Radioactivity Concentration Research Articles

Speciation simulation and sorption mechanism of 238Pu in radioactive waste repository lithosphere

Abstract The assessment of the migratory and environmental behavior of radioactive nuclides escaping from waste treatment facilities heavily relies on the use of numerical models capable of simulating and characterizing all significant processes of nuclides in complex geological environments. Adsorption models typically encompass the chemical properties of the nuclides themselves and their chemical reactions with the surrounding environment, as well as processes such as ion exchange or physical adsorption. These processes must be taken into consideration in the long-term safety assessment of radioactive waste repositories. The redox-sensitive nuclide 238Pu, a critical member among transuranic elements, exhibits a diverse range of aqueous forms, and concurrently, it possesses high toxicity. The chemical behavior of 238Pu shows strong spatial variability with changes in environmental conditions. In this study, we constructed a theoretical model for the migration of nuclides in soil and groundwater environments through indoor static batch experiments and hydrogeochemical simulations. Experimental methods were employed to dissect the micro-scale, irreversible adsorption reaction processes of nuclides and identify their primary existing forms. According to field measurements, the pH of groundwater was recorded as 7.48, with an Eh of 125.7 mV. Introducing a solid-to-liquid ratio of 1:10 g/mL in centrifuge tubes, we measured the radioactive nuclide concentration after achieving adsorption and desorption equilibrium, obtaining adsorption and desorption isotherms. The PHREEQC software was employed to investigate the changes in 238Pu forms under varying conditions of pH and redox potential. Field measurements provided groundwater pH and Eh values. The activity concentration of the nuclide was measured after reaching adsorption and desorption equilibrium. The results show that the adsorption isotherms of 238Pu differ from its desorption isotherms, indicating an irreversible adsorption-desorption process. Ion exchange and surface complexation were identified as the main modes of adsorption. PHREEQC simulations revealed that 238Pu primarily existed in forms such as tetravalent Pu(OH)4 and trivalent Pu(SO4)2 −, PuSO4 +. Pu(OH)4 accounted for the largest proportion (97%) in the groundwater solution system, while a minimal amount of pentavalent PuO2 + was present. Environmental factors, such as pH and the presence of ions like SO4 2− and HCO3 −, influenced the forms of 238Pu.

Pharmacokinetic Study of Ultrasmall Superparamagnetic Iron Oxide Nanoparticles HY-088 in Rats.

HY-088 injection is an ultrasmall superparamagnetic iron oxide nanoparticle (USPIOs) composed of iron oxide crystals coated with polyacrylic acid (PAA) on the surface. The purpose of this study was to investigate the pharmacokinetics, tissue distribution, and mass balance of HY-088 injection. The pharmacokinetics of [55Fe]-HY-088 and [14C]-HY-088 were investigated in 48 SD rats by intravenous injection of 8.5 (low-dose group), 25.5 (medium-dose group), and 85 (high-dose group) mg/100 μCi/kg. Tissue distribution was studied by intravenous injection of 35 mg/100 μCi/kg in 48 SD rats, and its tissue distribution in vivo was obtained by ex vivo tissue assay. At the same time, [14C]-HY-088 was injected intravenously at a dose of 25.5 mg/100 μCi/kg into 16 SD rats, and its tissue distribution in vivo was studied by quantitative whole-body autoradiography. [14C]-HY-088 and [55Fe]-HY-088 were injected intravenously into 24 SD rats at a dose of 35 mg/100 μCi/kg, and their metabolism was observed. In the pharmacokinetic study, [55Fe]-HY-088 reached the maximum observed concentration (Cmax) at 0.08 h in the low- and medium-dose groups of SD rats. [14C]-HY-088 reached Cmax at 0.08 h in the three groups of SD rats. The area under the concentration-time curve (AUC) of [55Fe]-HY-088 and [14C]-HY-088 increased with increasing dose. In the tissue distribution study, [55Fe]-HY-088 and [14C]-HY-088 were primarily distributed in the liver, spleen, and lymph nodes of both female and male rats. In the mass balance study conducted over 57 days, the radioactive content of 55Fe from [55Fe]-HY-088 was primarily found in the carcass, accounting for 86.42±4.18% in females and 95.46±6.42% in males. The radioactive recovery rates of [14C]-HY-088 in the urine of female and male rats were 52.99±5.48% and 60.66±2.23%, respectively. Following single intravenous administration of [55Fe]-HY-088 and [14C]-HY-088 in SD rats, rapid absorption was observed. Both [55Fe]-HY-088 and [14C]-HY-088 were primarily distributed in the liver, spleen, and lymph nodes. During metabolism, the radioactivity of [55Fe]-HY-088 is mainly present in the carcass, whereas the 14C-labeled [14C]-HY-088 shell PAA is eliminated from the body mainly through the urine.

