Distribution Of Radionuclides Research Articles

Multivariate statistical approach on distribution of natural and anthropogenic radionuclides and associated radiation indices along the north-western coastline of Aegean Sea, Greece

A comprehensive radiological survey using multivariate statistical analysis was carried out to evaluate the distribution of 40K, 232Th, 226Ra, 235U, and 137Cs, and associated radiation indices in beach sand samples of the coastal area of the Aegean Sea. The activity concentration of selected radionuclides was measured and no clue of recent migration of radiocaesium by not only precipitation but also through an indirect way, such as ocean runoff, was found. As part of radiological risk assessment, external radiation hazard index, radium equivalent activity, effective dose, and absorbed dose rate were estimated. Pearson correlation, cluster, and PCA analysis were used by processing observed radiological parameters to determine the correlation between the radiological parameters and locations. Pearson correlation shows a strong association between all parameters and activity of 226Ra and 232Th. A spatial distribution map was provided to a distinct visual representation of the distribution of radionuclide contents in the study area.

An Experimental Apparatus for Monitoring Radon during Compression of Coal/Rock Samples and Its Preliminary Application

Based on the radionuclide distributions in sedimentary coal-bearing strata, this study analyzed the microrelease mechanisms of radon in coal-bearing strata. It was found that the microrelease process includes three stages: emanation, migration, and exhalation. Based on this, an experimental apparatus was independently designed for monitoring radon during compression of coal/rock samples from coal-bearing strata, whose major components include an electrohydraulic servocontrolled rock mechanics testing system, an airtight container, coal/rock samples, radon output device, and a continuous emanometer. The developed apparatus was preliminarily utilized for uniaxial compression tests on mudstone samples taken from the #21105 coalface of the Fourth Coal Mine in Yili Coalfield, China. The test results show that before sample failure under the uniaxial compressive load (UCL), the radon concentration is negatively correlated with the applied UCL and the magnitude of imposed elastic deformation. Increasing the applied load shortens the period of stable deformation, gradually decreasing the porosity of the rock, and as a result of declining the concentration of radon emanation from the rock. Finally, suggestions for future research are proposed, including mathematical equations to express the correlations between different experimental parameters and fractal characteristics of radon release from porous media.

Ecological impacts of Assuit fertiliser factory in Upper Egypt: environmental implications and spatial distribution of natural radionuclides

ABSTRACT In the present work, radioactivity level in 15 collected soil samples from the area around fertiliser factory in Upper Egypt has been measured using gamma ray Spectrometry due to radionuclides occurred naturally namely 226Ra, 232Th and 40K to study the concentrations of these nuclides in this soil and determine the effect of Assuit fertiliser factory exhaust on radiological contents of surrounding Soil Samples in Assuit Province, Egypt. Activity concentrations of 226Ra, 232Th and 40K for soil samples were measured by scintillation detector NaI (Tl), has recorded average values 49.45 ± 5.04, 59.113 ± 2.96 and 137.85 ± 6.89 Bq/kg, respectively. On the other hand the average value of radiological hazards affected on farmers and populations were 150.32 Bq/kg, 64.3 nG/h, 0.257, 0.544, 1.006, 0.246, 0.315 and 0.0788 mSv/y for radium equivalent activity, absorbed gamma dose, external and internal hazard indices, gamma index, indoor and outdoor effective dose, respectively. The absorbed dose, gamma index and the annual gonadal dose equivalent the radiological hazards were found higher than permissible level.

Distribution of radionuclides in modern sediments of the rivers flowing into the Dnieper-Bug Estuary

The article presents the results of large-scale studies of the content and distribution of natural and man-made radionuclides in the sediments of the rivers flowing into the Dnieper-Bug estuary. The article also presents the results of the granulometric analysis of the surveyed water bodies. The data about natural radioactive elements in the sediments rivers flowing into the Dnieper-Bug estuary obtained in this research are demonstrated moderate specific activity, which, however, clearly correlates with the granulometric composition of sediments. The 137Cs determined by us is contained in the sediments of all studied water bodies and the places of it greatest concentration coincide with the areas in which the sediment is represented mainly by the pelitic fraction. The data obtained in this research can serve as a baseline data in natural radionuclides concentration in sediments rivers flowing into the Dnieper-Bug estuary. The obtained data can also be used for further monitoring of the specific activity of man-made radionuclides, in particular 137Cs.

