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Western countries are eager to reduce their dependence on Russian-origin nuclear fuel but are hindered by capacity constraints in uranium conversion and enrichment. Governments hope to enhance supply security via uranium stockpiles and subsidies, yet such measures risk disrupting the market and are unlikely to accelerate capacity expansion in the short term. Recognizing the complexity of market dynamics and the fact that market adjustments are already taking place, governments should focus on providing market players with the incentives and certainty they need to protect their individual conversion and enrichment supply chains. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A comparison of the efficiencies of the optimum mixing and nonmixing (ideal) cascades comprising stages, the coefficients of separation of a mixture at which are dependent on their parameters, has been performed. It was established that an optimized mixing cascade can have a smaller number of centrifuges, as compared to that of a nonmixing cascade, the separation capacity of whose stages deviate from the optimum one by 1–10%. For an optimum mixing cascade, this deviation is smaller, which can be explained by that the requirement for the fulfillment of the nonmixing condition at the joints of flows in such a cascade narrows the area of search for the parameters of the cascade and thus excludes more effective variants of solving the separation problem. [ABSTRACT FROM AUTHOR]

Inspired by the intelligent gel phase transition effect, we applied temperature-responsive γ-FeOOH/KGM(Ga)/PNIPAM hydrogel with reversible sol-gel transition for uranium enrichment and separation in carbonate-containing wastewater. In carbonate-containing wastewater, the hydrogel achieved a high uranium removal rate of 92.3%, exceeding 90% even in actual uranium mine wastewater. Additionally, the adsorption-reduction-nucleation-crystallization mechanism of uranium on the temperature-responsive hydrogel was revealed using multi-spectral coupling techniques. [Display omitted] Exploiting the intelligent photocatalysts capable of phase separation provides a promising solution to the removal of uranium, which is expected to solve the difficulty in separation and the poor selectivity of traditional photocatalysts in carbonate-containing uranium wastewater. In this paper, the γ-FeOOH/konjac glucomannan grafted with phenolic hydroxyl groups/poly- N -isopropylacrylamide (γ-FeOOH/KGM(Ga)/PNIPAM) thermosensitive hydrogel is proposed as the photocatalysts for extracting uranium from carbonate-containing uranium wastewater. The dynamic phase transformation is demonstrated to confirm the arbitrary transition of γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel from a dispersed state with a high specific surface area at low temperatures to a stable aggregated state at high temperatures. Notably, the γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel achieves a remarkably high rate of 92.3% in the removal of uranium from the wastewater containing carbonates and maintains the efficiency of uranium removal from uranium mine wastewater at over 90%. Relying on electron spin resonance and free radical capture experiment, we reveal the adsorption-reduction-nucleation-crystallization mechanism of uranium on γ-FeOOH/KGM(Ga)/PNIPAM thermosensitive hydrogel. Overall, this strategy provides a promising solution to treating uranium-contaminated wastewater, showing a massive potential in water purification. [ABSTRACT FROM AUTHOR]

As a strategic mineral and energy resource, the enrichment and metallogenic mechanism of sandstone-hosted uranium deposits are highly dependent on hydrogeological conditions. However, the relationship between sandstone uranium mineralization and hydrogeological conditions has not received sufficient attention yet. The pumping test, hydrogeological parameters and hydrochemical characteristics were employed to analyze the change characteristics of hydrogeological conditions and evaluate the suitability of in situ leaching (ISL). The results showed that the study area in the Inner Mongolia Autonomous Region could be divided into two groundwater subsystems, namely Quanzha-Engeriyin and Luhai-Zhendai. The latter with relatively high water richness is confined and a main ore-bearing aquifer, which consists of four orebodies. The well discharge (Q) and hydraulic conductivity (K) of Orebody II ranged from 98.40 to 867.36 m3/d and 0.25 to 5.64 m/d, respectively, indicating the aquifer is suitable for the migration, enrichment and mineralization of uranium due to relatively high permeability and fast flow rate. The water storage of Orebodies III-IV gradually deteriorated from east to west in a stepped pattern. And the highest values of Q and K in Orebodies III-IV decreased from 1200 m3/d to 120 m3/d and 1.75 m/d to 0.035 m/d, respectively, suggesting these were conducive to a reduction in and accumulation of uranium under poor hydrodynamic conditions. Additionally, the study area would be defined as three grades, including favorable, relatively favorable and unfavorable areas of ISL according to a comprehensive evaluation. This study provided a scientific basis for evaluating the possibility of in situ leaching for sandstone-hosted uranium deposit. [ABSTRACT FROM AUTHOR]

