field-scale uranium reactive: Topics by WorldWideScience.org

Sample records for field-scale uranium reactive

Post Audit of a Field Scale Reactive Transport Model of Uranium at a Former Mill Site

Science.gov (United States)

Curtis, G. P.

2015-12-01

Reactive transport of hexavalent uranium (U(VI)) in a shallow alluvial aquifer at a former uranium mill tailings site near Naturita CO has been monitored for nearly 30 years by the US Department of Energy and the US Geological Survey. Groundwater at the site has high concentrations of chloride, alkalinity and U(VI) as a owing to ore processing at the site from 1941 to 1974. We previously calibrated a multicomponent reactive transport model to data collected at the site from 1986 to 2001. A two dimensional nonreactive transport model used a uniform hydraulic conductivity which was estimated from observed chloride concentrations and tritium helium age dates. A reactive transport model for the 2km long site was developed by including an equilibrium U(VI) surface complexation model calibrated to laboratory data and calcite equilibrium. The calibrated model reproduced both nonreactive tracers as well as the observed U(VI), pH and alkalinity. Forward simulations for the period 2002-2015 conducted with the calibrated model predict significantly faster natural attenuation of U(VI) concentrations than has been observed by the persistent high U(VI) concentrations at the site. Alternative modeling approaches are being evaluating evaluated using recent data to determine if the persistence can be explained by multirate mass transfer models developed from experimental observations at the column scale(~0.2m), the laboratory tank scale (~2m), the field tracer test scale (~1-4m) or geophysical observation scale (~1-5m). Results of this comparison should provide insight into the persistence of U(VI) plumes and improved management options.
Laboratory and field scale demonstration of reactive barrier systems

International Nuclear Information System (INIS)

Dwyer, B.P.; Marozas, D.C.; Cantrell, K.; Stewart, W.

1996-10-01

In an effort to devise a cost efficient technology for remediation of uranium contaminated groundwater, the Department of Energy's Uranium Mill Tailings Remedial Action (DOE-UMTRA) Program through Sandia National Laboratories (SNL) fabricated a pilot scale research project utilizing reactive subsurface barriers at an UMTRA site in Durango, Colorado. A reactive subsurface barrier is produced by placing a reactant material (in this experiment, metallic iron) in the flow path of the contaminated groundwater. The reactive media then removes and/or transforms the contaminant(s) to regulatory acceptable levels. Experimental design and results are discussed with regard to other potential applications of reactive barrier remediation strategies at other sites with contaminated groundwater problems
Final Report, University of California Merced: Uranium and strontium fate in waste-weathered sediments: Scaling of molecular processes to predict reactive transport (DE-SC0007095)

Energy Technology Data Exchange (ETDEWEB)

O' Day, Peggy Anne [University of California Merced; Chorover, Jon [University of Arizona; Steefel, Carl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mueller, Karl [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Um, Wooyong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-06-30

Objectives of the Project: 1. Determine the process coupling that occurs between mineral transformation and contaminant (U and Sr) speciation in acid-uranium waste weathered Hanford sediments. 2. Establish linkages between molecular-scale contaminant speciation and meso-scale contaminant lability, release and reactive transport. 3. Make conjunctive use of molecular- to bench-scale data to constrain the development of a mechanistic, reactive transport model that includes coupling of contaminant sorption-desorption and mineral transformation reactions. Hypotheses Tested: Uranium and strontium speciation in legacy sediments from the U-8 and U-12 Crib sites can be reproduced in bench-scale weathering experiments conducted on unimpacted Hanford sediments from the same formations; Reactive transport modeling of future uranium and strontium releases from the vadose zone of acid-waste weathered sediments can be effectively constrained by combining molecular-scale information on contaminant bonding environment with grain-scale information on contaminant phase partitioning, and meso-scale kinetic data on contaminant release from the waste-weathered porous media; Although field contamination and laboratory experiments differ in their diagenetic time scales (decades for field vs. months to years for lab), sediment dissolution, neophase nucleation, and crystal growth reactions that occur during the initial disequilibrium induced by waste-sediment interaction leave a strong imprint that persists over subsequent longer-term equilibration time scales and, therefore, give rise to long-term memory effects. Enabling Capabilities Developed: Our team developed an iterative measure-model approach that is broadly applicable to elucidate the mechanistic underpinnings of reactive contaminant transport in geomedia subject to active weathering.
System-Scale Model of Aquifer, Vadose Zone, and River Interactions for the Hanford 300 Area - Application to Uranium Reactive Transport

Energy Technology Data Exchange (ETDEWEB)

Rockhold, Mark L.; Bacon, Diana H.; Freedman, Vicky L.; Parker, Kyle R.; Waichler, Scott R.; Williams, Mark D.

2013-10-01

This report represents a synthesis and integration of basic and applied research into a system-scale model of the Hanford 300 Area groundwater uranium plume, supported by the U.S. Department of Energy’s Richland Operations (DOE-RL) office. The report integrates research findings and data from DOE Office of Science (DOE-SC), Office of Environmental Management (DOE-EM), and DOE-RL projects, and from the site remediation and closure contractor, Washington Closure Hanford, LLC (WCH). The three-dimensional, system-scale model addresses water flow and reactive transport of uranium for the coupled vadose zone, unconfined aquifer, and Columbia River shoreline of the Hanford 300 Area. The system-scale model of the 300 Area was developed to be a decision-support tool to evaluate processes of the total system affecting the groundwater uranium plume. The model can also be used to address “what if” questions regarding different remediation endpoints, and to assist in design and evaluation of field remediation efforts. For example, the proposed cleanup plan for the Hanford 300 Area includes removal, treatment, and disposal of contaminated sediments from known waste sites, enhanced attenuation of uranium hot spots in the vadose and periodically rewetted zone, and continued monitoring of groundwater with institutional controls. Illustrative simulations of polyphosphate infiltration were performed to demonstrate the ability of the system-scale model to address these types of questions. The use of this model in conjunction with continued field monitoring is expected to provide a rigorous basis for developing operational strategies for field remediation and for defining defensible remediation endpoints.
Variably Saturated Flow and Multicomponent Biogeochemical Reactive Transport Modeling of a Uranium Bioremediation Field Experiment

International Nuclear Information System (INIS)

Yabusaki, Steven B.; Fang, Yilin; Williams, Kenneth H.; Murray, Christopher J.; Ward, Anderson L.; Dayvault, Richard; Waichler, Scott R.; Newcomer, Darrell R.; Spane, Frank A.; Long, Philip E.

2011-01-01

Field experiments at a former uranium mill tailings site have identified the potential for stimulating indigenous bacteria to catalyze the conversion of aqueous uranium in the +6 oxidation state to immobile solid-associated uranium in the +4 oxidation state. This effectively removes uranium from solution resulting in groundwater concentrations below actionable standards. Three-dimensional, coupled variably-saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport rates and biogeochemical reaction rates that determine the location and magnitude of key reaction products. A comprehensive reaction network, developed largely through previous 1-D modeling studies, was used to simulate the impacts on uranium behavior of pulsed acetate amendment, seasonal water table variation, spatially-variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. A principal challenge is the mechanistic representation of biologically-mediated terminal electron acceptor process (TEAP) reactions whose products significantly alter geochemical controls on uranium mobility through increases in pH, alkalinity, exchangeable cations, and highly reactive reduction products. In general, these simulations of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado confirmed previously identified behaviors including (1) initial dominance by iron reducing bacteria that concomitantly reduce aqueous U(VI), (2) sulfate reducing bacteria that become dominant after ∼30 days and outcompete iron reducers for the acetate electron donor, (3) continuing iron-reducer activity and U(VI) bioreduction during dominantly sulfate reducing conditions, and (4) lower apparent U(VI) removal from groundwater during dominantly sulfate reducing conditions. New knowledge on simultaneously active metal and sulfate reducers has been
Using proteomic data to assess a genome-scale "in silico" model of metal reducing bacteria in the simulation of field-scale uranium bioremediation

Science.gov (United States)

Yabusaki, S.; Fang, Y.; Wilkins, M. J.; Long, P.; Rifle IFRC Science Team

2011-12-01

A series of field experiments in a shallow alluvial aquifer at a former uranium mill tailings site have demonstrated that indigenous bacteria can be stimulated with acetate to catalyze the conversion of hexavalent uranium in a groundwater plume to immobile solid-associated uranium in the +4 oxidation state. While this bioreduction of uranium has been shown to lower groundwater concentrations below actionable standards, a viable remediation methodology will need a mechanistic, predictive and quantitative understanding of the microbially-mediated reactions that catalyze the reduction of uranium in the context of site-specific processes, properties, and conditions. At the Rifle IFRC site, we are investigating the impacts on uranium behavior of pulsed acetate amendment, acetate-oxidizing iron and sulfate reducing bacteria, seasonal water table variation, spatially-variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. The simulation of three-dimensional, variably saturated flow and biogeochemical reactive transport during a uranium bioremediation field experiment includes a genome-scale in silico model of Geobacter sp. to represent the Fe(III) terminal electron accepting process (TEAP). The Geobacter in silico model of cell-scale physiological metabolic pathways is comprised of hundreds of intra-cellular and environmental exchange reactions. One advantage of this approach is that the TEAP reaction stoichiometry and rate are now functions of the metabolic status of the microorganism. The linkage of in silico model reactions to specific Geobacter proteins has enabled the use of groundwater proteomic analyses to assess the accuracy of the model under evolving hydrologic and biogeochemical conditions. In this case, the largest predicted fluxes through in silico model reactions generally correspond to high abundances of proteins linked to those reactions (e.g. the condensation reaction catalyzed by the protein
Building Conceptual Models of Field-Scale Uranium Reactive Transport in a Dynamic Vadose Zone-Aquifer-River System

International Nuclear Information System (INIS)

Yabusaki, Steven B.; Fang, Yilin; Waichler, Scott R.

2008-01-01

Subsurface simulation is being used to build, test, and couple conceptual process models to better understand controls on a 0.4 km by 1.0 km uranium plume that has persisted above the drinking water standard in the groundwater of the Hanford 300 Area over the last 15 years. At this site, uranium-contaminated sediments in the vadose zone and aquifer are subject to significant variations in water levels and velocities driven by the diurnal, weekly, seasonal, and episodic Columbia River stage dynamics. Groundwater flow reversals typically occur twice a day with significant exchange of river water and groundwater in the near-river aquifer. Mixing of the dilute solution chemistry of the river with the groundwater complicates the uranium sorption behavior as the mobility of U(VI) has been shown experimentally to be a function of pH, carbonate, calcium, and uranium. Furthermore, uranium mass transfer between solid and aqueous phases has been observed to be rate-limited in the context of the high groundwater velocities resulting from the river stage fluctuations and the highly transmissive sediments (hydraulic conductivities ∼1500 m/d). One- and two-dimensional vertical cross-sectional simulations of variably-saturated flow and reactive transport, based on laboratory-derived models of distributed rate mass transfer and equilibrium multicomponent surface complexation, are used to assess uranium transport at the dynamic vadose zone aquifer interface as well as changes to uranium mobility due to incursions of river water into the aquifer
Mechanistically-Based Field-Scale Models of Uranium Biogeochemistry from Upscaling Pore-Scale Experiments and Models

International Nuclear Information System (INIS)

Tim Scheibe; Alexandre Tartakovsky; Brian Wood; Joe Seymour

2007-01-01

Effective environmental management of DOE sites requires reliable prediction of reactive transport phenomena. A central issue in prediction of subsurface reactive transport is the impact of multiscale physical, chemical, and biological heterogeneity. Heterogeneity manifests itself through incomplete mixing of reactants at scales below those at which concentrations are explicitly defined (i.e., the numerical grid scale). This results in a mismatch between simulated reaction processes (formulated in terms of average concentrations) and actual processes (controlled by local concentrations). At the field scale, this results in apparent scale-dependence of model parameters and inability to utilize laboratory parameters in field models. Accordingly, most field modeling efforts are restricted to empirical estimation of model parameters by fitting to field observations, which renders extrapolation of model predictions beyond fitted conditions unreliable. The objective of this project is to develop a theoretical and computational framework for (1) connecting models of coupled reactive transport from pore-scale processes to field-scale bioremediation through a hierarchy of models that maintain crucial information from the smaller scales at the larger scales; and (2) quantifying the uncertainty that is introduced by both the upscaling process and uncertainty in physical parameters. One of the challenges of addressing scale-dependent effects of coupled processes in heterogeneous porous media is the problem-specificity of solutions. Much effort has been aimed at developing generalized scaling laws or theories, but these require restrictive assumptions that render them ineffective in many real problems. We propose instead an approach that applies physical and numerical experiments at small scales (specifically the pore scale) to a selected model system in order to identify the scaling approach appropriate to that type of problem. Although the results of such studies will
Mechanistically-Based Field-Scale Models of Uranium Biogeochemistry from Upscaling Pore-Scale Experiments and Models

Energy Technology Data Exchange (ETDEWEB)

Tim Scheibe; Alexandre Tartakovsky; Brian Wood; Joe Seymour

2007-04-19

Effective environmental management of DOE sites requires reliable prediction of reactive transport phenomena. A central issue in prediction of subsurface reactive transport is the impact of multiscale physical, chemical, and biological heterogeneity. Heterogeneity manifests itself through incomplete mixing of reactants at scales below those at which concentrations are explicitly defined (i.e., the numerical grid scale). This results in a mismatch between simulated reaction processes (formulated in terms of average concentrations) and actual processes (controlled by local concentrations). At the field scale, this results in apparent scale-dependence of model parameters and inability to utilize laboratory parameters in field models. Accordingly, most field modeling efforts are restricted to empirical estimation of model parameters by fitting to field observations, which renders extrapolation of model predictions beyond fitted conditions unreliable. The objective of this project is to develop a theoretical and computational framework for (1) connecting models of coupled reactive transport from pore-scale processes to field-scale bioremediation through a hierarchy of models that maintain crucial information from the smaller scales at the larger scales; and (2) quantifying the uncertainty that is introduced by both the upscaling process and uncertainty in physical parameters. One of the challenges of addressing scale-dependent effects of coupled processes in heterogeneous porous media is the problem-specificity of solutions. Much effort has been aimed at developing generalized scaling laws or theories, but these require restrictive assumptions that render them ineffective in many real problems. We propose instead an approach that applies physical and numerical experiments at small scales (specifically the pore scale) to a selected model system in order to identify the scaling approach appropriate to that type of problem. Although the results of such studies will
Reactivity of Uranium and Ferrous Iron with Natural Iron Oxyhydroxides.

Science.gov (United States)

Stewart, Brandy D; Cismasu, A Cristina; Williams, Kenneth H; Peyton, Brent M; Nico, Peter S

2015-09-01

Determining key reaction pathways involving uranium and iron oxyhydroxides under oxic and anoxic conditions is essential for understanding uranium mobility as well as other iron oxyhydroxide mediated processes, particularly near redox boundaries where redox conditions change rapidly in time and space. Here we examine the reactivity of a ferrihydrite-rich sediment from a surface seep adjacent to a redox boundary at the Rifle, Colorado field site. Iron(II)-sediment incubation experiments indicate that the natural ferrihydrite fraction of the sediment is not susceptible to reductive transformation under conditions that trigger significant mineralogical transformations of synthetic ferrihydrite. No measurable Fe(II)-promoted transformation was observed when the Rifle sediment was exposed to 30 mM Fe(II) for up to 2 weeks. Incubation of the Rifle sediment with 3 mM Fe(II) and 0.2 mM U(VI) for 15 days shows no measurable incorporation of U(VI) into the mineral structure or reduction of U(VI) to U(IV). Results indicate a significantly decreased reactivity of naturally occurring Fe oxyhydroxides as compared to synthetic minerals, likely due to the association of impurities (e.g., Si, organic matter), with implications for the mobility and bioavailability of uranium and other associated species in field environments.
Bioimmobilization of uranium-practical tools for field applications

Science.gov (United States)

Istok, J. D.

2011-12-01

Extensive laboratory and field research has conclusively demonstrated that it is possible to stimulate indigenous microbial activity and create conditions favorable for the reductive precipitation of uranium from groundwater, reducing aqueous U concentrations below regulatory levels. A wide variety of complex and coupled biogeochemical processes have been identified and specific reaction mechanisms and parameters have been quantified for a variety of experimental systems including pure, mixed, and natural microbial cultures, and single mineral, artificial, and natural sediments, and groundwater aquifers at scales ranging from very small (10s nm) to very large (10s m). Multicomponent coupled reactive transport models have also been developed to simulate various aspects of this process in 3D heterogeneous environments. Nevertheless, full-scale application of reductive bioimmobilization of uranium (and other radionuclides and metals) remains problematical because of the technical and logistical difficulties in creating and maintaining reducing environment in the many large U contaminated groundwater aquifers currently under aerobic and oxidizing conditions and often containing high concentrations of competing and more energetically favorable electron acceptors (esp. nitrate). This talk will discuss how simple tools, including small-scale in situ testing and geochemical reaction path modeling, can be used to quickly assess the feasibility of applying bioimmobilization to remediate U contaminated groundwater aquifers and provide data needed for full-scale design.
Obtaining of uranium tetrafluoride UF4 by electrodialysis reactive from uranium concentrates

International Nuclear Information System (INIS)

Munoz Lay, Danny Mauricio

2014-01-01

The generation of uranium fuels has always been a topic worldwide. The uranium fuel manufacturing base is made under very strict parameters of radiological and industrial safety, being a stage called 'nuclear fuel cycle'. In Chile, it is done constant research for fuels. This report focuses primarily on participating in such research; mainly in the production of uranium tetrafluoride (UF 4 ) .The tetrafluoride production is very crucial for the nuclear fuel industry. Its production varies from precipitation in stirred conditions to electrolysis in mercury. However, both processes has shortcomings either in performance and environmental pollution, which is why it is proposed a new method of production based on a friendly process to the environment and easier to operate, the reactive electrodialysis (RED). Electrodialysis is a hybrid reactive process of separation by membranes, cationic and / or anionic, namely, ionic species. In the process, ions are induced to move by an electric potential applied and separated by these membranes, a highly selective physical barrier which allows passage of ions with certain charge, and prevents the passage of oppositely charged ions. And in turn, it is reactive because it forces a chemical reaction, redox, to obtain uranium tetrafluoride (UF 4 ). The results of these experiments show that by reactive electrodialysis, NH 4 UF 5 deposits were obtained. However, calcinating the NH 4 UF 5 to 450 o C, it decomposes to obtain uranium tetrafluoride, UF 4 . The best working conditions were obtained with an electric current of 0.5 (A), 41 o C and a flow of 16 (ml / s) of the electrolyte. It was possible to obtain 5,995 (g) to 3 (h), giving a current efficiency of 71.42%. In turn, working at high temperatures and flow recirculation is possible to operate with a potential difference of 1.7 (V)
Redox reactivity and coordination chemistry of uranium

International Nuclear Information System (INIS)

Nocton, G.

2009-09-01

The study and the understanding of actinides chemistry have important implications in the nuclear field both for the development of new actinides materials and the retreatment of the nuclear wastes. One of the major issues in that chemistry is that the actinides elements are known to undergo redox reaction and to form assemblies of different size and different topologies. In that context uranium can be a good model of the heavier radioelement because it is much less radioactive. So, this work concerns the synthesis and the study of the spectroscopy and the magnetic properties of several uranium based polymetallic assemblies synthesized by taking advantage of the redox properties and the coordination chemistry of uranium. The hydrolysis reactivity of trivalent uranium has been studied in absence of sterically hindered ligands and led to the synthesis of oxo/hydroxo uranium assemblies with different sizes by changing the starting complex or the reaction conditions. By following the same strategy, the controlled oxidation of trivalent uranium complexes led to an original azido/nitrido uranium complex. The coordination chemistry of the pentavalent uranyl polymer {[UO 2 py 5 ][KI 2 py 3 ]} n has also been studied with different ligand and in different conditions and led to several cation-cation complexes for which the stability is sufficient for studying there dismutation by proton NMR. By changing the ancillary ligands stable monomeric complexes of pentavalent uranyl complexes were also obtained. The magnetic properties of all the complexes, monomers and polymetallic complexes were studied and an antiferromagnetic coupling was observed for the cation-cation pentavalent uranyl dimer [UO 2 (dbm) 2 (K 18 C 6 )] 2 . (author)
Upscaling of Long-Term U9VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models

Energy Technology Data Exchange (ETDEWEB)

Andy Miller

2009-01-25

Environmental systems exhibit a range of complexities which exist at a range of length and mass scales. Within the realm of radionuclide fate and transport, much work has been focused on understanding pore scale processes where complexity can be reduced to a simplified system. In describing larger scale behavior, the results from these simplified systems must be combined to create a theory of the whole. This process can be quite complex, and lead to models which lack transparency. The underlying assumption of this approach is that complex systems will exhibit complex behavior, requiring a complex system of equations to describe behavior. This assumption has never been tested. The goal of the experiments presented is to ask the question: Do increasingly complex systems show increasingly complex behavior? Three experimental tanks at the intermediate scale (Tank 1: 2.4m x 1.2m x 7.6cm, Tank 2: 2.4m x 0.61m x 7.6cm, Tank 3: 2.4m x 0.61m x 0.61m (LxHxW)) have been completed. These tanks were packed with various physical orientations of different particle sizes of a uranium contaminated sediment from a former uranium mill near Naturita, Colorado. Steady state water flow was induced across the tanks using constant head boundaries. Pore water was removed from within the flow domain through sampling ports/wells; effluent samples were also taken. Each sample was analyzed for a variety of analytes relating to the solubility and transport of uranium. Flow fields were characterized using inert tracers and direct measurements of pressure head. The results show that although there is a wide range of chemical variability within the flow domain of the tank, the effluent uranium behavior is simple enough to be described using a variety of conceptual models. Thus, although there is a wide range in variability caused by pore scale behaviors, these behaviors appear to be smoothed out as uranium is transported through the tank. This smoothing of uranium transport behavior transcends
Uranium Removal from Groundwater by Permeable Reactive Barrier with Zero-Valent Iron and Organic Carbon Mixtures: Laboratory and Field Studies

Directory of Open Access Journals (Sweden)

Borys Kornilovych

2018-06-01

Full Text Available Zhovty Vody city, located in south-central Ukraine, has long been an important center for the Ukrainian uranium and iron industries. Uranium and iron mining and processing activities during the Cold War resulted in poorly managed sources of radionuclides and heavy metals. Widespread groundwater and surface water contamination has occurred, which creates a significant risk to drinking water supplies. Hydrogeologic and geochemical conditions near large uranium mine tailings storage facility (TSF were characterized to provide data to locate, design and install a permeable reactive barrier (PRB to treat groundwater contaminated by leachate infiltrating from the TSF. The effectiveness of three different permeable reactive materials was investigated: zero-valent iron (ZVI for reduction, sorption, and precipitation of redox-sensitive oxyanions; phosphate material to transform dissolved metals to less soluble phases; and organic carbon substrates to promote bioremediation processes. Batch and column experiments with Zhovty Vody site groundwater were conducted to evaluate reactivity of the materials. Reaction rates, residence time and comparison with site-specific clean-up standards were determined. Results of the study demonstrate the effectiveness of the use of the PRB for ground water protection near uranium mine TSF. The greatest decrease was obtained using ZVI-based reactive media and the combined media of ZVI/phosphate/organic carbon combinations.
Upscaling of Long-Term U(VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models. Final report

International Nuclear Information System (INIS)

Miller, Andy

2009-01-01

Environmental systems exhibit a range of complexities which exist at a range of length and mass scales. Within the realm of radionuclide fate and transport, much work has been focused on understanding pore scale processes where complexity can be reduced to a simplified system. In describing larger scale behavior, the results from these simplified systems must be combined to create a theory of the whole. This process can be quite complex, and lead to models which lack transparency. The underlying assumption of this approach is that complex systems will exhibit complex behavior, requiring a complex system of equations to describe behavior. This assumption has never been tested. The goal of the experiments presented is to ask the question: Do increasingly complex systems show increasingly complex behavior? Three experimental tanks at the intermediate scale (Tank 1: 2.4m x 1.2m x 7.6cm, Tank 2: 2.4m x 0.61m x 7.6cm, Tank 3: 2.4m x 0.61m x 0.61m (LxHxW)) have been completed. These tanks were packed with various physical orientations of different particle sizes of a uranium contaminated sediment from a former uranium mill near Naturita, Colorado. Steady state water flow was induced across the tanks using constant head boundaries. Pore water was removed from within the flow domain through sampling ports/wells; effluent samples were also taken. Each sample was analyzed for a variety of analytes relating to the solubility and transport of uranium. Flow fields were characterized using inert tracers and direct measurements of pressure head. The results show that although there is a wide range of chemical variability within the flow domain of the tank, the effluent uranium behavior is simple enough to be described using a variety of conceptual models. Thus, although there is a wide range in variability caused by pore scale behaviors, these behaviors appear to be smoothed out as uranium is transported through the tank. This smoothing of uranium transport behavior transcends
Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado, Quality Assurance Project Plan

International Nuclear Information System (INIS)

Fix, N. J.

2008-01-01

The U.S. Department of Energy (DOE) is cleaning up and/or monitoring large, dilute plumes contaminated by metals, such as uranium and chromium, whose mobility and solubility change with redox status. Field-scale experiments with acetate as the electron donor have stimulated metal-reducing bacteria to effectively remove uranium [U(VI)] from groundwater at the Uranium Mill Tailings Site in Rifle, Colorado. The Pacific Northwest National Laboratory and a multidisciplinary team of national laboratory and academic collaborators has embarked on a research proposed for the Rifle site, the object of which is to gain a comprehensive and mechanistic understanding of the microbial factors and associated geochemistry controlling uranium mobility so that DOE can confidently remediate uranium plumes as well as support stewardship of uranium-contaminated sites. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the Rifle Integrated Field-Scale Subsurface Research Challenge Project
Microbiological, Geochemical and Hydrologic Processes Controlling Uranium Mobility: An Integrated Field-Scale Subsurface Research Challenge Site at Rifle, Colorado, Quality Assurance Project Plan

Energy Technology Data Exchange (ETDEWEB)

Fix, N. J.

2008-01-07

The U.S. Department of Energy (DOE) is cleaning up and/or monitoring large, dilute plumes contaminated by metals, such as uranium and chromium, whose mobility and solubility change with redox status. Field-scale experiments with acetate as the electron donor have stimulated metal-reducing bacteria to effectively remove uranium [U(VI)] from groundwater at the Uranium Mill Tailings Site in Rifle, Colorado. The Pacific Northwest National Laboratory and a multidisciplinary team of national laboratory and academic collaborators has embarked on a research proposed for the Rifle site, the object of which is to gain a comprehensive and mechanistic understanding of the microbial factors and associated geochemistry controlling uranium mobility so that DOE can confidently remediate uranium plumes as well as support stewardship of uranium-contaminated sites. This Quality Assurance Project Plan provides the quality assurance requirements and processes that will be followed by the Rifle Integrated Field-Scale Subsurface Research Challenge Project.
Synthesis and reactivity of triscyclopentadienyl uranium (III) and (IV) complexes

International Nuclear Information System (INIS)

Berthet, J.C.

1992-01-01

The reactions of (RC 5 H 4 ) 3 U with R=trimethylsilylcyclopentadienyl or tertiobutylcyclopentadienyl are studied for the synthesis of new uranium organometallic compounds. Reactions with sodium hydride are first described uranium (III) anionic hydrides obtained are oxidized for synthesis of stable uranium (IV) organometallic hydrides. Stability of these compounds is discussed. Reactivity of these uranium (III) and (IV) hydrides are studied. Formation of new binuclear compounds with strong U-O and U-N bonds is examined and crystal structure are presented. Monocyclooctatetraenylic uranium complexes are also investigated
Polynuclear compounds of uranium: structure, reactivity and properties

International Nuclear Information System (INIS)

Mougel, V.

2012-01-01

The study and comprehension of actinide's fundamental chemistry have important implications both for the development of new nuclear fuel and for the nuclear fuel reprocessing. One of the major issues in these processes is the ease of uranium to undergo redox reactions and to form polynuclear assemblies, which largely perturb these processes. However, despite their relevance, only few synthetic routes towards polynuclear uranium assemblies are described in the literature, and most of the polynuclear complexes reported are formed by serendipity rather than by rational design. Moreover, polynuclear uranium compounds are highly promising for the design of magnetic materials with improved properties and for reactivity studies. The aim of this work is the synthesis of polynuclear uranium complexes and the study of their reactivity and coordination properties. New synthetic routes to uranium polynuclear assemblies were developed and the study of their physico-chemical properties was carried out. The first approach investigated was based on pentavalent uranyl chemistry. Uranyl(V) is known to form aggregates via an interaction between uranyl moieties often named cation-cation interaction, but the isolation of uranyl(V) complexes had been largely limited by its ease of disproportionation. We isolated the first stable uranyl(V) polynuclear assembly using Salen-type Schiff base ligand. Based on this result, a fine tuning of the ligand and counter-ion properties resulted in the isolation of a large family of uranyl(V) polynuclear assemblies and in a better understanding of the parameters ruling their stability. Moreover, rare examples of clear antiferromagnetic couplings were observed with these complexes. In addition, this synthetic path was used to build the first 5f-3d cluster presenting single molecule magnet properties. The second approach used in this thesis consisted in the synthesis of oxo/hydroxo uranium clusters. The controlled hydrolysis of trivalent uranium in

Calculation of the void reactivity of CANDU lattices using the SCALE code system

Energy Technology Data Exchange (ETDEWEB)

Valko, J. [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Feher, S. [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Hoogenboom, J.E. [Technische Univ. Delft (Netherlands). Interfacultair Reactor Inst.; Slobben, J. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands)

1995-11-01

The reactivity effect of coolant voiding in CANDU-type fuel lattices has been calculated with different methods using the SCALE code system. The known positive void reactivity coefficient of the original lattice was correctly obtained. A modified fuel bundle containing dysprosium and slightly enriched uranium to eliminate the positive reactivity effect was also calculated. Owing to the increased heterogeneity of this modified fuel the one-dimensional cylindrical calculation with XSDRN proved to be inadequate. Code options allowing bundle geometry were successfully used for the calculation of the strongly space dependent flux and spectrum changes which determine the void reactivity. (orig.).
Activation of chalcogens and chalcogenides at reactive uranium centers

Energy Technology Data Exchange (ETDEWEB)

Franke, Michael Sebastian

2015-07-23

The high reactivity of many trivalent uranium complexes was investigated in the Meyer group, however, these studies were not limited to small-molecule activation, but were extended to other relatively inert reagents like the heavier elemental chalcogens sulfur, selenium, and tellurium. The tripodal N-anchored chelate ({sup Ad,Me}ArO){sub 3}N{sup 3-} (trianion of tris(3-Adamantyl-2-hydroxy-5-methylbenzyl)amine) was found to be a very suitable candidate for this task and the respective uranium(III) complex [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)] is able to activate elemental sulfur and selenium to form the dinuclear, chalcogenido-bridged complexes [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-E)] (E = S, Se). Starting from this previously accomplished work, research in this thesis aimed at furthering reactivity studies of trivalent [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)], but also its chalcogenido-bridged uranium(IV) products, and the spectroscopic characterization of all newly synthesized compounds. Furthermore, the development of the new phenol HOAr* (Ar* = 2,6-(CHPh{sub 2}){sub 2}-4-Me-C{sub 6}H{sub 2}, 2,6-bis(diphenylmethyl)-4-methylphenyl) and its establishment as a ligand to be used for uranium coordination chemistry was another goal of this thesis. The activation of CO{sub 2} by uranium(III) complex [(({sup Ad,Me}ArO){sub 3}N)U{sup III}(DME)] to yield the dinuclear, carbonate-bridged uranium(IV/IV) complex [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-κ{sup 1}:κ{sup 2}-CO{sub 3})] and CO was reported in 2010 by Meyer and co-workers. These previous results led to the pursuit of the isolation of mixed chalcogenocarbonate complexes from the reaction of the bridging chalcogenidos [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-E)] (E = S, Se) with either CO{sub 2} or its heterocumulene analogs COS or CS{sub 2}. The chalcogeno-carbonates [{(("A"d","M"eArO)_3N)U"I"V(DME)}{sub 2}(μ-κ{sup 1}:κ{sup 2}-CO{sub 2}E)] und [{(("A"d","M"eArO)_3N)U"I"V-(DME)}{sub 2}(�
In situ remediation of uranium contaminated groundwater

International Nuclear Information System (INIS)

Dwyer, B.P.; Marozas, D.C.