Natural ambient gamma radiation levels, distribution of radionuclides, and evaluation of radiological hazards around Bellary thermal power plant, India

The ambient gamma radiation around the Bellary thermal power plant was measured by Scintillometer of NaI (Tl) detector. The ambient gamma radiation level is mainly dependent upon the activity of primordial radionuclides present in soil and building materials. The activity of natural radionuclides presents in the soil and building materials of some villages around the Bellary thermal power plant is labelled by gamma-ray spectroscopy. The activity of natural radionuclides in soil such as 226Ra, 232Th and 40K varies from 24 to 86.2 Bq·kg−1, 45 to 115 Bq·kg−1 and 145 to 910 Bq·kg−1 with a mean value of 32.5, 79 and 640 Bq·kg−1, respectively. The total measured annual effective dose rate of gamma varies from 0.85 to 1.37 mSv·year−1 and the total calculated annual effective dose rate varies from 0.88 to 1.47 with a mean value of 1.18 mSv·year−1. The measured and calculated values of ambient gamma radiation are very nearer to each other and show positive correlation with a correlation coefficient of 0.44. All the measured radiological indices in soil and building materials are lower than the safe level limit except fly ash bricks, fly ash brick shows a value higher than the safe level limit. The fly ash emitted from the thermal power plant enhances the radiation level in nearby villages. The results are presented and analyzed in this paper.

Radionuclides Contamination in Soil: Effects, Sources and Spatial Distribution

Radionuclide concentrations in the soil depend on the geological and anthropogenic activities of an area. They influence level of gamma radiation in the environment, which can cause significant health risk in humans. Due to the non-uniform distribution of radionuclides in the soil, various measurement methods have been adopted to monitor our environment. The challenges involved in collecting environmental samples, duration, technicality and cost of measurement have led to various models for predicting unmeasured locations. This article presents geostatistical method using kriging techniques, which adopt the theory of regionalized variables, to characterize the spatial distribution of radionuclide in un-sampled locations using data obtained from sampled locations. Among other things, this paper presents results of application of this method to a study area. Spatial distribution of radionuclides reveal the non-uniform distribution in the study area. Though the radionuclides level in the study area are below global average set by United Nations Scientific Committee on the Effects of atomic Radiation (UNSCEAR), the spatial distribution map can be used to provide adequate information needed by regulatory authorities in identifying the contaminated area in need of remediation.

The Initiators of the Appearance of Organic Compounds on Earth, the Distribution of Natural Radionuclides in the Plant Mass

An experiment was performed on the synthesis of organic substances from a mixture of carbon monoxide and hydrogen on the surface of iron and cobalt, coated with carbide clusters, formed during processing at 573 K in an atmosphere of carbon monoxide. The obtained results indicate that the most likely direction of the formation of organic substances from mixtures of molecular hydrogen and carbon oxides is the thermal hydrogenation (radiation-thermal hydrogenation has a higher speed) at 300-573 K of carbide clusters covering the surface of metals. A significant fraction of organic matter on the Earth is formed during the solidification and cooling of the surface of a “hot” planet from 600 K to 300 K. Initiation by ionizing radiation creates the real condition for the highly endothermic processes of dissociation of water and carbon dioxide molecules, synthesis of new organic molecules and molecular oxygen. On a completely cooling up to 300 K planet this process continued by the vital activity of living organisms and during photosynthesis. The energy of quanta of visible light is much less than the energy of C=O bonds in the CO₂ molecule and the dissociation energy of the H-O bond in the H₂O molecules. The value of the energy of gamma quanta emitted by the K40 isotope is many times higher than the value of the dissociation energy of the H-O and C=O bonds. The analysis of numerous samples of water, soil, vegetation, livestock products showed the presence of K⁴⁰ radioisotopes in all samples. The role of gamma radiation of K⁴⁰ radioisotope should be taken into account at comprehensive analysis of initial stage of photosynthesis. This conclusion is consistent with the revealed facts of increased plant yields on soils with relatively high concentrations of natural radioisotopes, observation of photosynthesis under thick layers of water in the presence of only long-wave infrared rays or in the absence of chlorophyll and oxygen.

