Uranium Research Articles (Page 1)

Comparative evaluation of self-attenuation corrections in uranium ore: intrinsic versus Eu-152 gamma-ray techniques

Novel electrospun ionic liquid/crown ether functionalized polyacrylonitrile nanofibrous membranes as bifunctional materials for selective extraction and separation of 210Pb and 226Ra from digest solutions of uranium ore

This review presents data about the potential radiotoxic effects of uranium exposure on the human body and determination of uranium concentration in urine as a bioindicator of uranium accumulation in the human body. The paper discusses the potential applications and methods for determining uranium in urine. The article highlights epidemiological data related to uranium biomonitoring in urine among uranium workers, military personnel exposed to depleted uranium, and population living in contaminated areas. This article discusses the detected relationships between uranium concentration in urine and health outcomes, including nephrotoxicity. Additionally, the potential of alternative biosubstrates such as hair and nails for assessing chronic uranium exposure inenvironmental researches discussed. The review also presents our own studies of uranium content in the urine of Group A uranium workers of radiation-hazardous enterprises, for whom biomonitoring is a mandatory component of the annual medical examination, required by national legislation. Over 2,000 urine samples were analyzed using inductively coupled plasma mass spectrometry method. The average uranium concentration was 0.90 μg/l, and peak levels reaching up to 47.15 μg/L. The highest concentrations of uranium in urine were recorded among uranium workers involved in main technological processes. To assess the permissible level of uranium in the human body, the maximum allowable concentration in kidneys was calculated and compared with urinary excretion levels. It was determined that concentrations exceeding 15 μg/l indicate potential nephrotoxicity and necessitate improvements in working conditions for Category A uranium workers. The obtained biomonitoring data not only allow monitoring compliance with permissible dose loads, but also provide the necessary information for optimizing radiation protection measures and making decisions on intervention in cases where exposure levels are exceeded. Recognition of the risks associated with uranium mining and processing in Kazakhstan lead to policy changes aimed at protecting the health of workers and local populations. Key words:uranium, mass spectrometry, uranium industry workers, uranium ore province, epidemiological studies, health status.

1,2‐Diols are elemental building blocks in organic synthesis. The standard preparation methods involve the reductive coupling of ketones such as acetone, often using in situ reduced electropositive metal species. Uranium tetrachloride in combination with Na(Hg) as reductant was shown previously to allow for mechanistic studies of the pinacol coupling reaction, but not for direct isolation of intermediates. In this study, using three well‐defined uranium(III) complexes with different cyclopentadienyl ligands, pinacol coupling of acetone was observed resulting in a pinacolate moiety between two uranium(IV) compounds. The uranium pinacolate complexes were characterized by IR, NMR, mass spectrometry, and in one case by single crystal x‐ray diffraction. This first direct structural characterization of the reaction product confirms the previously suggested role of metallapinacolates in the pinacol coupling mechanism. Mass spectrometry additionally confirmed the proposed formation of uranium hydroxide complexes in the subsequent hydrolysis step releasing the pinacol.

This study aims to evaluate the concentration of naturally occurring radioactive elements in commercial tea samples available in Libyan markets using gamma-ray spectrometry. Twelve different tea brands were analyzed to determine the levels of Uranium-238 (U-238), Thorium-232 (Th-232), and Potassium-40 (K-40). The average activity concentrations for each of the examined samples. The levels of the detected elements were as follows: (7.07 - 54.74), (2.14 - 31.42), (12.74 - 50.95), and (63.48 - 156.12 Bq kg-1) for 226Ra, 238U, 232Th, and 40K, respectively. The results of the specific activity concentrations of radionuclides 226Ra and 40K for all tea samples are lower than the world recommended values 50 and 15 Bqkg- 1, respectively. But the higher value of activity concentration of 238U and 232Th for most samples under investigation was lower than the internationally recommended value of 20 and 420 Bq kg-1. The results showed varying concentrations across samples, but all were within internationally accepted safety limits, indicating no significant radiological health risk from consuming these products. The results revealed that the differences in the radioactive levels in the studied tea samples were mainly attributed to many reasons as the use of pesticides, water irrigation, type of soil around the collections of tea samples