[Display omitted] The presence of radioactive U(VI) ions in sewage poses a significant threat to both the ecological environment and human health. In recent years, an electricity-driven remediation strategy has emerged as a prominent technique for the elimination of radionuclides. Specifically, the square wave transformation method is an emerging technology for electrochemical separation and enrichment of uranium. It offers several merits, such as high extraction capacity, facile recovery of products, and effective suppression of water decomposition. However, conventional electrodes typically require the utilization of adhesives, which severely restricts their adsorption performance. In this study, we fabricated a self-supporting membrane electrode based on amidoxime-functionalized Ti 3 C 2 T x MXene (TCP) for efficient extraction of uranium from radioactive solutions. The polyamidoxime (PAO) is incorporated into the interlayer of Ti 3 C 2 T x through non-covalent bonds, leading to an increase in interlayer spacing and specific surface area while also providing an abundance of specific binding sites. Notably, by applying an alternating current (AC) voltage ranging from −5 to 0 V, uranyl ions can migrate and concentrate onto TCP membrane, achieving an exceptional extraction capacity of 2809 mg/g. Further characterization confirmed that the captured uranium(VI) was reduced to U(V), and then the unstable U(V) was re-oxidized to U(VI), eventually generating Na 2 O 7 U 22 precipitates in the presence of Na+. Considering its remarkable electro-extraction performance and convenient preparation process, the TCP membrane electrode is regarded as a promising candidate for U(VI) extraction from wastewater. [ABSTRACT FROM AUTHOR]

Photocatalytic assisted uranium extraction technology is a rapidly developed technology for uranium extraction from wastewater and seawater in recent years, which can significantly improve the extraction capacity and extraction rate of uranium. However, the activity of most photocatalysts in air atmosphere is inhibited, which hinders the practical application of this technology. Based on this, this paper discusses the latest progress of photocatalytic assisted uranium extraction technology in air atmosphere, focusing on the analysis of different mechanisms and product characteristics of photocatalytic assisted uranium extraction in air atmosphere, especially the photoreaction and chemical reaction mechanism in the absence of catalyst. There are mainly two mechanisms for the photocatalysis assist uranium extraction. The first one is based on the photocatalytic reduction of U(Ⅵ) to U(Ⅳ). Under illumination, electrons and holes pairs are generated on photocatalysts, and the electrons could reduce the soluble \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} to insoluble uranium oxide(UO2). However, under air atmosphere, at the presence of oxygen, the newly formed UO2 could be oxidated back to \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} and dissolved into solution, resulting in the decrease of uranium extraction performance. Therefore, this mechanism is usually applied under inert atmosphere. Although with proper design of photocatalyst, the oxygen could be covert to \begin{document}${ · {\mathrm{O}}_2^- } $\end{document} to further reduce \begin{document}${\mathrm{UO}}_2^{2+} $\end{document}, the performance is still not comparable with that under inert atmosphere. The other recently developed photocatalysis assisted extraction mechanism is based on the convert of soluble \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} to uranium peroxide((UO2)O2•xH2O), which can work well under air atmosphere. Under light illumination, hydrogen peroxide(H2O2) can be first produced with the assist of efficient photocatalysts or the photoactivity of \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} itself. Then H2O can react with to \begin{document}${\mathrm{UO}}_2^{2+} $\end{document} form insoluble uranium peroxide. As uranium peroxide is stable under air and oxygen may contribute to the formation of H2O2, this mechanism can obtain excellent performance under air. Researchers have developed composite materials such as carbon nitride, carbon dots, graphene aerogels, and metal-organic frameworks(MOFs), which exhibit superior uranium removal performance under aerobic conditions. Besides, research on uranium extraction via photocatalysis under air is still in its infancy, and the specific reaction mechanisms may vary under different environments, necessitating further investigation. Based on the mechanism of uranium extraction via the photo-assisted transformation to uranium peroxides, the design of catalysts and uranium extraction materials will be greatly broadened. Combined with the discussion of the reaction mechanism of uranium extraction under light conditions and the design of catalyst materials, we hope to provide inspiration for researchers to develop highly efficient uranium extraction catalyst and mechanism research under air atmosphere.