Spatial distribution of natural and technogenic radionuclides in arctic soils of the Moller gulf, Novaya Zemlya archipelago

Spatial distribution of natural and technogenic radionuclides in arctic soils of the Moller gulf, Novaya Zemlya archipelago

Ecogenetic monitoring of ionizing radiation for radon-hazardous territories

This work is devoted to studying the alpha activity distribution of natural radionuclides in boarding schools located near zones of tectonic faults. There are many tectonic faults in the Almaty and this is the basis for referring the southern capital of Kazakhstan to the radon-hazardous territories. As a result of radiometric measurements a 2D-topology of the alpha-radiation flux density distribution from the distance to the tectonic fault was found. Based on the measurements results the coefficient of radon concentration from the distance to the tectonic rupture was found. Using the obtained pattern, it is possible to plot the dependence of volumetric alpha activity for other schools, if their distances from the tectonic fault are known. In addition, interest in biomedical and ecogenetic effects of radon and its decay products has grown considerably in the last few years. These effects have been investigated in biotests on Drosophila’s two systems. It was found that alpha-particles, with the help of which the situation in radon-hazardous territories was simulated, possess mutagenic influence manifested mainly in formation of morphoses or deformities.

AN ASSESSMENT OF THE SPATIAL VARIATION OF ISOTOPIC RATIOS IN A CANDU REACTOR FOR NUCLEAR TREATY MONITORING

A 3-D Quarter-Core CANDU-6 is modeled using Serpent 2 for nuclear treaty monitoring. The spatial variation of flux spectra and isotopic concentrations is analyzed to determine the potential isotopic distribution of key radionuclides from standard reactor operations relevant to non-proliferation. The initial results of the model show a 46% difference in overall flux magnitude throughout the core as well as a 2-30% difference in discrete energy flux. The coupled production rate (magnitude) and spectral differences can contribute to significant spatial variations in isotope ratios throughout the core. Initial results indicate 239Pu/240Pu ratios vary by as much as 51% across a single CANDU-6 fuel bundle at final burnup. The model is currently being used to develop an accurate representation of spent fuel to perform spatial isotopic analysis across the entire CANDU-6 core.

ТЕХНОГЕННОЕ ВОЗДЕЙСТВИЕ РАДИОАКТИВНОГО ЗАГРЯЗНЕНИЯ ПРОДУКТОВ ПЛАВКИ МЕТАЛЛА НА ОКРУЖАЮЩУЮ СРЕДУ И НАСЕЛЕНИЕ

The analysis of the distribution of radionuclides in the products of blast furnace and steelmaking melting operation processes is carried out. It was shown that the blast furnace melting process is considerably affected by natural radionuclides whereas steelmaking furnace process - by technogenic ones. The main impact on the environment is exerted by the gas-dust fraction, which contaminates the surrounding soil, vegetation and ground water during the settling process. An additional dose of external irradiation of the population and personnel is created by slag and metal fractions. High radiation doses are possible in case of ingestion of high-intensity sources of 60Co and 137Cs into the melt. Internal irradiation of people occurs due to gas and dust emissions.

Propagation Analysis of Pu Radionuclides as a Result of Fire Incidents in the Exclusion Zone of the Chernobyl NPP in April 2020

In consequence of nuclear accidents that have occurred in various parts of the world, radioactive contamination of the environment is observed. The risks of spreading pollution can increase during floods, fires and some natural disasters. The lack of effective measures that aimed at eliminating possible sources of fire in the meadow zone and forest lands in the Chernobyl exclusion zone (ChEZ) leads to a high risk of fire emergence. The temporal and spatial distribution of fires shows that they occur throughout the ChEZ, including in the most contaminated areas. The risk of fires increases with climate change and measures to prevent them should be considered in emergency programs. ChEZ area is contaminated with long-lived radionuclides such as 137Cs, 90Sr, Pu isotopes (238Pu, 239 + 240Pu, 241Pu) and 241Am. As a result of forest fires radionuclides contained in wood and underlying surface are carried out into the atmosphere along with smoke. Diseases arising under the influence of ionizing radiation from Pu and 241Am isotopes pose a serious problem for human health. To assess of the spatial distribution of Pu isotopes and 241Am we used data on forest fires that occurred in the Chernobyl zone in April 2020. To evaluatе the dynamics of the release of radioactive substances into the atmosphere during fire incidents on the ChEZ territory, the following software products were used: NASA WorldView, HYSPLIT program. The HYSPLIT program allows to reconstruct the trajectories of radionuclide propagation in the atmosphere using meteorological data and to obtain a reliable picture of the distribution of radionuclides in the study area. The maps of the volumetric activity of Pu isotopes in the air and the fallout on the soil as a result of fires were obtained. It was found that the radioactivity due to the presence of this element in the air and during the fallout of radioactive particles on the soil is low (it reaches 1.0E-7...0.1 Bq/m3 in the air, 1.0E-6...1 Bq/m2 on the soil). The analysis of the propagation of Pu isotopes as a result of the movement of air masses in the places of fires in the exclusion zone of the Chernobyl nuclear power plant and the associated dangers for the population and the environment has been carried out.