Maintenance study on WCLL-TBS ancillary systems in process room

The Water-Cooled Lithium Lead Test Blanket System (WCLL-TBS) is one of the European TBS candidates for being installed and operated in ITER. The ongoing activities toward the Preliminary Design Review of the WCLL-TBS Ancillary Systems include the reallocation of their units in the reserved space, also in the view of the proper execution of the maintenance activities. Starting from the available documentation (System Design Description, Process Flow Diagrams, Process and Instrumentation Diagrams), detailed 3D CAD models have been developed for two Ancillary Systems to be installed in the Process room: the Tritium Extraction System (TES) and the Tritium Accountancy System (TAS). In the Process room (PR), the largest part of the TES process units is placed inside a Glove-box, as enclosure to avoid the contamination of the room in case of radioactive release due to failure of units. Based on the expected radioactivity content, all the TAS units are placed inside the Glove-box. Maintainability studies have been performed, focusing on the preventive (i.e. planned) and corrective (i.e. required by failures) maintenance tasks on the units installed inside the Glove-box. They were based on the 3D CAD models and supported using Virtual Reality as intuitive and immersive human-computer interface. They provided insights for the iterative improvement and consolidation of the Systems design and information for the evaluation of their availability.

Radiological Safety Assessment of Tailings Extracted from Kaolin Mining Sites in Katsina State

This research was carried out to sufficiently justify the recent increased awareness and concern for the potential hazards associated NORMs in the environment of the research around Kankara and Dutsin-ma Kaolin mining sites Katsina State; Nine (09) Kaolin samples were collected randomly from the mining sites for the study. The radioactivity analysis was done experimentally using NaI(TI) gamma spectrometer at Center for energy research and training, Ahmadu Bello University Zaria. The health hazards were evaluated using numerous radiological, Statistical and USEPA models. The overall hazard index (HI) was found to be 1.496609 for children found in third sampling point of Yar-goje are; it is the only possibility of a children to be affected while 0.799486 for adults, this value was below the USEPA threshold limit for non-carcinogenic risks of 1.0 indicating that the exposed population ages are unlikely to experience any adverse non-carcinogenic risks. The radiological parameters obtained are 226Ra (238U), 232Th and 40K of a NORMs with activity concentration of is 100.889, 0.129 and 224.040 (Bqkg-1) in the soil samples, at the studied area. Absorbed frequency in air measured in nGy/h by one-meter directly above the crushed, was considered, since the forbidding radioactivity concentrations is obtained as 77.575 while the total annual effective dose (AED) in mSv/y had average value of 0.099 in soil. The values obtained for external and internal radiological hazard indices Hext and Hint are 0.471 and 0.741 in soil; which were lower than the UNSCEAR suggested boundary limit of unity. Lastly, the overall excess lifetime cancer menace owed to NORMs, stood as 5.63E-06 and 4.15E-06 for whole populations indicating that (a maximum of 6 people/1 million may be affected) for adults while (a maximum of 4 people /1 million may be affected) for children. These values were within the USEPA threshold of 1E-04.

Simple Moving Average Applied to "ISO Method" CPAM Concentration Estimates: An Unexpected Result.