This article focuses on apartheid South Africa’s nuclear sector and the regime’s attempts to cooperate with overseas energy companies to provide financial investments and crucial technologies. It highlights the connectedness of the South Africans in the global nuclear marketplace and their ability to secure technical support from Western states during the Cold War between 1953 and 1976. The article analyses the parallel negotiations with French and German firms to engage with the regime in sharing of sensitive knowledge and bargaining lucrative contracts. Using newly discovered archival records it is shown that French-German competition was at a boiling point at least twice in the 1970s. Moreover, the regime in Pretoria managed to garner enough support in the nuclear field to further the growth of its domestic industry, ultimately being capable of enriching uranium and obtaining a turnkey nuclear power reactor. The white minority government in Pretoria however failed to position itself as an important uranium supplier on a global scale, because of sanctions targeting domestic racial apartheid policies and a more robust international non-proliferation regime towards the 1980s. [ABSTRACT FROM AUTHOR]

Extracting uranium from water bodies is urgently needed whether from a waste nuclear resource utilization or a new energy exploration perspective. Herein, a novel robust hierarchical porous CAP membrane was fabricated from the nucleophilic condensation of phenolphthalein and 2,6-difluorobenzonitrile, followed by classical amidoximation and nonsolvent-induced phase separation (NIPS) methods. Fast uranium uptake kinetics with sorption equilibrium at a mere 12 h was demonstrated, and the uranium uptake capacity was found to be 499 mg g−1. The significant improvement in uranium enrichment performance was probably endowed by the outstanding hydrophilic surface and the hierarchical pores throughout the cross-sectional CAP membrane. Meanwhile, it was confirmed that the CAP molecular backbone may endure polymer degradation during amidoximation, and the amount of hydroxylamine used should be strictly controlled. The sorption mechanism was explored, and practical testing experimentally indicated the excellent desorption, reusability and selectivity properties of the CAP membrane. Overall, the easy processability, robustness and outstanding uranium sorption performance made the CAP membrane an ideal candidate for uranium enrichment from water bodies. [ABSTRACT FROM AUTHOR]

Using nuclear power to replace electricity generated from fossil fuels is an effective strategy to reduce global carbon dioxide emissions and also spurs the search for new sources of nuclear fuel. Extracting uranium from seawater has a significant reserve advantage, although its ultralow concentration presents substantial challenges. Here, inspired by the fractal structure of cardiac trabeculae on the inner surface of the heart, a uranium enrichment electrode with a superhydrophilic and uranium‐affinitive fractal surface is developed. This innovative design enhances rapid charge/ion transfer, ensures complete surface wetting, and provides numerous adsorption sites. By synergistically integrating the advantages of electric‐assisted processes and bioinspired microstructures predicated on chemical coordination principles, the electrode demonstrates a uranium adsorption capacity of 13.2 mg g−1 following a 7‐d exposure to natural seawater. This research not only demonstrates an effective strategy for the development of advanced uranium enrichment electrodes but also provides more possibilities for innovative approaches in sustainable energy technology. [ABSTRACT FROM AUTHOR]

Copyright of World Nuclear Geoscience is the property of World Nuclear Geoscience Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Leaching experiments were carried out using the Deino-ure, a genetically engineered bacterium of Deinococcus radiodurans, to investigate its impact on the migration patterns of uranium in soil. In comparison to Deino-wt and control group, the Deino-ure exhibited a decrease in leached uranium (VI) content, an increase in total soil uranium content, yielding a uranium retention rate of 60.98%. The equilibrium enrichment capacity was 53 mg/g, which was consistent with the pseudo-first-order reaction kinetic model (correlation coefficient R2 = 0.99792). This validates the impact of Deino-ure on the forms of uranium in soil, demonstrating a transformation of the free state uranium into less migratory forms. The products of uranium enrichment were mainly the hydrated calcium uranyl oxide minerals. [ABSTRACT FROM AUTHOR]