Nuclear forensics remains critical in addressing threatsassociatedwith the illicit and malicious use of radioactive materials, necessitatingcontinuous advancements in the characterization of uranium ore concentrates(UOCs). In this study, we investigate the influence of precipitationstrike order on the morphological features of U3O8 derived from four synthetic routes: ammonium uranyl carbonate (AUC),ammonium diuranate (ADU), uranyl peroxide (UO4), and magnesiumdiuranate (MDU). Machine learning classification was performed todifferentiate between the synthetic route and strike order, capturingsubtle variations in product morphology. Morphological signaturesof scanning electron microscopy (SEM) images were analyzed using aconvolutional neural network (CNN) architecture based on a ResNet34backbone for transfer learning, with images processed into “spot”locations that combine multiple magnifications and detector modesto enhance feature extraction. While most synthetic pathways displayedmarked differences in morphology between strike orders (p < 0.05), the magnesium diuranate (MDU) route exhibited only minormorphological differences, 42–72% discrimination accuracy,and no statistical significance, as determined by the CNN analysis.These findings indicate that the dependence of the final morphologyof UOCs on strike order is dependent on the synthetic route, resultingin distinct signatures for AUC, ADU, and UO4 but not MDUfor the synthesis processes used. A distinct strike order fingerprintmay have wider implications for forensic attribution and process monitoring.

ABSTRACT To explore the influence of microwave power, irradiation time and other factors on the grinding effect and leaching rate of uranium ores, intermittent microwave pretreatment feasibility was verified via comparison with continuous. The research shows that when the microwave power is 800 W, using continuous microwave pretreatment on granite uranium ore, the irradiation for 120s as the best process parameter, the parameter under 0.15 mm of uranium ore mass fraction is 68.97%, the leaching rate is 72.98%. For intermittent microwave pretreatment, the optimal process parameters are a 30s pulse, an intermittent time of 40s, and a total time of 210s. Under these parameters, the grinding mass fraction is 70.57%, and the leaching rate is 75.42%. Compared with the continuous microwave pretreatment, the mass fraction is increased by 1.6%, and the microwave energy output is reduced by 25%. While enhancing the grinding effect of uranium ores, it reduces energy consumption.

Study on the real-time radon release pattern of granite under temperature-pressure coupling.

Based on the research status of rock mass accumulative damage and summarizing the application fields of ²²²Rn, the Earth’s physical and chemical properties of ²²²Rn were tried to be applied in the field of rock damage mechanics, and the cumulative damage of rock mass would be monitored. The ²²²Rn continuous detection uranium ore rock accumulation test device was designed. Firstly, the device simulates the cyclic blasting load by preparing uranium ore test blocks and carrying out multiple blasting by similarity theory. Secondly, the longitudinal wave velocity of the test block before and after blasting was obtained by using a non-metallic ultrasonic detector, and the cumulative damage evolution of uranium ore rocks under cyclic blasting load was analyzed; Then the ²²²Rn measuring instrument was used to continuously measure the variation of accumulated ²²²Rn concentration caused by cyclic blasting load, and the data were processed to obtain the ²²²Rn exhalation rate. Finally, it is concluded that the kind of uranium ore rock cumulative damage characteristics and continuous change of the relationship between the ²²²Rn exhalation rate, can further verify surface ²²²Rn gas is used to detect the feasibility of uranium loaded rock cumulative damage, as to provide the theoretical basis for prevention and control of uranium mine ²²²Rn radiation.