A surprisingly large amount of variance reduction has been observed when filtering International Organization for Standardization (ISO) "ISO Method" continuous particulate air monitor (CPAM) airborne radioactivity concentration estimates with a simple three-point moving average. This processing has relatively little lag relative to the amount of variance reduction obtained. The key factor producing this effect is the specific autocorrelation structure of the estimated concentrations, which are based on taking first differences of integrated-count data; this scheme results in successive count differences that contain a common count value between them. The observed variance reduction factor has also been derived analytically.

Measuring the radioactivity concentration of 40K, 226Ra, 232Th with PH, conductivity and radiological risk in tap water

ABSTRACT Water is important in environmental studies because of its daily usage by humans and its ability to transport pollutants. The radiological quality of 226Ra, 232Th and 40K in 20 samples of water taps were collected in Kirkuk Governorate, Iraq, and those data have been measured and analysed by gamma ray spectroscopy HPGe detector. The activity concentration of 226Ra ranged from (140.84 to 89.43) mBq.L−1with an average value of 121.95 mBq.L−1, from (106.89 to 47.39) mBq.L−1with an average value of 81.523 mBq.L−1of 232Th, and from (1550.51 to 379.55) mBq.L−1with an average value of 1091.37 mBq.L−1 of 40K, those were lower than the world average values suggested by UNSCEAR: 35, 30, 400 Bq.kg−1. The results show that the values of Raeq varied from (223.24 to 369.90) mBq.kg−1 with a mean of 339.95 mBq.kg−1 which is lower than worldwide average value (370 Bq.kg−1). And the AEDE ranged between minimum and maximum values 120.36 μSvy−1 and 208.33 μSvy−1 with an average value of 186.64 μSvy−1. Also, the values of ELCR ranged from (0.421 to 0.729) × 10−3 with an average value of 0.653 × 10−3, these values were lower than the world’s average value of 3.21 × 10−3. The values of AGDE were ranged from (67.96 to 118.41) μSvy−1 with a mean value of 106.29 μSvy−1 these values were lower than the world average values 300 μSvy−1. Average ingestion of 226Ra, 222Rn 232Th and 40K were found to be 0.6032 μSv y−1 for infants, 0.1141μSv y−1 for children, 0.0350μSv y−1 for adults of 232Th, and 0.57312 μSv y−1 for infants, 7.557 μSv y−1 for children, 3.4146μSv y−1 for adults of 226Ra, also 0.0676 μSv y−1 for infants, 0.0229 μSv y−1 for children, 0.0075 μSv y−1 for adults of 40K. all those values were below the WHO permissible limit of 0.1 mSv y−1 for all ages.

Radiological landscape of natural resources and mining: Unveiling the environmental impact of naturally occurring radioactive materials in Ghana's mining areas

This study provides a general observation of the status of naturally occurring radioactive materials (NORMs) distribution in mining and industrial areas of Ghana in order to establish regional and national data on NORMs. The study includes data on radioactivity concentrations of U-238, Th-232, and K-40 in soils and for water concentrations of Ra-226, Th-228, and K-40 from various mining, oil, and gas communities, as well as water sources used for crop farming and farmlands. The average activity concentrations of U-238, Th-232, and K-40 in the soil samples were found to be 59 ± 16 Bq/kg, 48 ± 15 Bq/kg, and 286 ± 57 Bq/kg, respectively. The average concentration of Ra-226, Th-228, and K-40 in the water samples were found to be 1.62 ± 0.33 Bq/L, 2.08 ± 0.53 Bq/L, and 22.36 ± 3.44 Bq/L, respectively. The estimated average annual effective doses from external and internal exposure pathways in soil and water samples were 0.09 mSv/y and 0.54 mSv/y, respectively. The total annual effective dose resulting from both exposure pathways was calculated to be 0.63 mSv/y, which is below the 1 mSv/y dose limit recommended by the International Commission on Radiological Protection (ICRP) for controlling public radiation exposure. Based on the radiological hazard indices, the majority of the soil samples were found to be suitable as building materials as their respective indices were below the limits except for two sample locations and the sludge and scale samples. The average Excess Lifetime Cancer Risk (ELCR) value of the water samples was 1.6 times greater than the recommended value of 1.16 × 10−3, presenting a relatively higher risk to the public of developing cancer. No significant regional differences in the levels of radioactive elements. The regression models demonstrate strong interrelationships between the studied elements, with high R-squared values suggesting a predictable nature of one element’s concentration based on others.