The Kunduleng granite hosts one of several significant uranium anomalies within the southern Great Xing'an Range, NE China. Whole-rock geochemistry and mineral chemistry data, along with the zircon U-Pb-Hf isotope have been used to constrain the petrogenesis of this granitic intrusion and the origin of the uranium anomaly. Microscopically, quartz, alkali-feldspar, and plagioclase are the essential mineral constituents of the granite, with minor biotite, while monazite, apatite, xenotime, and zircon are accessory minerals. Geochemically, the silica- and alkali-rich granites show a highly fractionated character with "seagull-shaped" REE patterns and significant negative anomalies of Ba and Sr, along with low Zr/Hf and Nb/Ta ratios. The granite has positive zircon εHf(t) values ranging from +12.7 to +14.5 and crustal model ages (TDM2) of 259–376 Ma, indicating a Paleozoic juvenile crustal source. Uraninite and brannerite are the main radioactive minerals responsible for the uranium anomaly within the Kunduleng granite. Uraninite presents well-developed cubic crystals and occurs as tiny inclusions in quartz and K-feldspar with magmatic characteristics (e.g., elevated ThO2, Y2O3, and REE2O3 contents and low CaO, FeO, and SiO2 concentrations). The calculated U-Th-Pb chemical ages (135.4 Ma) are contemporaneous with the U-Pb zircon age (135.4–135.6 Ma) of the granite, indicating a magmatic genesis for uraninite. The granites are highly differentiated, and extreme magmatic fractionation might be the main mechanism for the initial uranium enrichment. Brannerite is relatively less abundant and typically forms crusts on ilmenite and rutile or it cements them, representing the local redistribution and accumulation of uranium. [ABSTRACT FROM AUTHOR]

Permian alkaline granitoids are widely distributed throughout the Tien Shan Orogen and adjacent region of the southern Central Asian Orogenic Belt. However, their petrogenesis and related tectonic setting remain equivocal. A detailed mineralogical, U-Pb zircon dating, in situ elemental and Sr-Nd-Hf isotopic studies of the uranium-rich Akkulen syenite intrusion in the Northern Tien Shan of Kyrgyzstan were undertaken to better understand its magmatic processes and geodynamic evolution. Four independent oxygen barometers have shown that the oxygen fugacity of the Akkulen syenitic magma evolved from initial low fO2 (NNO +1) during magma ascent and cooling; Apatite geochemical characteristics also indicate that the magma is relatively high F (2.9–5.1 wt.%), with low Cl (0.053–0.13 wt.%) and anhydrous (<4 wt %) contents. According to whole-rock geochemical data, the syenite samples have abnormally high U (38.5–57.1 ppm) and Th (96.2–137 ppm) concentrations, we suggest that high F content and moderate oxygen fugacity are beneficial for uranium enrichment. Zircon grains from a syenite sample yielded a weighted 206Pb/238U age of 283.5 ± 2.6 Ma. The intrusion has an A-type granite affinity with high alkali (Na2O + K2O) contents and Fe/(Fe+Mg) ratios, high LREE/HREE (~5), and low Sr, Ba, and Eu contents. They have negative εNd(t) (−5.2 to −3.6) values with Mesoproterozoic two-stage model ages (T DM2 = 1.35–1.47 Ga), and variable εHf(t) values (−4.6 to +2.4) with Mesoproterozoic two-stage model ages (T DM2 = 1. 2–1.59 Ga), which suggest these rock derivations from the relatively old crustal with minor contribution from juvenile crustal melts. In comparison with regional available dataset, we propose that the alkaline Permian granitoids in Kyrgyz Northern Tien Shan may have been originated from large-scale partial melting of Mesoproterozoic metamorphic basement with minor juvenile crustal material in a post-extensional setting. In contrast, the Early Permian granitoid magmatism in the Tarim Craton may have been caused by the partial melting of Neoproterozoic basement rocks associated with Permian mantle plume activities. [ABSTRACT FROM AUTHOR]