1997-01-01

In an effort to develop cost-efficient techniques for remediating uranium contaminated groundwater at DOE Uranium Mill Tailing Remedial Action (UMTRA) sites nationwide, Sandia National Laboratories (SNL) deployed a pilot scale research project at an UMTRA site in Durango, CO. Implementation included design, construction, and subsequent monitoring of an in situ passive reactive barrier to remove Uranium from the tailings pile effluent. A reactive subsurface barrier is produced by emplacing a reactant material (in this experiment various forms of metallic iron) in the flow path of the contaminated groundwater. Conceptually the iron media reduces and/or adsorbs uranium in situ to acceptable regulatory levels. In addition, other metals such as Se, Mo, and As have been removed by the reductive/adsorptive process. The primary objective of the experiment was to eliminate the need for surface treatment of tailing pile effluent. Experimental design, and laboratory and field results are discussed with regard to other potential contaminated groundwater treatment applications
Study on the application of permeable reactive barriers for remediation of uranium mine pit water

International Nuclear Information System (INIS)

Li Na'na; Zhu Yucheng

2012-01-01

Permeable reactive barrier (PRB) is economical and convenient on in suit remediation of polluted groundwater. In this paper, according to characteristics of uranium mine pit water, laboratory-scale PRB reactors were designed with the mixture of valent iron, active carbon, hydrated lime and quartz sands as reaction media. The feasibility and effectiveness of treating uranium mine pit water by PRB were tested under 3 different proportions of contaminants through dynamic simulation tests, which came out the optimal proportion of contaminants. The result indicated that the remediation effect of reactor B was the best, whose average removal rate to U was up to 99%. The quality of effluent attained the relevant standards, which indicated that the PRB technology is a feasible method for the treatment of uranium mine pit water. (authors)
Possible uranium sources of Streltsovsky uranium ore field

International Nuclear Information System (INIS)

Zhang Lisheng

2005-01-01

The uranium deposit of the Late Jurassic Streltsovaky caldera in Transbaikalia of Russia is the largest uranium field associated with volcanics in the world, its uranium reserves are 280 000 t U, and it is the largest uranium resources in Russia. About one third of the caldera stratigraphic pile consists of strongly-altered rhyolites. Uranium resources of the Streltsovsky caldera are much larger than any other volcanic-related uranium districts in the world. Besides, the efficiency of hydrothermal alteration, uranium resources appear to result from the juxtaposition of two major uranium sources; highly fractionated peralkaline rhyolites of Jurassic age in the caldera, and U-rich subalkaline granites of Variscan age in the basement in which the major uranium-bearing accessory minerals were metamict at the time of the hydrothermal ore formation. (authors)
Sensitivity Analysis and Parameter Estimation for a Reactive Transport Model of Uranium Bioremediation

Science.gov (United States)

Meyer, P. D.; Yabusaki, S.; Curtis, G. P.; Ye, M.; Fang, Y.

2011-12-01

A three-dimensional, variably-saturated flow and multicomponent biogeochemical reactive transport model of uranium bioremediation was used to generate synthetic data . The 3-D model was based on a field experiment at the U.S. Dept. of Energy Rifle Integrated Field Research Challenge site that used acetate biostimulation of indigenous metal reducing bacteria to catalyze the conversion of aqueous uranium in the +6 oxidation state to immobile solid-associated uranium in the +4 oxidation state. A key assumption in past modeling studies at this site was that a comprehensive reaction network could be developed largely through one-dimensional modeling. Sensitivity analyses and parameter estimation were completed for a 1-D reactive transport model abstracted from the 3-D model to test this assumption, to identify parameters with the greatest potential to contribute to model predictive uncertainty, and to evaluate model structure and data limitations. Results showed that sensitivities of key biogeochemical concentrations varied in space and time, that model nonlinearities and/or parameter interactions have a significant impact on calculated sensitivities, and that the complexity of the model's representation of processes affecting Fe(II) in the system may make it difficult to correctly attribute observed Fe(II) behavior to modeled processes. Non-uniformity of the 3-D simulated groundwater flux and averaging of the 3-D synthetic data for use as calibration targets in the 1-D modeling resulted in systematic errors in the 1-D model parameter estimates and outputs. This occurred despite using the same reaction network for 1-D modeling as used in the data-generating 3-D model. Predictive uncertainty of the 1-D model appeared to be significantly underestimated by linear parameter uncertainty estimates.
Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

Energy Technology Data Exchange (ETDEWEB)

Burgos, W.D.

2009-09-02

This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.
Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado

International Nuclear Information System (INIS)

Moore, Robert C.; Szecsody, James; Rigali, Mark J.; Vermuel, Vince; Leullen, Jon

2016-01-01

We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.
Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

Energy Technology Data Exchange (ETDEWEB)

Moore, Robert C.; Szecsody, James (PNNL); Rigali, Mark J.; Vermuel, Vince (PNNL); Leullen, Jon (AECOM)

2016-02-01

We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.
Mineral transformation and biomass accumulation associated with uranium bioremediation at Rifle, Colorado.

Science.gov (United States)

Li, Li; Steefel, Carl I; Williams, Kenneth H; Wilkins, Michael J; Hubbard, Susan S

2009-07-15

Injection of organic carbon into the subsurface as an electron donor for bioremediation of redox-sensitive contaminants like uranium often leads to mineral transformation and biomass accumulation, both of which can alter the flow field and potentially bioremediation efficacy. This work combines reactive transport modeling with a column experiment and field measurements to understand the biogeochemical processes and to quantify the biomass and mineral transformation/accumulation during a bioremediation experiment at a uranium contaminated site near Rifle, Colorado. We use the reactive transport model CrunchFlow to explicitly simulate microbial community dynamics of iron and sulfate reducers, and their impacts on reaction rates. The column experiment shows clear evidence of mineral precipitation, primarily in the form of calcite and iron monosulfide. At the field scale, reactive transport simulations suggest that the biogeochemical reactions occur mostly close to the injection wells where acetate concentrations are highest, with mineral precipitate and biomass accumulation reaching as high as 1.5% of the pore space. This work shows that reactive transport modeling coupled with field data can bean effective tool for quantitative estimation of mineral transformation and biomass accumulation, thus improving the design of bioremediation strategies.
Physics study of Canada deuterium uranium lattice with coolant void reactivity analysis

Energy Technology Data Exchange (ETDEWEB)

Park, Jin Su; Lee, Hyun Suk; Tak, Tae Woo; Lee, Deok Jung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Shin, Ho Cheol [Korea Hydro and Nuclear Power Central Research Institute (KHNP-CRI), Daejeon (Korea, Republic of)

2017-02-15

This study presents a coolant void reactivity analysis of Canada Deuterium Uranium (CANDU)-6 and Advanced Canada Deuterium Uranium Reactor-700 (ACR-700) fuel lattices using a Monte Carlo code. The reactivity changes when the coolant was voided were assessed in terms of the contributions of four factors and spectrum shifts. In the case of single bundle coolant voiding, the contribution of each of the four factors in the ACR-700 lattice is large in magnitude with opposite signs, and their summation becomes a negative reactivity effect in contrast to that of the CANDU-6 lattice. Unlike the coolant voiding in a single fuel bundle, the 2 x 2 checkerboard coolant voiding in the ACR-700 lattice shows a positive reactivity effect. The neutron current between the no-void and voided bundles, and the four factors of each bundle were analyzed to figure out the mechanism of the positive coolant void reactivity of the checkerboard voiding case. Through a sensitivity study of fuel enrichment, type of burnable absorber, and moderator to fuel volume ratio, a design strategy for the CANDU reactor was suggested in order to achieve a negative coolant void reactivity even for the checkerboard voiding case.
Heap leach studies on the removal of uranium from soil. Report of laboratory-scale test results

Energy Technology Data Exchange (ETDEWEB)

Turney, W.R.J.R.; York, D.A.; Mason, C.F.V.; Chisholm-Brause, C.J.; Dander, D.C.; Longmire, P.A.; Morris, D.E.; Strait, R.K.; Brewer, J.S.

1994-05-01

This report details the initial results of laboratory-scale testing of heap leach that is being developed as a method for removing uranium from uranium-contaminated soil. The soil used was obtained from the site of the Feed Materials Production Center (FMPC) near the village of Fernald in Ohio. The testing is being conducted on a laboratory scale, but it is intended that this methodology will eventually be enlarged to field scale where, millions of cubic meters of uranium-contaminated soil can be remediated. The laboratory scale experiments show that, using carbonate/bicarbonate solutions, uranium can be effectively removed from the soil from initial values of around 600 ppM down to 100 ppM or less. The goal of this research is to selectively remove uranium from the contaminated soil, without causing serious changes in the characteristics of the soil. It is also hoped that the new technologies developed for soil remediation at FEMP will be transferred to other sites that also have uranium-contaminated soil.
Reactivity feedbacks of a material test research reactor fueled with various low enriched uranium dispersion fuels

International Nuclear Information System (INIS)

Muhammad, Farhan; Majid, Asad

2009-01-01

The reactivity feedbacks of a material test research reactor using various low enriched uranium fuels, having same uranium density were calculated. For this purpose, the original aluminide fuel (UAl x -Al) containing 4.40 gU/cm 3 of an MTR was replaced with silicide (U 3 Si-Al and U 3 Si 2 -Al) and oxide (U 3 O 8 -Al) dispersion fuels having the same uranium density as of the original fuel. Calculations were carried out to find the fuel temperature reactivity feedback, moderator temperature reactivity feedback, moderator density reactivity feedback and moderator void reactivity feedback. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It was observed that the magnitudes all the respective reactivity feedbacks from 38 deg. C to 50 deg. C and 100 deg. C, at the beginning of life, of all the fuels were very close to each other. The fuel temperature reactivity feedback of the U 3 O 8 -Al was about 2% more than the original UAl x -Al fuel. The magnitudes of the moderator temperature, moderator density and moderator void reactivity feedbacks of all the fuels, showed very minor variations from the original aluminide fuel.
Simulation of uranium oxides reduction kinetics by hydrogen. Reactivities of germination and growth

International Nuclear Information System (INIS)

Brun, C.

1997-01-01

The aim of this work is to simulate the reduction by hydrogen of the tri-uranium octo-oxide U 3 O 8 (obtained by uranium trioxide calcination) into uranium dioxide. The kinetics curves have been obtained by thermal gravimetric analysis, the hydrogen and steam pressures being defined. The geometrical modeling which has allowed to explain the trend of the kinetics curves and of the velocity curves is an anisotropic germination-growth modeling. The powder is supposed to be formed of spherical grains with the same radius. The germs of the new UO 2 phase appear at the surface of the U 3 O 8 grains with a specific germination frequency. The growth reactivity is anisotropic and is very large in the tangential direction to the grains surface. Then, the uranium dioxide growths inside the grain and the limiting step is the grain surface. The variations of the growth reactivity and of the germination specific frequency in terms of the gases partial pressures and of the temperature have been explained by two different mechanisms. The limiting step of the growth mechanism is the desorption of water in the uranium dioxide surface. Concerning the germination mechanism the limiting step is a water desorption too but in the tri-uranium octo-oxide surface. The same geometrical modeling and the same germination and growth mechanisms have been applied to the reduction of a tri-uranium octo-oxide obtained by calcination of hydrated uranium trioxide. The values of the germination specific frequency of this solid are nevertheless weaker than those of the solid obtained by direct calcination of the uranium trioxide. (O.M.)
Sulphatising roasting of a Greenlandic uranium ore, reactivity of minerals and recovery

International Nuclear Information System (INIS)

Gamborg Hansen, J.K.

1977-03-01

Uranium in the lujavrite ore from Kvanefjeld, South Greenland, can be solubilised by sulphatising roasting at 700degC. The reactivity of various lujavrite minerals in the roasting process and the mechanism of the reaction were investigated by X-ray diffraction, optical microscopy, electron microprobe, thermal analysis, Moessbauer and infrared spectroscopy. Soluble sulphates are formed on the surface of the grains; an outer zone of the grains is transformed; usually a core remains unchanged. Variations in uranium recovery can be explained by variations in the contents of the uranium-bearing minerals, steenstrupine and uranium-containing pigmentary material (altered Zr containing silicate minerals), and in the degree of alteration os steenstrupine. Characterization of these minerals required many qualitative and a few quantitative electron microprobe analyses. (author)
Improved locations of reactivity devices in future CANDU reactors fuelled with natural uranium or enriched fuels

International Nuclear Information System (INIS)

Boczar, P.G.; Van Dyk, M.T.

1987-02-01

A new configuration of reactivity devices is proposed for future CANDU reactors which improves the core characteristics with enriched fuels, while still allowing the use of natural uranium fuel. Physics calculations for this new configuration are presented for four fuel types: natural uranium, mixed plutonium - uranium oxide (MOX) having a burnup of 21 MWd/kg, and slightly enriched uranium (SEU) having burnups of either 21 or 31 MWd/kg
Discussion on prospecting potential for rich uranium deposits in Xiazhuang uranium ore-field, northern Guangdong

International Nuclear Information System (INIS)

Wu Lieqin; Tan Zhengzhong

2004-01-01

Based on analyzing the prospecting potential for uranium deposits in Xiazhuang uranium ore field this paper discusses the prospecting for rich uranium deposits and prospecting potential in the region. Research achievements indicate: that the Xiazhuang ore-field is an ore-concentrated area where uranium has been highly enriched, and possesses good prospecting potential and perspective, becoming one of the most important prospecting areas for locating rich uranium deposits in northern Guangdong; that the 'intersection type', the alkaline metasomatic fractured rock type and the vein-group type uranium deposits are main targets and the prospecting direction for future uranium prospecting in this region
Approximate photochemical dynamics of azobenzene with reactive force fields

Science.gov (United States)

Li, Yan; Hartke, Bernd

2013-12-01

We have fitted reactive force fields of the ReaxFF type to the ground and first excited electronic states of azobenzene, using global parameter optimization by genetic algorithms. Upon coupling with a simple energy-gap transition probability model, this setup allows for completely force-field-based simulations of photochemical cis→trans- and trans→cis-isomerizations of azobenzene, with qualitatively acceptable quantum yields. This paves the way towards large-scale dynamics simulations of molecular machines, including bond breaking and formation (via the reactive force field) as well as photochemical engines (presented in this work).
Reactivity change measurements on plutonium-uranium fuel elements in hector experimental techniques and results

International Nuclear Information System (INIS)

Tattersall, R.B.; Small, V.G.; MacBean, I.J.; Howe, W.D.

1964-08-01

The techniques used in making reactivity change measurements on HECTOR are described and discussed. Pile period measurements were used in the majority of oases, though the pile oscillator technique was used occasionally. These two methods are compared. Flux determinations were made in the vicinity of the fuel element samples using manganese foils, and the techniques used are described and an error assessment made. Results of both reactivity change and flux measurements on 1.2 in. diameter uranium and plutonium-uranium alloy fuel elements are presented, these measurements being carried out in a variety of graphite moderated lattices at temperatures up to 450 deg. C. (author)
Removal of uranium from uranium plant wastewater using zero-valent iron in an ultrasonic field

Energy Technology Data Exchange (ETDEWEB)

Li, Jing; Zhang, Libo; Peng, Jinhui; Ma, Aiyuan; Xia, Hong Ying; Guo, Wen Qian; Yu, Xia [Yunnan Provincial Key Laboratory of Intensification Metallurgy, Kunming (China); Hu, Jinming; Yang, Lifeng [Nuclear Group Two Seven Two Uranium Industry Limited Liability Company, Hengyang (China)

2016-06-15

Uranium removal from uranium plant wastewater using zero-valent iron in an ultrasonic field was investigated. Batch experiments designed by the response surface methodology (RSM) were conducted to study the effects of pH, ultrasonic reaction time, and dosage of zero-valent iron on uranium removal efficiency. From the experimental data obtained in this work, it was found that the ultrasonic method employing zero-valent iron powder effectively removes uranium from uranium plant wastewater with a uranium concentration of 2,772.23 μg/L. The pH ranges widely from 3 to 7 in the ultrasonic field, and the prediction model obtained by the RSM has good agreement with the experimental results.

Uranium partitioning under acidic conditions in a sandy soil aquifer

International Nuclear Information System (INIS)

Johnson, W.H.; Serkiz, S.M.; Johnson, L.M.

1995-01-01

The partitioning of uranium in an aquifer down gradient of two large mixed waste sites was examined with respect to the solution and soil chemistry (e.g., pH redox potential and contaminant concentration) and aqueous-phase chemical speciation. This involved generation of field-derived, batch sorption, and reactive mineral surface sorption data. Field-derived distribution coefficients for uranium at these waste sites were found to vary between 0.40 and 15,000. Based on thermodynamic speciation modeling and a comparison of field and laboratory data, gibbsite is a potential reactive mineral surface present in modified soils at the sites. Uranium partitioning data are presented from field samples and laboratory studies of background soil and the mineral surface gibbsite. Mechanistic and empirical sorption models fit to the field-derived uranium partitioning data show an improvement of over two orders of magnitude, as measured by the normalized sum of errors squared, when compared with the single K d model used in previous risk work. Models fit to batch sorption data provided a better fit of sorbed uranium than do models fit to the field-derived data
Reactivity feedback coefficients of a low enriched uranium fuelled material test research reactor at end-of-life

International Nuclear Information System (INIS)

Muhammad, Farhan

2011-01-01

Highlights: → The isotopic concentration in the fuel changes as soon as it starts its operation. → The neutronic properties of a reactor also change with fuel burnup. → The reactivity feedbacks at end-of-life of a material test reactor fuelled with low enriched uranium fuel are calculated. → Codes used include WIMS-D4 and CITATION. - Abstract: The reactivity feedback coefficients at end-of-life of a material test reactor fuelled with low enriched uranium fuel were calculated. The reactor used for the study was the IAEA's 10 MW benchmark reactor. Simulations were carried out to calculate the different reactivity feedback coefficients including Doppler feedback coefficient, reactivity coefficient for change of water temperature and reactivity coefficient for change of water density. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It was observed that the magnitude of all the reactivity feedback coefficients increased at end of life of the reactor by almost 2-5%.
Small-scale field test of simple earthen covers for uranium mill tailings

International Nuclear Information System (INIS)

Nielson, K.K.; Rogers, V.C.; Rich, D.C.

1983-01-01

A series of field tests has been conducted during the past year to provide benchmark data on the performance of simple, single-layer earthen covers at thee uranium tailings sites. The performance of the covers was evaluated in terms of their reduction of radon gas releases, although moisture profiles and other cover parameters were also monitored. The tests were designed to evaluate the effectiveness of local soils applied with minimum engineering design or compaction effort. The tests, therefore, tend to represent a lowest-cost, and perhaps a worst-case scenario for tailings reclamation. The field benchmark tests are part of a major research program being conducted by the US Department of Energy to develop technology for uranium tailings disposal. The present tests with simple earthen covers thus provide a comparative basis for evaluating the effectiveness of more highly-engineered systems and their proportionately higher costs. These tests were conducted on the inactive tailings piles at Salt Lake City; Mexican Hat, Utah; and Grand Junction, Colorado. The test covers were installed during the summer of 1981 (Ri81) and have been monitored during the following year. This report describes the experimental details of the cover tests, the data that were collected during the one-year monitoring period, and the conclusions that were drawn from the experiments. 5 refs., 5 figs., 13 tabs
Synthesis and reactivity of uranium (III) cyclopentadienyl complexes

International Nuclear Information System (INIS)

Foyentin, M.

1987-01-01

New uranium organometallic complexes are synthetized from the addition compound Cp U (THF). Reactions with lithium compounds, chlorides, alkynes and borohydrides. Oxidizing addition reactions are evidenced with alkyl halogenides. With a strong reducing agent, the complex Cp-UCH-Li allows the fixation and the reduction of nitrogen into ammonia. Lability of ligands bound to U (III) is evidenced, giving very reactive species and hence catalytic properties for these compounds. Catalytic hydrogenation of olefins is studied. Substitution reactions of alkyl groups of these complexes with olefins in presence or not of hydrogen or with alkyllithium are original [fr
Novel Sensor for the In Situ Measurement of Uranium Fluxes

Energy Technology Data Exchange (ETDEWEB)

Hatfield, Kirk [Univ. of Florida, Gainesville, FL (United States)

2015-02-10

The goal of this project was to develop a sensor that incorporates the field-tested concepts of the passive flux meter to provide direct in situ measures of flux for uranium and groundwater in porous media. Measurable contaminant fluxes [J] are essentially the product of concentration [C] and groundwater flux or specific discharge [q ]. The sensor measures [J] and [q] by changes in contaminant and tracer amounts respectively on a sorbent. By using measurement rather than inference from static parameters, the sensor can directly advance conceptual and computational models for field scale simulations. The sensor was deployed in conjunction with DOE in obtaining field-scale quantification of subsurface processes affecting uranium transport (e.g., advection) and transformation (e.g., uranium attenuation) at the Rifle IFRC Site in Rifle, Colorado. Project results have expanded our current understanding of how field-scale spatial variations in fluxes of uranium, groundwater and salient electron donor/acceptors are coupled to spatial variations in measured microbial biomass/community composition, effective field-scale uranium mass balances, attenuation, and stability. The coupling between uranium, various nutrients and micro flora can be used to estimate field-scale rates of uranium attenuation and field-scale transitions in microbial communities. This research focuses on uranium (VI), but the sensor principles and design are applicable to field-scale fate and transport of other radionuclides. Laboratory studies focused on sorbent selection and calibration, along with sensor development and validation under controlled conditions. Field studies were conducted at the Rifle IFRC Site in Rifle, Colorado. These studies were closely coordinated with existing SBR (formerly ERSP) projects to complement data collection. Small field tests were conducted during the first two years that focused on evaluating field-scale deployment procedures and validating sensor performance under
Surface area and chemical reactivity characteristics of uranium metal corrosion products

International Nuclear Information System (INIS)

Totemeier, T. C.

1998-01-01

The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m 2 /g. The reactivity of the products in Ar-9%O 2 and Ar-20%O 2 were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal
Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

Energy Technology Data Exchange (ETDEWEB)

Szecsody, James E.; Truex, Michael J.; Zhong, Lirong; Qafoku, Nikolla; Williams, Mark D.; McKinley, James P.; Wang, Zheming; Bargar, John; Faurie, Danielle K.; Resch, Charles T.; Phillips, Jerry L.

2010-12-01

This investigation is focused on refining an in situ technology for vadose zone remediation of uranium by the addition of ammonia (NH3) gas. Objectives are to: a) refine the technique of ammonia gas treatment of low water content sediments to minimize uranium mobility by changing uranium surface phases (or coat surface phases), b) identify the geochemical changes in uranium surface phases during ammonia gas treatment, c) identify broader geochemical changes that occur in sediment during ammonia gas treatment, and d) predict and test injection of ammonia gas for intermediate-scale systems to identify process interactions that occur at a larger scale and could impact field scale implementation.Overall, NH3 gas treatment of low-water content sediments appears quite effective at decreasing aqueous, adsorbed uranium concentrations. The NH3 gas treatment is also fairly effective for decreasing the mobility of U-carbonate coprecipitates, but shows mixed success for U present in Na-boltwoodite. There are some changes in U-carbonate surface phases that were identified by surface phase analysis, but no changes observed for Na-boltwoodite. It is likely that dissolution of sediment minerals (predominantly montmorillonite, muscovite, kaolinite) under the alkaline conditions created and subsequent precipitation as the pH returns to natural conditions coat some of the uranium surface phases, although a greater understanding of these processes is needed to predict the long term impact on uranium mobility. Injection of NH3 gas into sediments at low water content (1% to 16% water content) can effectively treat a large area without water addition, so there is little uranium mobilization (i.e., transport over cm or larger scale) during the injection phase.
Remediation of Uranium in the Hanford Vadose Zone Using Ammonia Gas: FY 2010 Laboratory-Scale Experiments

International Nuclear Information System (INIS)

Szecsody, James E.; Truex, Michael J.; Zhong, Lirong; Qafoku, Nikolla; Williams, Mark D.; McKinley, James P.; Wang, Zheming; Bargar, John; Faurie, Danielle K.; Resch, Charles T.; Phillips, Jerry L.

2010-01-01

This investigation is focused on refining an in situ technology for vadose zone remediation of uranium by the addition of ammonia (NH3) gas. Objectives are to: (a) refine the technique of ammonia gas treatment of low water content sediments to minimize uranium mobility by changing uranium surface phases (or coat surface phases), (b) identify the geochemical changes in uranium surface phases during ammonia gas treatment, (c) identify broader geochemical changes that occur in sediment during ammonia gas treatment, and (d) predict and test injection of ammonia gas for intermediate-scale systems to identify process interactions that occur at a larger scale and could impact field scale implementation. Overall, NH3 gas treatment of low-water content sediments appears quite effective at decreasing aqueous, adsorbed uranium concentrations. The NH3 gas treatment is also fairly effective for decreasing the mobility of U-carbonate coprecipitates, but shows mixed success for U present in Na-boltwoodite. There are some changes in U-carbonate surface phases that were identified by surface phase analysis, but no changes observed for Na-boltwoodite. It is likely that dissolution of sediment minerals (predominantly montmorillonite, muscovite, kaolinite) under the alkaline conditions created and subsequent precipitation as the pH returns to natural conditions coat some of the uranium surface phases, although a greater understanding of these processes is needed to predict the long term impact on uranium mobility. Injection of NH3 gas into sediments at low water content (1% to 16% water content) can effectively treat a large area without water addition, so there is little uranium mobilization (i.e., transport over cm or larger scale) during the injection phase.
Oxidation and crystal field effects in uranium

Energy Technology Data Exchange (ETDEWEB)

Tobin, J. G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Booth, C. H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Shuh, D. K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); van der Laan, G. [Diamond Light Source, Didcot (United Kingdom); Sokaras, D. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States); Weng, T. -C. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States); Yu, S. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bagus, P. S. [Univ. of North Texas, Denton, TX (United States); Tyliszczak, T. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nordlund, D. [Stanford Synchrotron Radiation Lightsource, Stanford, CA (United States)

2015-07-06

An extensive investigation of oxidation in uranium has been pursued. This includes the utilization of soft x-ray absorption spectroscopy, hard x-ray absorption near-edge structure, resonant (hard) x-ray emission spectroscopy, cluster calculations, and a branching ratio analysis founded on atomic theory. The samples utilized were uranium dioxide (UO₂), uranium trioxide (UO₃), and uranium tetrafluoride (UF₄). As a result, a discussion of the role of non-spherical perturbations, i.e., crystal or ligand field effects, will be presented.
Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

Energy Technology Data Exchange (ETDEWEB)

Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

2011-09-01

Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.
Magnetic-field dependence of the signal of a uranium-scintillator calorimeter

International Nuclear Information System (INIS)

Bruehl, S.

1991-11-01

The magnetic-field dependence of the signal from 3 GeV electrons and the signal from the uranium radioactivity of a uranium-SCSN-38 test calorimeter was studied with the three in the ZEUS calorimeter implemented uranium-plate coatings 0.2 mm V2A, 0.4 mm V2A, and 0.2 mm V2A and 0.2 mm magnetic C10 in two field directions with fields between 0.01 and 1.4 tesla. In fields oriented parallel to the calorimeter axis uranium and particle signal behave equally except for the case, in which V2A and C10 are applied. At 0.01 tesla the particle signal varies by 1% and the uranium signal by 1.5%. Both signals remain up to 0.1 tesla on this level and increase from this magnetic field. The variation reaches at 1 tesla 4.5% for the particle and 6% for the uranium signal. In the application of V2A and C10 no variation of the particle signal is to be recognized within the errors, while the uranium signal increases monotoneously from 0 to 1.5%. In perpendicularly to the calorimeter axis oriented fields from ≅ 0.3 tesla a different development in the particle and uranium signal occurs. Up to this fields the behaviour of particle and uranium signal is identical with the behaviour in the other field direction. In the application of V2A and C10 the particle respectively the uranium signal increases from 0 at 0.01 tesla to 1% respectively 1.5% at 0.03 tesla. Thereafter the plateau up to 0.1 tesla with the subsequent increasement follows. Independently on the uranium-plate coating the increasement of the uranium signal decreases from 0.3 tesla, reaches at 0.5 tesla a maximum of 3 to 4% and decreases thereafter to 1% at 1 tesla. The particle signal increases as in the other field direction and reaches a signal variation of 7% at 1 tesla. The results are used in the regardment of the magnetic-field effects on the calibration of the ZEUS calorimeter. (orig.) [de
High-Resolution Mineralogical Characterization and Biogeochemical Modeling of Uranium Reduction Pathways at the NABIR Field-Research Center

International Nuclear Information System (INIS)

David R. Veblen; Chen Zhu; Lee Krumholz; Claudine Stirling; Emma-Kate Potter; Alex N. Halliday

2004-01-01

The effectiveness and feasibility of bioremediation at the field scale cannot be fully assessed until the mechanisms of immobilization and U speciation in the solid matrix are resolved. However, characterization of the immobilized U and its valence states is extremely difficult, because microbially mediated mineral precipitates are generally nanometer (nm)-sized, poorly crystalline, or amorphous. We are developing combined field emission gun--scanning electron microscopy (FEG-SEM, at Indiana University) and FEG transmission electron microscopy (TEM, at Hopkins) to detect and isolate uranium containing phases; (1) method developments for TEM sample preparations and parallel electron energy loss spectroscopy (EELS) determination of uranium valence; and (2) to determine the speciation, fate, reactivity, valence states of immobilized uranium, using the state-of-the-art 300-kV, FEG-TEM. We have obtained preliminary results on contaminated sediments from Area 3 at the Oak Ridge Field Research Center (FRC). TEM results show that the sediments contain numerous minerals, including quartz, mica/clay (muscovite and/or illite), rutile, ilmenite, zircon, and an Al-Sr-Ce-Ca phosphate mineral, none of which contain uranium above the EDS detection limit. Substantial U (up to ∼2 wt.%) is, however, clearly associated with two materials: (1) the Fe oxyhydroxide and (2) clots of a chemically complex material that is likely a mixture of several nm-scale phases. The Fe oxyhydroxide was identified as goethite from its polycrystalline SAED pattern and EDS analysis showing it to be very Fe-rich; the aggregate also displays one of several morphologies that are common for goethite. U is strongly sorbed to goethite in the FRC sediment, and the ubiquitous association with phosphorous suggests that complexes containing both U and P may play an important role in that sorption. Results from bulk analysis and SEM had previously demonstrated the association of U with Fe and thus suggested that U
Surface area and chemical reactivity characteristics of uranium metal corrosion products.

Energy Technology Data Exchange (ETDEWEB)

Totemeier, T. C.

1998-02-17

The results of an initial characterization of hydride-containing corrosion products from uranium metal Zero Power Physics Reactor (ZPPR) fuel plates are presented. Sorption analyses using the BET method with a Kr adsorbate were performed to measure the specific areas of corrosion product samples. The specific surface areas of the corrosion products varied from 0.66 to 1.01 m{sup 2}/g. The reactivity of the products in Ar-9%O{sub 2} and Ar-20%O{sub 2} were measured at temperatures between 35 C and 150 C using a thermo-gravimetric analyzer. Ignition of the products occurred at temperatures of 150 C and above. The oxidation rates below ignition were comparable to rates observed for uranium metal.
Reactive transport modeling of uranium 238 and radium 226 in groundwater of the Königstein uranium mine, Germany

Science.gov (United States)

Nitzsche, O.; Merkel, B.

