determining dose rate-relevant elements. A second focus is on average water content during burial, by comparing measured sediment moisture with water uptake capability. Furthermore, layer models are used to investigate the impact of inhomogeneous stratification on dose rate. Finally, different scenarios to correct for radioactive disequilibrium in the uranium decay chain are investigated. While most of the applied corrections appear to have only a minor to moderate effect on age calculation, the results for one core are contradictory. Possibly, some of the applied correction scenarios are not reflecting the complex natural setting sufficiently, in particular average sediment moisture during burial and the timing of radioactive disequilibrium might be incorrectly estimated. While deposition in one core can be quite securely attributed to the period 100–70 ka, assigning the sediment sequence in the other core to the time between ca. 130 ka and 90 ka remains to some extent insecure.

An assessment of committed effective dose and lifetime cancer risk due to the ingestion of infant milk

Infant milk is a manufactured food designed for feeding babies and infants under 12 months of age. This product is indicated when, for some reason, the baby can not be fed by breast milk. It is used in case of intolerance to milk from farmed animals and is widely used for the nutrition of newborns in artificial lactation, in place of breastfeeding. It can be used as a complete or partial substitute for human milk. In the current study, the committed effective dose and lifetime cancer risk due to ingestion of 4 K, 226Ra, and 228Ra were estimated using activity concentration obtained from high-resolution gamma spectrometry. Consumption data and dose coefficients were obtained from Brazilian Institute of Geography and Statistics and data published by ICRP 119. Infant milk and water samples were collected in the Rio de Janeiro trade, placed in a polystyrene container, and then sealed to reach the secular radioactive equilibrium condition (at least 45 days). The samples were analyzed by gamma spectrometry using a High Purity Germanium (HPGE). Detection efficiency for each sample was obtained with LabSOCS software. For infant milk samples, the highest values of activity concentrations were (242 ± 9) Bq.kg−1 for 4 K, (5 ± 1) Bq.kg−1 for 228Ra and presented values below the detection limit for 226Ra. The higher values obtained for water samples were (10 ± 1) Bq.l−1, (5 ± 1) Bq.l−1, (5.3 ± 0.1) Bq.l−1 for 4 K, 226Ra and 228Ra, respectively. These values of committed effective dose are below the values stipulated by UNSCEAR (290 μSv.y−1) and by the ICRP (1 mSv.y−1). The values obtained for lifetime cancer risk are considered negligible, once they are below the limit considered for taking action (10−4). It can be concluded that the values calculated do not present a significant risk regarding the intake of infant milk in the first two years of the child's life.

Assay of nuclear grade primary sodium in the fast breeder test reactor for radionuclides and corrosion elements

Periodic assay of primary sodium used as a coolant in the fast breeder test reactor (FBTR) at Kalpakkam is necessary and pre-requisite for the safe and continuous operation of the reactor. Contamination of nuclear grade purity of the primary sodium is monitored either online or offline for the radionuclides and chemical impurities to ascertain the integrity of the various components. Chemical elements which can entrain into sodium due to the corrosion of structural materials is troublesome as they might clog the coolant channels resulting in to a reduced coolant flow which further leads to fuel clad failure. The corrosion elements present in the primary sodium were determined by ICP-OES and their activation products were assayed by high resolution gamma spectrometry. In case of fuel clad rupture, the fission products such as 137Cs, 134Cs, 136Cs, 131I, 90Sr, 125Sb etc. along with actinides U and Pu are released into primary sodium. This paper reports actinides, fission products, corrosion elements as well as their activation products and concentration levels present in the primary sodium of FBTR. Activity variation of one of the long-lived fission products, viz. 137Cs over the period of time, before and after fuel clad rupture is profiled and discussed.

Anthropogenic accumulation based on chemometrics of the radionuclide K-40 in tropical soils in the northeast Brazil

The continuous use of fertilizers can increase the radionuclides levels in soils, and their accumulation and concentration are related to their characteristics and the various processes of use and soil occupation. Analyzing data from radiometric and pedological measurements often demands the use of more robust tools for better integration of results. This work presents the results of a study to evaluate the accumulation of 40K, in an area of the Zona da Mata region in Pernambuco, Northeastern Brazil, due to the contribution of natural or artificial sources. 40K activity concentration was measured by high resolution gamma spectrometry in 108 soil samples, as well the organic matter content and particle size distribution. Results showed the 40K activity ranged from 103 to 1843 Bq.Kg−1, with the arable soils showing levels above the world average value (420 Bq.Kg−1). A higher prevalence of 40K was observed on arable soils, regardless of soil type, organic matter content, depth or texture. Agricultural activities increased of 40K levels in different degrees, depending on the type of crop used, with an accumulation factor of up to 4 times greater compared to soils not impacted by agricultural activities. The radiochemometric diagnosis maded it possible to draw up a strategic management plan to improve the management practices of family farming in order to maximize production efficiency, and promote the conservation of natural resources and environmental preservation.

Investigation of self-attenuation of 210Pb (46 keV) gamma ray in sediment, certified reference material and high-density minerals: Implication to precise measurement of 210Pb

High resolution gamma spectrometry is one of the most widely used techniques in the measurements of environmental level 210Pb in sediment from coastal and freshwater environments and such measurements are needed to establish 210Pb chronology for the past 100–150 years. Precise measurement of 210Pb in sediment and soil requires appropriate self-absorption correction for its low-energy (46.5 keV) gamma radiation due to differences in the matrix between the sample and standard used to calibrate the instrument. Here we report a method that involves precise determination of 210Pb activity in sediment sample by calibrating the HPGe well detector with RGU-1-IAEA Certified Reference Material for well-defined geometries. A comparison of the 210Pb activity obtained from gamma-ray spectrometry with that obtained from alpha spectrometry via 210Po, using 209Po as yield tracer, indicates good agreement. We propose an empirical relation between the absolute efficiencies and packing densities of sample in a well-defined geometry (cylindrical counting vial) by affecting the count rate of 210Pb and its progenitor, 226Ra (via 214Pb and 214Bi). The effects of self-attenuation of 46.5 keV (210Pb), for naturally-occurring high-density minerals (apatite, titanite, monazite, and cerite) are evaluated. Specific activity of 210Pb on apatite measured by alpha and gamma spectrometry are compared. This study is relevant and useful for precise measurements of gamma-emitting environmental radionuclides such as 210Pb, 7Be, 137Cs as well as 226Ra.