Concentrations Of 238U Research Articles

Mobility, activity ratio significance and risk assessment of radionuclides in sandstone of Magharet El Miah, Southwestern Sinai, Egypt

Sedimentary rocks of Magharet El Miah were radiometrically analyzed for determination of radionuclides 238U, 232Th, 226Ra and 40K activity concentrations. The U-content and Th/U ratio in these rocks illustrated poor weathering and rapid deposition of rock detritus. Preferential dissolution of 234U due to α-decay related processes and its re-adsorption and precipitation are responsible for the observed radioactive disequilibrium in 234U/238U of Magharet El Miah sandstone. 234U mobilization could be related to the effect of surficial or underground water. 226Ra/238U disequilibrium could be revised to the difference in the geochemical characteristics of the two isotopes. 230Th/238U activity ratios were lower than unity in all samples (10 samples) except sample number 1, suggesting selective uranium accumulation in most samples or 230Th leaching by acidified water where the rocks contain high sulpher contents. Many of the 238U/235U activity ratios were shifted from the natural ratio due to the changes in redox conditions that leads to fractionation of higher isotope from lighter one. The plotted value of 234U/238U and 230Th/238U illustrated that the U-accumulation occurred in the period from <6 × 104–105 years. The studied sandstone had higher values for uranium (95.4 ± 7.1 to 130.3 ± 12.3 Bq.kg−1), thorium (65.8 ± 4.2 and 78.4 ± 6.7 Bq.kg−1) and radium (68.2 ± 4.4 and 80.3 ± 9.1 Bq.kg−1) but lower for potassium (38.4 ± 1.2 and 54.2 ± 2.3 Bq.kg−1) in comparison with international permissible levels. All the estimated environmental hazard indices illustrated that most samples lied in the permissible level ranges. Cluster analyses indicated that the main environmental health hazard parameters exist due to the activity concentrations of 238U and 226Ra.

A review on radionuclide pollution in global soils with environmental and health hazards evaluation.

Human populations are being exposed to a wide spectrum of radiation from soils as a result of the availability of radiation sources. Assessing the ecological and health effects of radionuclides in soils is crucial to support the optimal soil management practices but large-scale studies are limited. This study compiled data on radionuclides (226Ra, 232Th, 40K, 238U, and 137Cs) in soils located across the world (44 countries and 159 places) between 2008 and 2022 and applied radiological hazards indices and several multivariate statistical approaches. The average activity concentration (Bq/kg) of 226Ra, 232Th, 40K, 238U, and 137Cs were 408.56, 144.80, 508.78, 532.78, and 83.12, respectively, whereas 226Ra, 232Th, 40K, and 238U exceeded the standard limits. The principal component analysis explained more than 91% of variation in soils. Based on the geoaccumulation index, 40K posed moderately to heavy contamination whereas 238U and 226Ra posed moderate contamination in soils. Moreover, the mean values of radiological hazards evaluation such as radium equivalent activity (487.17Bq/kg), external radiation hazard indices (1.32), internal hazard indices (2.15), absorbed dose rate (247.86 nGyh-1), annual effective dose rate (1.82 mSvy-1), activity utilization index (4.54) and excess lifetime cancer risk (63.84 × 10-4) were higher than recommended limit suggesting significant radiological risks in study region soils. The findings indicated that the study area soils were contaminated by radionuclides and unsafe for hazards in terms of the health risks linked with studied radioactive contents. The study is valuable for mapping radioactivity across the globe to determine the level of radioactivity hazards.

Natural radionuclides in thermal mineral springs in Edipsos Greece.