STUDY OF URANIUM VALENCE SPECIES IN PHOSPHATE PHASES OF PRECIPITATE

This study presents the development of a simulation model for the in-situ leaching (ISL) process of uranium, incorporating the complex kinetics of the dissolution of both tetravalent and hexavalent uranium compounds, as well as the interaction of the leaching solution with the ore-bearing host rock. To determine the reaction rate constants, experimental data were obtained from a flow-through leaching setup using a representative ore sample. Analysis of the resulting uranium extraction curves enabled the identification of the rate constants for the key chemical reactions between the ore constituents and the leaching reagent. These parameters were subsequently used as input for numerical simulations aimed at predicting the temporal dynamics of uranium recovery. The model was validated against field data collected from the Budenovskoye uranium deposit. The comparison between simulated and experimental extraction curves demonstrated strong agreement, thereby confirming the robustness and reliability of the model. The results underscore the model’s potential for practical application in forecasting and optimizing the performance of in-situ leaching operations for uranium recovery.

Rare earth elements (REEs) have significant application value in the quality control of nuclear materials and in traceability research in nuclear forensics. Methods were developed for the determination of REEs in uranium-bearing nuclear materials. The digestion parameters for uranium oxides and uranium ores, such as the digestion acid, digestion temperature, and digestion time, were optimized and reported. The optimized digestion parameters for uranium oxides were 2 mL HNO3 at 160 °C for 3 h, and those for uranium ores were 7 mL mixed acid (HNO3–HClO4–HF = 5:5:3) at 180 °C for 36 h. Two digestion methods were demonstrated to be effective for the quantitative recovery of REEs. The suitable system and specifications for different resin columns were investigated to achieve a high decontamination factor of U (105) by UTEVA resin. The corresponding loading system was 10 mL 4 M HNO3, and the elution system was 6 mL 4 M HNO3. Additionally, the analysis of ultra-trace REEs in high-uranium matrices was accomplished using two UTEVA resins. The developed methods were subjected to the Cochran test and the Grubbs test, and the relative standard deviation (RSD) for all REEs was below 6%. In uranium oxide samples with different spiked amounts, the recovery of REEs exceeded 80% in all cases, and the RSDs were all less than 10%. The method’s detection limits were below 10 ppt for all REEs (except for Ce), ensuring the accurate measurement of REEs in uranium-bearing nuclear materials.

Uranium-based materials show great promise as scintillators in ultraprecise detector application owing to their strong radiation stopping capabilities and excellent spatial resolution. However, the excited-state-driven ultrafast lattice dynamics of uranium compounds remain insufficiently understood. In this study, the lattice dynamics of Cs2UCl6 were investigated through density functional theory (DFT) and machine learning (ML). The results indicate that [UCl6]4- predominates at high frequencies (>100 cm-1), which interacts with Cs at low frequencies (<100 cm-1). The asymmetric stretching (ω0) and bending (ω1) octahedral vibrations of [UCl6]4- exhibit a high degree of temperature sensitivity, while the ML results indicate nonlinear synergistic effects, especially the disorder of bond angles resulting in the oscillation of the potential energy surface. These findings suggest that the phonon scattering is attributable to the structure distortion of the [UCl6]4- complex under asymmetric low-frequency bending vibration, thereby providing theoretical insight for the lattice dynamics behavior and spectral regulation in Cs2UCl6.

mineral deposits in soil or rock samples using method such as neutron activation analysis (NAA). Neutron flux is an important requirement for this method. Epithermal neutrons induced nuclear reactions more efficiently than with thermal neutrons when analyzing elements with high resonance integrals, it is also useful in analyzing element such as Uranium, Thorium and certain transition metals. In this study, epithermal neutron fluxes in channels of Nigeria Research Reactor-1 (NIRR-1) installed with Cadmium (Cd) were determined for use in NAA procedures. The measurements were performed after Low Enriched Uranium (LEU) fuel substituted the High enriched Uranium (HEU) fuel in the reactor. The epithermal neutron fluxes were experimentally determined using Al-0.1%Au monitor foil via 197Au(n,γ)198Au reaction. The epithermal neutron fluxes determined in the inner and outer Cd-lined irradiation channels A1 and A2 were found to be 2.539×1010 n/cm2s and 4.459×109 n/cm2s respectively at half operating power (15 kW) which corresponds to a thermal neutron flux of 5×1011 n/cm2s on the control console of NIRR-1. The values obtained before fuel conversion by previous authors in the A1-inner irradiation channel and in the A2-Outer Cd-lined irradiation channel were 2.72×1010 n/cm2s and 4.459×109 n/cm2s respectively. These values were both in agreement with the values of this study. This shows that the Cd installation and the fuel conversion from the (HEU LEU does not affect the epithermal neutron fluxes. It also implies that the stability of the neutrons in NIRR-1 were not altered. Thus, the facility is good for Epithermal NAA. The use of additional flux monitors, implementation of ENAA in geochemical analysis and evaluation of epithermal neutron shaping factor (α) were recommended.