Knowledge of the transport behavior of radionuclides in groundwater is needed for both groundwater protection and remediation of abandoned uranium mines and milling sites. Dispersion, diffusion, mixing, recharge to the aquifer, and chemical interactions, as well as radioactive decay, should be taken into account to obtain reliable predictions on transport of primordial nuclides in groundwater. This paper demonstrates the need for carrying out rehabilitation strategies before closure of the Königstein in-situ leaching uranium mine near Dresden, Germany. Column experiments on drilling cores with uranium-enriched tap water provided data about the exchange behavior of uranium. Uranium breakthrough was observed after more than 20 pore volumes. This strong retardation is due to the exchange of positively charged uranium ions. The code TReAC is a 1-D, 2-D, and 3-D reactive transport code that was modified to take into account the radioactive decay of uranium and the most important daughter nuclides, and to include double-porosity flow. TReAC satisfactorily simulated the breakthrough curves of the column experiments and provided a first approximation of exchange parameters. Groundwater flow in the region of the Königstein mine was simulated using the FLOWPATH code. Reactive transport behavior was simulated with TReAC in one dimension along a 6000-m path line. Results show that uranium migration is relatively slow, but that due to decay of uranium, the concentration of radium along the flow path increases. Results are highly sensitive to the influence of double-porosity flow. Résumé La protection des eaux souterraines et la restauration des sites miniers et de prétraitement d'uranium abandonnés nécessitent de connaître le comportement des radionucléides au cours de leur transport dans les eaux souterraines. La dispersion, la diffusion, le mélange, la recharge de l'aquifère et les interactions chimiques, de même que la décroissance radioactive, doivent être
Relationship between the feature of gravity and magnetic fields and uranium mineralization in the south piedmont of Tianshan mountain

International Nuclear Information System (INIS)

Cui Huanmin; Luo Juecheng.

1988-01-01

The figures of Bouguer anomalies and vertical magnetic anomalies obtained at the scales of 1:1000 000, 1:500 000 and 1:100 000 were processed and the Moho depths were calculated. The feature of gravity and magnetic fields over uranium deposits was determined through interpreting cmprehensive data from uranium deposits No. 504 and No. 509 and potential areas of uranium mineralization were predicted
Uranium facilitated transport by water-dispersible colloids in field and soil columns

International Nuclear Information System (INIS)

Crancon, P.; Pili, E.; Charlet, L.

2010-01-01

The transport of uranium through a sandy podzolic soil has been investigated in the field and in column experiments. Field monitoring, numerous years after surface contamination by depleted uranium deposits, revealed a 20 cm deep uranium migration in soil. Uranium retention in soil is controlled by the 238 U initially present in the soil column and 233 U brought by input solution are desorbed. The mobilization process observed experimentally after a drop of ionic strength may account for a rapid uranium migration in the field after a rainfall event, and for the significant uranium concentrations found in deep soil horizons and in groundwater, 1 km downstream from the pollution source.
Scale-Up Information for Gas-Phase Ammonia Treatment of Uranium in the Vadose Zone at the Hanford Site Central Plateau

Energy Technology Data Exchange (ETDEWEB)

Truex, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Szecsody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhong, Lirong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thomle, Jonathan N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-09-01

Uranium is present in the vadose zone at the Hanford Central Plateau and is of concern for protection of groundwater. The Deep Vadose Zone Treatability Test Plan for the Hanford Central Plateau identified gas-phase treatment and geochemical manipulation as potentially effective treatment approaches for uranium and technetium in the Hanford Central Plateau vadose zone. Based on laboratory evaluation, use of ammonia vapor was selected as the most promising uranium treatment candidate for further development and field testing. While laboratory tests have shown that ammonia treatment effectively reduces the mobility of uranium, additional information is needed to enable deployment of this technology for remediation. Of importance for field applications are aspects of the technology associated with effective distribution of ammonia to a targeted treatment zone, understanding the fate of injected ammonia and its impact on subsurface conditions, and identifying effective monitoring approaches. In addition, information is needed to select equipment and operational parameters for a field design. As part of development efforts for the ammonia technology for remediation of vadose zone uranium contamination, field scale-up issues were identified and have been addressed through a series of laboratory and modeling efforts. This report presents a conceptual description for field application of the ammonia treatment process, engineering calculations to support treatment design, ammonia transport information, field application monitoring approaches, and a discussion of processes affecting the fate of ammonia in the subsurface. The report compiles this information from previous publications and from recent research and development activities. The intent of this report is to provide technical information about these scale-up elements to support the design and operation of a field test for the ammonia treatment technology.
Uranium recovery from slags of metallic uranium

International Nuclear Information System (INIS)

Fornarolo, F.; Frajndlich, E.U.C.; Durazzo, M.

2006-01-01

The Center of the Nuclear Fuel of the Institute of Nuclear Energy Research - IPEN finished the program of attainment of fuel development for research reactors the base of Uranium Scilicet (U 3 Si 2 ) from Hexafluoride of Uranium (UF 6 ) with enrichment 20% in weight of 235 U. In the process of attainment of the league of U 3 Si 2 we have as Uranium intermediate product the metallic one whose attainment generates a slag contend Uranium. The present work shows the results gotten in the process of recovery of Uranium in slags of calcined slags of Uranium metallic. Uranium the metallic one is unstable, pyrophoricity and extremely reactive, whereas the U 3 O 8 is a steady oxide of low chemical reactivity, what it justifies the process of calcination of slags of Uranium metallic. The calcination of the Uranium slag of the metallic one in oxygen presence reduces Uranium metallic the U 3 O 8 . Experiments had been developed varying it of acid for Uranium control and excess, nitric molar concentration gram with regard to the stoichiometric leaching reaction of temperature of the leaching process. The 96,0% income proves the viability of the recovery process of slags of Uranium metallic, adopting it previous calcination of these slags in nitric way with low acid concentration and low temperature of leaching. (author)
Dissolution of metallic uranium and its alloys. Part 1. Review of analytical and process-scale metallic uranium dissolution

International Nuclear Information System (INIS)

Laue, C.A.; Gates-Anderson, D.; Fitch, T.E.

2004-01-01

This review focuses on dissolution/reaction systems capable of treating uranium metal waste to remove its pyrophoric properties. The primary emphasis is the review of literature describing analytical and production-scale dissolution methods applied to either uranium metal or uranium alloys. A brief summary of uranium's corrosion behavior is included since the corrosion resistance of metals and alloys affects their dissolution behavior. Based on this review, dissolution systems were recommended for subsequent screening studies designed to identify the best system to treat depleted uranium metal wastes at Lawrence Livermore National Laboratory (LLNL). (author)
Treatment of reactive process wastewater with high-level ammonia by blow-off method

International Nuclear Information System (INIS)

Chen Xiaotong; Quan Ying; Wang Yang; Fu Genna; Liu Bing; Tang Yaping

2012-01-01

The ceramic UO 2 kernels for nuclear fuel elements of high temperature gas cooled reactors were prepared through sol-gel process with uranyl nitrate, which produces process wastewater containing high-level ammonia and uranium. The blow-off method on a bench scale was investigated to remove ammonia from reactive wastewater. Under the optimized operating conditions, the ammonia can be removed by more than 95%, with little reactive uranium distilled. The effects of pH, heating temperature and stripping time were studied. Static tests with ion-exchange resin indicate that ammonia removal treatment increases uranium accumulation in anion exchange resin. (authors)

Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center, Subproject to Co-PI Eric E. Roden. Final Report

International Nuclear Information System (INIS)

Roden, Eric E.

2011-01-01

This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.
Field demonstration of technologies for delineating uranium contaminated soils

International Nuclear Information System (INIS)

Tidwell, V.C.; Cunnane, J.C.; Schwing, J.; Lee, S.Y.; Perry, D.L.; Morris, D.E.

1993-01-01

An Integrated Demonstration Program, hosted by the Fernald Environmental Restoration Management Corporation (FERMCO), has been established for investigating technologies applicable to the characterization and remediation of soils contaminated with uranium. An important part of this effort is the evaluation of field screening tools capable of acquiring high resolution information on the distribution of uranium contamination in surface soils in a cost-and-time efficient manner. Consistent with this need, four field screening technologies have been demonstrated at two hazardous waste sites at the FERMCO. The four technologies tested are wide-area gamma spectroscopy, beta scintillation counting, laser ablation-inductively coupled plasma-atomic emission spectroscopy (LA-ICP-AES), and long-range alpha detection (LRAD). One of the important findings of this demonstration was just how difficult it is to compare data collected by means of multiple independent measurement techniques. Difficulties are attributed to differences in measurement scale, differences in the basic physics upon which the various measurement schemes are predicated, and differences in the general performance of detector instrumentation. It follows that optimal deployment of these techniques requires the development of an approach for accounting for the intrinsic differences noted above. As such, emphasis is given in this paper to the development of a methodology for integrating these techniques for use in site characterization programs as well as the development of a framework for interpreting the collected data. The methodology described here also has general application to other field-based screening technologies and soil sampling programs
The basement control on Xiazhuang uranium ore field in south sector of Wuyi tumescence and relevant geological problems

International Nuclear Information System (INIS)

Xu Dazhong; Xue Zhenhua

1994-01-01

Based on the two rift-trench tectonic framework in Wuyi as well as its adjacent areas proposed previously, this study takes Yingtan-Nancheng-Anyuan-Heyuan tenacity fracture belt as the geological boundary between two types of uranium deposits (granite and volcanic rock). It is noted that the distinct function of Caledonian movement in this area is the formation of the linear migmatization and granitization on the basis of rift and tumescence basement. Simultaneously, according to the new discovery of hypometamorphic rock and large scaled ductile mylonitized zone in Xiazhuang uranium ore field and its adjacent area, it is concluded that the Xiazhuang uranium ore field is the result of multiple tectonism and magmatic activations on the Caledonian hot dome on the basis of ancient basement. Because the uranium mineralization is present in two kinds of rocks (ductile and brittle), it is suggested that the types of mineralization in Xiazhuang can be considered in order to guide the further prospecting
Field-Scale Evaluation of Biostimulation for Remediation of Uranium-Contaminated Groundwater at a Proposed NABIR Field Research Center in Oak Ridge, TN

International Nuclear Information System (INIS)

Criddle, Craig S.

2003-01-01

A hydrologic, geochemical and microbial characterization of the Area 3 field site has been completed. The formation is fairly impermeable, but there is a region of adequate flow approximately 50 feet bgs. The experiment will be undertaken within that depth interval. Groundwater from that depth is highly acidic (pH 3.2), and has high levels of nitrate, aluminum, uranium, and other heavy metals, as well as volatile chlorinated solvents (VOCs). Accordingly, an aboveground treatment train has been designed to remove these contaminants. The train consists of a vacuum stripper to remove VOCs, two chemical precipitation steps to adjust pH and remove metals, and a fluidized bed bioreactor to remove nitrate. The aboveground system will be coupled to a belowground recirculation system. The belowground system will contain an outer recirculation cell and a nested inner recirculation cell: the outer cells will be continuously flushed with nitrate-free treated groundwater. The inner cell will receive periodic inputs of uranium, tracer, and electron donor. Removal of uranium will be determined by comparing loss rates of conservative tracer and uranium within the inner recirculation cell. Over the past year, a detailed workplan was developed and submitted for regulatory approval. The workplan was presented to the Field Research Advisory Panel (FRAP), and after some extensive revision, the FRAP authorized implementation. Detailed design drawings and numerical simulations of proposed experiments have been prepared. System components are being prefabricated as skid-mounted units in Michigan and will be shipped to Oak Ridge for assembly. One manuscript has been submitted to a peer reviewed journal. This paper describes a novel technique for inferring subsurface hydraulic conductivity values. Two posters on this project were presented at the March 2002 NABIR PI meeting. One poster was presented at the Annual conference of the American Society for Microbiology in Salt Lake City, UT in
Influence of magnetic fields on the response of a uranium scintillator electromagnetic calorimeter

International Nuclear Information System (INIS)

Mainusch, J.; Corriveau, F.; Klanner, R.

1991-04-01

The response of a uranium scintillator sampling calorimeter to incident electrons and to the uranium radioactivity was measured in transverse magnetic fields up to 1.4 Tesla. The signal from electrons rises by as much as 9% due to the expected increase in light output of plastic scintillators in magnetic fields. For fields below 0.3 Tesla the response to the uranium radioactivity tracks the electron signal to within about 0.5%. At higher fields it drops sharply, reaching -1.5% at 1.4 Tesla. The consequences for the calibration of the ZEUS uranium scintillator calorimeter are discussed. We found no evidence for a change in the electromagnetic sampling fraction for fields below 0.3 Tesla. (orig.)
Uranium facilitated transport by water-dispersible colloids in field and soil columns

Energy Technology Data Exchange (ETDEWEB)

Crancon, P., E-mail: pierre.crancon@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Pili, E. [CEA, DAM, DIF, F-91297 Arpajon (France); Charlet, L. [Laboratoire de Geophysique Interne et Tectonophysique (LGIT-OSUG), University of Grenoble-I, UMR5559-CNRS-UJF, BP53, 38041 Grenoble cedex 9 (France)

2010-04-01

The transport of uranium through a sandy podzolic soil has been investigated in the field and in column experiments. Field monitoring, numerous years after surface contamination by depleted uranium deposits, revealed a 20 cm deep uranium migration in soil. Uranium retention in soil is controlled by the < 50 {mu}m mixed humic and clayey coatings in the first 40 cm i.e. in the E horizon. Column experiments of uranium transport under various conditions were run using isotopic spiking. After 100 pore volumes elution, 60% of the total input uranium is retained in the first 2 cm of the column. Retardation factor of uranium on E horizon material ranges from 1300 (column) to 3000 (batch). In parallel to this slow uranium migration, we experimentally observed a fast elution related to humic colloids of about 1-5% of the total-uranium input, transferred at the mean porewater velocity through the soil column. In order to understand the effect of rain events, ionic strength of the input solution was sharply changed. Humic colloids are retarded when ionic strength increases, while a major mobilization of humic colloids and colloid-borne uranium occurs as ionic strength decreases. Isotopic spiking shows that both {sup 238}U initially present in the soil column and {sup 233}U brought by input solution are desorbed. The mobilization process observed experimentally after a drop of ionic strength may account for a rapid uranium migration in the field after a rainfall event, and for the significant uranium concentrations found in deep soil horizons and in groundwater, 1 km downstream from the pollution source.
300 Area Integrated Field-Scale Subsurface Research Challenge (IFRC) Field Site Management Plan

Energy Technology Data Exchange (ETDEWEB)

Freshley, Mark D.

2008-12-31

Pacific Northwest National Laboratory (PNNL) has established the 300 Area Integrated Field-Scale Subsurface Research Challenge (300 Area IFRC) on the Hanford Site in southeastern Washington State for the U.S. Department of Energy’s (DOE) Office of Biological and Environmental Research (BER) within the Office of Science. The project is funded by the Environmental Remediation Sciences Division (ERSD). The purpose of the project is to conduct research at the 300 IFRC to investigate multi-scale mass transfer processes associated with a subsurface uranium plume impacting both the vadose zone and groundwater. The management approach for the 300 Area IFRC requires that a Field Site Management Plan be developed. This is an update of the plan to reflect the installation of the well network and other changes.
An experimental and modeling study of grain-scale uranium desorption from field-contaminated sediments and the potential influence of microporosity on mass-transfer

Science.gov (United States)

Stoliker, D.; Liu, C.; Kent, D. B.; Zachara, J. M.

2012-12-01

The aquifer below the 300-Area of the Hanford site (Richland, WA, USA) is plagued by a persistent plume of dissolved uranium (U(VI)) in excess of the Environmental Protection Agency drinking water maximum contamination level even after the removal of highly contaminated sediments. The aquifer sediments in the seasonally saturated lower vadose zone act as both a source and sink for uranium during stage changes in the nearby Columbia River. Diffusion limitation of uranium mass-transfer within these sediments has been cited as a potential cause of the plume's persistence. Equilibrium U(VI) sorption is a strong function of variable chemical conditions, especially carbonate, hydrogen, and uranyl ion activities. Field-contaminated sediments from the site require up to 1,000 hours to reach equilibrium in static batch reactors. Increases in U(VI) concentrations over longer time-scales result from changes in chemical conditions, which drive reactions with sediments that favor U(VI) desorption. Grain-scale U(VI) sorption/desorption rates are slow, likely owing to diffusion of U(VI) and other solutes through intra-granular pore domains. In order to improve understanding of the impact of intra-granular diffusion and chemical reactions controlling grain-scale U(VI) release, experiments were conducted on individual particle size fractions of a single set of constant chemical conditions with multiple stop-flow events, were similar for all size fractions displacement from equilibrium and multiple diffusion domains were described with a two-parameter lognormal distribution of mass-transfer rate coefficients. Parameters describing mass transfer were the same for all size fractions reaction models calibrated with individual size fractions predicted U(VI) and chemical composition as a function of time for the bulk sediment sample. Volumes of pores less than 2.4 nm, quantified using nitrogen adsorption-desorption isotherms, were the same for all size fractions < 2 mm, nearly double
Reactivity of iron-rich phyllosilicates with uranium and chromium through redox transition zones

International Nuclear Information System (INIS)

Burgos, William D.

2016-01-01

This project performed thermodynamic, kinetic, and mineral structural studies on the reactivity of phyllosilicate Fe(II/III) with metal-reducing bacteria, and with two important poly-valent DOE contaminants (chromium and uranium) that show high mobility in their oxidized state. We focused on Fe-bearing phyllosilicates because these are important components of the reactive, fines fraction of Hanford, Oak Ridge, and Idaho National Laboratory sediments. Iron-bearing phyllosilicates strongly influence the redox state and mobility of Cr and U because of their limited hydraulic conductivity, high specific surface area, and redox reactivity. This was a collaborative project between Penn State (W.D. Burgos - PI), Miami University (H. Dong - Co-PI), and Argonne National Laboratory (K. Kemner and M. Boyanov - Co-PIs). Penn State and Miami University were funded together but separately from ANL. This report summarizes research findings and publications produced by Penn State and Miami University.
Reactivity of iron-rich phyllosilicates with uranium and chromium through redox transition zones

Energy Technology Data Exchange (ETDEWEB)

Burgos, William D. [Pennsylvania State Univ., University Park, PA (United States)

2016-09-01

This project performed thermodynamic, kinetic, and mineral structural studies on the reactivity of phyllosilicate Fe(II/III) with metal-reducing bacteria, and with two important poly-valent DOE contaminants (chromium and uranium) that show high mobility in their oxidized state. We focused on Fe-bearing phyllosilicates because these are important components of the reactive, fines fraction of Hanford, Oak Ridge, and Idaho National Laboratory sediments. Iron-bearing phyllosilicates strongly influence the redox state and mobility of Cr and U because of their limited hydraulic conductivity, high specific surface area, and redox reactivity. This was a collaborative project between Penn State (W.D. Burgos – PI), Miami University (H. Dong – Co-PI), and Argonne National Laboratory (K. Kemner and M. Boyanov – Co-PIs). Penn State and Miami University were funded together but separately from ANL. This report summarizes research findings and publications produced by Penn State and Miami University.
Uranium facilitated transport by water-dispersible colloids in field and soil columns

Energy Technology Data Exchange (ETDEWEB)

Crancon, P.; Pili, E. [CEA Bruyeres-le-Chatel, DIF, 91 (France); Charlet, L. [Univ Grenoble 1, Lab Geophys Interne and Tectonophys LGIT OSUG, CNRS, UJF, UMR5559, F-38041 Grenoble 9 (France)

2010-07-01

The transport of uranium through a sandy podsolic soil has been investigated in the field and in column experiments. Field monitoring, numerous years after surface contamination by depleted uranium deposits, revealed a 20 cm deep uranium migration in soil. Uranium retention in soil is controlled by the {<=} 50 {mu}m mixed humic and clayey coatings in the first 40 cm i.e. in the E horizon. Column experiments of uranium transport under various conditions were run using isotopic spiking. After 100 pore volumes elution, 60% of the total input uranium is retained in the first 2 cm of the column. Retardation factor of uranium on E horizon material ranges from 1300 (column) to 3000 (batch). In parallel to this slow uranium migration, we experimentally observed a fast elution related to humic colloids of about 1-5% of the total-uranium input, transferred at the mean pore-water velocity through the soil column. In order to understand the effect of rain events, ionic strength of the input solution was sharply changed. Humic colloids are retarded when ionic strength increases, while a major mobilization of humic colloids and colloid-borne uranium occurs as ionic strength decreases. Isotopic spiking shows that both {sup 238}U initially present in the soil column and {sup 233}U brought by input solution are desorbed. The mobilization process observed experimentally after a drop of ionic strength may account for a rapid uranium migration in the field after a rainfall event, and for the significant uranium concentrations found in deep soil horizons and in groundwater, 1 km downstream from the pollution source. (authors)
Treatment of liquid effluents from uranium analytical method 'DAVIES & GRAY' by electrodialysis and electrodialysis reactive tests

International Nuclear Information System (INIS)

Zuniga Alvear, Karina Andrea

2014-01-01

This work describes the process which produces liquid waste coming from the chemical analysis laboratory of the Chilean Nuclear Energy Commission (CCHEN), from the analytical technique called 'Davies and Gray' and their further treatment, using electro dialysis (ED) and reactive electro dialysis (RED), in order to achieve lower uranium contents in solution. The contamination in water is a big problem, since there are many places in the world where is limited. For these reasons new treatments must be done, and the ion-selective membrane has opened a new path for these processes. The radioactive liquid waste have lots of other restrictions in their final disposal, which difficult even more the water recovery, because the law has very strict security margins with respect to these ones. In the case of liquid waste containing uranium, the concern increases, because being the uranium a radioactive element has it has to be lowered at its maximum, or eliminated directly, in order to avoid any kind of contamination. There exist national regulations and international recommendations. They have stipulated the correct management and disposal for radioactive waste. These can come from any uranium production process. In any of these, the liquid waste contains certain uranium content, which after the end of the process; the discarded waste must go through a conditioning and cleaning process for its afterward liberation or recycling. In this study, it was tested the electro dialysis as a radioactive waste treatment, only uranium containing waste coming from the chemical analysis laboratory in CCHEN. The electro dialysis process has a direct competition with other separation process, such as distillation, ionic exchange, and reverse osmosis, among others. The classic electro dialysis has been developed during the 50's, and until today, there has been different version, as inverse, reactive, reversible. The unidirectional and reactive electro dialysis will be the
Simulation of uranium oxides reduction kinetics by hydrogen. Reactivities of germination and growth; Modelisation de la cinetique de reduction d`oxydes d`uranium par l`hydrogene. Reactivites de germination et de croissance

Energy Technology Data Exchange (ETDEWEB)

Brun, C

1997-12-04

The aim of this work is to simulate the reduction by hydrogen of the tri-uranium octo-oxide U{sub 3}O{sub 8} (obtained by uranium trioxide calcination) into uranium dioxide. The kinetics curves have been obtained by thermal gravimetric analysis, the hydrogen and steam pressures being defined. The geometrical modeling which has allowed to explain the trend of the kinetics curves and of the velocity curves is an anisotropic germination-growth modeling. The powder is supposed to be formed of spherical grains with the same radius. The germs of the new UO{sub 2} phase appear at the surface of the U{sub 3}O{sub 8} grains with a specific germination frequency. The growth reactivity is anisotropic and is very large in the tangential direction to the grains surface. Then, the uranium dioxide growths inside the grain and the limiting step is the grain surface. The variations of the growth reactivity and of the germination specific frequency in terms of the gases partial pressures and of the temperature have been explained by two different mechanisms. The limiting step of the growth mechanism is the desorption of water in the uranium dioxide surface. Concerning the germination mechanism the limiting step is a water desorption too but in the tri-uranium octo-oxide surface. The same geometrical modeling and the same germination and growth mechanisms have been applied to the reduction of a tri-uranium octo-oxide obtained by calcination of hydrated uranium trioxide. The values of the germination specific frequency of this solid are nevertheless weaker than those of the solid obtained by direct calcination of the uranium trioxide. (O.M.) 45 refs.
D. C. electric field behavior of high lying states in atomic uranium

International Nuclear Information System (INIS)

Paisner, J.A.; Carlson, L.R.; Worden, E.F.; Johnson, S.A.; May, C.A.; Solarz, R.W.

1976-01-01

The effects of D. C. electric fields on high lying Rydberg and valence states in atomic uranium have been studied. Results of measurements of Stark shifts, lifetime lengthening via l-mixing, critical fields for ionization, barrier tunneling, and the appearance of zero-field parity forbidden transitions are presented for atomic uranium along with the observation of field induced autoionization of valence states. 3 figs
Field Testing of Downgradient Uranium Mobility at an In-Situ Recovery Uranium Mine

Science.gov (United States)

Reimus, P. W.; Clay, J. T.; Rearick, M.; Perkins, G.; Brown, S. T.; Basu, A.; Chamberlain, K.

2015-12-01

In-situ recovery (ISR) mining of uranium involves the injection of O2 and CO2 (or NaHCO3) into saturated roll-front deposits to oxidize and solubilize the uranium, which is then removed by ion exchange at the surface and processed into U3O8. While ISR is economical and environmentally-friendly relative to conventional mining, one of the challenges of extracting uranium by this process is that it leaves behind a geochemically-altered aquifer that is exceedingly difficult to restore to pre-mining geochemical conditions, a regulatory objective. In this research, we evaluated the ability of the aquifer downgradient of an ISR mining area to attenuate the transport of uranium and other problem constituents that are mobilized by the mining process. Such an evaluation can help inform both regulators and the mining industry as to how much restoration of the mined ore zone is necessary to achieve regulatory compliance at various distances downgradient of the mining zone even if complete restoration of the ore zone proves to be difficult or impossible. Three single-well push-pull tests and one cross-well test were conducted in which water from an unrestored, previously-mined ore zone was injected into an unmined ore zone that served as a geochemical proxy for the downgradient aquifer. In all tests, non-reactive tracers were injected with the previously-mined ore zone water to allow the transport of uranium and other constituents to be compared to that of the nonreactive species. In the single-well tests, it was shown that the recovery of uranium relative to the nonreactive tracers ranged from 12-25%, suggesting significant attenuation capacity of the aquifer. In the cross-well test, selenate, molybdate and metavanadate were injected with the unrestored water to provide information on the transport of these potentially-problematic anionic constituents. In addition to the species-specific transport information, this test provided valuable constraints on redox conditions within
Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation

International Nuclear Information System (INIS)

Biermann, V.

2007-01-01

Elemental iron (Fe 0 ) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using 237 U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca 5 (PO 4 ) 3 OH, 99 % 0 (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe 0 columns with effluent uranium con-centrations being below the detection limit of 10 μg/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe 0 columns with 200 PV of uranium free AGW. However, columns with high Fe 0 content (≥ 50%) suffered from severe loss of permeability when AGW with ≥ 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 μg/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing from HAP surfaces. The uranium phases chernikovite and meta-ankoleite of the autunite group were identified by x-ray diffraction. The existence of these mineral phases proves that surface precipitation also occurs under favourable conditions. No uranium
Spatial distribution of an uranium-respiring betaproteobacterium at the Rifle, CO field research site.

Directory of Open Access Journals (Sweden)

Nicole M Koribanics

Full Text Available The Department of Energy's Integrated Field-Scale Subsurface Research Challenge Site (IFRC at Rifle, Colorado was created to address the gaps in knowledge on the mechanisms and rates of U(VI bioreduction in alluvial sediments. Previous studies at the Rifle IFRC have linked microbial processes to uranium immobilization during acetate amendment. Several key bacteria believed to be involved in radionuclide containment have been described; however, most of the evidence implicating uranium reduction with specific microbiota has been indirect. Here, we report on the cultivation of a microorganism from the Rifle IFRC that reduces uranium and appears to utilize it as a terminal electron acceptor for respiration with acetate as electron donor. Furthermore, this bacterium constitutes a significant proportion of the subsurface sediment community prior to biostimulation based on TRFLP profiling of 16S rRNA genes. 16S rRNA gene sequence analysis indicates that the microorganism is a betaproteobacterium with a high similarity to Burkholderia fungorum. This is, to our knowledge, the first report of a betaproteobacterium capable of uranium respiration. Our results indicate that this microorganism occurs commonly in alluvial sediments located between 3-6 m below ground surface at Rifle and may play a role in the initial reduction of uranium at the site.
Ligand influences on properties of uranium coordination complexes. Structure, reactivity, and spectroscopy

International Nuclear Information System (INIS)

Kosog, Boris

2012-01-01

example of a uranium(IV) μ-trithiocarbonate was synthesized and characterized. Reaction of the μ-sulfide complex [{(( Ad ArO) 3 N)U IV } 2 (μ-S)], which is obtained by reaction of the uranium(III) complex with triphenylphosphine sulfide, with CS 2 leads to the formation of the [{(( Ad ArO) 3 N)U IV } 2 (μ-κ 2 :κ 2 -CS 3 )]. The coordination mode of the trithicarbonate differes from that of the respective carbonate, obtained previously from a similar reaction of the μ-oxo complex with CO 2 . With the help of detailed DFT calculations, the different reactivity of uranium(III) towards CO 2 and CS 2 is rationalized. Finally, a series of the first uranium vinyl complexes is presented. These are obtained through inter- and intramolecular C-C-coupling reactions of terminal mono- or bisalkynes on a uranium(III) complex. Detailed mechanistic DFT calculations show that a bimetallic mechanism is energetically most likely. This mechanism can be transferred to the catalytic alkyne coupling using both uranium(III), as reported by Eisen in the late 90's, and also transition metal catalyzed C-C-coupling, where a bimetallic mechanism should be taken into account.
Reactivity worth of the thermal column of a MTR type swimming pool research reactor using low enriched uranium fuel

International Nuclear Information System (INIS)

Ali Khan, L.; Ahmad, N.

2002-01-01

The reactivity worth of the thermal column of a typical MTR type swimming pool research reactor using low enriched uranium fuel has been determined by modeling the core using standard computer codes. It was also measured experimentally by operating the reactor in the stall and open ends. The calculated value of the reactivity worth of the thermal column is about 14% greater than the experimentally determined value
Characteristics of gravity and magnetic field and their relationship with uranium mineralization in northern Guangxi area

International Nuclear Information System (INIS)

Shu Xiaojing; Yin Zhongfan; Hao Yuhua; guan Nansheng; Li Xuexun

1993-08-01

The characteristics of gravity and magnetic field, deep-seated structures and their relationship with uranium mineralization in Northern Guangxi are investigated. Especially, based on geophysical investigation, the distinguishing features of uranium ore-forming are discussed, involved with the uranium source body, the heating force and mechanical force of granite magma acted on uranium mineralization, the deep-seated geological process, the hydrothermal activity, the formation environments of granite-type uranium deposit, the source of pyrite and its influence on uranium mineralization, the uranium ore-forming of Sinian-Cambrian periods and devonian period formations, and the simple model of uranium ore-forming. On the basis of the relationship of uranium mineralization with geophysical field, as well as the ore-forming geological environments inferred by gravity and magnetic field investigation, the physical-geological model is established in order to predicate uranium prospect

Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model.

Science.gov (United States)

Fang, Yilin; Scheibe, Timothy D; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E; Lovley, Derek R

2011-03-25

The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint-based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species and multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The
Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model

Science.gov (United States)

Fang, Yilin; Scheibe, Timothy D.; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E.; Lovley, Derek R.

2011-03-01

The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint-based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species and multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The
The solubility of uranium in cementitious near-field chemical conditions

Energy Technology Data Exchange (ETDEWEB)

Baston, G.M.N.; Brownsword, M.; Cross, J.E.; Hobley, J.; Moreton, A.D.; Smith-Briggs, J.L.; Thomason, H.P. [AEA Decommissioning and Waste Management, Harwell (United Kingdom)

1993-05-01

Tetravalent and hexavalent uranium solubilities have been measured in cement-equilibriated water for pH values from 4 to 13. Tetravalent uranium solubilities at pH 12 have been measured by three experimental techniques: oversaturation, undersaturation and by the use of an electrochemical cell which controlled the redox conditions. The experimentally obtained data have been simulated using the thermodynamic equilibrium program HARPHRQ in conjunction with three different sets of thermodynamic data for uranium. In each case, differences were found between the predicted and measured uranium behaviour. For hexavalent uranium at high pH values the model suggested the formation of anionic hydrolysis products which led to the prediction of uranium solubilities significantly higher than those observed. Refinement of the thermodynamic data used in the model enabled the derivation of maximum values for the formation constants of these species under cementitious conditions. Similarly, the experimental data have been used to refine a model of tetravalent uranium solubility under cementitious near-field conditions. (author).
The solubility of uranium in cementitious near-field chemical conditions

International Nuclear Information System (INIS)

Baston, G.M.N.; Brownsword, M.; Cross, J.E.; Hobley, J.; Moreton, A.D.; Smith-Briggs, J.L.; Thomason, H.P.