Natural thermal and mineral therapeutic springs exist all over Greece. A radiological survey has been carried out in the municipality of Edipsos to study the naturally occurring alpha emitter radionuclides, 226Ra and the uranium isotopes. Thirteen thermal spring water samples and six tap water samples which were collected from five locations in the municipality of Edipsos, were analysed and measured by a-spectrometry. The obtained results show that 238U activity varies between 2.8±0.3 and 65.0±5.3 mBq/L in hot springs and between 2.70±0.35 and 10.6±0.9 mBq/L in tap water samples. The 234U/238U activity ratio lying between 1.12±0.17 and 2.12±0.30 indicates enrichment in the 234U concentration that can be explained through its ability to be easily leached from mineral surfaces. The 226Ra activity concentration varies between 3.5±0.4 and 1470±127 mBq/L in hot springs and between 6.5±0.9 and 28.2±2.8 mBq/L in tap water samples. Based on these results the estimated doses in this study are below the recommended dose of 1mSv/y. Highlights A radiological survey was carried out in the thermal springs of Edipsos, one of the most popular spa towns in Greece. Determination of uranium isotopes and 226Ra via a-spectrometry was performed. Low uranium content was a common characteristic for all the samples.

Dolphin-shaped island: Exploring the natural resources and radiological hazards of Wadi El Gemal Island

The objective of this study is to assess the natural resources and radiological risks of Wadi El Gemal Island by examining its topography, mineralogy, geochemistry, and radioactive distributions. This island, which is situated at the outlet of Wadi El Gemal in Egypt's southeastern Desert, has a unique shape resembling a dolphin based on Landsat imagery. It's a part of the Wadi El Gemal-Hamata Protectorate and is notable for its diverse environmental, geological, economic, and archeological features, including recent reefs, sandy deposits, Quaternary carbonate sediments, and mangroves. The main natural resources on the island are fauna, mangrove forests, and flora. Samples collected from the island were analyzed using a NaI detector to measure the concentrations of radionuclides such as 238U, 232Th, 226Ra, and 40K, which were found to be within acceptable levels according to UNSCAR guidelines. The radionuclide 238U, 232Th, 226Ra, and 40K activity concentrations of the collected samples were 32.55 ± 9, 12.63 ± 4, 12.49 ± 4, and 325 ± 34 Bq/kg, respectively. Regarding radiological hazard indices, the values of absorbed gamma dose rate (36.06 ± 5.42 nGy/h), radium equivalent activity (73.88 ± 14.4 Bq/kg), annual effective dose indoor (0.18 ± 0.03 mSv/y) and outdoor (0.04 ± 0.01 mSv/y), internal (0.29 ± 0.05) and external (0.2 ± 0.03) indices, and excess lifetime cancer index (0.15 ± 0.05 × 10−3).This is suggest that there is no significant risk associated with these sediments.

Investigation on the radioactivity levels of seawater, sediments, and biota in Daya Bay, China

ObjectiveTo investigate the radioactivity levels of seawater, sediments, and biota in the Daya Bay sea area, China, in order to establish the radioactivity baseline values, and provide basic data for the assessment of potential radiological risks that might result from the application of nuclear technology or human activities. MethodsSamples of seawater, sediments, and biota were collected from the Daya Bay sea area and analyzed. Their radioactivity baseline data were then compared with information from other regions in China and around the world reported in related literature. ResultsFor the seawater samples, the activity concentrations of natural radionuclide 40K were 9.9–10.4 Bq/L, while 238U, 226Ra, 210Pb, 137Cs, and 110Agm were below the minimum detectable activity (MDA). Regarding the sediment samples, the activity concentrations of 238U, 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 38.1–40.4, 49.1−53.7, 32.6−38.6, 59−95, 590−650, and 0.48–0.88 Bq/(kg dry weight), respectively, while 110Agm was below the MDA. For the marine shrimps in the biota samples, the activity concentrations of 228Ra, 226Ra, 40K, and 137Cs were 1.14–2.75, 0.17−0.43, 63–76, and 0.038–0.045 Bq/(kg wet weight), respectively, while 238U, 210Pb, and 110Agm were all below the MDA. Furthermore, for the marine fishes in the biota samples, the activity concentrations of 228Ra, 226Ra, 210Pb, 40K, and 137Cs were 2.1–19.7, 0.32–3.78, <2.2–2.8, 59–70, and <0.007–0.026 Bq/(kg wet weight), respectively, while 238U and 110Agm were all below the MDA. 228Ra was found to be concentrated in Osteomugil ophuyseni with 19.7 Bq/(kg wet weight). ConclusionsThe radioactivity levels of seawater and marine sediments in the Daya Bay sea area are within the range of the normal background values. Osteomugil ophuyseni exhibited higher concentrations of 228Ra than other species in this study, while the other species in the biota show no significant difference in the radioactivity levels from data in relevant literature.