2D lamellar membranes (2DLMs) are used for efficient desalination and nanofiltration. However, weak interactions between adjacent stacked nanosheets result in susceptibility to swelling that limits practical applicability. Inspired by the super adhesion of multi-point suction cups on octopus tentacles, a 2DLM is constructed from Ti3 C2 Tx MXene supported by the macrocyclic "multi-point" molecule cucurbit[5]uril (CB5) and demonstrated for nanofiltration of methyl blue (MB) and enrichment of uranyl carbonate. Experimental results and density functional theory calculations indicate that CB5 rivets to the surface of the nanoflakes through strong stable interactions between its multiple binding sites and surface hydroxyl functional groups on MXene nanosheets. This novel 2DLM exhibits excellent nanofiltration performance (69 L m-2 h-1 bar-1 permeance with 93.6% rejection for MB) and can be recycled at least 30 times without significant degradation. The 2DLM exhibits excellent swelling resistance at high salinity, with a demonstration of selective enrichment of uranyl carbonate from artificial water and natural seawater. The results provide a new strategy for constructing highly stable 2DLMs with interlayer spacing controllable from sub-nano to nanometer scales, for size-selective sieving of molecules and ions, high-efficiency nanofiltration, and other applications.

AbstractThis paper presents a numerical study on the condensation process of uranium hexafluoride (UF6) in the supply and extraction system of a uranium enrichment plant. The numerical study was conducted using a standard UF6 receiving container with a nominal diameter of 127 mm and a volume of 8L under constant temperature boundary conditions. A phase change heat and mass transfer model for the desublimation process of uranium hexafluoride gas was established, and this model was combined with the Euler two fluid model to predict the distribution of key parameters such as temperature, pressure, and volume fraction of each phase during the UF6 cooling process, as well as the gas flow characteristics inside the container. In addition, this study also investigated the influence of various factors on the cooling rate. The research results indicated that UF6 gas initially condensed on the container wall and gradually diffused inward, with the highest solid density observed on the wall. Furthermore, increasing the inlet gas temperature, inlet mass flow rate, and reducing the cooling temperature, initial pressure inside the container could all enhance the desublimation rate to various degrees. The optimization plan proposed based on the above influencing factors could increase the yield of UF6 solid by 64.20% in 2 h, compared to the basic operating conditions. [ABSTRACT FROM AUTHOR]

Purpose: Several studies using life cycle assessment (LCA) have highlighted nuclear electricity's possible role as a low carbon-emitting electricity source. But the variability of results has also been questioned by several published LCA reviews, the latest identified dating back from 2016. This article aims at assessing whether new developments and knowledge confirm this statement. Methods: Meta-analysis is a systematic review approach that allows to assess this variability. It was applied in this study to measure and understand the dynamics behind the greenhouse gases (GHG) emissions of nuclear electricity in a life cycle perspective. From 114 publications identified since 2012, 22 primary studies were selected and analysed to provide a meta-database of 63 estimations of greenhouse gases (GHG) per kWh generated. A descriptive analysis of the meta-database provided a status of the art on the topic in terms of approaches adopted, data sources, etc. Additional data exploitation using boxplot graphs was performed to assess the dispersion and variability of the results around these figures depending on several factors such as extraction mining technique and energy demand, enrichment technology used, reactor's size, and type of LCA practitioners. Results and discussion: The life cycle GHG emissions of nuclear electricity found with the meta-analysis were 3.09 g CO2 eq./kWh (min), 6.36 g CO2 eq./kWh (median), 12.4 g CO2 eq./kWh (average excluding extrema), and 43.2 g CO2 eq./kWh (max), although extremum values were also identified at 53.4, 60.0, and one outlier, based on theoretical scenarios. Using principal component analysis (PCA), the two most influential variables of the environmental performance of nuclear electricity were identified: GHG emissions intensity of the electricity consumed during the enrichment of uranium and energy demand for the extraction of uranium ore. Conclusions: Finally, the contributions of this meta-analysis to current knowledge on the GHG emissions intensity of nuclear electricity generation systems were discussed, including life cycle step breakdown, data gaps, limits, and uncertainties associated to the back end and reactor activities. Among the main areas for improvement for future LCA studies, the study helped identify a need for consolidated industrial data along with harmonised practices regarding system boundary definition. [ABSTRACT FROM AUTHOR]