Natural radioactivity in Turkish foodstuff consumed in Iraq

Different levels of natural radionuclides were found in food items, and these variations were attributed to factors such as background radiation levels, climate, and agricultural practices. These radionuclides are recognized as the primary contributors to the internal radiation exposure experienced by humans. Among the natural radionuclides, the ones of most significant concern for radiation protection are those belonging to the decay series of 238U and 232Th, as well as 40K. The concentration of natural radioactivity in several Turkish food products accessible on the Iraqi market was measured using a NaI (Tl) gamma-ray spectroscopy detector. The measured concentrations in unit Bq kg−1 of 238U, 232Th, and 40K ranged from 3.2 to 19, 1.2 to 24.1, and 22.5 to 690.9, respectively. The study also calculated the annual effective dose for individuals who consume such foods. The annual internal dose from ingesting studied radionuclides found in foodstuff was calculated to be 0.274 ± 0.05 mSv/y. Notably, this calculated dose falls below the worldwide value of 0.32 mSv/y established for the general public.

Investigating radiation profiles and conducting risk assessment for ecological and environmental components on Vaan and Koswari islands in the Tuticorin group of islands, India.

Natural radioactive concentration assessment was conducted on sediment, water, and biota obtained on Vaan and Koswari islands in the Tuticorin group of islands, Tamil Nadu, India. For biotic and abiotic components, radiation profiles such as gross alpha, beta, primordial radionuclide, polonium, and lead analyses were performed. The gross α and β range from BDL to 15.18 ± 1.7Bq/kg and 40.43 ± 4.9Bq/kg to 105.12 ± 11.7Bq/kg, respectively. Primordial radionuclides were analyzed using Nal(TI)-based scintillator with PC-MCA, and the concentrations ranged from 13.43 ± 3.3Bq/kg to 30.97 ± 9.6Bq/kg with a mean of 21.31 ± 2.7Bq/kg for 238U; for 232Th, the values ranged from 11.09 ± 2.6Bq/kg to 33.55 ± 9.5Bq/kg with an average value of 23.89 ± 3.7Bq/kg; and for 40K, the values are 93.33 ± 27.3Bq/kg to 219.91 ± 39.6Bq/kg with an average value of 148.27 ± 21.7Bq/kg. The present study values are lesser than the world average values. 210Po and 210Pb concentrations with an average value were determined to be 33.13Bq/L and 16.56Bq/L, 47.55Bq/L and 22.37Bq/L in the water sample, and 50.437Bq kg1 and 62.012Bq kg1, 46.99Bq/kg and 58.625Bq/kg in sediments of Vaan island and Koswari island. The concentrations of 210Po and 210Pb of Pogonias cromis were 19.27 ± 1.5Bq/kg and 8.27 ± 1.01Bq/kg, Belonidae 28.54 ± 2.4Bq/kg and 18.32 ± 2.3Bq/kg, Lepisosteidae 18.68 ± 1.4Bq/kg and 11.17 ± 1.8Bq/kg. The committed effective dosage was determined to be 35.74-54.61 µSv/y for 210Po and 25.39-56.25 µSv/y for 210Pb, in which the 210Pb value is lower; however, the 210Po value is higher than the global average value. The annual committed effective dosage as well as the radiological hazard indices were assessed and found to be much below the global average and the recommended limit, respectively. This research provides an extensive analysis of natural background radiation and establishes a baseline report on the radiological profile of biotic and abiotic factors in the Tuticorin group of islands, namely Vaan and Koswari, in Tamil Nadu, India.

Feasibility of Treatment Agents in Radioactive Iodine Separation from Waste Liquids.