Characterization of seasonal behaviors of naturally occurring radioactive materials in a groundwater borehole using an in situ monitoring system

Understanding the temporal behaviors of naturally occurring radioactive materials is important for safeguarding groundwater as a secure water resource for drinking, agriculture, and industry usage. This study reports the vertical profiles of 238U concentration and 222Rn activity and the management of in situ monitoring systems during intensive field sampling of a national groundwater-monitoring borehole for seven years (2015–2021). The aim was to capture the seasonal characteristics of the 238U concentrations and 222Rn activity. Both factors were low in the rainy season and high in the winter season, reflecting the dilution effect of rainfall recharge. The 238U and 222Rn behaviors were associated with water–rock interactions of calcite dissolution in fracture zones filled with carbonate minerals. Furthermore, multilayer perceptron models estimated the 238U concentration and 222Rn activity with reasonable regression and classification accuracy. Hydrometeorological indicators (temperature and groundwater-level fluctuations) were more important estimators of 238U concentration and 222Rn activity than geochemical process indicators. The regression accuracy performance was higher at deeper sampling depths, where seasonality in the 238U and 222Rn behaviors dominated. From the predicted distributions of 238U concentrations and 222Rn activities, we could estimate the ranges of 238U concentrations and 222Rn activities emerging from groundwater boreholes. High exposure threats from 238U and 222Rn during groundwater usage were found in the winter season. When the multilayer perceptron models use the entire in situ monitoring data at refined temporal resolution, we can quickly determine the naturally occurring radioactive materials and further develop the national groundwater-monitoring borehole equipped with the in-situ monitoring system, supplementing the occasionally obtained field-measurement data.

Assessing environmental and radiological impacts and lithological mapping of beryl-bearing rocks in Egypt using high-resolution sentinel-2 remote sensing images

Emerald and other beryls represent a family of the most valuable gemstone around the world and particularly in Egypt. Beryllium (Be) contents in beryl-bearing bedrocks in south Sinai (Wadi Ghazala and Wadi Sedri), and in central and south Eastern Desert of Egypt (Igla area, Zabara-Um Addebaa belt, Homret Akarem, and Homret Mukpid) were investigated in this study. The environmental risk levels of Be, associated major ions, and heavy metals in groundwater nearby to beryl-bearing mineralization were also evaluated. Results showed that Be contents ranged from 1 to 374 ppm in beryl-bearing bedrocks, while in nearby groundwater, Be content has a range of 0.0001–0.00044 mg/L with an average of 0.00032 mg/L, which is within the permissible levels and below (0.004) the U.S. EPA maximum contaminant level (MCL). Most levels of heavy metals (e.g., Be, B, Ni, V, Fe, and Al) in the investigated groundwater of central and south Eastern Desert and south Sinai are within the permissible levels and below their corresponding U.S. EPA MCLs. This study also investigated the radiological risk of natural radionuclides distributed in beryl-bearing bedrocks in the study area using gamma spectrometry; Sodium Iodide [NaI(Tl)] scintillation detector. Among the estimated mean 238U, 232Th, and 226Ra activity concentrations of the studied beryl-bearing rocks, Homret Mukpid (79, 87.15, 60.26 Bq kg−1) and Homret Akarem (111.6, 51.17, 85.1 Bq kg−1) contain the highest values. This may be attributed to their highly fractionated granitic rocks that host uranium and thorium reservoir minerals such as zircon, allanite, and monazite. The estimated data of multi-radiological parameters such as absorbed gamma dose, outdoor and indoor annual effective dose, radium equivalent activity, internal and external indices, index of excess cancer, and effective dose to human organs reflecting no significant impacts from the emitted natural gamma radiation.