Thermodiffusion is the migration of a species due to a temperature gradient and is the driving phenomenon in many applications ranging from early cancer detection to uranium enrichment. Molecular dynamics (MD) simulations can be a useful tool for exploring the rather complex thermodiffusive behavior of species, such as proteins and ions. However, current MD models of thermodiffusion in aqueous ionic solutions struggle to quantitatively predict the Soret coefficient, which indicates the magnitude and direction of species migration under a temperature gradient. In this work, we aim to improve the accuracy of MD thermodiffusion models by assessing how well different water models can recreate thermodiffusion in a benchmark aqueous NaCl solution. We tested four of the best available rigid non-polarizable water models (TIP3P-FB, TIP4P-FB, OPC3, and OPC) and the commonly used TIP3P and SPC/E water models for their ability to predict the inversion temperature and Soret coefficient in 0.5, 2, and 4M aqueous NaCl solutions. Each water model predicted a noticeably different ion distribution yielding different inversion temperatures and magnitudes of the Soret coefficient. By comparing the modeled Soret coefficients to published experimental values, we determine TIP3P-FB to be the water model that best recreates thermodiffusion in aqueous NaCl solutions. Our findings can aid future works in selecting the most accurate rigid non-polarizable water model, including water and ion parameters for investigating thermodiffusion through MD simulations. [ABSTRACT FROM AUTHOR]

Gamma-ray spectrometry uses the X-ray and characteristic gamma-rays associated with 235U, 238U and their decay daughters in uranium samples for analytical calculations to achieve rapid and timely nondestructive detection of sample enrichment. As one of the methods for determining uranium enrichment by gamma-ray spectrometry, the relative detection efficiency calibration method has been commonly used in nuclear safeguards on-site inspections to measure the enrichment of samples. Its core is the relative efficiency self-calibration using multiple characteristic gamma-rays of 235U in the low energy region of 120-186 keV and the characteristic gamma-rays of 238U decay daughter 234Pam in the high energy region of 258-1 001 keV. In this paper, the relative detection efficiency of the detector was obtained using the Monte Carlo method based on the actual characterization results of a coaxial-type high-purity germanium detector, the fitting results and errors of three different types of fitting formulas in different energy region ranges were investigated. A comprehensive analysis of the effect of the fitting formulas from the low-energy region to the medium-high energy region on the relative efficiency of the characteristic peaks shows the logarithmic transfer series function performs better results among the three fitting formulas. During the on-site inspection, the aluminum and stainless steel shieldings of the sample and the self-absorption of the uranium dioxide and uranium hexafluoride body source have a certain impact on the relative detection efficiency curve. The specific influence and changing trend of these factors on the curve were studied, and the fitted curves for thicker shields and strong self-absorption were then corrected by adding correction factors. The results show that after adding the correction factor, the fitting error of the relative detection efficiency curve for different shielding and self-absorption cases is reduced from 2%-4% to 1%-2% at the characteristic peaks used for enrichment calculation. The results of this paper have reference value for the nondestructive assay of uranium enrichment in the on-site inspection of nuclear safeguards.