1993-05-01

Tetravalent and hexavalent uranium solubilities have been measured in cement-equilibriated water for pH values from 4 to 13. Tetravalent uranium solubilities at pH 12 have been measured by three experimental techniques: oversaturation, undersaturation and by the use of an electrochemical cell which controlled the redox conditions. The experimentally obtained data have been simulated using the thermodynamic equilibrium program HARPHRQ in conjunction with three different sets of thermodynamic data for uranium. In each case, differences were found between the predicted and measured uranium behaviour. For hexavalent uranium at high pH values the model suggested the formation of anionic hydrolysis products which led to the prediction of uranium solubilities significantly higher than those observed. Refinement of the thermodynamic data used in the model enabled the derivation of maximum values for the formation constants of these species under cementitious conditions. Similarly, the experimental data have been used to refine a model of tetravalent uranium solubility under cementitious near-field conditions. (author)
Tests of a Higgins contactor for the engineering-scale resin loading of uranium

International Nuclear Information System (INIS)

Spence, R.D.; Haas, P.A.

1978-01-01

The loading of uranium on weak-acid ion exchange resin is a basic step in the production of fuel particles for high-temperature gas-cooled reactors (HTGRs). In the work reported here, an engineering-scale continuous resin loader (2-in.-ID Higgins contactor) was tested with existing engineering-scale process equipment. The Higgins contactor was first successfully used to convert Na + -form resin to the H + -form; then it was evaluated as a uranium loader. Results show that the 2-in.-ID Higgins contactor can easily load 25 kg of uranium per day, indicating that a 4-in.-ID contactor could load 100 kg/day. Process control was achieved by monitoring and controlling the density, pH, and inventory volume of the uranium feed solution. This control scheme is amenable to remote operation
Geology and exploration of the Rum Jungle Uranium Field

International Nuclear Information System (INIS)

Fraser, W.J.

1980-01-01

The Rum Jungle Uranium Field was discovered by a private prospector in 1949. A total of 3530 tonnes of uranium oxide was mined and treated from four ore-bodies by Territory Enterprises Pty. Limited who managed the Rum Jungle Project on behalf of the Australian Atomic Energy Commission until the closure of operations in 1971. One small low grade uranium orebody remains to be developed. Lead, zinc, copper, cobalt and nickel were found zoned sub vertically with uranium at one deposit. One medium sized lead, zinc, copper, cobalt and nickel deposit remains to be developed and one small copper deposit with minor uranium was mined. The basemetal deposits show a regional zoning relationship with the known uranium mineralization. Uranium and basemetal mineralization is hosted by graphitic or chloritic, pyritic shales at the contact with a magnesite. These rocks are in the lower part of a sequence of Lower Proterozoic sediments which unconformably overlie Archaean basement complexes. The sediments and complexes are displaced by Giants Reef Fault and sub-parallel shears and linears may further control mineralization. Nearly 50km of the prospective shale/magnesite contact was tested by total count radiometric surveys, various electrical methods, auger, rotary percussion and diamond drilling. The source for the uranium mineralization was probably the Archaean basement complexes from which uranium was initially deposited as protore by either chemical precipitation or clay adsorption in the shale units or as detrital placers in quartz pebble conglomerates immediately overlying the basement complexes. (author)
Effects of high density dispersion fuel loading on the uncontrolled reactivity insertion transients of a low enriched uranium fueled material test research reactor

Energy Technology Data Exchange (ETDEWEB)

Muhammad, Farhan [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)], E-mail: farhan73@hotmail.com; Majid, Asad [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)

2009-08-15

The effects of using high density low enriched uranium on the uncontrolled reactivity insertion transients of a material test research reactor were studied. For this purpose, the low density LEU fuel of an MTR was replaced with high density U-Mo (9w/o) LEU fuels currently being developed under the RERTR program having uranium densities of 6.57 gU/cm{sup 3}, 7.74 gU/cm{sup 3} and 8.57 gU/cm{sup 3}. Simulations were carried out to determine the reactor performance under reactivity insertion transients with totally failed control rods. Ramp reactivities of 0.25$/0.5 s and 1.35$/0.5 s were inserted with reactor operating at full power level of 10 MW. Nuclear reactor analysis code PARET was employed to carry out these calculations. It was observed that when reactivity insertion was 0.25$/0.5 s, the new power level attained increased by 5.8% as uranium density increases from 6.57 gU/cm{sup 3} to 8.90 gU/cm{sup 3}. This results in increased maximum temperatures of fuel, clad and coolant outlet, achieved at the new power level, by 4.7 K, 4.4 K and 2.4 K, respectively. When reactivity insertion was 1.35$/0.5 s, the feedback reactivities were unable to control the reactor which resulted in the bulk boiling of the coolant; the one with the highest fuel density was the first to reach the boiling point.
Field evaporation test of uranium tailings solution

International Nuclear Information System (INIS)

Chandler, B.L.; Shepard, T.A.; Stewart, T.A.

1985-01-01

A field experiment was performed to observe the effect on evaporation rate of a uranium tailings impoundment pond water as salt concentration of the water increased. The duration of the experiment was long enough to cause maximum salt concentration of the water to be attained. The solution used in the experiment was tailings pond water from an inactive uranium tailings disposal site in the initial stages of reclamation. The solution was not neutralized. The initial pH was about 1.0 decreasing to a salt gel at the end of the test. The results of the field experiment show a gradual and slight decrease in evaporation efficiency. This resulted as salt concentrations increased and verified the practical effectiveness of evaporation as a water removal method. In addition, the physical and chemical nature of the residual salts suggest that no long-term stability problem would likely result due to their presence in the impoundment during or after reclamation
Technical Basis for Assessing Uranium Bioremediation Performance

International Nuclear Information System (INIS)

PE Long; SB Yabusaki; PD Meyer; CJ Murray; AL N'Guessan

2008-01-01

In situ bioremediation of uranium holds significant promise for effective stabilization of U(VI) from groundwater at reduced cost compared to conventional pump and treat. This promise is unlikely to be realized unless researchers and practitioners successfully predict and demonstrate the long-term effectiveness of uranium bioremediation protocols. Field research to date has focused on both proof of principle and a mechanistic level of understanding. Current practice typically involves an engineering approach using proprietary amendments that focuses mainly on monitoring U(VI) concentration for a limited time period. Given the complexity of uranium biogeochemistry and uranium secondary minerals, and the lack of documented case studies, a systematic monitoring approach using multiple performance indicators is needed. This document provides an overview of uranium bioremediation, summarizes design considerations, and identifies and prioritizes field performance indicators for the application of uranium bioremediation. The performance indicators provided as part of this document are based on current biogeochemical understanding of uranium and will enable practitioners to monitor the performance of their system and make a strong case to clients, regulators, and the public that the future performance of the system can be assured and changes in performance addressed as needed. The performance indicators established by this document and the information gained by using these indicators do add to the cost of uranium bioremediation. However, they are vital to the long-term success of the application of uranium bioremediation and provide a significant assurance that regulatory goals will be met. The document also emphasizes the need for systematic development of key information from bench scale tests and pilot scales tests prior to full-scale implementation
Technical Basis for Assessing Uranium Bioremediation Performance

Energy Technology Data Exchange (ETDEWEB)

PE Long; SB Yabusaki; PD Meyer; CJ Murray; AL N’Guessan

2008-04-01

In situ bioremediation of uranium holds significant promise for effective stabilization of U(VI) from groundwater at reduced cost compared to conventional pump and treat. This promise is unlikely to be realized unless researchers and practitioners successfully predict and demonstrate the long-term effectiveness of uranium bioremediation protocols. Field research to date has focused on both proof of principle and a mechanistic level of understanding. Current practice typically involves an engineering approach using proprietary amendments that focuses mainly on monitoring U(VI) concentration for a limited time period. Given the complexity of uranium biogeochemistry and uranium secondary minerals, and the lack of documented case studies, a systematic monitoring approach using multiple performance indicators is needed. This document provides an overview of uranium bioremediation, summarizes design considerations, and identifies and prioritizes field performance indicators for the application of uranium bioremediation. The performance indicators provided as part of this document are based on current biogeochemical understanding of uranium and will enable practitioners to monitor the performance of their system and make a strong case to clients, regulators, and the public that the future performance of the system can be assured and changes in performance addressed as needed. The performance indicators established by this document and the information gained by using these indicators do add to the cost of uranium bioremediation. However, they are vital to the long-term success of the application of uranium bioremediation and provide a significant assurance that regulatory goals will be met. The document also emphasizes the need for systematic development of key information from bench scale tests and pilot scales tests prior to full-scale implementation.
Accumulation of uranium, cesium, and radium by microbial cells: bench-scale studies

International Nuclear Information System (INIS)

Strandberg, G.W.; Shumate, S.E. II.

1982-07-01

This report describes bench-scale studies on the utilization of microbial cells for the concentration and removal of uranium, radium, and cesium from nuclear processing waste streams. Included are studies aimed at elucidating the basic mechanism of uranium uptake, process development efforts for the use of a combined denitrification-uranium removal process to treat a specific nuclear processing waste stream, and a preliminary investigation of the applicability of microorganisms for the removal of 137 Cs and 226 Ra from existing waste solutions
Uranium Sequestration During Biostimulated Reduction and In Response to the Return of Oxic Conditions In Shallow Aquifers

Science.gov (United States)

Fuller, Christopher C.; Johnson, Kelly J.; Akstin, Katherine; Singer, David M.; Yabusaki, Steven B.; Fang, Yilin; Fuhrmann, M.

2015-01-01

A proposed approach for groundwater remediation of uranium contamination is to generate reducing conditions by stimulating the growth of microbial populations through injection of electron donor compounds into the subsurface. Sufficiently reducing conditions will result in reduction of soluble hexavalent uranium, U(VI), and precipitation of the less soluble +4 oxidation state uranium, U(IV). This process is termed biostimulated reduction. A key issue in the remediation of uranium (U) contamination in aquifers by biostimulated reduction is the long term stability of the sequestered uranium. Three flow-through column experiments using aquifer sediment were used to evaluate the remobilization of bioreduced U sequestered under conditions in which biostimulation extended well into sulfate reduction to enhance precipitation of reduced sulfur phases such as iron sulfides. One column received added ferrous iron, Fe(II), increasing production of iron sulfides, to test their effect on remobilization of the sequestered uranium, either by serving as a redox buffer by competing for dissolved oxygen, or by armoring the reduced uranium. During biostimulation of the ambient microbial population with acetate, dissolved uranium was lowered by a factor of 2.5 or more with continued removal for over 110 days of biostimulation, well after the onset of sulfate reduction at ~30 days. Sequestered uranium was essentially all U(IV) resulting from the formation of nano-particulate uraninite that coated sediment grains to a thickness of a few 10’s of microns, sometimes in association with S and Fe. A multicomponent biogeochemical reactive transport model simulation of column effluents during biostimulation was generally able to describe the acetate oxidation, iron, sulfate, and uranium reduction for all three columns using parameters derived from simulations of field scale biostimulation experiments. Columns were eluted with artificial groundwater at equilibrium with atmospheric oxygen to
Operating experience in processing of differently sourced deeply depleted uranium oxide and production of deeply depleted uranium metal ingots

International Nuclear Information System (INIS)

Manna, S.; Ladola, Y.S.; Sharma, S.; Chowdhury, S.; Satpati, S.K.; Roy, S.B.

2009-01-01

Uranium Metal Plant (UMP) of BARC had first time experience on production of three Depleted Uranium Metal (DUM) ingots of 76kg, 152kg and 163kg during March 1991. These ingots were produced by processing depleted uranyl nitrate solution produced at Plutonium Plant (PP), Trombay. In recent past Uranium Metal Plant (UMP), Uranium Extraction Division (UED), has been assigned to produce tonnage quantity of Deeply DUM (DDUM) from its oxide obtained from PP, PREFRE and RMP, BARC. This is required for shielding the high radioactive source of BHABHATRON Tele-cobalt machine, which is used for cancer therapy. The experience obtained in processing of various DDU oxides is being utilized for design of large scale DDU-metal plant under XIth plan project. The physico- chemical characteristics like morphology, density, flowability, reactivity, particle size distribution, which are having direct effect on reactivity of the powders of the DDU oxide powder, were studied and the shop-floor operational experience in processing of different oxide powder were obtained and recorded. During campaign trials utmost care was taken to standardized all operating conditions using the same equipment which are in use for natural uranium materials processing including safety aspects both with respect to radiological safety and industrial safety. Necessary attention and close monitoring were specially arranged and maintained for the safety aspects during the trial period. In-house developed pneumatic transport system was used for powder transfer and suitable dust arresting system was used for reduction of powder carry over
Effects of drop testing on scale model shipping containers shielded with depleted uranium

International Nuclear Information System (INIS)

Butler, T.A.

1980-02-01

Three scale model shipping containers shielded with depleted uranium were dropped onto an essentially unyielding surface from various heights to determine their margins to failure. This report presents the results of a thorough posttest examination of the models to check for basic structural integrity, shielding integrity, and deformations. Because of unexpected behavior exhibited by the depleted uranium shielding, several tests were performed to further characterize its mechanical properties. Based on results of the investigations, recommendations are made for improved container design and for applying the results to full-scale containers. Even though the specimens incorporated specific design features, the results of this study are generally applicable to any container design using depleted uranium
Experimental Plan: 300 Area Treatability Test: In Situ Treatment of the Vadose Zone and Smear Zone Uranium Contamination by Polyphosphate Infiltration

International Nuclear Information System (INIS)

Wellman, Dawn M.; Pierce, Eric M.; Oostrom, Mart; Fruchter, Jonathan S.

2007-01-01

The overall objectives of the treatability test is to evaluate and optimize polyphosphate remediation technology for infiltration either from ground surface, or some depth of excavation, providing direct stabilization of uranium within the deep vadose and capillary fringe above the 300 Area aquifer. Expected result from this experimental plan is a data package that includes: (1) quantification of the retardation of polyphosphate, (2) the rate of degradation and the retardation of degradation products as a function of water content, (3) an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, (4) an understanding of the transformation mechanism, identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and silicate minerals with the polyphosphate remedy under solubility-limiting conditions, (5) quantification of the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and capillary fringe, and (6) quantification of reliable equilibrium solubility values for autunite under hydraulically unsaturated conditions allowing accurate prediction of the long-term stability of autunite. Moreover, results of intermediate scale testing will quantify the transport of polyphosphate and degradation products, and yield degradation rates, at a scale that is bridging the gap between the small-scale UFA studies and the field scale. These results will be used to test and verify a site-specific, variable saturation, reactive transport model and to aid in the design of a pilot-scale field test of this technology. In particular, the infiltration approach and monitoring strategy of the pilot test would be primarily based on results from intermediate-scale testing. Results from this
Hyperspectral information identification for characterizing metallogenic factors of Taoshan uranium ore-field

International Nuclear Information System (INIS)

Zhang Jielin

2007-01-01

The application of high resolution remote sensing technology to uranium mineralization is discussed in detail. By utilizing field hyperspectrum measurement method (VIS/NIR-SWIR-FIR) and fusion technology of ETM image and Radarsat data, the spectral characteristic of uranium mineralization factors including rock mass, ore-control fault and hydrothermal alteration are studied in Taoshan granite type uranium deposits. The main ore-control structure has been identified based on remote sensing image feature. Those results and experiences provide the new remote sensing approaches to the prospecting and evaluation of uranium resources. (authors)
1981 radon barrier field test at Grand Junction uranium mill tailings pile

International Nuclear Information System (INIS)

Hartley, J.N.; Gee, G.W.; Baker, E.G.; Freeman, H.D.

1983-04-01

Technologies to reduce radon released from uranium mill tailings are being investigated by Pacific Northwest Laboratory as part of the Department of Energy's Uranium Mill Tailings Remedial Action Project (UMTRAP) Technology development program. These technologies include: (1) earthen cover systems, (2) multilayer cover systems, and (3) asphalt emulsion radon barrier systems. During the summer of 1981, a field test was initiated at the Grand Junction, Colorado, uranium tailings pile to evaluate and compare the effectiveness of each radon barrier system. Test plots cover about 1.2 ha (3 acres). The field test has demonstrated the effectiveness of all three cover systems in reducing radon release to near background levels ( 2 s - 1 ). In conjunction with the field tests, column tests (1.8 m diameter) were initiated with cover systems similar to those in the larger field test plots. The column tests allow a direct comparison of the two test procedures and also provide detailed information on radon transport
300 Area Uranium Stabilization Through Polyphosphate Injection: Final Report

Energy Technology Data Exchange (ETDEWEB)

Vermeul, Vincent R.; Bjornstad, Bruce N.; Fritz, Brad G.; Fruchter, Jonathan S.; Mackley, Rob D.; Newcomer, Darrell R.; Mendoza, Donaldo P.; Rockhold, Mark L.; Wellman, Dawn M.; Williams, Mark D.

2009-06-30

The objective of the treatability test was to evaluate the efficacy of using polyphosphate injections to treat uranium-contaminated groundwater in situ. A test site consisting of an injection well and 15 monitoring wells was installed in the 300 Area near the process trenches that had previously received uranium-bearing effluents. This report summarizes the work on the polyphosphate injection project, including bench-scale laboratory studies, a field injection test, and the subsequent analysis and interpretation of the results. Previous laboratory tests have demonstrated that when a soluble form of polyphosphate is injected into uranium-bearing saturated porous media, immobilization of uranium occurs due to formation of an insoluble uranyl phosphate, autunite [Ca(UO2)2(PO4)2•nH2O]. These tests were conducted at conditions expected for the aquifer and used Hanford soils and groundwater containing very low concentrations of uranium (10-6 M). Because autunite sequesters uranium in the oxidized form U(VI) rather than forcing reduction to U(IV), the possibility of re-oxidation and subsequent re-mobilization is negated. Extensive testing demonstrated the very low solubility and slow dissolution kinetics of autunite. In addition to autunite, excess phosphorous may result in apatite mineral formation, which provides a long-term source of treatment capacity. Phosphate arrival response data indicate that, under site conditions, the polyphosphate amendment could be effectively distributed over a relatively large lateral extent, with wells located at a radial distance of 23 m (75 ft) reaching from between 40% and 60% of the injection concentration. Given these phosphate transport characteristics, direct treatment of uranium through the formation of uranyl-phosphate mineral phases (i.e., autunite) could likely be effectively implemented at full field scale. However, formation of calcium-phosphate mineral phases using the selected three-phase approach was problematic. Although
Strain fields and line energies of dislocations in uranium dioxide

International Nuclear Information System (INIS)

Parfitt, David C; Bishop, Clare L; Wenman, Mark R; Grimes, Robin W

2010-01-01

Computer simulations are used to investigate the stability of typical dislocations in uranium dioxide. We explain in detail the methods used to produce the dislocation configurations and calculate the line energy and Peierls barrier for pure edge and screw dislocations with the shortest Burgers vector 1/2 . The easiest slip system is found to be the {100}(110) system for stoichiometric UO 2 , in agreement with experimental observations. We also examine the different strain fields associated with these line defects and the close agreement between the strain field predicted by atomic scale models and the application of elastic theory. Molecular dynamics simulations are used to investigate the processes of slip that may occur for the three different edge dislocation geometries and nudged elastic band calculations are used to establish a value for the Peierls barrier, showing the possible utility of the method in investigating both thermodynamic average behaviour and dynamic processes such as creep and plastic deformation.
Identifying the site of granite uranium deposit with radon survey and soil-natural themoluminescence survey. A case study of Xiazhuang granite uranium field

International Nuclear Information System (INIS)

Yang Yaxin; Wu Yamei; Wu Xinmin; Chen Yue; Zheng Yongming; Zhang Ye; Wu Lieqin

2007-01-01

This paper briefly introduces the methods and procedures for field and indoor radon survey and themoluminescence (TL) survey. The application of these two methods to Xiazhuang uranium field in Guangdong province shows: (1) the positive anomalies of radon survey coincide well with fractured zone and the positive anomalies of TL survey response to uranium mineralization on granite type uranium deposit of silicated fracture zone, the uranium deposit can be effectively explored when these two kinds of anomalies match together. (2) the positive anomalies of radon survey coincide well with fractured zone and the positive anomalies of TL response to the position that intersection between the fractured zone and diabase dyke is projected on the ground. (authors)

Geochemical investigations by the U.S. Geological Survey on uranium mining, milling, and environmental restoration

Science.gov (United States)

Landa, Edward R.; Cravotta, Charles A.; Naftz, David L.; Verplanck, Philip L.; Nordstrom, D. Kirk; Zielinski, Robert A.

2000-01-01

Recent research by the U.S. Geological Survey has characterized contaminant sources and identified important geochemical processes that influence transport of radionuclides from uranium mining and milling wastes. 1) Selective extraction studies indicated that alkaline earth sulfates and hydrous ferric oxides are important hosts of 226Ra in uranium mill tailings. The action of sulfate-reducing and ironreducing bacteria on these phases was shown to enhance release of radium, and this adverse result may temper decisions to dispose of uranium mill tailings in anaerobic environments. 2) Field studies have shown that although surface-applied sewage sludge/wood chip amendments aid in revegetating pyritic spoil, the nitrogen in sludge leachate can enhance pyrite oxidation, acidification of groundwater, and the consequent mobilization of metals and radionuclides. 3) In a U.S. Environmental Protection Agencyfunded study, three permeable reactive barriers consisting of phosphate-rich material, zero-valent iron, or amorphous ferric oxyhydroxide have been installed at an abandoned uranium upgrader facility near Fry Canyon, UT. Preliminary results indicate that each of the permeable reactive barriers is removing the majority of the uranium from the groundwater. 4) Studies on the geochemistry of rare earth elements as analogues for actinides such as uranium and thorium in acid mine drainage environments indicate high mobility under acid-weathering conditions but measurable attenuation associated with iron and aluminum colloid formation. Mass balances from field and laboratory studies are being used to quantify the amount of attenuation. 5) A field study in Colorado demonstrated the use of 234U/238U isotopic ratio measurements to evaluate contamination of shallow groundwater with uranium mill effluent.
Preliminary research on finite difference method to solve radon field distribution over sandstone-type uranium ore body

International Nuclear Information System (INIS)

Li Bihong; Shuang Na; Liu Qingcheng

2006-01-01

The principle of finite difference method is introduced, and the radon field distribution over sandstone-type uranium deposit is narrated. The radon field distribution theory equation is established. To solve radon field distribution equation using finite difference algorithm is to provide the value computational method for forward calculation about radon field over sandstone-type uranium mine. Study on 2-D finite difference method on the center of either high anomaly radon fields in view of the character of radon field over sandstone-type uranium provide an algorithm for further research. (authors)
Field-scale evaluation of biological uranium reduction and reoxidation in the near-source zone at the NABIR Field Research Center in Oak Ridge, TN

International Nuclear Information System (INIS)

Craig S. Criddle; Peter Kitanidis; Scott Fendorf; Weimin Wu; Philip M. Jardine; Jizhong Zhou; Baohua Gu

2006-01-01

The primary objective of the project is to advance the understanding and predictive capability of coupled hydrological, geochemical, and microbiological processes that control the in situ transport and bioremediation radionuclides and co-contaminants at multiple scales. Specific objectives include: (1) Investigate the feasibility of in situ bioremediation of uranium in a highly contaminated region within the subsurface of Area 3 of the DoE ERSP FRC (2) Using a variety of tracer strategies, develop and model a system that establishes hydraulic control of the target region for biostimulation (3) Perform long term in situ biostimulation studies that create a microbial communities capable of reducing residual nitrate to N2 and mobile U(VI) to sparingly soluble U(IV) (4) Use a variety of solid and solution phase interrogation techniques to quantify the extent of in situ reduction and immobilization of U(VI). (5) Investigate a variety of geochemical factors that influence the stability and possible reoxidation of reduced uranium
Uranium chemistry: significant advances

International Nuclear Information System (INIS)

Mazzanti, M.

2011-01-01

The author reviews recent progress in uranium chemistry achieved in CEA laboratories. Like its neighbors in the Mendeleev chart uranium undergoes hydrolysis, oxidation and disproportionation reactions which make the chemistry of these species in water highly complex. The study of the chemistry of uranium in an anhydrous medium has led to correlate the structural and electronic differences observed in the interaction of uranium(III) and the lanthanides(III) with nitrogen or sulfur molecules and the effectiveness of these molecules in An(III)/Ln(III) separation via liquid-liquid extraction. Recent work on the redox reactivity of trivalent uranium U(III) in an organic medium with molecules such as water or an azide ion (N 3 - ) in stoichiometric quantities, led to extremely interesting uranium aggregates particular those involved in actinide migration in the environment or in aggregation problems in the fuel processing cycle. Another significant advance was the discovery of a compound containing the uranyl ion with a degree of oxidation (V) UO 2 + , obtained by oxidation of uranium(III). Recently chemists have succeeded in blocking the disproportionation reaction of uranyl(V) and in stabilizing polymetallic complexes of uranyl(V), opening the way to to a systematic study of the reactivity and the electronic and magnetic properties of uranyl(V) compounds. (A.C.)
Recovering uranium from coal in-situ. Final report, February 1980-July 1981

International Nuclear Information System (INIS)

1981-01-01

In Situ Technology, Inc., ''InTech,'' has designed a new process for recovery of uranium from coal in situ. Prime objectives of the program reported herein are to reduce two uncertainties related to eventual commercialization of the process. The first uncertainty concerns appropriate field sites and their potential. The work involved laboratory tests and analysis of field samples, burning the samples to ash and leaching uranium from residual ash at laboratory scale, and burning the samples to ash and leaching uranium from residual ash at pilot plant scale. Laboratory and pilot plant tests were designed to simulate significant elements of the underground process. Field samples from New Mexico averaged 0.061% U 3 O 8 and from North Dakota 0.058% of U 3 O 8 in the coal, both on a dry basis. Phase I laboratory tests on New Mexico field samples were successfully conducted with no difficulties in reducing uraniferous coal to ash. Leaching tests resulted in uranium recoveries to 77.9% with acid leach and to 56% with alkaline leach. Phase II laboratory and pilot plant scale tests were successfully conducted on North Dakota field samples, but required supplemental fuel and/or enrichment for reducing uraniferous coal to ash. Acid leaching of residual ash resulted in uranium recoveries to 83.8%. Acid consumption was 71.0 pounds per ton during pilot plant scale leaching tests. The overall analysis and test program is considered to be highly successful and resulted in significant reduction of the uncertainties for eventual commercialization of the process. 3 refs
Measurement of disequilibrium in uranium and geochemical cartography by XRF field measurements for uranium exploration in a roll-front context (Mongolia)

International Nuclear Information System (INIS)

Andre, G.; Licht, A.

2009-01-01

Exploration studies in the South-eastern Mongolia revealed uranium mineralisation associated with a roll-front development in sands and clays of the Sainshand formation (late Cretaceous). The authors report a field measurement campaign performed with a portable X-ray fluorescence apparatus which allows on-site analysis of 30 species including uranium. This on-site analysis of uranium contents quickly characterizes the equilibrium state of new sectors. Visualization of disequilibria informs on the genesis and on the evolution of the deposit. The tracking of elements like selenium, vanadium and molybdenum helps the understanding of uranium trap or release mechanisms
Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume

Energy Technology Data Exchange (ETDEWEB)

Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark E.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammon, Glenn; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Ward, Anderson L.; Zheng, Chunmiao

2010-02-01

The Integrated Field-Scale Subsurface Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex hydrogeologic setting where groundwater and riverwater interact. A series of forefront science questions on mass transfer are posed for research which relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated system. The project was initiated in February 2007, with CY 2007 and CY 2008 progress summarized in preceding reports. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2009 with completion of extensive laboratory measurements on field sediments, field hydrologic and geophysical characterization, four field experiments, and modeling. The laboratory characterization results are being subjected to geostatistical analyses to develop spatial heterogeneity models of U concentration and chemical, physical, and hydrologic properties needed for reactive transport modeling. The field experiments focused on: (1) physical characterization of the groundwater flow field during a period of stable hydrologic conditions in early spring, (2) comprehensive groundwater monitoring during spring to characterize the release of U(VI) from the lower vadose zone to the aquifer during water table rise and fall, (3) dynamic geophysical monitoring of salt-plume migration during summer, and (4) a U reactive tracer experiment (desorption) during the fall. Geophysical characterization of the well field was completed using the down-well Electrical Resistance Tomography (ERT) array, with results subjected to robust
Use of a Ca-Citrate-Phosphate Solution to Form Hydroxyapatite for Uranium Stabilization of Old Rifle Sediments: Laboratory Proof of Principle Studies

Energy Technology Data Exchange (ETDEWEB)

Szescody, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moore, Robert C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rigali, Mark J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Vermeul, Vincent R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Luellen, Jon [AECOM, Denver, CO (United States)

2016-03-01

The Old Rifle Site is a former vanadium and uranium ore-processing facility located adjacent to the Colorado River and approximately 0.3 miles east of the city of Rifle, CO. The former processing facilities have been removed and the site uranium mill tailings are interned at a disposal cell north of the city of Rifle. However, some low level remnant uranium contamination still exists at the Old Rifle site. In 2002, the United States Nuclear Regulatory Commission (US NRC) concurred with United States Department of Energy (US DOE) on a groundwater compliance strategy of natural flushing with institutional controls to decrease contaminant concentrations in the aquifer. In addition to active monitoring of contaminant concentrations, the site is also used for DOE Legacy Management (LM) and other DOE-funded small-scale field tests of remediation technologies. The purpose of this laboratory scale study was to evaluate the effectiveness of a hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) permeable reactive barrier and source area treatment in Old Rifle sediments. Phosphate treatment impact was evaluated by comparing uranium leaching and surface phase changes in untreated to PO₄-treated sediments. The impact of the amount of phosphate precipitation in the sediment on uranium mobility was evaluated with three different phosphate loadings. A range of flow velocity and uranium concentration conditions (i.e., uranium flux through the phosphate-treated sediment) was also evaluated to quantify the uranium uptake mass and rate by the phosphate precipitate.
Reports on investigations of uranium anomalies. National Uranium Resource Evaluation

International Nuclear Information System (INIS)

Goodknight, C.S.; Burger, J.A.

1982-10-01

During the National Uranium Resource Evaluation (NURE) program, conducted for the US Department of Energy (DOE) by Bendix Field Engineering Corporation (BFEC), radiometric and geochemical surveys and geologic investigations detected anomalies indicative of possible uranium enrichment. Data from the Aerial Radiometric and Magnetic Survey (ARMS) and the Hydrogeochemical and Stream-Sediment Reconnaissance (HSSR), both of which were conducted on a national scale, yielded numerous anomalies that may signal areas favorable for the occurrence of uranium deposits. Results from geologic evaluations of individual 1 0 x 2 0 quadrangles for the NURE program also yielded anomalies, which could not be adequately checked during scheduled field work. Included in this volume are individual reports of field investigations for the following six areas which were shown on the basis of ARMS, HSSR, and (or) geologic data to be anomalous: (1) Hylas zone and northern Richmond basin, Virginia; (2) Sischu Creek area, Alaska; (3) Goodman-Dunbar area, Wisconsin; (4) McCaslin syncline, Wisconsin; (5) Mt. Withington Cauldron, Socorro County, New Mexico; (6) Lake Tecopa, Inyo County, California. Field checks were conducted in each case to verify an indicated anomalous condition and to determine the nature of materials causing the anomaly. The ultimate objective of work is to determine whether favorable conditions exist for the occurrence of uranium deposits in areas that either had not been previously evaluated or were evaluated before data from recent surveys were available. Most field checks were of short duration (2 to 5 days). The work was done by various investigators using different procedures, which accounts for variations in format in their reports. All papers have been abstracted and indexed
Uranium recovery from seawater

International Nuclear Information System (INIS)

Bitte, J.; Fremery, M.I.; Kellner, A.; Schroeer, K.; Knippenberg, W.