Hydrogeological conditions and hydrogeochemistry of the Kamenskoye hydro-radon occurrence, Novosibirsk, Russia

Hydrogeological and hydrogeochemical conditions, the concentrations of major and some minor ions and 222Rn were determined in the Kamenskoye hydro-radon occurrence in the Southern part of West Siberia. Two different aquifer systems were revealed in the hydrogeological section: the Quaternary sediments with pore waters and the Upper Paleozoic granites including the waters of regional fracturing zone and fracture-vein waters. They are located in a common mixing area and are affected by flooding and anthropogenic pollution. Mineral radon fracture-vein waters in granites, not affected by anthropogenic impact, have been revealed in two boreholes. These waters are cool, fresh (TDS 613.4 to 689.9 mg/L) and Si4+ content within a range from 10.3 to 13.6 mg/L. The pH of these waters is neutral to weakly alkaline (6.9–7.8), the gases dissolved in the waters are oxygen and nitrogen. The determined activity of 222Rn varies within the range from 1101 to 1570 Bq/L; 238U concentration varies between 5.6·10−3–6.5·10−3 mg/L, while 226Ra ranges from 2.7·10−9 to 1.8·10−8 mg/L. The relative fractions of cations (Mg2+, Ca2+, Na+, Sr2+, Ba2+) decrease with an increase in TDS value due to the formation of poorly soluble carbonate and sulphate compounds. The forms of Fe(II) are represented by Fe2+, FeHCO3+, FeCO30, and Fe(III) migrates in the forms of hydroxo complexes Fe(OH)2+ and neutral species Fe(OH)30. Manganese migrates mainly as a cation, while other forms (MnHCO3+, MnCO30) are less abundant, and MnSO40, MnCl+, MnOH+ are minor. The chemical forms of nickel and copper migration are free cations, as well as hydrocarbonate and carbonate complexes. Copper, as well as beryllium, also migrate as hydroxo complexes. The forms in which chemical elements migrate and their migration coefficients provide evidence that the equilibrium minerals become more complicated when passing from surface waters (greenalite, siderite, and ferrihydrite and greenalite) to the fracture-vein waters in the Upper Paleozoic granites saturated with dolomite, calcite, talc, magnesite and rhodochrosite.

A grain-by-grain comparison of apatite fission-track analysis by LA-ICP-MS and the External Detector Method

Laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is increasingly used in fission-track analysis to determine the uranium content of host mineral specimens, particularly apatite. Fission-track dating by LA-ICP-MS (LAFT) has several advantages over the conventional External Detector Method (EDM), particularly in terms of sample turn-around times and the fact that neutron irradiations and the handling of radioactive materials are no longer necessary, while providing a similar level of in-situ information about parent nuclide (238U) concentrations. In addition, it facilitates the simultaneous measurement of multiple isotopes for double or triple-dating approaches or compositional characterisation. While it is often implicitly assumed that the EDM and LAFT fission-track dating approaches produce equivalent results, this assertion has yet to be adequately tested. We present an extensive dataset of apatite fission track results from 17 samples representing a large range of fission-track ages (∼0–2 Ga), 238U concentrations (0.14–410 ppm) and thermal histories that were analysed grain-by-grain using both techniques in order to investigate whether they yield concordant results during routine fission-track analysis.Apart from a few outliers, our data show that 238U concentrations measured by the EDM and LAFT techniques yield indistinguishable results across at least three orders of magnitude when a similar calibration system against rapidly cooled standards (e.g., Durango) is used. Comparison of single grain pooled and central ages reveals that LAFT ages are within error of EDM ages for apatite fission track standards such as Fish Canyon Tuff or Durango, as well as for a range of other samples whose shorter mean confined track lengths (<13 μm) and broader track distributions indicate they experienced more complex cooling histories. The most important conclusion here is that both the conventional EDM and LAFT methods can be expected to yield identical results for the breadth of ages, 238U concentrations, and underlying thermal histories commonly found in real world apatites.Importantly, the aggregate empirical calibrations for EDM and LAFT mask an underlying assumption that the mean etchable range of fission fragments is a constant having the mean value observed for spontaneous tracks in age standards such as the Durango apatite. Given that this assumption is known to be false in the great majority of samples, it is our view that empirically derived EDM and LAFT fission-track ages are best considered as model ages and that there should be greater clarity about the assumptions involved in their calculation.