Uranium hexafluoride (UF6) is a commonly utilized material feedstock in uranium enrichment processes due to its high vapor pressure and ease of sublimation. When exposed to air, UF6 undergoes spontaneous hydrolysis to form uranyl fluoride (UO2F2) particulates which are utilized for the detection of undeclared nuclear activities by nuclear safeguards organizations. The kinetics of the hydrolysis reaction and how they relate to particle morphology of the product are still debated in the literature. Here, we report the direct, in situ observation of UF6 reaction intermediates by cooling the reaction to cryogenic temperatures to significantly reduce the rate of hydrolysis. The reaction is then observable by Fourier transform infrared (FTIR) spectroscopy. The conversion of UF6 to UOF4 is observed as well as several other bands associated with possible long lived intermediate complexes. Chemometrics are used to further elucidate the reaction pathway from UF6 to UO2F2. [ABSTRACT FROM AUTHOR]

The paper is concerned with the use of uranium wastes after purification of regenerated fuel from 232U in a molten salt reactor (MSR) in application to minor actinide (MA) burning. The comparison of the uranium and plutonium loadings in an MSR was performed. The results of calculations show that the uranium loading in an MSR is a possible option that has a number of potential advantages: it allows for a higher rate of MA burning during the initial period of MSR operation with approximately the same burnup efficiency and increases the effective fraction of delayed neutrons. The presented calculations are of an approximate nature and first of all show the possibility of effective use of uranium from the waste stream of the enrichment cascade as a fissile material. [ABSTRACT FROM AUTHOR]

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In 1972, before shipping natural uranium to the USSR for enrichment operations in 235 U, the analysts at Pierrelatte plant noted a slight deficit in 235U: 0.7171 instead of 0.7202. The Direction des Productions of the CEA launched a vast campaign of analyses for the different mines exploited, at all stages of the elaboration of uranium; for this analysis campaign, the Direction des Productions relied on the analytical laboratory of the Pierrelatte plant and on the Central Analytical Laboratory of the CEA where I was in charge of analyses by mass spectrometry. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The materials characterization based on gamma measurements is one of the main features for verifying the radioactive materials for safeguards purposes. This work focuses on the optimization approach in order to find solutions that include some influence parameters, which should be taken into consideration during measurements. The considered samples in our work are certified reference nuclear materials of chemical composition (U3O8) with different enrichment ratios ranging from 0.31 wt.% to 4.46 wt.%. The gamma spectrometer based on a planar high-purity germanium detector of high-resolution was used in the current study. The study of various setups was experimentally carried out for different cans at different positions for different energy lines. The verified parameters influencing the characterization of the measured samples have been estimated. This approach for the measurement setup of the measured gamma spectra has been successfully explored to be very affected by different parameters such as the source to detector position and the various enrichment ratios. Consequently, the verified and characterized samples could be estimated based on this optimization approach. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The natural radioactivity data revealed that eU reached up to 157.4, 1625 and 178 ppm in microgranite and dolerite dikes as well as japer vein, respectively, whereas the two-mica granite possesses the higher eTh-contents up to 53.8 ppm. Mineralogically, the two-mica granite is enriched in thorite, brockite and uranothorite, whereas uraninite and coffinite are recorded in dolerite, and the latter one is recorded in microgranite, bostonite and jasper. Primary uranium minerals as uraninite and coffinite could be a source for uranium enrichment and the formation of secondary uranium mineralisation. Uranium mobilisation was active towards the two perpendicular shear zones having NNW-SSE and ENE-WSW rejuvenated trends. Successive hydrothermal alterations play their role in the formation of uranium ore deposits to be trapped in post-granitic dikes. [ABSTRACT FROM AUTHOR]

Purification of nuclear wastewater is urgently needed due to the radioactivity and toxicity of uranium. In this work, a novel modified polyamide acid membrane adsorbent (GPAA) was facilely fabricated via a Schiff base reaction between glutaraldehyde and an amino terminated polyamide acid oligomer (NPAA), followed by nonsolvent induced phase separation (NIPS) treatment at room temperature. The resultant GPAA membrane has a hydrophilic surface and a porous structure with a low water contact angle of 29°, and the GPAA membrane exhibited a high surface area of 105 m2 g−1 with a multi-scale mesoporous feature. Fast uranium adsorption dynamics of the GPAA membrane were observed with adsorption equilibrium at 16 h at 20 ppm uranium initial concentration. The maximum uranium adsorption capacity was found to be 413 mg g−1 with the chemisorption dominating the uranium enrichment process. Importantly, the resultant GPAA membrane demonstrated an ultrahigh uranium uptake of 350 mg g−1 in acidic aqueous solution (pH = 4), ascribing to the hydrophilic carboxyl and the low isoelectric point membrane surface. Meanwhile, the GPAA membrane manifested excellent acid and salt resistance and good selectivity towards common interfering ions. Furthermore, no apparent structural destruction was observed on the membrane after a three-cycle adsorption–desorption practice. Consequently, the sample preparation techniques and the outstanding adsorption performance made the GPAA membrane an ideal adsorbent candidate for uranium enrichment and separation, especially in acidic wastewater. [ABSTRACT FROM AUTHOR]