Assessment of the radiation situation and distribution of radionuclides in the air of the uranium protoxide-oxide calcination shop

The exposure dose rates, the equivalent equilibrium volume activity of radon, and the activity of long-lived alpha-nuclides in the air of the uranium protoxide-oxide calcination shop were determined. Annual effective doses for workers were calculated. Through the use of nuclear-based polietilentereftalata and chemical filters, the disperse composition of particles in the air was studied. The effectiveness of filters in sampling was evaluated for the uranium content. The kinetics of distribution of uranium in various fractions was studied. The quality coefficients of filters that accumulate uranium relative to its norm in various working places of the shop were estimated.

ARTIFICIAL RADIONUCLIDES IN THE FOREST LITTER AT THE TERRITORY ADJACENT TO SEMIPALATINSK TEST SITE

The paper provides results of research of concentration and distribution of artificial radionuclides in the components of forest litter and in the top soil layer of the pine forest of Priirtyshie long after nuclear tests at the territory of Semipalatinsk Test Site (the STS). Minimum and maximum values of specific activity were determined for 137Cs, 90Sr, 241Am, 239+240Pu in the soils researched as well as in mineral and organic components of litter. Series of radionuclides were formed depending on their ability to be accumulated in the top layer of soil and in the components of forest litter. Dependence between concentrations of 137Cs, 90Sr, 241Am, 239+240Pu in the litter and its thickness was determined.

Quantification of radionuclide distribution and migration during Cu-(Fe)-sulphide mineral processing by alpha particle autoradiography

Understanding the movement of radionuclides (RNs) between different mineral hosts during processing of base metal ores is critical for accurate modelling of RN deportment and optimisation of processes designed to reduce or eliminate RNs. Here, we demonstrate that spatially resolving quantitative alpha particle autoradiography combined with backscatter electron imaging and energy dispersive X-ray spectroscopy (EDS) can establish the correlation between alpha-emitting RNs (notably 226Ra and 210Po, daughters of the abundant 238U decay series) and certain minerals, in different stages of processing. This is achieved by locating the RNs to a specific mineral grain, the species of which can subsequently be identified using EDS. The mineralogy of RN-associated grains can then be compared with the mineral suite and relative abundances of the species within the sample, by relating how often each mineral is associated with alpha decay-events. In the processing of uranium-bearing copper ores, migration of alpha-emitting RN daughters of the 238U series were observed, and these RNs were demonstrated to correlate strongly with barite, bornite and covellite over other coexisting minerals.

Evaluation of uncertainties in environmental impact assessment of naturally occurring radiation exposure situations on example of undisturbed and legacy NORM sites in the Fen Complex, Norway.

The risk from naturally occurring radioactive materials (NORM) has been extensively assessed, and this has led to the integration of specific NORM radiation protection requirements within the latest EU Directive 2013/59. Nevertheless, it has been internationally recognised that remaining NORM knowledge gaps and uncertainties now present similarly significant issues in addressing recent regulatory requirements. The multi-tiered nature of environmental impact assessment (EIA) implies per se possibility for uncertainties, but when EIA at radiation exposure sites includes consideration of sites with multiple radiation and contamination sources, different ecosystem transport pathways, effects and risks by applying different parameters and models, level of overall uncertainty increases. The results of EIA study in the Fen area in Norway, comprised of undisturbed and legacy NORM sites, have been evaluated in this analysis, in order to identify all existing input uncertainties and how they may impact the final conclusions, and thus, influence any subsequent decision-making. The main uncertainties have been identified in the measurement and exposure analysis tier, and were related to the heterogeneous distribution of radionuclides, radionuclide speciation, as well as to generic variability issues in the concepts used for mobility and biota uptake analysis (such as distribution coefficient, transfer factors and concentration ratios) as well as radioecological modelling. The uncertainties in the input values to the calculation of the dose arising from radon exposure in the Fen area led to an overall elevated uncertainty of the magnitude of the radiation exposure dose of humans. It has been concluded that an integrated, ecosystem-based approach with consideration of complexity of prevailing environmental conditions and interconnections must be applied to fully understand possible radiation effects and risks.