Distribution of natural radionuclides in NORM samples from North Abu Rusheid area, Egypt

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. 238U and 232Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and 40K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of 238U, 232Th and 40K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of 238U, 232Th and 40K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials.

Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29–60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95–69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24–58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2–1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Estimation of Annual Gonadal Dose Equivalent in Some Livestock Food in Libyan Markets

In the present study, the concentrations of 226Ra, 232Th, 238U, and 40K in 10 different samples of foodstuff are investigated using a gamma spectrometer with a Sodium iodide detector NaI(TI). The results indicated that the concentration of 226Ra, 232Th, 238U, and 40K in the samples ranged from (19.14 to 99.79) Bq/kg for radium, the activity concentration of Thorium ranged from (31.09 to 124.93) Bq/kg, the activity concentration of uranium ranged from (24.86 to 103.01) Bq/kg and the activity concentration of potassium ranged from (101.83 to 480.92) Bq/Kg. The results indicated that the annual gonadal dose equivalent (AGDE) of 226Ra, 232Th, and 40K in the samples were higher than the permissible level (0.3mSv/y), except samples (S3, S5, S8).

Uranium tailings in the Istiqlol city: history, problems, solutions

The article provides an overview of the problems associated with the uranium tailings in Istiqlol city. Many uranium heritage sites in Central Asia, including the uranium tailings in Istiqlol, hadn’t been mothballed before the collapse of the USSR. The burial complex consists of a quarry, dumps of the “Poor Ores Factory”, an unpreserved open mine, destroyed industrial buildings and four tailings which contain 12 million tons of the uranium production waste. In the area of the tailings, the ambient dose rate of gamma radiation is 0.5–0.6 μSv/h, and at some points it reaches 3.0–4.0 μSv/h. The average annual radon emission from the surface is estimated at 3.9×1011 Bq/year. The contaminated areas also include the Sarym-Sakhly Sai stream, mine, industrial and quarry waters, which are characterized by an increased content of 234U, 238U and 226Ra. The facilities aren’t physically fenced, allowing free access for the public and livestock. Natural disasters such as mudflows, landslides, and earthquakes can lead to an ecological disaster. Attention is paid to the ways of solving problems such as monitoring radionuclides in water, soil, and air; working with the local population to inform and involve them in rehabilitation work; donors search. The Program for the Implementation of the National Concept for the Rehabilitation of Tailings of Uranium Ore Processing Wastes for 2016–2024 was developed and approved by the Government of the Republic of Tajikistan to minimize the radiation impact on the population and the environment. Implementation of the Program requires significant financial investments and trained personals in the field of radiation safety. Only through the joint efforts of the state, population and international organizations is it possible to fully carry out rehabilitation works. Only by joint the state, public, and international organizations efforts, it is possible to solve these problems. Also, one of the main reasons why the population had received unnecessary overexposure was its ignorance of the danger of using water, soil and building materials contaminated with radionuclides. Therefore, the culture of radiation safety should be studied starting from middle school, where students will be taught about ionizing radiation and possible ways of exposure. Then, both cases of intake of radionuclides into the body, which could have been avoided, and radiophobia among the population living near the extraction and processing of uranium ore, will be much lower. Some social and economic aspects are also touched upon.