1984-09-01

The present publication describes the development work of a process to recover uranium from seawater and the proposition of a commercial demonstration plant. The essential components of this process are verified in the laboratory scale as well as in some field tests. A detailed engineering design for a model plant in a semi-technical scale to allow field tests in the marine environment is also presented. These field tests are expected to produce more realistic data on the technical and economical feasibility of the proposed technology. Production cost estimates based on state-of-the-art technology lie around 250 Dollar/1b U 3 O 8 . However, the effect of a corresponding uranium price increase on electricity costs are comparable to cost increases in coal operated power plants caused by the desulfurisation of coal. Further reductions of the production costs in the range below 150 Dollar/1b U 3 O 8 seem possible through special research efforts in the area of sorber development and concept design. (orig.) [de
Prospects for increasing uranium resources in the Khiagda ore field (Russian Federation)

International Nuclear Information System (INIS)

Novgorodtcev, A.; Martynenko, V.; Gladyshev, A.

2014-01-01

The Khiagda ore field uranium deposits are located in the Republic of Buryatia, on the Amalat Plateau formed by the Neogene basalts. The position of the ore field is defined by a large tectonic structure having a north-eastern strike the Baisykhan Uplift. The slopes of the Baisykhan dividing uplift are incised by short (4 to 16 km) lateral tributaries of the Amalat and Atalanga paleorivers. The paleovalley network is filled with terrigenous-volcanogenic units of the Miocene Dzhilinda Formation (N1dz) buried under a thick cover of plateau basalts. The upheaval of the Baisykhan Uplift in the Neogene caused the penetration of the hydrodynamic flow of oxygenous uranium-bearing water into the sedimentary rock mass and formation of the subsoil/tabular oxidation zone (STOZ) on the boundary of which there formed uranium mineralisation.
Investigating Uranium Mobility Using Stable Isotope Partitioning of 238U/235U and a Reactive Transport Model

Science.gov (United States)

Bizjack, M.; Johnson, T. M.; Druhan, J. L.; Shiel, A. E.

2015-12-01

We report a numerical reactive transport model which explicitly incorporates the effectively stable isotopes of uranium (U) and the factors that influence their partitioning in bioactive systems. The model reproduces trends observed in U isotope ratios and concentration measurements from a field experiment, thereby improving interpretations of U isotope ratios as a tracer for U reactive transport. A major factor contributing to U storage and transport is its redox state, which is commonly influenced by the availability of organic carbon to support metal-reducing microbial communities. Both laboratory and field experiments have demonstrated that biogenic reduction of U(VI) fractionates the stable isotope ratio 238U/235U, producing an isotopically heavy solid U(IV) product. It has also been shown that other common reactive transport processes involving U do not fractionate isotopes to a consistently measurable level, which suggests the capacity to quantify the extent of bioreduction occurring in groundwater containing U using 238U/235U ratios. A recent study of a U bioremediation experiment at the Rifle IFRC site (Colorado, USA) applied Rayleigh distillation models to quantify U stable isotope fractionation observed during acetate amendment. The application of these simplified models were fit to the observations only by invoking a "memory-effect," or a constant source of low-concentration, unfractionated U(VI). In order to more accurately interpret the measured U isotope ratios, we present a multi-component reactive transport model using the CrunchTope software. This approach is capable of quantifying the cycling and partitioning of individual U isotopes through a realistic network of transport and reaction pathways including reduction, oxidation, and microbial growth. The model incorporates physical heterogeneity of the aquifer sediments through zones of decreased permeability, which replicate the observed bromide tracer, major ion chemistry, U concentration, and U
Analysis of the reactivity coefficients of the advanced high-temperature reactor for plutonium and uranium fuels

Energy Technology Data Exchange (ETDEWEB)

Zakova, Jitka [Department of Nuclear and Reactor Physics, Royal Institute of Technology, KTH, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)], E-mail: jitka.zakova@neutron.kth.se; Talamo, Alberto [Nuclear Engineering Division, Argonne National Laboratory, ANL, 9700 South Cass Avenue, Argonne, IL 60439 (United States)], E-mail: alby@anl.gov

2008-05-15

The conceptual design of the advanced high-temperature reactor (AHTR) has recently been proposed by the Oak Ridge National Laboratory, with the intention to provide and alternative energy source for very high temperature applications. In the present study, we focused on the analyses of the reactivity coefficients of the AHTR core fueled with two types of fuel: enriched uranium and plutonium from the reprocessing of light water reactors irradiated fuel. More precisely, we investigated the influence of the outer graphite reflectors on the multiplication factor of the core, the fuel and moderator temperature reactivity coefficients and the void reactivity coefficient for five different molten salts: NaF, BeF{sub 2}, LiF, ZrF{sub 4} and Li{sub 2}BeF{sub 4} eutectic. In order to better illustrate the behavior of the previous parameters for different core configurations, we evaluated the moderating ratio of the molten salts and the absorption rate of the key fuel nuclides, which, of course, are driven by the neutron spectrum. The results show that the fuel and moderator temperature reactivity coefficients are always negative, whereas the void reactivity coefficient can be set negative provided that the fuel to moderator ratio is optimized (the core is undermoderated) and the moderating ratio of the coolant is large.
Analysis of the reactivity coefficients of the advanced high-temperature reactor for plutonium and uranium fuels

International Nuclear Information System (INIS)

Zakova, Jitka; Talamo, Alberto

2008-01-01

The conceptual design of the advanced high-temperature reactor (AHTR) has recently been proposed by the Oak Ridge National Laboratory, with the intention to provide and alternative energy source for very high temperature applications. In the present study, we focused on the analyses of the reactivity coefficients of the AHTR core fueled with two types of fuel: enriched uranium and plutonium from the reprocessing of light water reactors irradiated fuel. More precisely, we investigated the influence of the outer graphite reflectors on the multiplication factor of the core, the fuel and moderator temperature reactivity coefficients and the void reactivity coefficient for five different molten salts: NaF, BeF 2 , LiF, ZrF 4 and Li 2 BeF 4 eutectic. In order to better illustrate the behavior of the previous parameters for different core configurations, we evaluated the moderating ratio of the molten salts and the absorption rate of the key fuel nuclides, which, of course, are driven by the neutron spectrum. The results show that the fuel and moderator temperature reactivity coefficients are always negative, whereas the void reactivity coefficient can be set negative provided that the fuel to moderator ratio is optimized (the core is undermoderated) and the moderating ratio of the coolant is large
Uranium

International Nuclear Information System (INIS)

Cuney, M.; Pagel, M.; Leroy, J.

1992-01-01

First, this book presents the physico-chemical properties of Uranium and the consequences which can be deduced from the study of numerous geological process. The authors describe natural distribution of Uranium at different scales and on different supports, and main Uranium minerals. A great place in the book is assigned to description and classification of uranium deposits. The book gives also notions on prospection and exploitation of uranium deposits. Historical aspects of Uranium economical development (Uranium resources, production, supply and demand, operating costs) are given in the last chapter. 7 refs., 17 figs
Uranium Elemental and Isotopic Constraints on Groundwater Flow Beneath the Nopal I Uranium Deposit, Pena Blanca, Mexico

International Nuclear Information System (INIS)

S.J. Goldstein; M.T. Murrell; A.M. Simmons

2005-01-01

The Nopal I uranium deposit in Chihuahua, Mexico, is an excellent analogue for evaluating the fate of spent fuel, associated actinides, and fission products over long time scales for the proposed Yucca Mountain high-level nuclear waste repository. In 2003, three groundwater wells were drilled directly adjacent to (PB-1) and 50 m on either side of the uranium deposit (PB-2 and PB-3) in order to evaluate uranium-series transport in three dimensions. After drilling, uranium concentrations were elevated in all of the three wells (0.1-18 ppm) due to drilling activities and subsequently decreased to ∼5-20% of initial values over the next several months. The 234 U/ 238 U activity ratios were similar for PB-1 and PB-2 (1.005 to 1.079) but distinct for PB-3 (1.36 to 1.83) over this time period, suggesting limited mixing between groundwater from these wells over these short time and length scales. Regional groundwater wells located up to several km from the deposit also have distinct uranium isotopic characteristics and constrain mixing over larger length and time scales. We model the decreasing uranium concentrations in the newly drilled wells with a simple one-dimensional advection-dispersion model, assuming uranium is introduced as a slug to each of the wells and transported as a conservative tracer. Using this model for our data, the relative uranium concentrations are dependent on both the longitudinal dispersion as well as the mean groundwater flow velocity. These parameters have been found to be correlated in both laboratory and field studies of groundwater velocity and dispersion (Klotz et al., 1980). Using typical relationships between velocity and dispersion for field and laboratory studies along with the relationship observed from our uranium data, both velocity (1-10 n/yr) and dispersion coefficient (1E-5 to 1E-2 cm 2 /s) can be derived from the modeling. As discussed above, these relatively small flow velocities and dispersivities agree with mixing
Gravity data processing and research in potential evaluation of uranium resource in China

International Nuclear Information System (INIS)

Liu Hu; Zhao Dan; Ke Dan; Li Bihong; Han Shaoyang

2012-01-01

Through data processing, anomaly extraction, geologic structure deduction from gravity in 39 uranium metallogenic zones and 29 prediction areas, the predicting factors such as tectonic units, faults, scope and depth of rocks, scope of basins and strata structure were provided for the evaluation of uranium resources potential. Gravity field features of uranium metallogenic environment were summarized for hydrothermal type uranium deposits (granite, volcanic and carbonate-siliceous-argillaceous type) as regional gravity transition from high to the low field or the region near the low field, and the key metallogenic factors as granite rocks and volcanic basins in the low gravity field. It was found that Large-scale sandstone type uranium mineralization basins are located in the high regional gravity field, provenance areas are in the low field, and the edge and inner uplift areas usually located in the high field of the residual gravity. Faults related to different type uranium mineralization occur as the gradient zones, boundaries, a string of bead anomalies and striped gravity anomalies in the gravity field. (authors)
Deep groundwater redox reactions in the Palmottu uranium deposit: The role of uranium and iron in these processes

International Nuclear Information System (INIS)

Bruno, J.; Cera, E.; Duro, L.; Ahonen, L.

1996-12-01

The reduction oxidation properties of the deep bedrock and groundwater are important geochemical factors with respect to the chemical stability of the multibarrier system, which isolates the disposed nuclear fuel from biosphere. In the report are described the results of the redox experiments carried out in the field using the natural groundwaters of Palmottu, in Nummi-Pusula, Finland. The experiments include (1) measurements of natural water redox potential values during four to eight hours continuous pumping; (2) monitoring of the redox-potential response to an artificial change of pH of the groundwater. Separate tests were made in iron and uranium-rich groundwaters, respectively. The data of the field experiments were used in the redox-modelling of the iron and uranium systems. In accordance with earlier knowledge, it was showed that dissolved iron is an important redox electrolyte in natural waters, at least at concentration levels of milligrams per liter. However, a striking observation was that in the absence of dissolved iron dissolved uranium (in concentrations of about 200 nM or more) seems to be able to give nernstian response on platinum electrode in acid/base titrations. The effective redox properties of the bedrock-groundwater system depend on the availability and reactivity of solid phases able to exchange electrons with dissolved redox electrolytes. The present results indicate that, in the bedrock/groundwater system of the Palmottu uranium mineralization, uranium minerals are important redox buffers. (orig.) (refs.)
Reactive transport of uranium in a groundwater bioreduction study: Insights from high-temporal resolution 238U/235U data

Science.gov (United States)

Shiel, A. E.; Johnson, T. M.; Lundstrom, C. C.; Laubach, P. G.; Long, P. E.; Williams, K. H.

2016-08-01

We conducted a detailed investigation of U isotopes in conjunction with a broad geochemical investigation during field-scale biostimulation and desorption experiments. This investigation was carried out in the uranium-contaminated alluvial aquifer of the Rifle field research site. In this well-characterized setting, a more comprehensive understanding of U isotope geochemistry is possible. Our results indicate that U isotope fractionation is consistently observed across multiple experiments at the Rifle site. Microbially-mediated reduction is suggested to account for most or all of the observed fractionation as abiotic reduction has been demonstrated to impart much smaller, often near-zero, isotopic fractionation or isotopic fractionation in the opposite direction. Data from some time intervals are consistent with a simple model for transport and U(VI) reduction, where the fractionation factor (ε = +0.65‰ to +0.85‰) is consistent with experimental studies. However, during other time intervals the observed patterns in our data indicate the importance of other processes in governing U concentrations and 238U/235U ratios. For instance, we demonstrate that departures from Rayleigh behavior in groundwater systems arise from the presence of adsorbed species. We also show that isotope data are sensitive to the onset of oxidation after biostimulation ends, even in the case where reduction continues to remove contaminant uranium downstream. Our study and the described conceptual model support the use of 238U/235U ratios as a tool for evaluating the efficacy of biostimulation and potentially other remedial strategies employed at Rifle and other uranium-contaminated sites.
Uranium redox transition pathways in acetate-amended sediments

Science.gov (United States)

Bargar, John R.; Williams, Kenneth H.; Campbell, Kate M.; Long, Philip E.; Stubbs, Joanne E.; Suvorova, Elenal I.; Lezama-Pacheco, Juan S.; Alessi, Daniel S.; Stylo, Malgorzata; Webb, Samuel M.; Davis, James A.; Giammar, Daniel E.; Blue, Lisa Y.; Bernier-Latmani, Rizlan

2013-01-01

Redox transitions of uranium [from U(VI) to U(IV)] in low-temperature sediments govern the mobility of uranium in the environment and the accumulation of uranium in ore bodies, and inform our understanding of Earth’s geochemical history. The molecular-scale mechanistic pathways of these transitions determine the U(IV) products formed, thus influencing uranium isotope fractionation, reoxidation, and transport in sediments. Studies that improve our understanding of these pathways have the potential to substantially advance process understanding across a number of earth sciences disciplines. Detailed mechanistic information regarding uranium redox transitions in field sediments is largely nonexistent, owing to the difficulty of directly observing molecular-scale processes in the subsurface and the compositional/physical complexity of subsurface systems. Here, we present results from an in situ study of uranium redox transitions occurring in aquifer sediments under sulfate-reducing conditions. Based on molecular-scale spectroscopic, pore-scale geochemical, and macroscale aqueous evidence, we propose a biotic–abiotic transition pathway in which biomass-hosted mackinawite (FeS) is an electron source to reduce U(VI) to U(IV), which subsequently reacts with biomass to produce monomeric U(IV) species. A species resembling nanoscale uraninite is also present, implying the operation of at least two redox transition pathways. The presence of multiple pathways in low-temperature sediments unifies apparently contrasting prior observations and helps to explain sustained uranium reduction under disparate biogeochemical conditions. These findings have direct implications for our understanding of uranium bioremediation, ore formation, and global geochemical processes.

Application of isotope techniques to groundwater pollution research for Xiangshan uranium ore field, China

International Nuclear Information System (INIS)

Liu Fulin; Liu Peilun; Zhu Chuande; Wu Xiaowei; Zeng Yinsheng

1998-01-01

The investigation of groundwater pollution due to uranium deposits focused on the most important uranium metallogenic area-Zhoujiashan district of Xiangshan uranium ore field, China. Groundwater collected from five completed exploration boreholes in the area is regarded as the pollution source and is traced and analysed by using isotope as well as radio-hydrochemical techniques. In addition, the pollution situation of a small uranium ore pile for heap-leaching and a big uranium ore open pit are monitored by the same techniques. It has been experimentally proven that the uranium concentration and the uranium isotope ratio 234 U/ 238 U in natural waters are two sensitive indicators of radioactive pollution in natural waters. It was concluded that under present conditions, exploration of uranium deposits may not cause serious groundwater pollution of radioactive elements (U, Ra, Rn and Th), however, it is difficult to avoid the serious surface water pollution coming from the exploitation of uranium ore by a big open pit. (author)
Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

Science.gov (United States)

Chen, M.; Kocar, B. D.

2016-12-01

Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).
Uranium thiolate complexes

International Nuclear Information System (INIS)

Leverd, Pascal C.

1994-01-01

This research thesis proposes a new approach to the chemistry of uranium thiolate complexes as these compounds are very promising for various uses (in bio-inorganic chemistry, in some industrial processes like oil desulphurization). It more particularly addresses the U-S bond or more generally bonds between polarizable materials and hard metals. The author thus reports the study of uranium organometallic thiolates (tricyclo-penta-dienic and mono-cyclo-octa-tetraenylic complexes), and of uranium homoleptic thiolates (tetra-thiolate complexes, hexa-thiolate complexes, reactivity of homoleptic thiolate complexes) [fr
Uranium isotope ratio measurements in field settings

International Nuclear Information System (INIS)

Shaw, R.W.; Barshick, C.M.; Young, J.P.; Ramsey, J.M.

1997-01-01

The authors have developed a technique for uranium isotope ratio measurements of powder samples in field settings. Such a method will be invaluable for environmental studies, radioactive waste operations, and decommissioning and decontamination operations. Immediate field data can help guide an ongoing sampling campaign. The measurement encompasses glow discharge sputtering from pressed sample hollow cathodes, high resolution laser spectroscopy using conveniently tunable diode lasers, and optogalvanic detection. At 10% 235 U enrichment and above, the measurement precision for 235 U/( 235 U+ 238 U) isotope ratios was ±3%; it declined to ±15% for 0.3% (i.e., depleted) samples. A prototype instrument was constructed and is described
Impact of magnetic fields on the response behaviour of an uranium-scintillator-calorimeter

International Nuclear Information System (INIS)

Mainusch, J.

1990-10-01

For an examination of the signals of the ZEUS calorimeter, an uranium-scintillator calorimeter has been built in cooperation with Toronto University in Canada. This calorimeter very largely corresponds to an HAC1 section of the ZEUS calorimeter. The measurements in the magnetic field were done perpendicular to the incoming beam at field strengths of 0.01 Tesla up to 1.4 Tesla, with electrons of 1-6 GeV. In addition, the magnetic field impact on the signal of the uranium radioactivity was measured. An LED signal was used to check and verify sufficient shielding of the photo tubes against magnetic field effects. It was possible to keep amplification changes to less than 0.1%. (orig./DG) [de
Risk evaluation of uranium mining: a new kinetic approach

Energy Technology Data Exchange (ETDEWEB)

Scislewski, Alexandro [Brazilian Nuclear Energy Comission (CNEN), Avenida Santana, 680, Centro, Caetite-Bahia, 46400-000 (Brazil); Zuddas, Pierpaolo [Universite Pierre et Marie Curie, Paris-Sorbonne, ISTEP place Jussieu, Tour 56-55, case 116, F75252 Paris Cedex 05 (France)

2013-07-01

Release of uranium and associated heavy metals is the main environmental concern regarding exploitation and processing of U-ore. Increasing uranium mining activities potentially increase the risks linked to radiation exposure. As a tool to evaluate these risks, a geochemical inverse modeling approach was developed to estimate the water-mineral interaction in the presence of uranium. Our methodology is based on the estimation of dissolution rate and reactive surface area of the different minerals participating in the reaction by reconstructing the chemical evolution of the interacting fluids. We found that the reactive surface area of parent-rock minerals changes over several orders of magnitude during the investigated reaction time. We propose that the formation of coatings on dissolving mineral surfaces significantly reduces reactivity. Our results show that negatively charged uranium complexes decrease when alkalinity and rock buffer capacity is similarly lower, indicating that the dissolved carbonate is an important parameter impacting uranium mobility. (authors)
Risk evaluation of uranium mining: a new kinetic approach

International Nuclear Information System (INIS)

Scislewski, Alexandro; Zuddas, Pierpaolo

2013-01-01

Release of uranium and associated heavy metals is the main environmental concern regarding exploitation and processing of U-ore. Increasing uranium mining activities potentially increase the risks linked to radiation exposure. As a tool to evaluate these risks, a geochemical inverse modeling approach was developed to estimate the water-mineral interaction in the presence of uranium. Our methodology is based on the estimation of dissolution rate and reactive surface area of the different minerals participating in the reaction by reconstructing the chemical evolution of the interacting fluids. We found that the reactive surface area of parent-rock minerals changes over several orders of magnitude during the investigated reaction time. We propose that the formation of coatings on dissolving mineral surfaces significantly reduces reactivity. Our results show that negatively charged uranium complexes decrease when alkalinity and rock buffer capacity is similarly lower, indicating that the dissolved carbonate is an important parameter impacting uranium mobility. (authors)
Information derived from French studies and achievements in the field of uranium isotope separation

International Nuclear Information System (INIS)

Frejacques, C; Galley, R.

1964-01-01

The work carried out in the field of uranium isotope separation, by gaseous diffusion and by ultracentrifugation, is reviewed. An economic estimate of the various parameters involved in the cost is given, and it is shown that only very large gaseous diffusion plants, corresponding to a programme of enriched uranium reactors of at least 4000 MWe to be installed yearly, can give an economically acceptable enriched uranium production. (authors) [fr
Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford's 300 Area Uranium Plume January 2011 to January 2012

International Nuclear Information System (INIS)

Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark S.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammond, Glenn E.; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Zheng, Chunmiao

2012-01-01

The Integrated Field Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex subsurface biogeochemical setting where groundwater and riverwater interact. A series of forefront science questions on reactive mass transfer motivates research. These questions relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated biogeochemical system. The project was initiated in February 2007, with CY 2007, CY 2008, CY 2009, and CY 2010 progress summarized in preceding reports. A project peer review was held in March 2010, and the IFRC project acted upon all suggestions and recommendations made in consequence by reviewers and SBR/DOE. These responses have included the development of 'Modeling' and 'Well-Field Mitigation' plans that are now posted on the Hanford IFRC web-site, and modifications to the IFRC well-field completed in CY 2011. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2011 including: (i) well modifications to eliminate well-bore flows, (ii) hydrologic testing of the modified well-field and upper aquifer, (iii) geophysical monitoring of winter precipitation infiltration through the U-contaminated vadose zone and spring river water intrusion to the IFRC, (iv) injection experimentation to probe the lower vadose zone and to evaluate the transport behavior of high U concentrations, (v) extended passive monitoring during the period of water table rise and fall, and (vi) collaborative down-hole experimentation with the PNNL SFA on the biogeochemistry of the 300 A Hanford-Ringold contact and the
Direct coupling of a genome-scale microbial in silico model and a groundwater reactive transport model

International Nuclear Information System (INIS)

Fang, Yilin; Scheibe, Timothy D.; Mahadevan, Radhakrishnan; Garg, Srinath; Long, Philip E.; Lovley, Derek R.

2011-01-01

The activity of microorganisms often plays an important role in dynamic natural attenuation or engineered bioremediation of subsurface contaminants, such as chlorinated solvents, metals, and radionuclides. To evaluate and/or design bioremediated systems, quantitative reactive transport models are needed. State-of-the-art reactive transport models often ignore the microbial effects or simulate the microbial effects with static growth yield and constant reaction rate parameters over simulated conditions, while in reality microorganisms can dynamically modify their functionality (such as utilization of alternative respiratory pathways) in response to spatial and temporal variations in environmental conditions. Constraint-based genome-scale microbial in silico models, using genomic data and multiple-pathway reaction networks, have been shown to be able to simulate transient metabolism of some well studied microorganisms and identify growth rate, substrate uptake rates, and byproduct rates under different growth conditions. These rates can be identified and used to replace specific microbially-mediated reaction rates in a reactive transport model using local geochemical conditions as constraints. We previously demonstrated the potential utility of integrating a constraint based microbial metabolism model with a reactive transport simulator as applied to bioremediation of uranium in groundwater. However, that work relied on an indirect coupling approach that was effective for initial demonstration but may not be extensible to more complex problems that are of significant interest (e.g., communities of microbial species, multiple constraining variables). Here, we extend that work by presenting and demonstrating a method of directly integrating a reactive transport model (FORTRAN code) with constraint-based in silico models solved with IBM ILOG CPLEX linear optimizer base system (C library). The models were integrated with BABEL, a language interoperability tool. The
Metallogenetic prospecting in 1:2,000,000 scale for in-situ leachable sandstone type uranium deposit

International Nuclear Information System (INIS)

Wang Zhengbang; Qin Mingkuan; Zhao Ruiquan; Dong Wenming; Li Tiangang; Zheng Dayu; Li Sen; Lin Shuangxing

2002-01-01

By introducing the advanced theory and technology of systematic geo-mapping which is popularized in Central-Asian countries, the project is aimed at metallogenic prospecting in 1:2,000,000 scale for in-situ leachable sandstone type uranium deposits in Xinjiang and its adjacent area. Based on the comprehensive understanding of accumulated data and on the field study in both the work area and the abroad nearby, the authors propose creatively a new concept that the uranium mineralization in the area is controlled by the moderate tectonic movements during the last large-scale orogenic movement, and set up a new epi-genetically metallogenic system of Meso-Cenozoic depositional basins. Furthermore, the temporal-spatial evolution of the ore-controlled Himalaya orogenic movement is brought to light, and a new method to reconstruct the palaeo-tectonic and palaeo-hydrodynamic systems is created. Accordingly, the main differences in metallogenic conditions and prospecting evaluation between the work area and the Central-Asian areas are illustrated, and the favorable and unfavorable influences of the reduction by the exudative oil and gas on the sandstone type uranium mineralization in the work area are explained in detail. Finally, on the basis of compiling the systematic geo-maps and summarizing the assessment criteria, 2 metallogenic provinces and 12 prospecting areas are predicted. This conclusion can provide a scientific foundation for strategic plans to be made by leading groups and other branches. Another achievement of the project is that a guidebook of the systematic geo-mapping theory and technology has been compiled, which is beneficial to the spreading of the method
Resin-based preparation of HTGR fuels: operation of an engineering-scale uranium loading system

International Nuclear Information System (INIS)

Haas, P.A.

1977-10-01

The fuel particles for recycle of 233 U to High-Temperature Gas-Cooled Reactors are prepared from uranium-loaded carboxylic acid ion exchange resins which are subsequently carbonized, converted, and refabricated. The development and operation of individual items of equipment and of an integrated system are described for the resin-loading part of the process. This engineering-scale system was full scale with respect to a hot demonstration facility, but was operated with natural uranium. The feed uranium, which consisted of uranyl nitrate solution containing excess nitric acid, was loaded by exchange with resin in the hydrogen form. In order to obtain high loadings, the uranyl nitrate must be acid deficient; therefore, nitric acid was extracted by a liquid organic amine which was regenerated to discharge a NaNO 3 or NH 4 NO 3 solution waste. Water was removed from the uranyl nitrate solution by an evaporator that yielded condensate containing less than 0.5 ppM of uranium. The uranium-loaded resin was washed with condensate and dried to a controlled water content via microwave heating. The loading process was controlled via in-line measurements of the pH and density of the uranyl nitrate. The demonstrated capacity was 1 kg of uranium per hour for either batch loading contractors or a continuous column as the resin loading contractor. Fifty-four batch loading runs were made without a single failure of the process outlined in the chemical flowsheet or any evidence of inability to control the conditions dictated by the flowsheet
Removal of uranium from uranium-contaminated soils -- Phase 1: Bench-scale testing

International Nuclear Information System (INIS)

Francis, C.W.

1993-09-01

To address the management of uranium-contaminated soils at Fernald and other DOE sites, the DOE Office of Technology Development formed the Uranium in Soils Integrated Demonstration (USID) program. The USID has five major tasks. These include the development and demonstration of technologies that are able to (1) characterize the uranium in soil, (2) decontaminate or remove uranium from the soil, (3) treat the soil and dispose of any waste, (4) establish performance assessments, and (5) meet necessary state and federal regulations. This report deals with soil decontamination or removal of uranium from contaminated soils. The report was compiled by the USID task group that addresses soil decontamination; includes data from projects under the management of four DOE facilities [Argonne National Laboratory (ANL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and the Savannah River Plant (SRP)]; and consists of four separate reports written by staff at these facilities. The fundamental goal of the soil decontamination task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil's physicochemical characteristics or generating waste forms that are difficult to manage and/or dispose of. Emphasis in research was placed more strongly on chemical extraction techniques than physical extraction techniques
Towards new developments in uranium chemistry. Scientific report presented to obtain and Accreditation to Supervise Research

International Nuclear Information System (INIS)

Berthet, Jean-Claude

2003-01-01

After a presentation of his academic curriculum, the author proposes an overview of some of his main research activities and works which notably addressed the reactivity of uranium III complexes (synthesis and reactivity of uranium hydride complexes, synthesis of poly-metallic complexes), amide complexes (synthesis of uranium IV amide precursors, reactivity of cationic complexes, synthesis of uranium IV complexes), uranium triflate (or trifluoromethanesulfonate) complexes, the synthesis of U(Cot)X_2(L)_n complexes and of their derivatives, the complexing of lanthanide iodides and triflates
Uranium Elemental and Isotopic Constraints on Groundwater Flow Beneath the Nopal I Uranium Deposit, Pena Blanca, Mexico

Energy Technology Data Exchange (ETDEWEB)

S.J. Goldstein; M.T. Murrell; A.M. Simmons

2005-07-11

The Nopal I uranium deposit in Chihuahua, Mexico, is an excellent analogue for evaluating the fate of spent fuel, associated actinides, and fission products over long time scales for the proposed Yucca Mountain high-level nuclear waste repository. In 2003, three groundwater wells were drilled directly adjacent to (PB-1) and 50 m on either side of the uranium deposit (PB-2 and PB-3) in order to evaluate uranium-series transport in three dimensions. After drilling, uranium concentrations were elevated in all of the three wells (0.1-18 ppm) due to drilling activities and subsequently decreased to {approx}5-20% of initial values over the next several months. The {sup 234}U/{sup 238}U activity ratios were similar for PB-1 and PB-2 (1.005 to 1.079) but distinct for PB-3 (1.36 to 1.83) over this time period, suggesting limited mixing between groundwater from these wells over these short time and length scales. Regional groundwater wells located up to several km from the deposit also have distinct uranium isotopic characteristics and constrain mixing over larger length and time scales. We model the decreasing uranium concentrations in the newly drilled wells with a simple one-dimensional advection-dispersion model, assuming uranium is introduced as a slug to each of the wells and transported as a conservative tracer. Using this model for our data, the relative uranium concentrations are dependent on both the longitudinal dispersion as well as the mean groundwater flow velocity. These parameters have been found to be correlated in both laboratory and field studies of groundwater velocity and dispersion (Klotz et al., 1980). Using typical relationships between velocity and dispersion for field and laboratory studies along with the relationship observed from our uranium data, both velocity (1-10 n/yr) and dispersion coefficient (1E-5 to 1E-2 cm{sup 2}/s) can be derived from the modeling. As discussed above, these relatively small flow velocities and dispersivities agree with
Scale-up of mixer-settler for uranium extraction

International Nuclear Information System (INIS)

Santana, A.O. de.