The analysis of natural radionuclides activity in the soil and vegetation cover in the South of the Tyumen Region

The paper deals with the study of the radiation state of the soil and herbaceous vegetation represented by perennial grasses (Poa pratensis, Calamagrostis epigejos, Rubus saxatilis, Carex acuta, Phleum pratense) in the south of the Tyumen Region. The content and distribution of natural radionuclides in soil and herbaceous vegetation was studied in the Nizhnetavdinsky District of the Tyumen Region at the site of an underground nuclear explosion. Sampling and laboratory tests were carried out according to generally accepted methods. Soil samples were taken at the epicenter of the explosion and at the cardinal directions. Layer-by-layer sampling allowed us to study the vertical distribution of radionuclides in the soil profile. Sampling of perennial grasses was carried out at the same sampling points. Radiation studies of soil and vegetation samples were carried out on the Progress-2000 spectrometric complex. The authors have revealed specific activity of natural radionuclides (K-40, Th-232 and Ra-226) in the profile of grey forest soil in the Nizhnetavdinsky District. They have calculated effective specific activity of radionuclides in the soil. The comparative analysis of the obtained results with the data on administrative areas in the south of the Tyumen Region showed that in the soil of the Nizhnetavdinsky District specific activity of natural radionuclides is higher than in the South region in general. The specific activity of natural radionuclides in perennial grasses of the Nizhnetavdinsky District was determined, and the coefficient of accumulation of radionuclides was calculated.

A proposal to design a new high volume standard air filter for efficiency calibration of HPGe detector

A prototype of a standard high volume air filter was proposed and constructed by a novel method, which provides a symmetric distribution of radionuclides for accurate measurements of radioactivity in air samples. Then air samples were collected at an air flow rate of 300 m3 h−1 to 900 m3 h−1 samplers for 24 h per sample. The average concentrations of 7Be and 210Pb were measured as 3.80 ± 0.46 mBq m−3 and 0.92 ± 0.33 mBq m−3, respectively. The data can be used as a basis for related measurements in the atmospheric pollution research in Iran.

Time of flight dual photon emission computed tomography

Time-of-flight dual photon emission computed tomography (TOF-DuPECT) is an imaging system that can obtain radionuclide distributions using time information recorded from two cascade-decay photons. The potential decay locations in the image space, a hyperbolic response curve, can be determined via time-difference-of-arrival (TDOA) estimations from two instantaneous coincidence photons. In this feasibility study, Monte Carlo simulations were performed to generate list-mode coincidence data. A full-ring positron emission tomography-like detection system geometry was built in the simulation environment. A contrast phantom and a Jaszczak-like phantom filled with Selenium-75 (Se-75) were used to evaluate the image quality. A TOF-DuPECT system with varying coincidence time resolution (CTR) was then evaluated. We used the stochastic origin ensemble (SOE) algorithm to reconstruct images from the recorded list-mode data. The results indicate that the SOE method can be successfully employed for the TOF-DuPECT system and can achieve acceptable image quality when the CTR is less than 100 ps. Therefore, the TOF-DuPECT imaging system is feasible. With the improvement of the detector with time, future implementations and applications of TOF-DuPECT are promising. Further quantitative imaging techniques such as attenuation and scatter corrections for the TOF-DuPECT system will be developed in future.

Impact of the phantom geometry on the evaluation of the minimum detectable activity following a radionuclide intake: From physical to numerical phantoms

The establishment of an in vivo internal monitoring programme requires the use of phantoms to represent an activity distribution of an incorporated radionuclide within the body. The aim of this study was to quantify the impact of the phantom geometry on the minimum detectable activity (MDA) of an incorporated radionuclide. The MDA was assessed for two instruments: a conventional radiation protection instrument and a portable gamma spectrometer. Four phantoms were considered: two physical phantoms, a simplified torso phantom and a commercial whole body phantom, as well as two numerical phantoms, the reference adult male and female voxel phantoms published by the International Commission on Radiological Protection (ICRP). The phantoms were loaded with activity at the level of the thorax and abdomen using reference sources of 57Co, 133Ba, 137Cs, 60Co and 152Eu. The MDA for both instruments was experimentally assessed using the two physical phantoms. The experimental setup was modelled in GEANT4 and the simulated instrument responses were validated by the experimental data. The Monte Carlo model was then used to compute the instruments response and corresponding MDA when using the ICRP voxel phantoms. The simplified torso phantom provided one of the highest MDA estimates, up to a factor of 5 higher than the ones obtained with the voxel phantoms when considering a 57Co source. Depending on the considered source distribution within the phantoms, physical phantoms may lead to an underestimation of the MDA when compared to more complex and anatomically accurate numerical phantoms. This work presents a quantitative comparison between the MDA obtained with different phantoms and radionuclide distributions.