Physicochemical and radiological characterization of flue gas desulfuration waste samples from Brazilian coal-fired power plants

Flue gas desulfurization (FGD) waste is an industrial by-product generated during the flue gas desulfurization process in coal-fired power plants. This by-product contain trace quantities of naturally occurring radionuclides and elements such as As, Ba, Co, Cr, Zn. The characteristics of FGD waste are important for its reuse and are mainly depend on the desulfurization process. In this work, two types of FGD materials collected from three coal-fired power plants using semi-dry and wet processes were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), X-ray fluorescence (XFR) and particle size analysis. The radioactive content of 238U, 232Th, 228Th, 226Ra, 228Ra, 210Pb and 40K and trace elements were also determined using Neutron activation analysis and Gamma-ray spectrometry. The major constituents for all samples were Ca, Si, S, Al and Fe. Wet FGD by-product presented also high magnesium content. The wastes contain mainly semi-hydrate calcium sulfite and calcium sulfate. The particle size of FGD from semi-dry process was lower than that from the wet process. The average activity concentration of 238U, 232Th, 226Ra, 210Pb, 228Ra, 228Th and 40K varied between were 50-71, 33-42, 28-52, 113-150, 26-33, 33-39, 161-390 Bq kg-1, respectively. According to the results of leaching and solubilization tests, FGD samples were classified as non-hazardous and non-inert. The obtained data are useful for evaluation of possible applications of FGD by-products.

Influence of phosphate fertilizers on the radioactivity of agricultural soils and tobacco plants in Kenya, Tanzania, and Uganda

Three brands of NPK fertilizers that contain variable concentrations of natural radioactivity are commonly used in tobacco plantations in Kenya, Tanzania, and Uganda. Tobacco plants are known for hyper-accumulation of natural radionuclides, particularly 238U. This study investigated if the elevated radioactivity in phosphate fertilizers could enhance radioactivity in soils and tobacco plant leaves. The 232Th, 238U, and 40K radionuclide levels in NPK-fertilized soils and tobacco leaves were measured using gamma-ray spectroscopy. The research included a one-year reference experiment with tobacco growing in plots, a ten-year semi-controlled experiment in well-managed tobacco farms, and a field survey of radioactivity in soils and tobacco leaves at three traditional tobacco fields in Migori (Kenya), Urambo (Tanzania), and Kanungu (Uganda). The findings demonstrated that soils and tobacco leaves exposed to NPK fertilizers with increased radioactivity had activity concentrations of 232Th, 238U, and 40K that were considerably higher (at all sites) than in the control samples (with no use of NPK fertilizers). As the continued application of NPK fertilizers raises concentrations of 232Th, 238U, and 40K in agricultural soils, the study assessed radiological risks for humans from exposure to agricultural soils enriched with phosphate fertilizers, and it was found to be below the exposure limit of 1 mSvy-1 suggested by the International Commission on Radiological Protection (ICRP). However, tobacco consumers, both by snuffing and smoking, may face significant radiological risks, as the snuffing and smoking resulted in effective doses that were 2.41 to 6.53 and 1.14 to 2.45 times greater than the average yearly dose that the general public receives from inhalation of natural radionuclides (United Nations Scientific Committee on Atomic Radiations estimates). Furthermore, the results indicate that the lifetime excess cancer risk for tobacco snuffers and smokers ranged from 5 × 10-5 to 24.48 × 10-3 and 2.0 × 10-5 to 9.18 × 10-3, respectively. The influence of phosphorus-derived fertilizer containing relatively high natural radioactivity, potential human radiation exposure, and radiological risk due to gamma radionuclides is estimated and discussed. The results reveal that applying phosphate fertilizers enhances natural radioactivity in soil and is subsequently influenced by soil to tobacco plant uptake. Therefore, the study recommends that countries use fertilizers with lower radionuclide content to conserve soil quality and reduce gamma-emitting radionuclides in tobacco plants.