1990-05-01

The aim of this work was to obtain scale-up relations for a box type mixer-settler used in uranium extraction process for chloridric leaches. Three box type units with different sizes and with the same geometry were used for scale-up of the mixer. The correlation between extraction rate and specific power input, D/T ratio (stirrer diameter/mixer length) and residence time were experimentally obtained. The results showed that the extraction increases with power input for a constant value of D/T equal to 1/3, remaining however independent from mixer sizes for a specific value of power input. This behavior was observed for power input values ranging from 100 to 750 w/m 9 . (author). 23 refs, 22 figs, 23 tabs
Dynamic Reactive Power Compensation of Large Scale Wind Integrated Power System

DEFF Research Database (Denmark)

Rather, Zakir Hussain; Chen, Zhe; Thøgersen, Paul

2015-01-01

wind turbines especially wind farms with additional grid support functionalities like dynamic support (e,g dynamic reactive power support etc.) and ii) refurbishment of existing conventional central power plants to synchronous condensers could be one of the efficient, reliable and cost effective option......Due to progressive displacement of conventional power plants by wind turbines, dynamic security of large scale wind integrated power systems gets significantly compromised. In this paper we first highlight the importance of dynamic reactive power support/voltage security in large scale wind...... integrated power systems with least presence of conventional power plants. Then we propose a mixed integer dynamic optimization based method for optimal dynamic reactive power allocation in large scale wind integrated power systems. One of the important aspects of the proposed methodology is that unlike...
URANIUM REMOVAL FROM DRINKING WATER USING A SMALL FULL-SCALE SYSTEM

Science.gov (United States)

This report presents background and history of water quality, the basis for design and nine months of actual operating data for a small, full-scale strong-base ion exchange system that is used to remove uranium from a water supply serving a school in Jefferson County, CO. Informa...
Multi-Scale Mass Transfer Processes Controlling Natural Attenuation and Engineered Remediation: An IFRC Focused on Hanford’s 300 Area Uranium Plume January 2011 to January 2012

Energy Technology Data Exchange (ETDEWEB)

Zachara, John M.; Bjornstad, Bruce N.; Christensen, John N.; Conrad, Mark S.; Fredrickson, Jim K.; Freshley, Mark D.; Haggerty, Roy; Hammond, Glenn E.; Kent, Douglas B.; Konopka, Allan; Lichtner, Peter C.; Liu, Chongxuan; McKinley, James P.; Murray, Christopher J.; Rockhold, Mark L.; Rubin, Yoram; Vermeul, Vincent R.; Versteeg, Roelof J.; Zheng, Chunmiao

2012-03-05

The Integrated Field Research Challenge (IFRC) at the Hanford Site 300 Area uranium (U) plume addresses multi-scale mass transfer processes in a complex subsurface biogeochemical setting where groundwater and riverwater interact. A series of forefront science questions on reactive mass transfer motivates research. These questions relate to the effect of spatial heterogeneities; the importance of scale; coupled interactions between biogeochemical, hydrologic, and mass transfer processes; and measurements and approaches needed to characterize and model a mass-transfer dominated biogeochemical system. The project was initiated in February 2007, with CY 2007, CY 2008, CY 2009, and CY 2010 progress summarized in preceding reports. A project peer review was held in March 2010, and the IFRC project acted upon all suggestions and recommendations made in consequence by reviewers and SBR/DOE. These responses have included the development of 'Modeling' and 'Well-Field Mitigation' plans that are now posted on the Hanford IFRC web-site, and modifications to the IFRC well-field completed in CY 2011. The site has 35 instrumented wells, and an extensive monitoring system. It includes a deep borehole for microbiologic and biogeochemical research that sampled the entire thickness of the unconfined 300 A aquifer. Significant, impactful progress has been made in CY 2011 including: (i) well modifications to eliminate well-bore flows, (ii) hydrologic testing of the modified well-field and upper aquifer, (iii) geophysical monitoring of winter precipitation infiltration through the U-contaminated vadose zone and spring river water intrusion to the IFRC, (iv) injection experimentation to probe the lower vadose zone and to evaluate the transport behavior of high U concentrations, (v) extended passive monitoring during the period of water table rise and fall, and (vi) collaborative down-hole experimentation with the PNNL SFA on the biogeochemistry of the 300 A Hanford
Western states uranium resource survey

International Nuclear Information System (INIS)

Tinney, J.F.

1977-01-01

ERDA's National Uranium Resource Evaluation (NURE) program was established to provide a comprehensive description of uranium resources in the United States. To carry out this task, ERDA has contracted with various facilities, including universities, private companies, and state agencies, to undertake projects such as airborne radiometric surveys, geological and geochemical studies, and the development of advanced geophysical technology. LLL is one of four ERDA laboratories systematically studying uranium distribution in surface water, groundwater, and lake and stream sediments. We are specifically responsible for surveying seven western states. This past year we have designed and installed facilities for delayed-neutron counting and neutron-activation analysis, completed seven orientation surveys, and analyzed several thousand field samples. Full-scale reconnaissance surveys began last fall

Formation mechanism of uranium minerals at sandstone-type uranium deposits

International Nuclear Information System (INIS)

Li Shengfu; Zhang Yun

2004-01-01

By analyzing the behavior and existence form of uranium in different geochemical environments, existence form of uranium and uranium minerals species, this paper expounds the formation mechanism of main commercial uranium mineral--pitchblende: (1) uranium is a valence-changeable element. It is reactivated and migrates in oxidized environment, and is reduced and precipitated in reducing environment; (2) [UO 2 (CO 3 ) 3 ] 4- , [UO 2 (CO 3 ) 2 ] 2- coming from oxidized environment react with reductants such as organic matter, sulfide and low-valence iron at the redox front to form simple uranium oxide--pitchblende; (3)the adsorption of uranium by organic matter and clay minerals accelerates the reduction and the concentration of uranium. Therefore, it is considered, that the reduction of SO 4 2- by organic matter to form H 2 S, and the reduction of UO 2 2+ by H 2 S are the main reasons for the formation of pitchblende. This reaction is extensively and universally available in neutral and weakly alkaline carbonate solution. The existense of reductants such as H 2 S is the basic factor leading to the decrease of Eh in environments and the oversaturation of UO 2 2+ at the redox front in groundwater, thus accelerating the adsorption and the precipitation of uranium
Accurate reactivity void coefficient calculation for the fast spectrum reactor FBR-IME

Energy Technology Data Exchange (ETDEWEB)

Lima, Fabiano P.C.; Vellozo, Sergio de O.; Velozo, Marta J., E-mail: fabianopetruceli@outlook.com, E-mail: vellozo@cbpf.br, E-mail: martajann@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Militar

2017-07-01

This paper aims to present an accurate calculation of the void reactivity coefficient for the FBR-IME, a fast spectrum reactor in development at the Engineering Military Institute (IME). The main design peculiarity lies in using mixed oxide [MOX - PuO{sub 2} + U(natural uranium)O{sub 2}] as fuel core. For this task, SCALE system was used to calculate the reactivity for several voids distributions generated by bubbles in the sodium beyond its boiling point. The results show that although the void reactivity coefficient is positive and location dependent, they are offset by other feedback effects, resulting in a negative overall coefficient. (author)
Removal of uranium from uranium-contaminated soils -- Phase 1: Bench-scale testing. Uranium in Soils Integrated Demonstration

Energy Technology Data Exchange (ETDEWEB)

Francis, C. W.

1993-09-01

To address the management of uranium-contaminated soils at Fernald and other DOE sites, the DOE Office of Technology Development formed the Uranium in Soils Integrated Demonstration (USID) program. The USID has five major tasks. These include the development and demonstration of technologies that are able to (1) characterize the uranium in soil, (2) decontaminate or remove uranium from the soil, (3) treat the soil and dispose of any waste, (4) establish performance assessments, and (5) meet necessary state and federal regulations. This report deals with soil decontamination or removal of uranium from contaminated soils. The report was compiled by the USID task group that addresses soil decontamination; includes data from projects under the management of four DOE facilities [Argonne National Laboratory (ANL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and the Savannah River Plant (SRP)]; and consists of four separate reports written by staff at these facilities. The fundamental goal of the soil decontamination task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics or generating waste forms that are difficult to manage and/or dispose of. Emphasis in research was placed more strongly on chemical extraction techniques than physical extraction techniques.
Size-dependent reactivity of magnetite nanoparticles: a field-laboratory comparison

Science.gov (United States)

Swindle, Andrew L.; Elwood Madden, Andrew S.; Cozzarelli, Isabelle M.; Benamara, Mourad

2014-01-01

Logistic challenges make direct comparisons between laboratory- and field-based investigations into the size-dependent reactivity of nanomaterials difficult. This investigation sought to compare the size-dependent reactivity of nanoparticles in a field setting to a laboratory analog using the specific example of magnetite dissolution. Synthetic magnetite nanoparticles of three size intervals, ∼6 nm, ∼44 nm, and ∼90 nm were emplaced in the subsurface of the USGS research site at the Norman Landfill for up to 30 days using custom-made subsurface nanoparticle holders. Laboratory analog dissolution experiments were conducted using synthetic groundwater. Reaction products were analyzed via TEM and SEM and compared to initial particle characterizations. Field results indicated that an organic coating developed on the particle surfaces largely inhibiting reactivity. Limited dissolution occurred, with the amount of dissolution decreasing as particle size decreased. Conversely, the laboratory analogs without organics revealed greater dissolution of the smaller particles. These results showed that the presence of dissolved organics led to a nearly complete reversal in the size-dependent reactivity trends displayed between the field and laboratory experiments indicating that size-dependent trends observed in laboratory investigations may not be relevant in organic-rich natural systems.
Uranium mineralization environment and prospecting potential of Dawan ore field in Nanling metallogenic belt

International Nuclear Information System (INIS)

Yang Shanghai

2011-01-01

Located in the middle part of Jiuyishan complex pluton, Nanling metallogenic belt, Dawan uranium ore field in Hunan Province is an important uranium-producing and rare metal, nonferrous metal cluster area due to the favourable mineralization environment. The Cambrian is the main uranium source bed and their contact zone to the pluton is the favorable part for mineralization. The uranium deposits which have been explored are all located in the exocontact zone of Jinjiling pluton in the middle part of Jiuyishan complex pluton which is composed of the independent eastern and western magma evolution centers. In the west center, Jinjiling pluton is closely related to uranium mineralization where the trinity geologic setting was formed with magma evolution, hydrothermal fluid action and mineralization. The deep slitted and large faults provide the pathway and thermodynamic source for circulating migration of mineralizing fluid. The uranium mineralization mainly occurred in crustal stress conversion period of Late Cretaceous and related to the tensive NW extending fault and deep originated fluid. The gravity, aero magnetic, airborne gamma-ray spectrometry anomalies and radioactivity hydrochemical anomaly are important criteria for uranium prospecting. Based on the analysis of regional uranium mineralization environment, the prospecting potential is forecasted. (authors)
Final Scientific/Technical Report - DE-FG02-06ER64172 - Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center - Subproject to Co-PI Eric E. Roden

International Nuclear Information System (INIS)

Roden, Eric E.

2009-01-01

This report summarizes research conducted in conjunction with a project entitled 'Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center', which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2. Area 2 is a shallow pathway for migration of contaminated groundwater to seeps in the upper reach of Bear Creek at ORNL, mainly through a ca. 1 m thick layer of gravel located 4-5 m below the ground surface. The gravel layer is sandwiched between an overlying layer of disturbed fill material, and 2-3 m of undisturbed shale saprolite derived from the underlying Nolichucky Shale bedrock. The fill was put in place when contaminated soils were excavated and replaced by native saprolite from an uncontaminated area within Bear Creek Valley; the gravel layer was presumably installed prior to addition of the fill in order to provide a stable surface for the operation of heavy machinery. The undisturbed saprolite is highly weathered bedrock that has unconsolidated character but retains much of the bedding and fracture structure of the parent rock (shale with interbedded limestone). Hydrological tracer studies conducted during the Scheibe et al. field
Inherently safe in situ uranium recovery

Science.gov (United States)

Krumhansl, James L; Brady, Patrick V

2014-04-29

An in situ recovery of uranium operation involves circulating reactive fluids through an underground uranium deposit. These fluids contain chemicals that dissolve the uranium ore. Uranium is recovered from the fluids after they are pumped back to the surface. Chemicals used to accomplish this include complexing agents that are organic, readily degradable, and/or have a predictable lifetime in an aquifer. Efficiency is increased through development of organic agents targeted to complexing tetravalent uranium rather than hexavalent uranium. The operation provides for in situ immobilization of some oxy-anion pollutants under oxidizing conditions as well as reducing conditions. The operation also artificially reestablishes reducing conditions on the aquifer after uranium recovery is completed. With the ability to have the impacted aquifer reliably remediated, the uranium recovery operation can be considered inherently safe.
Actual and Idealized Crystal Field Parameterizations for the Uranium Ions in UF 4

Science.gov (United States)

Gajek, Z.; Mulak, J.; Krupa, J. C.

1993-12-01

The crystal field parameters for the actual coordination symmetries of the uranium ions in UF 4, C2 and C1, and for their idealizations to D2, C2 v , D4, D4 d , and the Archimedean antiprism point symmetries are given. They have been calculated by means of both the perturbative ab initio model and the angular overlap model and are referenced to the recent results fitted by Carnall's group. The equivalency of some different sets of parameters has been verified with the standardization procedure. The adequacy of several idealized approaches has been tested by comparison of the corresponding splitting patterns of the 3H 4 ground state. Our results support the parameterization given by Carnall. Furthermore, the parameterization of the crystal field potential and the splitting diagram for the symmetryless uranium ion U( C1) are given. Having at our disposal the crystal field splittings for the two kinds of uranium ions in UF 4, U( C2) and U( C1), we calculate the model plots of the paramagnetic susceptibility χ( T) and the magnetic entropy associated with the Schottky anomaly Δ S( T) for UF 4.
Ultraviolet-B radiation mobilizes uranium from uranium-dissolved organic carbon complexes in aquatic systems, demonstrated by asymmetrical flow field-flow fractionation.

Science.gov (United States)

Nehete, Sachin Vilas; Christensen, Terje; Salbu, Brit; Teien, Hans-Christian

2017-05-05

Humic substances have a tendency to form complexes with metal ions in aquatic medium, impacting the metal mobility, decreasing bioavailability and toxicity. Ultraviolet-B (UV-B) radiation exposure degrades the humic substance, changes their molecular weight distribution and their metal binding capacity in aquatic medium. In this study, we experimented the effect of UV-B radiation on the uranium complexed with fulvic acids and humic acids in a soft water system at different pH, uranium concentrations and radiant exposure. The concentration and distribution of uranium in a complexed form were investigated by asymmetrical flow field-flow fractionation coupled to multi detection technique (AsFlFFF-UV-ICP-MS). The major concentration of uranium present in complexes was primarily associated with average and higher molecular weight fulvic and humic acids components. The concentration of uranium in a complexed form increased with increasing fulvic and humic acid concentrations as well as pH of the solution. The higher molecular weight fraction of uranium was degraded due to the UV-B exposure, transforming about 50% of the uranium-dissolved organic carbon complexes into low molecular weight uranium species in complex form with organic ligands and/or free form. The result also suggests AsFlFFF-UV-ICP-MS to be an important separation and detection technique for understanding the interaction of radionuclides with dissolved organic matter, tracking size distribution changes during degradation of organic complexes for understanding mobility, bioavailability and ecosystem transfer of radionuclides as well as metals. Copyright © 2017 Elsevier B.V. All rights reserved.
The theory and method of two-well field test for in-situ leaching uranium

International Nuclear Information System (INIS)

Yao Yixuan; Huo Jiandang; Xiang Qiulin; Tang Baobin

2007-01-01

Because leaching area in field test for in-situ leaching uranium is not accounted exactly, the reliability of obtaining parameters by calculating can not be ensured, and the whole test needs a long time and great investment. In two-well field test, lixiviant is injected from one well, pregnant solution is pumped out from the other, flow rate of the production well is more than that of the injection well, and uranium is not recoveried. In the case of keeping invariable ratio of pumping capacity to injecting capacity during the testing process, leaching area is not variable, can be exactly calculated. The full field test needs six months to one year. Two-well test is a scientific, rapid, minimal spending field test method, and is widely used in Commonwealth of Independent States. (authors)
Some potential strategies for the treatment of waste uranium metal and uranium alloys

International Nuclear Information System (INIS)

Burns, C.J.; Frankcom, T.M.; Gordon, P.L.; Sauer, N.N.

1993-01-01

Large quantities of uranium metal chips and turnings stored throughout the DOE Complex represent a potential hazard, due to the reactivity of this material toward air and water. Methods are being sought to mitigate this by conversion of the metal, via room temperature solutions routes, to a more inert oxide form. In addition, the recycling of uranium and concomitant recovery of alloying metals is a desirable goal. The emphasis of the authors' research is to explore a variety of oxidation and reduction pathways for uranium and its compounds, and to investigate how these reactions might be applied to the treatment of bulk wastes
Reactivity of hydrogen with uranium in the presence of Pt

International Nuclear Information System (INIS)

Balooch, M.; Siekhaus, W.J.

1997-07-01

The surface-reaction of di-hydrogen with uranium in the presence of Pt clusters has been studied using scanning tunneling microscopy (STM). Uranium was deposited on highly oriented pyrolytic graphite (HOPG) and annealed at temperatures up to 1200 degrees C to obtain atomically pyrolytic flat surfaces. Pt clusters were then formed using evaporation from a Pt source onto the surface and subsequent annealing. Hydrogen mainly attacked uranium in the vicinity of Pt clusters and formed hydride. The hydride formation probability is almost constant at 2.3x10 -4 over the range of exposures studied
Uranium hexafluoride handling

International Nuclear Information System (INIS)

1991-01-01

The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF 6 from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride
Uranium concentration in drinking water from small-scale water supplies in Schleswig-Holstein, Germany; Urankonzentration im Trinkwasser aus Hausbrunnen in Schleswig-Holstein

Energy Technology Data Exchange (ETDEWEB)

Ostendorp, G. [Landesamt fuer soziale Dienste, Kiel (Germany). Dezernat Umweltbezogener Gesundheitsschutz

2015-07-01

In this study the drinking water of 212 small-scale water supplies, mainly situated in areas with intensive agriculture or fruit-growing, was analysed for uranium. The median uranium concentration amounted to 0.04 μg/lL, the 95th percentile was 2.5 μg/L. The maximum level was 14 μg/L. This sample exceeded the guideline value for uranium in drinking water. The uranium concentration in small-scale water supplies was found to be slightly higher than that in central water works in Schleswig-Holstein. Water containing more than 10 mg/L nitrate showed significantly higher uranium contents. The results indicate that the uranium burden in drinking water from small wells is mainly determined by geological factors. An additional anthropogenic effect of soil management cannot be excluded. Overall uranium concentrations were low and not causing health concerns. However, in specific cases higher concentrations may occur.
Analysis on void reactivity of DCA lattice

International Nuclear Information System (INIS)

Min, B. J.; Noh, K. H.; Choi, H. B.; Yang, M. K.

2001-01-01

In case of loss of coolant accident, the void reactivity of CANDU fuel provides the positive reactivity and increases the reactor power rapidly. Therefore, it is required to secure credibility of the void reactivity for the design and analysis of reactor, which motivated a study to assess the measurement data of void reactivity. The assessment of lattice code was performed with the experimental data of void reactivity at 30, 70, 87 and 100% of void fractions. The infinite multiplication factors increased in four types of fuels as the void fractions of them grow. The infinite multiplication factors of uranium fuels are almost within 1%, but those of Pu fuels are over 10% by the results of WIMS-AECL and MCNP-4B codes. Moreover, coolant void reactivity of the core loaded with plutonium fuel is more negative compared with that with uranium fuel because of spectrum hardening resulting from large void fraction
NEUTRONICS STUDIES OF URANIUM-BASED FULLY CERAMIC MICRO-ENCAPSULATED FUEL FOR PWRs

Energy Technology Data Exchange (ETDEWEB)

George, Nathan M [ORNL; Maldonado, G Ivan [ORNL; Terrani, Kurt A [ORNL; Gehin, Jess C [ORNL; Godfrey, Andrew T [ORNL

2012-01-01

This study evaluates the core neutronics and fuel cycle characteristics that result from employing uranium-based fully ceramic micro-encapsulated (FCM) fuel in a pressurized water reactor (PWR). Specific PWR bundle designs with FCM fuel have been developed, which by virtue of their TRISO particle based elements, are expected to safely reach higher fuel burnups while also increasing the tolerance to fuel failures. The SCALE 6.1 code package, developed and maintained at ORNL, was the primary software employed to model these designs. Analysis was performed using the SCALE double-heterogeneous (DH) fuel modeling capabilities. For cases evaluated with the NESTLE full-core three-dimensional nodal simulator, because the feature to perform DH lattice physics branches with the SCALE/TRITON sequence is not yet available, the Reactivity-Equivalent Physical Transformation (RPT) method was used as workaround to support the full core analyses. As part of the fuel assembly design evaluations, fresh feed lattices were modeled to analyze the within-assembly pin power peaking. Also, a color-set array of assemblies was constructed to evaluate power peaking and power sharing between a once-burned and a fresh feed assembly. In addition, a parametric study was performed by varying the various TRISO particle design features; such as kernel diameter, coating layer thicknesses, and packing fractions. Also, other features such as the selection of matrix material (SiC, Zirconium) and fuel rod dimensions were perturbed. After evaluating different uranium-based fuels, the higher physical density of uranium mononitride (UN) proved to be favorable, as the parametric studies showed that the FCM particle fuel design will need roughly 12% additional fissile material in comparison to that of a standard UO2 rod in order to match the lifetime of an 18-month PWR cycle. Neutronically, the FCM fuel designs evaluated maintain acceptable design features in the areas of fuel lifetime, temperature
Transmutation of uranium and thorium in the particle field of the Quinta sub-critical assembly

Science.gov (United States)

Hashemi-Nezhad, S. R.; Asquith, N. L.; Voronko, V. A.; Sotnikov, V. V.; Zhadan, Alina; Zhuk, I. V.; Potapenko, A.; Husak, Krystsina; Chilap, V.; Adam, J.; Baldin, A.; Berlev, A.; Furman, W.; Kadykov, M.; Khushvaktov, J.; Kudashkin, I.; Mar'in, I.; Paraipan, M.; Pronskih, V.; Solnyshkin, A.; Tyutyunnikov, S.

2018-03-01

The fission rates of natural uranium and thorium were measured in the particle field of Quinta, a 512 kg natural uranium target-blanket sub-critical assembly. The Quinta assembly was irradiated with deuterons of energy 4 GeV from the Nuclotron accelerator of the Joint Institute for Nuclear Research (JINR), Dubna, Russia. Fission rates of uranium and thorium were measured using Gamma spectroscopy and fission track techniques. The production rate of 239Np was also measured. The obtained experimental results were compared with Monte Carlo predictions using the MCNPX 2.7 code employing the physics and fission-evaporation models of INCL4-ABLA, CEM03.03 and LAQGSM03.03. Some of the neutronic characteristics of the Quinta are compared with the "Energy plus Transmutation (EpT)" subcritical assembly, which is composed of a lead target and natU blanket. This comparison clearly demonstrates the importance of target material, neutron moderator and reflector types on the performance of a spallation neutron driven subcritical system. As the dimensions of the Quinta are very close to those of an optimal multi-rod-uranium target, the experimental and Monte Carlo calculation results presented in this paper provide insights on the particle field within a uranium target as well as in Accelerator Driven Systems in general.
Activation of Chalcogens and Chalcogenides at Reactive Uranium Centers

OpenAIRE

Franke, Sebastian

2015-01-01

The coordination chemistry of uranium has experienced a tremendous recent increase of interest within the last three decades, likely due to the fact that complexes of trivalent uranium can effectively engage activation and functionalization of small molecules, such as carbon monoxide (CO), carbon dioxide (CO2), dinitrogen (N2), or dioxygen (O2). Many small molecules are of great biochemical and industrial relevance, but their thermodynamical stability requires high pressures and temperatures...
Process engineering challenges of uranium extraction from phosphoric acid on industrial scale

International Nuclear Information System (INIS)

Mouriya, Govind; Singh, Dhirendra; Nath, A.K.; Majumdar, D.

2014-01-01

Heavy Water Board (HWB) is a constituent unit of the Department of Atomic Energy. One of the diversified activities undertaken by HWB is pursuing exploitation of non-conventional resources for recovery of uranium from wet phosphoric acid being the most prominent one. Amongst the feasible processes for recovery of uranium from phosphoric acid is solvent extraction. Use of in-house solvent produced by HWB, is another key driver. To garner necessary information for developing the industrial scale facilities, the process has been studied in the laboratory scale, mini scale, bench scale at Heavy Water Plant, Talcher. The process was subsequently scaled up to an industrial prototype scale unit and was set up as a Technology Demonstration Plant coupled with a commercial phosphoric acid plant. The plant has successfully processed more than 2 lakh m 3 of wet phosphoric acid and all the parameters including the product, Yellow Cake have been qualified. No adverse effect has been observed in the fertilizer produced. The main characteristics of the process and subsequent process innovations are discussed in this paper. These innovations have been carried out to overcome hurdles faced during commissioning and subsequent operations of the Plant. The innovations include improved pretreatment of the wet phosphoric acid for feeding to the extraction cycle, improved control of the first cycle chemical environment, reducing the strength of the phosphoric acid used for stripping, reducing the number of equipment and machineries, alteration in solvent composition used in the first and second cycle in the solvent extraction units of the plant. (author)
EPR of uranium ions

International Nuclear Information System (INIS)

Ursu, I.; Lupei, V.

1984-02-01

A review of the electron paramagnetic resonance data on the uranium ions is given. After a general account of the electronic structure of the uranium free atoms and ions, the influence of the external fields (magnetic field, crystal fields) is discussed. The main information obtained from EPR studies on the uranium ions in crystals are emphasized: identification of the valence and of the ground electronic state, determination of the structure of the centers, crystal field effects, role of the intermediate coupling and of the J-mixing, role of the covalency, determination of the nuclear spin, maqnetic dipole moment and electric quadrupole moment of the odd isotopes of uranium. These data emphasize the fact that the actinide group has its own identity and this is accutely manifested at the beginning of the 5fsup(n) series encompassed by the uranium ions. (authors)

The study of necessity of verification-methods for Depleted Uranium

International Nuclear Information System (INIS)

Park, J. B.; Ahn, S. H.; Ahn, G. H.; Chung, S. T.; Shin, J. S.

2006-01-01

ROK has tried to establish management system for depleted uranium from 2004, and ROK achieved some results in this field including management software, management skill, and the list of company using the nuclear material. But, the studies for the depleted uranium are insufficient exclude the studies of KAERI. In terms of SSAC, we have to study more about whether the depleted uranium is really dangerous material or not and how is the depleted uranium diverted to the nuclear weapon. The depleted uranium was controlled by the item counting in the national system for the small quantity nuclear material. We don't have unique technical methods to clarify the depleted uranium on-the-spot inspection not laboratory scale. Therefore, I would like to suggest of the necessity of the verification methods for depleted uranium. Furthermore, I would like to show you the methods of the verification of the depleted uranium in national system up to now
The Perceived Stress Reactivity Scale: Measurement Invariance, Stability, and Validity in Three Countries

Science.gov (United States)

Schlotz, Wolff; Yim, Ilona S.; Zoccola, Peggy M.; Jansen, Lars; Schulz, Peter

2011-01-01

There is accumulating evidence that individual differences in stress reactivity contribute to the risk for stress-related disease. However, the assessment of stress reactivity remains challenging, and there is a relative lack of questionnaires reliably assessing this construct. We here present the Perceived Stress Reactivity Scale (PSRS), a…
Use of vacuum in processing of uranium

International Nuclear Information System (INIS)

Saify, M.T.; Rai, C.B.; Singh, S.P.; Singh, R.P.

2003-01-01

Full text: Natural uranium in the form of metal and alloys with suitable heat treatment are being used as fuel in research and some of the power reactors. The fuel is required to satisfy the purity specification from the criteria of neutron economy, corrosion resistance and fabricability. Uranium and its alloys fall under the category of reactive materials. They readily react with atmospheric air to form oxides. If molten uranium is exposed to atmosphere, it reacts violently with atmospheric gases and moisture, leading to explosion in extreme cases. Hence, protective inert atmosphere or high vacuum is required in processing of the materials especially during the melting and casting operation. Vacuum is preferred for melting and remelting of metals and alloys to remove the gaseous and high volatile impurities, to improve the mechanical properties of the material. Also, under vacuum sound castings are produced for further processing by mechanical working or use in casting forms. The addition of reactive alloying elements in uranium is efficiently carried out under vacuum. The paper highlights vacuum systems deployed and applications of vacuum in various operations involved in the processing of uranium and its alloys
Evaluation of a permeable reactive barrier technology for use at Rocky Flats Environmental Technology Site (RFETS)

International Nuclear Information System (INIS)

Dwyer, Brian P.

2000-01-01

Three reactive materials were evaluated at laboratory scale to identify the optimum treatment reagent for use in a Permeable Reactive Barrier Treatment System at Rocky Flats Environmental Technology Site (RFETS). The contaminants of concern (COCS) are uranium, TCE, PCE, carbon tetrachloride, americium, and vinyl chloride. The three reactive media evaluated included high carbon steel iron filings, an iron-silica alloy in the form of a foam aggregate, and a peculiar humic acid based sorbent (Humasorb from Arctech) mixed with sand. Each material was tested in the laboratory at column scale using simulated site water. All three materials showed promise for the 903 Mound Site however, the iron filings were determined to be the least expensive media. In order to validate the laboratory results, the iron filings were further tested at a pilot scale (field columns) using actual site water. Pilot test results were similar to laboratory results; consequently, the iron filings were chosen for the fill-scale demonstration of the reactive barrier technology. Additional design parameters including saturated hydraulic conductivity, treatment residence time, and head loss across the media were also determined and provided to the design team in support of the final design. The final design was completed by the Corps of Engineers in 1997 and the system was constructed in the summer of 1998. The treatment system began fill operation in December, 1998 and despite a few problems has been operational since. Results to date are consistent with the lab and pilot scale findings, i.e., complete removal of the contaminants of concern (COCs) prior to discharge to meet RFETS cleanup requirements. Furthermore, it is fair to say at this point in time that laboratory developed design parameters for the reactive barrier technology are sufficient for fuel scale design; however,the treatment system longevity and the long-term fate of the contaminants are questions that remain unanswered. This
Reactivating dynamics for the susceptible-infected-susceptible model: a simple method to simulate the absorbing phase

Science.gov (United States)

Macedo-Filho, A.; Alves, G. A.; Costa Filho, R. N.; Alves, T. F. A.

2018-04-01

We investigated the susceptible-infected-susceptible model on a square lattice in the presence of a conjugated field based on recently proposed reactivating dynamics. Reactivating dynamics consists of reactivating the infection by adding one infected site, chosen randomly when the infection dies out, avoiding the dynamics being trapped in the absorbing state. We show that the reactivating dynamics can be interpreted as the usual dynamics performed in the presence of an effective conjugated field, named the reactivating field. The reactivating field scales as the inverse of the lattice number of vertices n, which vanishes at the thermodynamic limit and does not affect any scaling properties including ones related to the conjugated field.
Preparation and characterization of uranium alkoxides through oxidation of uranium metal

International Nuclear Information System (INIS)

Gordon, P.L.; Sauer, N.N.; Burns, C.J.; Watkin, J.G.; Van Der Sluys, W.G.

1993-01-01

Currently the authors are investigating the preparation of halide-containing uranium alkoxides by simultaneous halogen and alcohol oxidation of uranium metal. They recently reported the formation of U 2 I 4 (O-i-Pr) 4 (HO-i-Pr) 2 which upon addition of excess isopropanol forms UI 2 (O-i-Pr) 2 (HO-i-Pr) 2 . They report further characterization and reactivity for this monomeric species. Attempts to prepare similar complexes are being made using chlorine gas in the presence of other alcohols. They describe this ongoing research
Field technique for the measurement of uranium in natural waters

Energy Technology Data Exchange (ETDEWEB)

Robbins, J C [Scintrex Ltd., Concord, Ontario

1978-05-01

An analytical method suitable for field determination of trace levels of uranium in natural waters is described. Laser UV radiation causes persistent fluorescence of a uranyl complex. Electronic gating substantially rejects detection of short-lived natural organic matter fluorescence. Further work is required on effects of interferences in samples with complex matrices and interpretative aids such as concurrent conductivity and organic content measurements.
Removal of 226Ra from tailings pond effluents and stabilization of uranium mine tailings. Bench and pilot scale studies

International Nuclear Information System (INIS)

Schmidtke, N.W.; Averill, D.; Bryant, D.N.; Wilkinson, P.; Schmidt, J.W.