To discharge waste liquid containing radioactive iodine into sewage systems, long-term storage or dilution with a large amount of water may be required until the radioactivity concentration reduces below the standard value. Processing the waste liquid could be easier if radioactive iodine could be separated from the water. This study verified the effectiveness of superabsorbent polymer and α-cyclodextrin as treatment agents to separate radioactive iodine from waste liquids. Sodium iodide (Na 125 I) was added to purified water and artificial urine to prepare simulated waste liquids containing iodine equivalent to the urine of patients treated with radioactive iodine. The as-prepared simulated waste liquid was poured into a container with superabsorbent polymer and left for 90 d. The residual iodine rate in the simulated waste liquid was estimated by measuring 125 I radioactivity. When the water was sufficiently dried, residual iodine rates on day 15 were 0.102 and 0.884 in the simulated waste liquids comprising purified water and artificial urine, respectively. The simulated waste liquid comprising purified water with 5% α-cyclodextrin absorbed by 1 g of superabsorbent polymer had a residual rate of 0.980. Moreover, the residual rate of simulated waste liquid comprising artificial urine with 2% α-cyclodextrin absorbed by 1 g of SAP was 0.949. Superabsorbent polymer combined with α-cyclodextrin was an effective treatment agent for separating radioactive iodine from waste liquids.

Negligible radiological impact of Indian nuclear power plants on the environment and the public: Findings from a 20-year study

Nuclear power plants, recognized for their extended operational life, minimal greenhouse gas emissions, and high-power density, are deemed as reliable energy sources. Nonetheless, concerns persist regarding the radioactive discharges from these plants and their potential impact on health and the environment. To comprehend the radiological implications of such releases, this study presents, for the first time, an analysis of radiological data from 7 Indian nuclear power plants (NPPs), collected by Indian environmental survey laboratories (ESL) over the past two decades (2000-2020). This dataset encompasses radioactivity concentrations in the atmospheric, aquatic, and terrestrial environments within a 30 km radius of each NPP, as well as the annual cumulative external gamma doses recorded by environmental thermoluminescence dosimeters (TLDs). The analysis yielded several key findings: (i) Radioactivity concentrations around the NPPs were low and comparable to values measured at other nuclear power plant sites worldwide; (ii) Tritium concentrations in receiving water bodies were <1 % of the internationally recommended limit of 10,000 Bq/l; (iii) The estimated total radiation doses to the public were at most 10 % of the stipulated regulatory dose limit of 1000 μSv and consistently decreased over the study period and (iv) Variations in doses among the NPP sites were primarily attributed to legacy technology used in specific reactors. These results indicate efficient and secure reactor operations and the minimal contribution of Indian nuclear power plants to anthropogenic doses in the country. The findings hold potential significance for reinforcing India's commitment to advancing its nuclear power program.

The determination of the optimal threshold on measurement of thyroid volume using quantitative SPECT/CT for Graves' hyperthyroidism