Through a systematic scanning of 235U and 238U emission lines between 280 nm and 745 nm, the optimal emission line for direct gaseous uranium hexafluoride (UF6) enrichment assay using laser-induced breakdown spectroscopy (LIBS) was found. Screening for spectral features that are potentially useful for U isotopic analysis was gauged from the magnitude of the 235U–238U isotopic shift and the signal-to-background ratio of the emission line through a parameter termed ΔSBR 235U–238U. The ΔSBR spectrum shows peaks at wavelength positions where there are strong lines with significant 235U–238U shifts. The screening identified 13 spectral-window candidates, which were down selected based on their overall accuracy in predicting the 235U enrichment of three UF6 samples of natural (0.720 atom% 235U) and low-enriched (4.675 atom% and 9.157 atom% 235U) grades. The U(I) 646.498 nm emission line, with a determined 235U–238U isotopic shift of −17.7 pm, was found to be the optimal spectral window for direct UF6 enrichment assay. The root mean square error for enrichment assays on the three natural and low-enriched UF6 samples, with each sample measured in six replicates, was 0.31% in absolute 235U content. Each measurement comprised LIBS signals accumulated from 3000 laser shots. The analytical bias and precision were better than 0.5% and 0.3%, respectively, in absolute [235U/(235U + 238U)] ratios. Specific for the two low-enriched UF6 samples, the relative standard deviations from six replicated measurements were around 2%. Graphical Abstract This is a visual representation of the abstract. [ABSTRACT FROM AUTHOR]

The Mangbang Formation in the Hanbazhai area is part of the uranium ore field in the Longchuanjiang Basin, China. Uraniferous sandstones from this formation are examined in this study. The type and mode of occurrence of uranium are investigated in detail using an experiment for the sequential extraction of uranium, as well as an electron probe, scanning electron microscopy, and energy spectrum analyses. The sequential extraction experiment indicates that the proportion of uranium minerals is significantly greater than that of the adsorbed uranium in the samples, with the latter being largely present in framboidal pyrites and clay minerals. The results show that these uranium minerals are mainly composed of coffinite and uranium phosphosilicates, which closely coexist with framboidal pyrites, carbon debris, feldspar minerals, and clay minerals. The discovery of coffinite and uranium phosphosilicates is discussed in context with their symbiotic relationship and geochemical environment. Uraniferous sandstones are considered to have undergone at least two stages of mineralization: the sedimentary–diagenetic stage and the later uranium enrichment by fluid. The geochemical environment of the sedimentary–diagenetic stage is generally a sulfide-reducing environment, and the later fluids are rich in U, Si, P, and Y. [ABSTRACT FROM AUTHOR]

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The materials characterization based on gamma measurements is one of the main features for verifying the radioactive materials for safeguards purposes. This work focuses on the optimization approach in order to find solutions that include some influence parameters, which should be taken into consideration during measurements. The considered samples in our work are certified reference nuclear materials of chemical composition (U3O8) with different enrichment ratios ranging from 0.31 wt.% to 4.46 wt.%. The gamma spectrometer based on a planar high-purity germanium detector of high-resolution was used in the current study. The study of various setups was experimentally carried out for different cans at different positions for different energy lines. The verified parameters influencing the characterization of the measured samples have been estimated. This approach for the measurement setup of the measured gamma spectra has been successfully explored to be very affected by different parameters such as the source to detector position and the various enrichment ratios. Consequently, the verified and characterized samples could be estimated based on this optimization approach.