1978-01-01

Increased world demand for uranium has resulted in recent expansion of Canadian uranium mining operations. Problems have been identified with the discharge of radionuclides such as 226 Ra from tailings pond effluents and with the stabilization of mine tailings. At Environment Canada's Wastewater Technology Centre (WTC) two projects were undertaken in cooperation with the Canadian Uranium Mining Industry and other federal government agencies to address these problems. The first project reports on the progress of bench and pilot scale process simulations for the development of a data base for the design of a full scale mechanical physical/chemical 226 Ra removal waste treatment system with an effluent target level of 10 pCi 226 Ra total per litre. The second project addresses problems of the leachability of radionuclides and the stabilization of both uranium mine tailings and BaRaSO 4 sediments from the treatment of acid seepages
Cost comparison of laboratory methods and four field screening technologies for uranium-contaminated soil

International Nuclear Information System (INIS)

Douthat, D.M.; Armstrong, A.Q.

1994-01-01

To address the problem of characterizing uranium-contaminated surface soil at federal facilities, the Department of Energy has the development of four uranium field screening technologies, under the direction of the Uranium-in-Soils Integrated Demonstration (USID) Program. These four technologies include: a long-range alpha detector a beta scintillation detector, an in situ gamma detector, and a mobile laser ablation-inductively coupled plasma/atomic emission spectrometry (LA-ICP/AES) laboratory. As part of the performance assessment for these field screening technologies, cost estimates for the development and operation of each technology were created. A cost study was conducted to compare three of the USID field screening technologies to the use of traditional field surveying equipment to adequately characterize surface soils of a one-acre site. The results indicate that the use of traditional equipment costs more than the in situ gamma detector, but less than the beta scintillation detector and LRAD. The use of traditional field surveying equipment results in cost savings of 4% and 34% over the use of the beta scintillation and LRAD technologies, respectively. A study of single-point surface soil sampling and laboratory analysis costs was also conducted. Operational costs of the mobile LA-ICP/AES laboratory were compared with operational costs of traditional sampling and analysis, which consists of collecting soil samples and conducting analysis in a radiochemical laboratory. The cost study indicates that the use of the mobile LA-ICP/AES laboratory results in cost savings of 23% and 40% over traditional field sampling and laboratory analysis conducted by characterization groups at two DOE facilities
Transport of the reactive substances eosin, uranium and lithium in a heterogeneous aquifer; Transport der reaktiven Stoffe Eosin, Uranin und Lithium in einem heterogenen Grundwasserleiter

Energy Technology Data Exchange (ETDEWEB)

Doering, U.

1997-02-01

To predict the movement of a contaminant plume in an aquifer is still a task of great uncertainty. This uncertainty is generally attributed to an insufficient understanding of the chemical reaction processes and/or to the natural aquifer heterogeneities. In an integrated approach of field experiments, laboratory experiments and numerical simulations, the transport of the weakly reactive solutes eosin, uranin and lithium was investigated at a test site near the Research Center in Juelich. The field scale transport behavior of the solutes was studied by large scale tracer tests. To characterize aquifer heterogeneities, in-situ and laboratory measurements were performed. In-situ measurements covered about 1500 flowmeter measurements and 90 determinations of the groundwater flow velocity by the borehole method. The spatial variability of hydraulic and physico-chemical parameters was further determined on 400 sediment samples. These parameters included: Grain size distribution, calculated hydraulic conductivity, unconformity and as physico-chemical parameters the organic carbon content, specific surface and the cation exchange capacity. Furthermore sorption coefficients were measured on 75 sediment samples for uranium and lithium. The statistical evaluation of these data showed that the hydraulic heterogeneity was larger but in the same order of magnitude as the physico-chemical parameters. (orig./SR) [Deutsch] Eine Schadstoff-Ausbreitung im Grundwasser vorherzusagen, ist noch immer eine Aufgabe mit unsicherem Ergebnis. Diese Prognose-Unsicherheiten werden im Allgemeinen auf ein unzureichendes Verstaendnis der chemischen Reaktionsprozesse und/oder auf die natuerliche Heterogenitaet des Grundwasserleiters zurueckgefuehrt. In dem hier beschriebenen Forschungsprojekt, das Feldversuche, Laborversuche und numerische Simulationen integriert, wurde der Transport der schwach reaktiven Substanzen Eosin, Uranin und Lithium auf einem Versuchsgelaende nahe des Forschungszentrums
Development and inculcation of new methods in the field of exploring, extraction and reprocessing of uranium raw materials

International Nuclear Information System (INIS)

Smirnov, Yu.V.; Efimova, Z.I.; Skorovarov, D.I.; Ivanov, G.F.

1979-01-01

The situation is briefly overviewed in the field of exploration, prospecting, extraction and processing of uranium raw material and industrial introduction of the recently developed methods. The method of underground leaching, including that from deep-seated deposits, is gaining wide acceptance. Of high importance is the industrial introduction of such promising processes as bacterial leaching, continuous column-sorption with a pseudo-luquefied sorbent layer, direct production of UF 6 in an ore-processing factory. Active works are under way now in the field of multi-purpose utilization of uranium ore. New methods are industrially introduced for the extraction of associated uranium from phosphoric acid solutions, copper ore, sea water
Separation of uranium isotopes

International Nuclear Information System (INIS)

Porter, J.T.

1980-01-01

Methods and apparatus are disclosed for separation of uranium isotopes by selective isotopic excitation of photochemically reactive uranyl salt source material at cryogenic temperatures, followed by chemical separation of selectively photochemically reduced U+4 thereby produced from remaining uranyl source material
Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

International Nuclear Information System (INIS)

Vermeul, Vince R.; Williams, M. D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

2007-01-01

The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 (micro)g/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area
Treatability Test Plan for 300 Area Uranium Stabilization through Polyphosphate Injection

Energy Technology Data Exchange (ETDEWEB)

Vermeul, Vincent R.; Williams, Mark D.; Fritz, Brad G.; Mackley, Rob D.; Mendoza, Donaldo P.; Newcomer, Darrell R.; Rockhold, Mark L.; Williams, Bruce A.; Wellman, Dawn M.

2007-06-01

The U.S. Department of Energy has initiated a study into possible options for stabilizing uranium at the 300 Area using polyphosphate injection. As part of this effort, PNNL will perform bench- and field-scale treatability testing designed to evaluate the efficacy of using polyphosphate injections to reduced uranium concentrations in the groundwater to meet drinking water standards (30 ug/L) in situ. This technology works by forming phosphate minerals (autunite and apatite) in the aquifer that directly sequester the existing aqueous uranium in autunite minerals and precipitates apatite minerals for sorption and long term treatment of uranium migrating into the treatment zone, thus reducing current and future aqueous uranium concentrations. Polyphosphate injection was selected for testing based on technology screening as part of the 300-FF-5 Phase III Feasibility Study for treatment of uranium in the 300-Area.
Uranium(III)-carbon multiple bonding supported by arene δ-bonding in mixed-valence hexauranium nanometre-scale rings.

Science.gov (United States)

Wooles, Ashley J; Mills, David P; Tuna, Floriana; McInnes, Eric J L; Law, Gareth T W; Fuller, Adam J; Kremer, Felipe; Ridgway, Mark; Lewis, William; Gagliardi, Laura; Vlaisavljevich, Bess; Liddle, Stephen T

2018-05-29

Despite the fact that non-aqueous uranium chemistry is over 60 years old, most polarised-covalent uranium-element multiple bonds involve formal uranium oxidation states IV, V, and VI. The paucity of uranium(III) congeners is because, in common with metal-ligand multiple bonding generally, such linkages involve strongly donating, charge-loaded ligands that bind best to electron-poor metals and inherently promote disproportionation of uranium(III). Here, we report the synthesis of hexauranium-methanediide nanometre-scale rings. Combined experimental and computational studies suggest overall the presence of formal uranium(III) and (IV) ions, though electron delocalisation in this Kramers system cannot be definitively ruled out, and the resulting polarised-covalent U = C bonds are supported by iodide and δ-bonded arene bridges. The arenes provide reservoirs that accommodate charge, thus avoiding inter-electronic repulsion that would destabilise these low oxidation state metal-ligand multiple bonds. Using arenes as electronic buffers could constitute a general synthetic strategy by which to stabilise otherwise inherently unstable metal-ligand linkages.
Recovery of uranium from crude uranium tetrafluoride

Energy Technology Data Exchange (ETDEWEB)

Ghosh, S K; Bellary, M P; Keni, V S [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author). 4 refs., 1 fig., 3 tabs.
Recovery of uranium from crude uranium tetrafluoride

International Nuclear Information System (INIS)

Ghosh, S.K.; Bellary, M.P.; Keni, V.S.

1994-01-01

An innovative process has been developed for recovery of uranium from crude uranium tetrafluoride cake. The process is based on direct dissolution of uranium tetrafluoride in nitric acid in presence of aluminium hydroxide and use of solvent extraction for removal of fluorides and other bulk impurities to make uranium amenable for refining. It is a simple process requiring minimum process step and has advantage of lesser plant corrosion. This process can be applied for processing of uranium tetrafluoride generated from various sources like uranium by-product during thorium recovery from thorium concentrate, first stage product of uranium recovery from phosphoric acid by OPPA process and off grade uranium tetrafluoride material. The paper describes the details of the process developed and demonstrated on bench and pilot scale and its subsequent modification arising out of bulky solid waste generation. The modified process uses a lower quantity of aluminium hydroxide by allowing a lower dissolution of uranium per cycle and recycles the undissolved material to the next cycle, maintaining the overall recovery at high level. This innovation has reduced the solid waste generated by a factor of four at the cost of a slightly larger dissolution vessel and its increased corrosion rate. (author)
BASIC program to compute uranium density and void volume fraction in laboratory-scale uranium silicide aluminum dispersion plate-type fuel

International Nuclear Information System (INIS)

Ugajin, Mitsuhiro

1991-05-01

BASIC program simple and easy to operate has been developed to compute uranium density and void volume fraction for laboratory-scale uranium silicide aluminum dispersion plate-type fuel, so called miniplate. An example of the result of calculation is given in order to demonstrate how the calculated void fraction correlates with the microstructural distribution of the void in a miniplate prepared in our laboratory. The program is also able to constitute data base on important parameters for miniplates from experimentally-determined values of density, weight of each constituent and dimensions of miniplates. Utility programs pertinent to the development of the BASIC program are also given which run in the popular MS-DOS environment. All the source lists are attached and brief description for each program is made. (author)
The latest study on development of metallogenic mechanism of Baimianshi uranium field, Jiangxi Province, China

International Nuclear Information System (INIS)

Fan, H.; He, D.; Wang, F.

2009-01-01

It has been considered that deposits in Baimianshi uranium field have similar features and ore-forming type, it is the syngenetic sedimentation that caused some U-bearing minerals to concentrate, and as a result of the enrichment in the late lithogenetic stage the deposit formed which is separate genesis to sandstone type and volcanic hydrothermal sub-type. This paper takes Huangnihu deposit in Baimianshi field as an example, and regards Baimianshi field as hydrothermal type according to research on intergrowth assemblage, fluid inclusions, U-Pb isotopic dating and Nd-Sr isotopic tracing. Ore minerals are mainly uraninite, brannerite, coffinite, etc, while the assistant gangue minerals are mainly galena, hematite, marcasite, blende, etc. The materials for uranium mineralization are mainly crust-derived rocks. Continuous extraction of uranium from the upper crust and basement granite by mantle-derived fluids with little of ore-forming elements may be responsible for the remobilization and transformation of uranium. Mixing of ore-enriched fluid with groundwater in some enclosed places overlain by basalt leads to the precipitation of ore-forming materials from the mixed fluid. There are three episodes of uranium mineralization: The first one is 160.4±0.5Ma, related to double-peak type volcanism, with basalt lithogenetic age of 172.8±7.7Ma and rhyolite lithogenetic age of 164.8±0.57Ma (from Chen Peirong, etc., 1999). The second one is 128±0.8Ma, related to Yanshanian Magmatic activities, for example, Danguanzhang rock mass and several phases of complements. The third one is about 100Ma, related to sub-volcanic rocks and dykes, namely quartz porphyry (99Ma) and diabase (105Ma). The above achievements will play an important part in the guidance of future prospecting in the deeper in that area. (author)
Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout.

Science.gov (United States)

Stitt, C A; Hart, M; Harker, N J; Hallam, K R; MacFarlane, J; Banos, A; Paraskevoulakos, C; Butcher, E; Padovani, C; Scott, T B

2015-03-21

How do you characterise the contents of a sealed nuclear waste package without breaking it open? This question is important when the contained corrosion products are potentially reactive with air and radioactive. Synchrotron X-rays have been used to perform micro-scale in-situ observation and characterisation of uranium encapsulated in grout; a simulation for a typical intermediate level waste storage packet. X-ray tomography and X-ray powder diffraction generated both qualitative and quantitative data from a grout-encapsulated uranium sample before, and after, deliberately constrained H2 corrosion. Tomographic reconstructions provided a means of assessing the extent, rates and character of the corrosion reactions by comparing the relative densities between the materials and the volume of reaction products. The oxidation of uranium in grout was found to follow the anoxic U+H2O oxidation regime, and the pore network within the grout was observed to influence the growth of uranium hydride sites across the metal surface. Powder diffraction analysis identified the corrosion products as UO2 and UH3, and permitted measurement of corrosion-induced strain. Together, X-ray tomography and diffraction provide means of accurately determining the types and extent of uranium corrosion occurring, thereby offering a future tool for isolating and studying the reactions occurring in real full-scale waste package systems. Copyright © 2014 Elsevier B.V. All rights reserved.

Field manual for ground water reconnaissance. Savannah River Laboratory National Uranium Resource Evaluation Program

International Nuclear Information System (INIS)

Ferguson, R.B.; Price, V.; Baucom, E.I.

1977-01-01

A manual is presented that is intended to direct and coordinate field operations, site selection, groundwater sample collection, and information codes for the Savannah River Laboratory (SRL) contribution to the National Uranium Resource Evaluation (NURE) program. The manual provides public relations information for field sampling teams as well as technical direction
Vaal Reefs South uranium plant

International Nuclear Information System (INIS)

Anon.

1979-01-01

The Vaal Reefs mining complex, part of the Anglo American Corporation, is the largest gold and uranium producing complex in the world, being South Africa's principal producer, accounting for about a quarter of the country's uranium production. Vaal Reefs South uranium plant in the Orkney district was recently officially opened by Dr AJA Roux, the retiring president of the Atomic Energy Board and chairman of the Uranium Enrichment Corporation and will increase the country's uranium production. In the field of technology, and particularly processing technology, South Africa has shown the world unprecedented technology achievement in the field of uranium extraction from low grade ores and the development of the unique uranium enrichment process. New technical innovations that have been incorporated in this new plant are discussed
Oxidation of uranium and uranium alloys

International Nuclear Information System (INIS)

Orman, S.

1976-01-01

The corrosion behaviour of uranium in oxygen, water and water + oxygen mixtures is compared and contrasted. A considerable amount of work, much of it conflicting, has been published on the U + H 2 O and U + H 2 O + O 2 systems. An attempt has been made to summarise this data and to explain the reasons for the lack of agreement between the experimental results. The evidence for the mechanism involving OH - ion diffusion as the reacting entity in both the U + H 2 O and U + O 2 + H 2 O reactions is advanced. The more limited corrosion data on some lean uranium alloys and on some higher addition alloys referred to as stainless materials is summarised together with some previously unreported results obtained with these materials at AWRE. The data indicates that in the absence of oxygen the lean alloys behave in a similar manner to uranium and evolve hydrogen in approximately theoretical quantities. But the stainless alloys absorb most of the product hydrogen and assessments of reactivity based on hydrogen evolution would be very inaccurate. The direction that future corrosion work on these materials should take is recommended
In Situ Community Control of the Stability of Bioreduced Uranium

International Nuclear Information System (INIS)

White, David C.

2006-01-01

The overall objective of this research is to understand the mechanisms for maintenance of bio-reduced uranium in an aerobic to microaerophylic aquifer under actual field conditions after electron donor addition for biostimulation has ended. Primary Objectives: (1) Determine the relative importance of microbial communities and/or chemical and physical environments mediating uranium reduction/oxidation after cessation of donor addition in an aerobic aquifer. (2) Determine, after cessation of donor addition, the linkages between microbial functions and abiotic processes mediating. Initial Hypotheses: (1) The typical bio-reduced subsurface environments that maintain U(VI) reduction rates after biostimulation contain limited amounts of oxidized iron on mineral surfaces. Therefore, the non sulfate-reducing dissimilatory iron reducing bacteria will move to more conducive areas or be out-competed by more versatile microbes. (2) Microbes capable of sulfate reduction play an important role in the post-treatment maintenance of bio-reduced uranium because these bacteria either directly reduce U(VI) or generate H2S, and/or FeS0.9 which act as oxygen sinks maintaining U(IV) in a reduced state. (3) The presence of bioprecipitated amorphous FeS0.9 in sediments will maintain low U(IV) reoxidation rates under conditions of low biomass, but FeS0.9 by itself is not sufficient to remove U(VI) from groundwater by abiotic reduction. FIELD SCALE EXPERIMENTS: Field-scale electron donor amendment experiments were conducted in 2002, 2003, and 2004 at the Old Rifle Uranium Mill Tailings Remedial Action (UMTRA) site in Rifle, Colorado
Magnetic separation for pre-concentration of uranium values from copper plant tailings

International Nuclear Information System (INIS)

Jha, R.S.; Sreenivas, T.; Natarajan, R.; Sridhar, U.; Rao, N.K.

1991-01-01

Using the paramagnetic character of uranium minerals, the preconcentration of uranium bearing ores and copper plant tailings of Singhbhum area have been investigated in a pilot plant scale wet high intensity magnetic separator (WHIMS). The variables studied include magnetic field intensity, matrix drum speed feed slurry flow rate and its pulp density. The results of these investigations have shown that 75-85% of the contained uranium values could be recovered in 45-55% weight in the magnetic fraction in the case of copper plant tailings from Rakha, Surda and Mosabani. The losses in the non magnetics were primarily due to the ultrafine liberated uraninite particles not collected by WHIMS due to machine limitations and the values occurring as fine inclusions in quartz. Improved recovery can be obtained by offering higher field gradients and preventing loss of very fine liberated uranium values. High gradient magnetic separator (HGMS) offers higher field gradients. A test sample of Mosabani copper tailings studied at the Sala Magnetic Inc in HGMS has indicated superior results in comparison to WHIMS. (author). 7 refs., 3 figs., 6 tabs
Meso-Cenozoic tectonic evolution and uranium potential evaluations of basins in Beishan-Gansu corridor region

International Nuclear Information System (INIS)

Guo Qingyin; Chen Zuyi; Liu Hongxu; Yu Jinshui

2006-01-01

Beishan-Gansu Corridor region is located at the intersection of the plates of Tarim, North China, Kazakhstan, Siberia and Qaidam. During the Meso-Cenozoic, the region experienced movements of Indo-sinian, Yanshanian, Sichuanian, North China, Himalayan and Neotectonic, and over 20 medium-small size superimposed continental basins were formed. On the basis of analyzing the tectonic stress field, sediment-filling and structure-deformation; the general trending of tectonic evolution in the Meso-Cenozoic is summarized as three-time compressional uplifting and two-time extensional down-faulting. The different evolution of basins under the above mentioned setting can be divided into six stages according to characteristics of filled sediment. The sand bodies developed in down-faulted basins are favorable for uranium ore-formation as they are formed under humid paleoclimates, and rich in reducing matter. Therefore, the Lower-Middle Jurassic is selected as the main target horizon for sandstone-hosted uranium deposit, and the Lower Cretaceous as the minor one. Although the tectonic reactivation of the target horizon after its deposition was generally strong, the slopes formed in some basins could be favorable for the infiltration of uranium-and oxygen-bearing groundwater into sand bodies and form uranium deposits. According to the favorable sand bodies and tectonic reactivation, the northern parts of Chaoshui and Bayingobi basins are regarded as potential regions which are worthy of further exploration. (authors)
Possible domestication of uranium oxides using biological assistance reduction

Directory of Open Access Journals (Sweden)

Slah Hidouri

2017-01-01

Full Text Available Uranium has been defined in material research engineering field as one of the most energetic radioactive elements in the entire Mendeleev periodic table. The manipulation of uranium needs higher theories and sophisticated apparatus even in nuclear energy extraction or in many other chemical applications. Above the nuclear exploitation level, the chemical conventional approaches used, require a higher temperature and pressure to control the destination of ionic form. However, it has been discovered later that at biological scale, the manipulation of this actinide is possible under friendly conditions. The review summarizes the relevant properties of uranium element and a brief characterization of nanoparticles, based on some structural techniques. These techniques reveal the common link between chemical approaches and biological assistance in nanoparticles. Also, those biological entities have been able to get it after reduction. Uranium is known for its ability to destroy ductile materials. So, if biological cell can really reduce uranium, then how does it work?
The use of graphite for the reduction of void reactivity in CANDU reactors

International Nuclear Information System (INIS)

Min, B.J.; Kim, B.G.; Sim, K-S.

1995-01-01

Coolant void reactivity can be reduced by using burnable poison in CANDU reactors. The use of graphite in the fuel bundle is introduced to reduce coolant void reactivity by adding an appropriate amount of burnable poison in the central rod. This study shows that sufficiently low void reactivity which in controllable by Reactor Regulating System (RRS) can be achieved by using graphite used fuel with slightly enriched uranium. Zero void reactivity can be also obtained by using graphite used fuel with a large central rod. A new fuel bundle with graphite rods can substantially reduce the void reactivity with less burnup penalty compared to previously proposed low void reactivity fuel with depleted uranium. (author)
Harnessing redox activity for the formation of uranium tris(imido) compounds

Science.gov (United States)

Anderson, Nickolas H.; Odoh, Samuel O.; Yao, Yiyi; Williams, Ursula J.; Schaefer, Brian A.; Kiernicki, John J.; Lewis, Andrew J.; Goshert, Mitchell D.; Fanwick, Phillip E.; Schelter, Eric J.; Walensky, Justin R.; Gagliardi, Laura; Bart, Suzanne C.

2014-10-01

Classically, late transition-metal organometallic compounds promote multielectron processes solely through the change in oxidation state of the metal centre. In contrast, uranium typically undergoes single-electron chemistry. However, using redox-active ligands can engage multielectron reactivity at this metal in analogy to transition metals. Here we show that a redox-flexible pyridine(diimine) ligand can stabilize a series of highly reduced uranium coordination complexes by storing one, two or three electrons in the ligand. These species reduce organoazides easily to form uranium-nitrogen multiple bonds with the release of dinitrogen. The extent of ligand reduction dictates the formation of uranium mono-, bis- and tris(imido) products. Spectroscopic and structural characterization of these compounds supports the idea that electrons are stored in the ligand framework and used in subsequent reactivity. Computational analyses of the uranium imido products probed their molecular and electronic structures, which facilitated a comparison between the bonding in the tris(imido) structure and its tris(oxo) analogue.
Field manual for stream sediment reconnaissance. Savannah River Laboratory National Uranium Resource Evaluation Program

International Nuclear Information System (INIS)

Ferguson, R.B.; Price, V.; Baucom, E.I.

1976-07-01

A manual is presented that is intended to direct and coordinate field operations, site selection, stream sediment sample collection, water sample collection, and information codes for the Savannah River Laboratory (SRL) contribution to the National Uranium Resource Evaluation (NURE) program. The manual provides public relations information for field sampling teams as well as technical direction
Uranium hexafluoride handling. Proceedings

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF{sub 6} from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.
Experiments of JRR-4 low-enriched-uranium-silicied fuel core

International Nuclear Information System (INIS)

Hirane, Nobuhiko; Ishikuro, Yasuhiro; Nagadomi, Hideki; Yokoo, Kenji; Horiguchi, Hironori; Nemoto, Takumi; Yamamoto, Kazuyoshi; Yagi, Masahiro; Arai, Nobuyoshi; Watanabe, Shukichi; Kashima, Yoichi

2006-03-01

JRR-4, a light-water-moderated and cooled, swimming pool type research reactor using high-enriched uranium plate-type fuels had been operated from 1965 to 1996. In order to convert to low-enriched-uranium-silicied fuels, modification work had been carried out for 2 years, from 1996 to 1998. After the modification, start-up experiments were carried out to obtain characteristics of the low-enriched-uranium-silicied fuel core. The measured excess reactivity, reactor shutdown margin and the maximum reactivity addition rate satisfied the nuclear limitation of the safety report for licensing. It was confirmed that conversion to low-enriched-uranium-silicied fuels was carried out properly. Besides, the necessary data for reactor operation were obtained, such as nuclear, thermal hydraulic and reactor control characteristics. This report describes the results of start-up experiments and burnup experiments. The first criticality of low-enriched-uranium-silicied core was achieved on 14th July 1998, and the operation for joint-use has been carried out since 6th October 1998. (author)
Ligand assisted cleavage of uranium oxo-clusters

Energy Technology Data Exchange (ETDEWEB)

Nocton, Gregory; Pecaut, Jacques; Mazzanti, Marinella [Laboratoire de Reconnaissance Ionique et Chimie de Coordination, Service de Chimie Inorganique et Biologique, UMR-E 3 CEA-UJF, CEA/DSM/INAC, CEA-Grenoble, 38054 Grenoble, Cedex 09 (France); Filinchuk, Yaroslav [Swiss Norwegian Beam Lines (SNBL) at the European Synchrotron Radiation Facility (ESRF), rue Jules Horowitz, 38043 Grenoble (France)

2010-07-01

Dibenzoylmethanate replaces the bridging triflate ligands in uranium triflate poly-oxo-clusters and cleaves the U{sub 12}O{sub 20} core yielding the new [U{sub 6}O{sub 4}(OH){sub 4}({eta}-dbm){sub 12}] dibenzoylmethanate (dbm{sup -}) cluster which slowly dissociates into a monomeric complex. This reactivity demonstrates the importance of bridging ligands in stabilizing uranium poly-oxo-clusters. (authors)
Uranium,Radium and Iron Absorption from Liquid Waste Uranium Ore Processing by Zeolite

International Nuclear Information System (INIS)

Wismawati, T; Sorot sudiro, A; Herjati, T

1998-01-01

The aim of this work is to determine zeolites sorption capacity and the distribution coefficient of uranium, radium, and iron in zeolite-liquid waste system. Mineralogical composition of zeolite used in the experiment has been determine by examining the thin sections of zeolite grains under a microscope. Zeolite has ben activated by the dilute sulfuric acid or sodium hydroxide solution. The results show that the use of 0.25 N sodium hydroxide solution could be optimizing the zeolite for uranium and iron ions sorption and that of 0.1 N sulfuric acid solution is for radium sorption. The re-activation process has been carried out in three hours. Under such a condition, the sorption efficiency of zeolite to those ions have been known to be 45.85% for uranium, 96.63 % for iron and 87.80 % for radium. The distribution coefficients of uranium, radium and iron ion in zeolite-liquid waste system have been calculated 0.85, 7.02, and 28.65 ml/g respectively
Recovery of uranium from sea-water

International Nuclear Information System (INIS)

Llewelyn, G.I.W.

1976-01-01

The possibility of extraction of uranium from sea-water on a sufficiently large scale to contribute significantly to national UK requirements is placed in perspective. It seems unlikely that there are sites around the UK coast where this could be achieved, and insufficient work has been done to be confident that sites exist anywhere to enable uranium extraction to be carried out on a large scale. Process techniques have been developed on a small scale, but extensive further research work would be necessary to reduce appreciably the present uncertainties. It would be unwise to expect uranium from sea-water to contribute significant amounts to the world's uranium demand for thermal reactors on an acceptable timescale. (author)
Event classification related to overflow of solvent containing uranium according to the INES scale (International Nuclear and Radiological Event Scale)

International Nuclear Information System (INIS)

Dourado, Eneida R.G.; Assis, Juliana T. de; Lage, Ricardo F.; Lopes, Karina B.

2013-01-01

This paper aims to frame the event overflow organic solvent rich in uranium, from a decanter of ore beneficiation plant, caused by the fall in the supply of electricity, according to the criteria established by the International Nuclear Event Scale and radiological (INES), facilitating the understanding of the occurrence and communication with the public regarding the radiation safety aspects involved. With the fall of electricity, routine procedures in situations of installation stop were performed, however, due to operational failure, the valve on the transfer line liquor was not closed. Thus, the mixer continued being fed with liquor, that led the consequent leakage of solvent loaded with uranium. It reached the drainage system, and the box of rainwater harvesting of the plant. However, immediately after the detection of the event, corrective actions were initiated and the overflow was contained. Regulatory agencies followed the removal of the solvent and on the results of the analysis of environmental monitoring, found that the event did not provide exposure to workers or any other impact. Therefore, comparing the characteristics of the event and the guidelines proposed by the INES scale, it is concluded that the classification of the event is below scale/level 0, confirming the absence of risk to the local population, workers and the environment
Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

Energy Technology Data Exchange (ETDEWEB)

Stitt, C.A., E-mail: Camilla.stitt@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hart, M., E-mail: oxford.mike@gmail.com [Diamond Light Source Limited, Harwell Science and Innovation Campus, Fermi Avenue, Didcot, Oxfordshire OX11 0QX (United Kingdom); Harker, N.J., E-mail: nicholas.harker@esrf.fr [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hallam, K.R., E-mail: k.r.hallam@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); MacFarlane, J., E-mail: james.macfarlane@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Banos, A., E-mail: antonis.banos@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paraskevoulakos, C., E-mail: cp13846@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Butcher, E., E-mail: ed.j.butcher@nnl.co.uk [National Nuclear Laboratory, Seascale, Cumbria CA20 1 PG (United Kingdom); Padovani, C., E-mail: cristiano.padovani@nda.gov.uk [Radioactive Waste Management Limited (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority), Curie Avenue, Didcot, Oxfordshire OX11 0RH (United Kingdom); Scott, T.B., E-mail: t.b.scott@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)

2015-03-21

Highlights: • Unirradiated Magnox uranium was encapsulated in grout and exposed to hydrogen. • Synchrotron X-ray tomography imaged the uranium corrosion before and after exposure. • Synchrotron X-ray powder diffraction identified the corrosion products; UH{sub 3} and UO{sub 2}. • Uranium encapsulated in grout oxidised via the anoxic U + H{sub 2}O regime. • Successful in-situ, non-invasive examination of pyrophoric and radioactive material - Abstract: How do you characterise the contents of a sealed nuclear waste package without breaking it open? This question is important when the contained corrosion products are potentially reactive with air and radioactive. Synchrotron X-rays have been used to perform micro-scale in-situ observation and characterisation of uranium encapsulated in grout; a simulation for a typical intermediate level waste storage packet. X-ray tomography and X-ray powder diffraction generated both qualitative and quantitative data from a grout-encapsulated uranium sample before, and after, deliberately constrained H{sub 2} corrosion. Tomographic reconstructions provided a means of assessing the extent, rates and character of the corrosion reactions by comparing the relative densities between the materials and the volume of reaction products. The oxidation of uranium in grout was found to follow the anoxic U + H{sub 2}O oxidation regime, and the pore network within the grout was observed to influence the growth of uranium hydride sites across the metal surface. Powder diffraction analysis identified the corrosion products as UO{sub 2} and UH{sub 3}, and permitted measurement of corrosion-induced strain. Together, X-ray tomography and diffraction provide means of accurately determining the types and extent of uranium corrosion occurring, thereby offering a future tool for isolating and studying the reactions occurring in real full-scale waste package systems.
Application of AMT in detecting deep geological structures in Lejia district of Xiangshan uranium ore field

International Nuclear Information System (INIS)

Duan Shuxin; Liu Hu

2014-01-01

In recent years, exploration in Xiangshan uranium ore field shows that the intersection of faults and the interface of different rock formation and the basement is an important sign of deep ore- prospecting. In order to evaluate deep uranium resource in Lejia district, audio magnetotelluric method (AMT) was undertaken to carry out profile investigation. With that method, we discerned the interface of different rock formation and the basement successfully, and faults in the deep, which provides a good basis for the prediction of deep uranium resource. Drilling results show that AMT method has an obvious advantage in detecting deep geological structures in Xiangshan. (authors)
Characteristics of uranium geological anomaly in Northern Guangdong province

International Nuclear Information System (INIS)

Wang Xinwu; Cheng Danping

2001-01-01

The geological anomaly characteristics of uranium deposit region in northern Guangdong are discussed on the aspects of uranium source, structure and thermal activity. Uranium deposits usually occur in the uranium-rich background field. Structure activity provides favourable places for the transportation and precipitation of uranium. Uranium deposits are formed in the central and edge of frequent thermal activity. The assembled entropy anomaly field is the synthetical display for above three anomaly. The biggest assembled entropy anomaly is the most favourable space field for forming uranium deposit
Uranium metal production by molten salt electrolysis

International Nuclear Information System (INIS)

Takasawa, Yutaka

1999-01-01

Atomic vapor laser isotope separation (AVLIS) is a promising uranium enrichment technology in the next generation. Electrolytic reduction of uranium oxides into uranium metal is proposed for the preparation of uranium metal as a feed material for AVLIS plant. Considering economical performance, continuos process concept and minimizing the amount of radioactive waste, an electrolytic process for producing uranium metal directly from uranium oxides will offer potential advantages over the existing commercial process. Studies of uranium metal by electrolysis in fluoride salts (BaF 2 -LiF-UF 4 (74-11-15 w/o) at 1150-1200degC, using both a laboratory scale apparatus and an engineering scale one, and continuous casting of uranium metal were carried out in order to decide the optimum operating conditions and the design of the industrial electrolytic cells. (author)

Neutronics Studies Of Uranium-Based Fully Ceramic Micro-Encapsulated Fuel For PWRs

International Nuclear Information System (INIS)

Maldonado, G. Ivan; Gehin, Jess C.