PurposeTo investigate the optimal threshold for measuring thyroid volume in patients with Grave's hyperthyroidism (GH) by SPECT/CT.Materials and methodsA 53 mL butterfly-shaped hollow container made of two 45-degree transparent elbows was put into a NEMA IEC phantom tank. The butterfly-shaped container and the tank were then filled with Na99mTcO4 of different radioactive concentrations, respectively, which could simulate thyroid gland with GH by different target-to-background ratios (T/B) (200:1, 600:1, 1000:1). The different T/B of planar imaging and SPECT/CT were acquired by a Discovery NM/CT 670 Pro SPECT/CT. With Thyroid software (Version 4.0) of GE-Xeleris workstation, the region of the thyroid gland in planar imaging was delineated. The thyroid area and average long diameter of both lobes were substituted into the Allen formula to calculate the thyroid volume. The calculation error was compared with the actual volume. Q-Metrix software was used to perform CT-based attenuation correction, scatter correction, resolution recovery. Ordered-subsets expectation maximization was used to reconstruct SPECT data. 20%, 25%, 30%, 40%, 50%, 60% thresholds were selected to automatically delineate the volume of interest and compared with the real volume, which determinated the optimal threshold. We measured the thyroid volume of 40 GH patients using the threshold and compared the volumes obtained by planar imaging and ultrasound three-dimensional. The differences of the volumes with different T/B and thresholds were compared by the ANOVA and least significant difference t test. The volumes delineated by SPECT/CT were evaluated using ANOVA, least significant difference t test, correlation analysis and, linear regression and Bland–Altman concordance test plot. The differences and consistency of thyroid volume were compared among the above three methods.ResultsThere was no significant difference in the results between different T/B models (P > 0.05). The thyroid volume calculated by the planar imaging formula method was higher than the real volume, with an average overestimation of 22.81%. The volumes delineated by SPECT/CT threshold automatically decreased while the threshold increased. There were significant differences between groups with different thresholds (P < 0.001). With an average error of 3.73%, the thyroid volume analyzed by the threshold of 25% was close to the results of ultrasound measurement (P > 0.05). Thyroid volume measured by planar imaging method was significantly higher than ultrasound and SPECT/CT threshold automatic delineation method (P < 0.05). The agreement between the SPECT/CT 25% threshold and ultrasound (r = 0.956, b = 0.961) was better than that between the planar imaging and ultrasound (r = 0.590, b = 0.574). The Bland–Altman plot also showed that the thyroid volume measured by the 25% threshold automatic delineation method was in good agreement with the ultrasound measurement.ConclusionsThe T/B has no effect on the measurement of thyroid volume in GH patients; planar imaging method can significantly overestimate thyroid volume in GH patients, and 25% threshold automatic delineation method can obtain more accurate thyroid volume in GH patients.

Automating the production of [Fe18FF2(BnMe2-tacn)] and investigating radiostabilisers for use with high-activity [18F]F−

Abstract The manual radiofluorination and purification of [FeF3(BnMe2-tacn)] (tacn = 1,4,7-triazacyclononane) using 18F− in aqueous EtOH has been translated to a GE FASTLab™ automatic synthesis platform and optimised by conducting a series of low-activity radiolabelling experiments to explore the effects of varying the precursor concentration, temperature, heating time, addition of NaOAc buffer and EtOH:H2O ratio. The optimal conditions were determined to be 1 mg/mL of the precursor being heated at 120 °C for 10 min in 75 %:25 % EtOH:H2O containing 18F−, with elution using 10 mM NaOAc, giving 61 % radiochemical yield (RCY). These conditions were then employed with high-activity 18F− giving a 97 % radiochemical purity (RCP) at t = 0, which decreases by 22 % over 5 h. Sodium ascorbate, nicotinamide and p-benzoic acid (pABA) were then tested as potential radiostabilisers for this system, initially using low-activity 18F−. These experiments revealed very rapid defluorination of the radioproduct in the presence of sodium ascorbate. In contrast, both nicotinamide and pABA appear to be effective radiostabilisers, resulting in RCP values of 91 % and 89 %, respectively, after 2 h, which compare with an RCP of 81 % under analogous conditions at t = 2 h in their absence. High-activity experiments were then undertaken with addition of 5 mg/mL of nicotinamide, with a radio-active concentration (RAC) of 220 MBq/mL, giving RCY of 26 % and following purification, RCP values for the [Fe18FF2(BnMe2-tacn)] product of 97 % at t = 0 and 86 % after 3 h.