A novel integration of self-organizing maps and NETPATH inverse modeling to trace uranium and toxic metal contamination risks in West Mecsek, Hungary.

Out-of-distribution detection with non-parametric density estimation for models predicting processing history of uranium ore concentrates

Comparative analysis of asphalt and geomembrane sealing systems for sustainable uranium pile remediation: Insights from hydrological modeling under climate change.

The rapid development of the nuclear industry and mining has increased environmental radioactive contamination, posing potentially ecological risks and health threats to humans. Uranium compounds are known to exhibit selective nephrotoxicity, but their toxicological processes and mechanisms still remain poorly understood and controversial. In this study, the uranyl-induced toxicity in human renal tubular epithelial cells (HK-2) were explored using flow cytometry, DAPI staining, and comet assays. Our results demonstrate that uranium exposure primarily triggers apoptosis. Kyoto Encyclopedia of Genes and Genomes pathway enrichment and protein–protein interaction (PPI) analyses revealed significant associations with DNA damage. Moreover, aberrant expression of ABC transporters (e.g., ABCB7) and mitochondrial-related proteins confirms uranium-induced mitochondrial dysfunction. Gene Ontology functional annotation implicated extrinsic apoptotic signaling pathways in uranium-induced cell death. The downregulation of the UBL5 protein also pointed to endoplasmic reticulum stress-mediated apoptosis. In summary, uranium exposure can induce the apoptosis of HK-2 cells through intrinsic pathways by damaging DNA and mitochondria and disrupting protein synthesis, with secondary contributions from endoplasmic reticulum stress and extrinsic apoptotic signaling.

Atomic scale origin of hydrogen induced pitting corrosion in metallic uranium: first principles study of hydrogen behavior at uranium grain boundaries

Abstract Uranyl silicates are common constituents of the oxidized portions of uranium ore deposits. They are also known to form on used nuclear fuel pellets under simulated geologic repository conditions. These phases can incorporate various cations, including higher actinides and fission products, which makes them relevant for studies that probe the stability of these phases in various contexts, including irradiation, high temperatures, and high pressures. The changes in the single-crystal structure and Raman spectroscopy of the uranyl silicate mineral boltwoodite, K0.63Na0.37[(UO2)(SiO3OH)](H2O)1.5, have been investigated at 11 pressures from ambient to 16.8 GPa. The bulk modulus was determined to be 26.3(4) GPa from a third-order Birch-Murnaghan fit of the unit-cell volume vs. pressure. No obvious phase transition was observed between ambient pressure and 16.8 GPa. The structure is most easily compressed along the a-axis, which decreases by ca. 15% throughout the investigated pressure range, leading to distortions in the bonding geometries and higher coordination numbers of the interlayer cations. The b- and c-axes parallel to the uranyl silicate sheets are each compressed by ca. 4% compared to the ambient-pressure structure at 16.8 GPa, attributed to the uranyl silicate sheets becoming more highly corrugated with increasing pressure. Previous experimental high-pressure work on uranium(VI) phases is limited due to the complexity of refining heavy atom crystal structures with disordered cations and/or water molecules, as well as the limitations imposed by the opening angle of the diamond-anvil cell used to achieve high pressures. A method for overcoming these challenges is presented here to facilitate further high-pressure studies of heavy element minerals and other phases.