Activity concentration of natural radionuclides and transfer factors from soil to vegetable in parts of South South Nigeria

Naturally occurring radionuclide materials are known to exist in soils and is transferred into vegetables and eventually gets into food chain. This work was aimed at determining the activity concentration of these radionuclides in soils and vegetable (fluted pumpkin) and the internal exposure due to the consumption of these materials in the vegetable in parts of South South Nigeria particularly Etim Ekpo Local Government area. The activity concentrations of twenty (20) soil samples and 20 vegetable samples from the farmlands were determined using gamma spectrometry. The activity concentration for 40K ,232Th and 238U from the soil samples ranged from 6.69±0.35 (Bqkg-1) to 168.19 ±8.82 (Bqkg-1) ,0.23 ±0.01 (Bqkg-1) to 5.91 ±0.35 (Bqkg-1) and BDL to 21.53±2.5 (Bqkg-1) respectively. The activity concentration of 40K, 232Th and 238U in the vegetable ranged from (584.23±27.71) Bqkg-1 to (958.67±48.46) Bqkg-1, from (1.84±0.11) Bqkg-1 to (9.72 ±0.56) and from (BDL) to (38.34±3.74) Bqkg-1 respectively. Transfer factors obtained ranged between 12.07±4.7 to 35.35 ±27.9 for 40K, 1.80±0.125 to 5.76 ± 4.31 for 232Th and BDL to 21.05 for 238U. Effective ingestion dose due to the consumption of vegetable from the study area obtained as 0.0021mSvy-1. This value is less than the 0.29mSvy-1 recommended dose limit for the general public; therefore, the consumption of this vegetable could not cause a radiological health effect on its consumers. However negligible or low risk could be minimised when the vegetable is washed and cooked before being consumed. Hence, the results obtained in this study indicate that the activity concentration of the farmland soils and crops represent no significant health risk on the farmers and the consumers of the vegetables.

Development of schemes from a single cascade to multi-cascades for separation of regenerated uranium

Returning precious fissile materials containing 235U, obtained from regenerated uranium, to the nuclear fuel cycle is important for the production of sustainable nuclear energy. Herein, starting from the basic single cascade separation scheme, schemes for enriching regenerated uranium are developed to satisfy the requirements for low-enriched uranium with a commercial grade and several supplementary separation conditions to the greatest extent for different considerations involving the consumption of natural uranium, scale of separation cascade, and material recovery. Double- and triple-cascade schemes are derived from the consideration of improving the basic scheme by eliminating its drawbacks such as the contamination of the entire cascade by artificial nuclides. All schemes are optimized based on a Q-model cascade and are compared. The results demonstrate that the triple-cascade scheme exhibits a good separation performance and may be a good choice among the existing schemes. However, the concentration of 235U in this scheme exceeds the limitation specified by the international standard for handling fissile materials; therefore, this scheme requires further improvement.

Assessment of natural radioactivity and radiological hazards of soil collected from rabia town in nineveh governorate (North Iraq)

The effects of the environment on human exposure to radiation from naturally occurring radioactive elements have been investigated around the world. In the group of natural radionuclides under examination, the study’s objective is to ascertain the distribution, potential anthropogenic origins, and activity of the radionuclides 226Ra, 232Th, 40K and their radiological risk parameters in twelve soil samples taken from Rabia town in Nineveh Governorate, North Iraq using NaI (Tl) detector. For the examined region, the activity concentrations of 238U, 232Th, and 40K ranged from 4.79 ± 0.211 to 21.77 ± 0.675 Bq kg−1, 11.21 ± 0.942 to 33.57 ± 2.185 Bq kg−1, and 112.8 ± 32.074 to 312.2 ± 95.463 Bq kg−1, respectively. The estimated radiological hazard parameters for the examined samples included the absorbed dose rate (Dair), annual effective dose equivalent (AED), gamma-ray hazard index (I), and annual gonadal dose equivalent. Furthermore, the current work revealed the distribution of radionuclides and their relationships with the mineralogical composition. Based on obtained results, this soil is safe for the population living in the study area and can be used as a building material or for other human activities without posing any radiological danger.