Environmental Radioactivity, Ecotoxicology (238U, 232Th and 40K) and Potentially Toxic Elements in Water and Sediments from North Africa Dams

The natural radioactivity of 238U, 232Th and 40K was measured in water and sediment samples collected from Sidi Salem dam (Tunisia) and Aïn Dalia dam (Algeria) in the Tuniso-Algerian transboundary basin. The samples were measured using a TERRA detector of gamma, beta, and alpha rays, and atomic absorption and gamma-ray spectrometry were used to analyze the levels of radionuclides and toxic elements, respectively. Potentially toxic elements (Fe, Pb, Zn, Ni, Cr, Cu and Cd) and associated health risks in surface water and sediment of dams were investigated in this present study. The concentrations of Fe, Pb, Zn, Ni, Cr, Cu and Cd in surface water ranged from 5.430 to 9.700 mg·L−1, 0.022 to 0.168, 0.018 to 0.142, 0.065 to 0.366, BDL to 0.0351, BDL to 0.071 and BDL to 0.048 mg·L−1, respectively. In the sediments, the concentrations of Fe, Pb, Zn, Cu, Ni, Cd and Cr were of the order of 136.7, 3.41, 3.22, 0.213, 0.182, 0.15 mg·L−1 and BDL, respectively. The mean radioactivity rates in the water samples were 1.72, 0.068 and 94.6 Bq·L−1 for 238U, 232Th and 40K, respectively (Tunisia dam), and were 1.9, 0.09 and 131.43 Bq·L−1 for 238U, 232Th and 40K, respectively (Algeria dam). The mean 238U, 232Th and 40K radioactivity concentrations measured in the sediment samples were 2.67, 0.18 and 197.87 Bq·kg−1, respectively (Tunisian dam), and were 4.34, 0.27 and 287.61 Bq·kg−1, respectively (Algeria dam). The activity concentration of 40K was higher than that of 238U and 232Th for the water and sediment samples. The activity concentrations follow the order 40K &gt; 238U &gt; 232Th. The cumulative impact of these radio-geochemical elements can cause immediate serious problems in the ecosystem due to their high potential toxicity to the environment and human health in this study area and can be transposable to any other similar region. A good knowledge of monitoring quality and quantity for transboundary water resources and international collaborations are essential to safeguard human health (women’s breast cancer, thyroid cancer, neurological impact) and avoid conflicts, especially during climatic upheavals of drought.

Fractionation of environmental radioactivity in road dust from a megacity: external and internal health risks.

Naturally occurring radioactive materials (NORMs: 232Th, 226Ra, 40K) can reach our respiratory system by breathing of road dust which can cause severe health risks. Targeting the pioneering consideration of health risks from the NORMs in road dust, this work reveals the radioactivity abundances of NORMs in road dust from a megacity (Dhaka) of a developing country (Bangladesh). Bulk chemical compositions of U, Th, and K obtained from neutron activation analysis were converted to the equivalent radioactivities. Radioactivity concentrations of 226Ra, 232Th, and 40K in road dust ranged from 60-106, 110-159, and 488-709Bqkg-1 with an average of 84.4 ± 13.1, 126 ± 11, and 549 ± 48Bqkg-1, respectively. Estimated 226Ra, 232Th, and 40K radioactivities were, respectively, 1.7-3.0-, 3.7-5.3-, and 1.2-1.8-folds greater than the affiliated world average values. Mechanistic pathway of NORMs' enrichment and fractionation relative to the major origin (pedosphere) were evaluated concerning the water logging, relative solubility-controlled leaching and translocation, climatic conditions, and aerodynamic fractionations (dry and wet atmospheric depositions). Computation of customary radiological risk indices invokes health risks. Noticing the ingress of NOMR-holding dust into the human respiratory system along with the associated ionizing radiations, the computed radiological indices represent only the least probable health hazards. Nevertheless, in real situations, α-particles from the radioactive decay products of 232Th and 238U can create acute radiation damages of respiratory system. Policymakers should emphasize on limiting the dust particle evolution, and public awareness is required to alleviate the health risks.

Radioactivity concentration and risk indices in intertidal sediments of the Red River Delta, Vietnam

Radioactivity concentration and risk indices in intertidal sediments of the Red River Delta, Vietnam

Quantitative evaluation of radioactive cesium concentration in leachate and landfill waste at a municipal waste final disposal site in Fukushima prefecture

Quantitative evaluation of radioactive cesium concentration in leachate and landfill waste at a municipal waste final disposal site in Fukushima prefecture

Evaluation of Radioactivity Contents and Excess Lifetime Cancer Risk Due to Ingestion from Natural Radionuclides in Maize Samples from Some Selected Maize Farms in Ekiti State, Nigeria

The study was carried out to evaluate the radioactivity concentrations of 40K, 232Th and 238U in five maize samples collected from maize farms within Ekiti State, Nigeria. The activity concentration measurements were determined using n – type co-axial HPGe detectors for the state. The activity concentrations were found to vary from 994.67 – 2457.01 Bq Kg-1 for 40K, 32.84 – 91.88 Bq kg-1 for 232Th and 43.21 – 97.77 Bq kg-1 for 238U respectively. The annual effective dose to individuals from the consumption of the Maize was estimated on the basis of the measured radionuclides content in the food crop which ranged between 0.41 and 1.51 m Svy-1 respectively. The value1.04 m Svy-1 were obtained for the state as the mean total annual effective dose. The mean excess life time cancer risk was also calculated to be 2.06x10-9 . The value was compared with the internationally acceptable limits and found to be far less to the maximum permissible dose of 1.0 x10-3 recommended for the public by the United Nations Scientific Committee on the Effects of Atomic Radiation. Hence, the maize was found to be safe for human consumption.

Impact of Different Acquisition Modes on Image Quality and Quantitative Accuracy for Bone SPECT Using Ordered Subset Conjugate-gradient Minimizer

We evaluated the effect of different xSPECT Bone acquisition methods on image quality and quantitative accuracy. A mixed bone-equivalent solution set to 250 HU and 99mTc was filled with the SIM2 Bone phantom. The xSPECT Bone acquisitions were performed with the step and shoot (SS) mode and two continuous modes (continuousview, continuoustotal) of the times per view, and the total acquisition times were the same as the SS mode. The radioactive concentration ratio of normal bone and tumor was set to 1 : 6. The reconstructed images were evaluated using uniformity, contrast, spatial resolution, recovery coefficient (RC) of the tumor part, and detectability. The detectability score (DS), an overall evaluation of detectability, was calculated from the results of uniformity and contrast. Uniformity of SS, continuousview, and continuoustotal methods was 29.4%, 17.4%, and 11.1%, respectively. Spatial resolution, RC, and detectability were similar among the SS mode and two continuous modes; however, the continuous modes showed good uniformity and contrast compared with the SS mode. In addition, the detectability of the continuous mode was equal to or superior to that of the SS mode.

ASSESSMENT OF KARAMUSTAFA GOLD-BEARING Zn-Pb MINE (GÜMÜŞHANE, TÜRKİYE) AREA IN TERMS OF NATURAL AND ARTIFICIAL RADIOACTIVITY

This study aimed to assess the environmental effects of natural and artificial radioactivity contents, especially in the context of medical geology of base metal-containing mineral deposits. In the study, artificial/anthropogenic (137Cs) and natural (226Ra, 232Th and 40K) radioactivity levels in the soil of the Karamustafa gold-bearing Zn-Pb-(±Cu) mining area, one of the important mines of Gümüşhane (NE Türkiye), were determined and evaluated. In order to determine the natural and artificial radioactivity of the mining area, 9 soil samples were collected from different parts of the field, taking into account the geological and alteration characteristics of the field. 232Th, 226Ra and 40K activities of the samples prepared according to the relevant laboratory procedures were determined by the gamma-ray spectrometry, and the artificial radioactivity values of 137Cs were also measured. As a result of the study, it was determined that the 40K and 226Ra average activities of the Karamustafa gold-bearing Zn-Pb-(±Cu) mining area exceeded the world averages in most sampling points, while the 232Th activities were above the world averages at some sampling points. It has been determined that the artificial/human-derived 137Cs radioisotope values in the field are remarkably high. Considering the major radio indices calculated for the field, it was determined that the absorbed dose rate and annual effective dose rate indices of the mine site exceeded the relevant threshold values. When all the data obtained from the field were evaluated together, it was concluded that the mine field needed detailed study in the context of radiation risk.