Radiological assessment of irrigation water used in Rustenburg, South Africa.

Water is an essential input in agricultural production, which is why it plays an important role in food security. According to the World Bank, water irrigated agriculture represents about 20% of the total cultivated land and 40% of the total food produced globally. This makes water a direct and indirect route of radiation exposure to humans via contact, ingestion and consumption of agricultural products. Radiological assessment of irrigation water around Rustenburg, one of the mining and industrial cities in South Africa, is investigated in this study. The activity concentrations of 238U, 232Th and 40K in irrigation water samples were determined using the total mass elemental concentrations of uranium, thorium and potassium, measured using inductively coupled plasma mass spectroscopy. The activity concentrations of 238U and 40K range from 1.24×10-04 to 1.09×10-02Bq/l, and 7.07×1000 to 1.32×10+01Bq/l, with mean activity concentrations of 2.78×10-03 and 1.16×10+01Bq/l, respectively. The activity concentration of 232Th was found below the detection level in all sampled irrigation water. Estimated annual effective dose because of ingestion because of 238U and 40K was also found to be below 120μSv/y for 238U and 232Th, 170μSv/y for 40K and a total of 290μSv/y by the United Nations Scientific Committee on the Effects of Atomic Radiation. The estimated radiation dose and lifetime cancer risk indices indicate insignificant radiological risk, making the irrigation water safe for domestic and agriculture purposes.

Assessment of radioactivity in particulate matter and soil from selected mining towns of Erongo region, Namibia

The presence of radionuclides in particulate matter (PM) associated with mining operations in communities located at the edge of the mine sites have been either greatly ignored or poorly understood, leading to the underestimations of the radionuclides concentrations in PM and health impact. In this study, measurements of radioactivity in PM and soil were made in the two mining towns of Karibib and Arandis to assess the human health radiological impact on the people around the mining sites. Dust fall samples were collected for a period of six months i.e. May 2017 to October 2017 using open bucket sampler procedure according to the American Society for Testing and Materials Standard Method (ASTM D1739) while some soil samples were collected using a soil auger. The samples were measured for the presence radionuclides using a well calibrated gamma-ray spectrometer coupled with a high purity germanium detector.In particulate matter samples, the mean activity concentrations of 226Ra, 238U, 232Th, 210Pb, and 40K were found to be 81.24±1.00, 57.99±2.61, 72.10±1.67, 55.89±6.21, 682±19.81 Bq.kg−1, respectively. Similarly, in soil samples, the mean activity concentrations were found to be 66.41±1.77 Bq.kg−1 for 226Ra, 52.79±3.40 Bq.kg−1 for 238U, 71.30±2.40 Bq.kg−1 for 232Th, Bq.kg−1 for 71.50±5.99 210Pb and 797.36±18.26 Bq.kg−1 for 40K. The activity concentrations revealed higher levels of radionuclides associated with the 238U series, which were distributed unevenly across the sites. The results were comparable to global values of 11 to 64 Bq.kg−1 for 238U, 17 to 60 Bq.kg−1 for 232Th, and 140 to 850 Bq.kg−1 for 40K.The activity concentrations were used to compute the absorbed dose (D), annual effective dose equivalent (AEDE), radium equivalent activity concentrations (Ra eq), external and internal hazard indices (H ex and H in), Gamma Index (Iγ), Alpha Index (Iα) and excess lifetime cancer risk (ELCR). The mean radiological parameters in most samples were found to be within acceptable limits, with Raeq 370 Bq.kg−1, which corresponds to an upper safe limit of AEDE of 1 mSv.yr−1, the prescribed safe limit by the International Commission on Radiological Protection (ICRP), and thus the potential radiological health effects may not be significant.