2012-01-01

This study evaluates the core neutronics and fuel cycle characteristics that result from employing uranium-based fully ceramic micro-encapsulated (FCM) fuel in a pressurized water reactor (PWR). Specific PWR bundle designs with FCM fuel have been developed, which by virtue of their TRISO particle based elements, are expected to safely reach higher fuel burnups while also increasing the tolerance to fuel failures. The SCALE 6.1 code package, developed and maintained at ORNL, was the primary software employed to model these designs. Analysis was performed using the SCALE double-heterogeneous (DH) fuel modeling capabilities. For cases evaluated with the NESTLE full-core three-dimensional nodal simulator, because the feature to perform DH lattice physics branches with the SCALE/TRITON sequence is not yet available, the Reactivity-Equivalent Physical Transformation (RPT) method was used as workaround to support the full core analyses. As part of the fuel assembly design evaluations, fresh feed lattices were modeled to analyze the within-assembly pin power peaking. Also, a color-set array of assemblies was constructed to evaluate power peaking and power sharing between a once-burned and a fresh feed assembly. In addition, a parametric study was performed by varying the various TRISO particle design features; such as kernel diameter, coating layer thicknesses, and packing fractions. Also, other features such as the selection of matrix material (SiC, Zirconium) and fuel rod dimensions were perturbed. After evaluating different uranium-based fuels, the higher physical density of uranium mononitride (UN) proved to be favorable, as the parametric studies showed that the FCM particle fuel design will need roughly 12% additional fissile material in comparison to that of a standard UO2 rod in order to match the lifetime of an 18-month PWR cycle. Neutronically, the FCM fuel designs evaluated maintain acceptable design features in the areas of fuel lifetime, temperature
Release of Aged Contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

Energy Technology Data Exchange (ETDEWEB)

Chorover, Jon [Univ. of Arizona, Tucson, AZ (United States); Perdrial, Nico [Univ. of Arizona, Tucson, AZ (United States); Mueller, Karl [Pennsylvania State Univ., University Park, PA (United States); Strepka, Caleb [Pennsylvania State Univ., University Park, PA (United States); O' Day, Peggy [Univ. of California, Merced, CA (United States); Rivera, Nelson [Univ. of California, Merced, CA (United States); Um, Wooyong [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chang, Hyun-Shik [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Steefel, Carl [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Thompson, Aaron [Univ. of Georgia, Athens, GA (United States)

2012-08-14

Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake (Chorover et al., 2008). In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided thorough characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, P_CO2, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions. Below, we provide some detailed descriptions of our results from this three year study, recently completed following a one-year no cost extension.
Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

Energy Technology Data Exchange (ETDEWEB)

Chorover, Jon; Perdrial, Nico; Mueller, Karl; Strepka, Caleb; OÃÂÃÂ¢ÃÂÃÂÃÂÃÂDay, Peggy; Rivera, Nelson; Um, Wooyong; Chang, Hyun-Shik; Steefel, Carl; Thompson, Aaron

2012-11-05

Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided thorough characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, partial pressure of carbon dioxide, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions. In this final report, we provide detailed descriptions of our results from this three-year study, completed in 2012 following a one-year no cost extension.
Reliability of the factor structure of the Multidimensional Scale of Interpersonal Reactivity (EMRI

Directory of Open Access Journals (Sweden)

Nilton S. Formiga

2013-10-01

Full Text Available This study aims to check the internal consistency and factor structure evaluative of the empathy scale in a high school and college sample in the state of Minas Gerais. The instruments that measure empathy can be easily found, however, of the existing, just multidimensional scale of interpersonal reactivity (Emri is the theoretical framework that has far more and better organized, and the scale that is most commonly used to assess this construct. Participated 488 subjects, male and female, with ages from 14-54 years old, distributed in primary and college levels in Patrocínio-MG composed this study sample. The subjects answered the Multidimensional Scale of Interpersonal Reactivity and socio-demographic data. From an equation analysis and structural modeling were observed psychometric indicators that assured the structural consistency of the scale, promoting in the security of the measure theoretical construct of empathy.
In-situ uranium mining: reservoir engineering aspects of leaching and restoration

International Nuclear Information System (INIS)

Kabir, M.I.

1982-01-01

To establish the feasibility of in-situ mining of uranium, a push-pull test of an in-situ uranium leaching process, which consists of a single injection/production test well and two observation wells, was designed to evaluate the parameters which govern the uranium production and restorability of a solution mined zone. The test procedure itself consists of injection (push cycle) of a preflush followed by lixiviant, a brief soak period (soak cycle), and subsequent production (pull cycle) into the same well. Based on computer modeling, procedures are defined which permit, for a properly designed test, the determination of both restoration and leaching parameters. The test procedure and design recommendations are also outlined. Two numerical simulators which model field scale uranium production and restoration operations are presented. These simulators are able to accommodate various well patterns and irregular reservoir boundaries, physical dispersion, directional permeability variations (if present), and a variety of injection/production strategies. A streamline-concentration balance technique has been used to develop the models. The assumption of time invariant boundary conditions and no transverse dispersion between the streamlines reduces the two dimensional problem to a bundle of one dimensional ones. It has been further shown that the production well effluent histories can easily be obtained by superposing the solution of the concentration balance equations for a single streamline, and thus reducing computation time significantly. Finally, the simulators have been used to study various reservoir engineering aspects to optimize in-situ uranium production from field scale operations
In-situ uranium mining: reservoir engineering aspects of leaching and restoration

Energy Technology Data Exchange (ETDEWEB)

Kabir, M.I.

1982-01-01

To establish the feasibility of in-situ mining of uranium, a push-pull test of an in-situ uranium leaching process, which consists of a single injection/production test well and two observation wells, was designed to evaluate the parameters which govern the uranium production and restorability of a solution mined zone. The test procedure itself consists of injection (push cycle) of a preflush followed by lixiviant, a brief soak period (soak cycle), and subsequent production (pull cycle) into the same well. Based on computer modeling, procedures are defined which permit, for a properly designed test, the determination of both restoration and leaching parameters. The test procedure and design recommendations are also outlined. Two numerical simulators which model field scale uranium production and restoration operations are presented. These simulators are able to accommodate various well patterns and irregular reservoir boundaries, physical dispersion, directional permeability variations (if present), and a variety of injection/production strategies. A streamline-concentration balance technique has been used to develop the models. The assumption of time invariant boundary conditions and no transverse dispersion between the streamlines reduces the two dimensional problem to a bundle of one dimensional ones. It has been further shown that the production well effluent histories can easily be obtained by superposing the solution of the concentration balance equations for a single streamline, and thus reducing computation time significantly. Finally, the simulators have been used to study various reservoir engineering aspects to optimize in-situ uranium production from field scale operations.
Reactivity of nitriles

International Nuclear Information System (INIS)

Kukushkin, Yu.N.

1987-01-01

Reactivity of coordination nitriles in transition metal (Ru, Mo, W, Zr, Hf) complexes, namely: transformation of nitriles of the first coordination sphere into N-acyl-substituted amides, amidines, nitrile interaction; with water, alkalines, alcoholes, hydrogen, azide and cyanide ions is considered. Introduction of acetonitrile molecule to uranium (4)-carbon double bond is discussed
Information derived from French studies and achievements in the field of uranium isotope separation; Enseignements tires des etudes et realisations francaises relatives a la separation des isotopes de l'uranium

Energy Technology Data Exchange (ETDEWEB)

Frejacques, C; Galley, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The work carried out in the field of uranium isotope separation, by gaseous diffusion and by ultracentrifugation, is reviewed. An economic estimate of the various parameters involved in the cost is given, and it is shown that only very large gaseous diffusion plants, corresponding to a programme of enriched uranium reactors of at least 4000 MWe to be installed yearly, can give an economically acceptable enriched uranium production. (authors) [French] La communication passe en revue les realisations effectuees dans le domaine de la separation des isotopes de l'uranium, par diffusion gazeuse et par ultracentrifugation. Elle donne une estimation economique des differents parametres intervenant dans les couts et met en evidence que seules les tres grandes usines de diffusion gazeuse, correspondant a un programme d'installation de reacteurs a uranium enrichi d'au moins 4000 MWe nouveaux par an, peuvent conduire a des productions d'uranium enrichi economiquement acceptables. (auteurs)
Uranium resources, 1983

International Nuclear Information System (INIS)

1983-01-01

The specific character of uranium as energy resources, the history of development of uranium resources, the production and reserve of uranium in the world, the prospect regarding the demand and supply of uranium, Japanese activity of exploring uranium resources in foreign countries and the state of development of uranium resources in various countries are reported. The formation of uranium deposits, the classification of uranium deposits and the reserve quantity of each type are described. As the geological environment of uranium deposits, there are six types, that is, quartz medium gravel conglomerate deposit, the deposit related to the unconformity in Proterozoic era, the dissemination type magma deposit, pegmatite deposit and contact deposit in igneaus rocks and metamorphic rocks, vein deposit, sandstone type deposit and the other types of deposit. The main features of respective types are explained. The most important uranium resources in Japan are those in the Tertiary formations, and most of the found reserve belongs to this type. The geological features, the state of yield and the scale of the deposits in Ningyotoge, Tono and Kanmon Mesozoic formation are reported. Uranium minerals, the promising districts in the world, and the matters related to the exploration and mining of uranium are described. (Kako, I.)
Clay vein and its implication for uranium exploration activity in the northern part of the Alligator Rivers Uranium Field, northern Australia

International Nuclear Information System (INIS)

Sasao, Eiji

2003-01-01

Clay veins have been found by uranium exploration drilling around the Black Rock uranium prospect in the northern part of the alligator Rivers Uranium Field (ARUF), northern Australia. The mineralogical and chemical features are described to clarify relations with uranium mineralization, because it is not accompanied by uranium mineralization. X-ray diffraction and chemical analysis for major elements indicate that the clay vein consists mainly of chlorite (clinochlore to ferroan clinochlore) and lesser mica clay mineral (t-1M dominant). The clay vein is compared with the clay alteration zone around the uranium deposits in ARUF in terms of mode of occurrence, mineral and chemical compositions. Mineral composition of the clay vein is only in accordance with that of the inner alteration halo of the clay alteration zone. It is, however, different from mineral composition of the outer alteration halo in terms of lack of Fe chlorite in the clay vein. Chemical composition of the clay vein is similar to that of the clay alteration zone, except for lack in the vein of high iron content which is observed in some samples of the alteration zone. As a whole, the feature of the clay vein corresponds to the inner alteration zone around the uranium deposit in ARUF. The mode of occurrence of the clay vein is very different from that of the clay alteration zone. Mode of occurrence, and mineral and chemical compositions of the clay vein resemble a chlorite vein in the Lower to Middle Proterozoic sandstone above the Jabiluka deposit, one of major uranium deposit in the ARUF. Because of the similarity between the clay and the chlorite veins, the clay vein is regarded as marginal facies of an alteration zone. The fluid that formed the clay vein is estimated to have been oxidized, because of the existence of hematite and ubiquitous Mg chlorite. This nature is in accordance with the mineralizing fluid that formed the inner alteration zone in the Nabarlek deposit. In conclusion, the vein
Processing of uranium-containing coal

International Nuclear Information System (INIS)

Cordero Alvarez, M.

1987-01-01

A direct storage of uranium-bearing coal requires the processing of large amounts of raw materials while lacking guarantee of troublefree process cycles. With the example of an uranium-bearing bituminous coal from Stockheim, it was aimed at the production of an uranium ore concentrate by means of mechanical, thermal and chemical investigations. Above all, amorphous pitch blende was detected as a uranium mineralization which occurs homogeneously distributed in the grain size classes of the comminuted raw material with particle diameters of a few μm and, after the combustion, enriches in the field of finest grain of the axis. Heterogeneous and solid-state reactions in the thermal decarburization above 700deg C result in the development of hardly soluble uranium oxides and and calcium uranates as well as in enclosures in mineral glass. Thus, the pre-enrichment has to take place in a temperature range below 600deg C. By means of a sorting classification of the ash at ± 2.0 mm, it is possible to achieve an enrichment of up to factor 15 for a mineral of a mainly low carbonate content and, for a mineral of a rich carbonate content, up to the factor 4. The separation of the uranium from the concentrates produced is possible with a yield of 95% by means of leaching with sulphuric acid at a temperature of 20deg C. As far as their reproducibility was concerned, the laboratory tests were verified on a semi-industrial scale. A processing method is suggested on the basis of the data obtained. (orig.) [de
Novel ceramic coatings for containment of uranium and reactive molten metals

International Nuclear Information System (INIS)

Sreekumar, K.P.; Satpute, R.U.; Ramanathan, S.; Thiyagarajan, T.K.; Padmanabhan, P.V.A.; Kutty, T.R.G.

2005-01-01

Plasma sprayed aluminium oxide coatings, which are currently used for casting uranium metal are, however, not suitable for long duration handling of molten uranium and is also unstable under reducing conditions. Yttrium oxide and rare earth phosphates are suggested as promising materials for prevention of high temperature corrosion by molten metals. The present paper reports research efforts directed towards development of plasma sprayed coatings of yttria and lanthanum phosphate. Thermal spray grade powders of yttrium oxide and lanthanum phosphate, synthesized using locally available raw materials have been used as feedstock powders for plasma spray deposition. The coatings have been deposited using the indigenously developed 40 kW atmospheric plasma spray system and have been characterized. Results of preliminary experiments on compatibility of yttria and lanthanum phosphate with molten uranium are quite encouraging. (author)
Status Report from Sweden [Processing of Low-Grade Uranium Ores

Energy Technology Data Exchange (ETDEWEB)

Peterson, A [AB Atomenergi, Stockholm (Sweden)

1967-06-15

The Ministry of Education was authorized in November 1945 to appoint a commission to study the organization of nuclear energy research. In April 1947 this commission, the Swedish Atomic Energy Commission, proposed the formation of a semi-state-owned company to be a central body for applied research work and development in the nuclear energy field in Sweden. In November 1947 the Atomic Energy Company (AB Atomenergi) had its statutory meeting. The State owns 4/7 of the share capital and the remaining 3/7 is owned by 71 private and municipal share-holders. Except for a part of the stock capital, all investments and running costs of the company have been financed by the Government. The company is in practice answerable to the Department of Commerce which has an advisory body, the Atomic Energy Board. AB Atomenergi is responsible for Government-financed research on the industrial applications of nuclear energy, the milling of uranium ores and refining of uranium. The total number of employees is at present about 1400, 800 of which work at the company's research establishment Studsvik about 120 km south of Stockholm. As early as 1945 the Research Institute of the Swedish National Defence started work in the field of uranium processing. Similar work was also started quite early by the Boliden Mining Company, the Swedish Shale Oil Company and Wargons AB. After the establishment of AB Atomenergi, all work in the uranium processing field was transferred to this company. In fact one of the main reasons for the formation of AB Atomenergi was the need for Swedish uranium production as there was no possibility of importing uranium at that time. As a result of research and development in uranium processing a pilot plant at Kvarntorp near Orebro in central Sweden started milling a low-grade uranium ore (shale) in 1953. The capacity of this plant was 5-10 tons of uranium a year. A uranium mill at Ranstad in south-west Sweden, near Skovde, with a capacity of 120 tons of uranium a
Ligand Influences on Properties of Uranium Coordination Complexes - Structure, Reactivity, and Spectroscopy

OpenAIRE

Kosog, Boris

2012-01-01

In this thesis several different aspects of uranium chemistry are presented. It was shown that terminal uranium(V) oxo and imido complexes [((RArO)3tacn)UV(O)] and [((RArO)3tacn)UV(NSiMe3)] (R = t Bu, Ad) can be oxidized by silver(I) hexafluoro-antimonate to the uranium(VI) oxo and imido complexes [((RArO)3tacn)UVI(O)]SbF6 and [((RArO)3tacn)UVI(NSiMe3)]SbF6. While for the t Bu-derivative of the oxo complex an equatorial coordination is observed due to stabilization by the inverse trans-influe...
Stream sediment geochemical surveys for uranium

International Nuclear Information System (INIS)

Price, V.; Ferguson, R.B.

1979-01-01

Stream sediment is more universally available than ground and surface waters and comprises the bulk of NURE samples. Orientation studies conducted by the Savannah River Laboratory indicate that several mesh sizes can offer nearly equivalent information. Sediment is normally sieved in the field to pass a 420-micrometer screen (US Std. 40 mesh) and that portion of the dried sediment passing a 149-micrometer screen (US Std. 100 mesh) is recovered for analysis. Sampling densities usually vary with survey objectives and types of deposits anticipated. Principal geologic features that can be portrayed at a scale of 1:250,000, such as major tectonic units, plutons, and pegmatite districts, are readily defined using a sampling density of 1 site per 5 square miles (13 km 2 ). More detailed studies designed to define individual deposits require greater sampling density. Analyses for elements known to be associated with uranium in a particular mineral host may be used to estimate the relative proportion of uranium in several forms. For example, uranium may be associated with thorium and cerium in monazite, and with zirconium and hafnium in zircon. Readily leachable uranium may be adsorbed to trapped in oxide coatings on mineral particles. Soluble or mobile uranium may indicate an ore source, whereas uranium in monazite or zircon is not likely to be economically attractive. Various schemes may be used to estimate for form of uranium in a sample. Simple elemental ratios are a useful first approach. Multiple ratios and subtractive formulas empirically designed to account for the presence of particular minerals are more useful. Residuals calculated from computer-derived regression equations or factor scores appear to have the greatest potential for locating uranium anomalies
A novel HPLC method for separation of uranium from thorium using BEHSA modified semi preparative support

International Nuclear Information System (INIS)

Raju, Ch.Siva Kesava; Subramanian, M.S.; Sivaraman, N.; Srinivasan, T.G.; Vasudeva Rao, P.R.

2006-01-01

The determination of uranium and thorium is of great importance with respect to nuclear industry and environmental samples. High performance liquid chromatography (HPLC) has revolutionized as a powerful separation and analytical tool in the field of chemistry, biology, medicine, pharmacy, chemical technology, food science and many more. The major advantages of HPLC are its ability to provide rapid, high performance separations and extending the separations range from laboratory scale to preparative scale purification. HPLC became powerful technique for the separation of uranium and thorium. These methods were widely employed in applications such as separation of uranium from fission products and for the measurement of number of fissions as in the case of burn-up measurements on nuclear reactor fuels
Field Evaluation of the Restorative Capacity of the Aquifer Downgradient of a Uranium In-Situ Recovery Mining Site

Energy Technology Data Exchange (ETDEWEB)

Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-05-22

A two-part field study was conducted in Smith Ranch-Highland in-situ recovery (ISR) near Douglas, Wyoming, to evaluate the restorative capacity of the aquifer downgradient (i.e., hydrologically downstream) of a Uranium ISR mining site with respect to the transport of uranium and other potential contaminants in groundwater after mining has ceased. The study was partially conducted by checking the Uranium content and the alkalinity of separate wells, some wells had been restored and others had not. A map and in-depth procedures of the study are included.
Final Project Report: Release of aged contaminants from weathered sediments: Effects of sorbate speciation on scaling of reactive transport

Energy Technology Data Exchange (ETDEWEB)

Jon Chorover, University of Arizona; Peggy O' ÃÂÃÂDay, University of California, Merced; Karl Mueller, Penn State University; Wooyong Um, Pacific Northwest National Laboratory; Carl Steefel, Lawrence Berkeley National Laboratory

2012-10-01

Hanford sediments impacted by hyperalkaline high level radioactive waste have undergone incongruent silicate mineral weathering concurrent with contaminant uptake. In this project, we studied the impact of background pore water (BPW) on strontium, cesium and iodine desorption and transport in Hanford sediments that were experimentally weathered by contact with simulated hyperalkaline tank waste leachate (STWL) solutions. Using those lab-weathered Hanford sediments (HS) and model precipitates formed during nucleation from homogeneous STWL solutions (HN), we (i) provided detailed characterization of reaction products over a matrix of field-relevant gradients in contaminant concentration, PCO2, and reaction time; (ii) improved molecular-scale understanding of how sorbate speciation controls contaminant desorption from weathered sediments upon removal of caustic sources; and (iii) developed a mechanistic, predictive model of meso- to field-scale contaminant reactive transport under these conditions.
Reactivity management and burn-up management on JRR-3 silicide-fuel-core

International Nuclear Information System (INIS)

Kato, Tomoaki; Araki, Masaaki; Izumo, Hironobu; Kinase, Masami; Torii, Yoshiya; Murayama, Yoji

2007-08-01

On the conversion from uranium-aluminum-dispersion-type fuel (aluminide fuel) to uranium-silicon-aluminum-dispersion-type fuel (silicide fuel), uranium density was increased from 2.2 to 4.8 g/cm 3 with keeping uranium-235 enrichment of 20%. So, burnable absorbers (cadmium wire) were introduced for decreasing excess reactivity caused by the increasing of uranium density. The burnable absorbers influence reactivity during reactor operation. So, the burning of the burnable absorbers was studied and the influence on reactor operation was made cleared. Furthermore, necessary excess reactivity on beginning of operation cycle and the time limit for restart after unplanned reactor shutdown was calculated. On the conversion, limit of fuel burn-up was increased from 50% to 60%. And the fuel exchange procedure was changed from the six-batch dispersion procedure to the fuel burn-up management procedure. The previous estimation of fuel burn-up was required for the planning of fuel exchange, so that the estimation was carried out by means of past operation data. Finally, a new fuel exchange procedure was proposed for effective use of fuel elements. On the procedure, burn-up of spent fuel was defined for each loading position. The average length of fuel's staying in the core can be increased by two percent on the procedure. (author)
Multi-scales modeling of reactive transport mechanisms. Impact on petrophysical properties during CO2 storage

International Nuclear Information System (INIS)

Varloteaux, C.

2012-01-01

The geo-sequestration of carbon dioxide (CO 2 ) is an attractive option to reduce the emission of greenhouse gases. Within carbonate reservoirs, acidification of brine in place can occur during CO 2 injection. This acidification leads to mineral dissolution which can modify the transport properties of a solute in porous media. The aim of this study is to quantify the impact of reactive transport on a solute distribution and on the structural modification induced by the reaction from the pore to the reservoir scale. This study is focused on reactive transport problem in the case of single phase flow in the limit of long time. To do so, we used a multi-scale up-scaling method that takes into account (i) the local scale, where flow, reaction and transport are known; (ii) the pore scale, where the reactive transport is addressed by using averaged formulation of the local equations; (iii) the Darcy scale (also called core scale), where the structure of the rock is taken into account by using a three-dimensions network of pore-bodies connected by pore-throats; and (iv) the reservoir scale, where physical phenomenon, within each cell of the reservoir model, are taken into account by introducing macroscopic coefficients deduced from the study of these phenomenon at the Darcy scale, such as the permeability, the apparent reaction rate, the solute apparent velocity and dispersion. (author)

Decommissioning of an uranium hexafluoride pilot plant

International Nuclear Information System (INIS)

Santos, Ivan; Abrao, Alcidio; Carvalho, Fatima M.S.; Ayoub, Jamil M.S.

2009-01-01

The Institute of Nuclear and Energetic Researches has completed fifty years of operation, belongs to the National Commission for Nuclear Energy, it is situated inside the city of Sao Paulo. The IPEN-CNEN/SP is a Brazilian reference in the nuclear fuel cycle, researches in this field began in 1970, having dominance in the cycle steps from Yellow Cake to Uranium Hexafluoride technology. The plant of Uranium Hexafluoride produced 35 metric tonnes of this gas by year, had been closed in 1992, due to domain and total transference of know-how for industrial scale, demand of new facilities for the improvement of recent researches projects. The Institute initiates decommissioning in 2002. Then, the Uranium Hexafluoride pilot plant, no doubt the most important unit of the fuel cycle installed at IPEN-CNEN/SP, beginning decommissioning and dismantlement (D and D) in 2005. Such D and D strategies, planning, assessment and execution are described, presented and evaluated in this paper. (author)
Fuel Temperature Coefficient of Reactivity

Energy Technology Data Exchange (ETDEWEB)

Loewe, W.E.

2001-07-31

A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.
On bacteria oxidizing enlargement scale test for uranium in-situ leaching at. 381 mine

International Nuclear Information System (INIS)

Hu Kaiguang; Wang Qingliang; Liu Yingjiu; Shi Wenge; Hu Shihe; Hu Yincai; Fang Qiu

1999-01-01

The results of enlarged scale test of bacteria as oxidizer for uranium in-situ leaching at No 381 mine showed that redox potential of the oxidized absorbed tailing water by bacteria is more than 510 mV, without any effects on after treatments by using bacteria as oxidizer and reduce oxidizer costs 70% compared with H 2 O 2 as oxidizer
Bench-scale/field-scale interpretations: Session overview

International Nuclear Information System (INIS)

Cunningham, A.B.; Peyton, B.M.

1995-04-01

In situ bioremediation involves complex interactions between biological, chemical, and physical processes and requires integration of phenomena operating at scales ranging from that of a microbial cell (10 -6 ) to that of a remediation site (10 to 1000 m). Laboratory investigations of biodegradation are usually performed at a relatively small scale, governed by convenience, cost, and expedience. However, extending the results from a laboratory-scale experimental system to the design and operation of a field-scale system introduces (1) additional mass transport mechanisms and limitations; (2) the presence of multiple phases, contants, and competing microorganisms (3) spatial geologic heterogeneities; and (4) subsurface environmental factors that may inhibit bacterial growth such as temperature, pH, nutrient, or redox conditions. Field bioremediation rates may be limited by the availability of one of the necessary constituents for biotransformation: substrate, contaminant, electron acceptor, nutrients, or microorganisms capable of degrading the target compound. The factor that limits the rate of bioremediation may not be the same in the laboratory as it is in the field, thereby leading, to development of unsuccessful remediation strategies
Exploration for uranium in Argentina: New policies of reactivation

International Nuclear Information System (INIS)

Bianchi, R.E.

2009-01-01

Full text: The policy established by the National Government of Argentina in August 2006 related to resuming the Nuclear activity in the country, lead the CNEA trough the Exploration of Raw Materials Manager (ERMM) to establish working strategies for the next 10 years. These strategies together with the assignment of an adequate budget will contribute to define new uranium resources, which together with the already known ones, will be used to supply the requirements of Nuclear Power and Research Plants in the future. Thus, the ERMM is applying a policy of human resources hiring new personnel in order to count with the minimum necessary workforce to reach these tasks. In Argentina known U resources are related to sedimentary, igneous and metamorphic environments. Considering the geology of the different regions, Argentina has been divided into 57 units in which the geological, geochemical, mineralogical and structural information is evaluated in order to estimate the uranium geological favorability of each unit. The final pursuit of this regional study is to circumscribe new areas with anomalous uranium contents in which prospection and exploration should be carried out. These studies together with prospection and exploration works are performed in the country by four exploration centers based in Salta (RN), Cordoba (R.Ce), Mendoza (R.Cu) and Trelew (RP). The works planned for each exploration center includes: Regional Noroeste, Mina Franca Deposit: peri-granitic vein- type mineralization: 25% of surface exploration has been performed. Mineralized areas: Istataco and San Buenaventura correspond to an igneous-metamorphic environment, Sierra de Vaqueria to a sedimentary one: Prospection stage. Regional Centro, Mineralized areas: El Gallo: drilling stage and Donato: prospection stage, correspond to an igneous-metamorphic environment with intra and peri-granitic anomalies. Noya: prospection stage, sedimentary environment. Regional Cuyo, Mineralized area: Western Sierra
Cost results from the 1994 Fernald characterization field demonstration for uranium-contaminated soils

International Nuclear Information System (INIS)

Douthat, D.M.; Stewart, R.N.; Armstrong, A.Q.

1995-04-01

One of the principal objectives of the US Department of Energy (DOE) Office of Technology Development is to develop an optimum integrated system of technologies for removing uranium substances from soil. This system of technologies, through demonstration, must be proven in terms of cost reduction, waste minimization, risk reduction, and user applicability. To evaluate the effectiveness of these technologies, a field demonstration was conducted at the Fernald site in the summer of 1994. Fernald was selected as the host site for the demonstration based on environmental problems stemming from past production of uranium metal for defense-related applications. The following six alternative technologies were developed and/or demonstrated by the principal investigators in the Characterization Task Group at the field demonstration: (1) beta scintillation detector by Pacific Northwest Laboratory (PNL), (2) in situ gamma detector by PNL, (3) mobile laser ablation-inductively coupled plasma/atomic emission spectrometry (LA-ICP/AES) laboratory by Ames Laboratory, (4) long-range alpha detector (LRAD) by Los Alamos National Laboratory (LANL), (5) passive radon monitoring by ORNL, and (6) electret ion chamber by ORNL
Discussion on uranium ore-formation age in Xiazhuang ore-field, northern Guangdong

International Nuclear Information System (INIS)

Wu Lieqin; Tan Zhengzhong; Liu Ruzhou; Huang Guolong

2003-01-01

There exist two genetic types of granite-type uranium deposits, i.e. the early-stage one, and the late-stage one. The early-stage uranium deposits are characterized by ore-formation ages of 122-138 Ma, and are high-grade uranium deposits of postmagmatic hydrothermal origin. The late-stage uranium deposits have ore-formation ages of 54-96 Ma. They mostly are low-grade uranium deposits, and of hydrothermal-regeneration origin with the uranium source derived from the mobilization of consolidated rocks. The early-stage uranium deposits should be the main target of further prospecting for high-grade uranium deposits in the region
Final Report Coupling in silico microbial models with reactive transport models to predict the fate of contaminants in the subsurface.

Energy Technology Data Exchange (ETDEWEB)

Lovley, Derek R.

2012-10-31

This project successfully accomplished its goal of coupling genome-scale metabolic models with hydrological and geochemical models to predict the activity of subsurface microorganisms during uranium bioremediation. Furthermore, it was demonstrated how this modeling approach can be used to develop new strategies to optimize bioremediation. The approach of coupling genome-scale metabolic models with reactive transport modeling is now well enough established that it has been adopted by other DOE investigators studying uranium bioremediation. Furthermore, the basic principles developed during our studies will be applicable to much broader investigations of microbial activities, not only for other types of bioremediation, but microbial metabolism in diversity of environments. This approach has the potential to make an important contribution to predicting the impact of environmental perturbations on the cycling of carbon and other biogeochemical cycles.
Development of a Kelp-Type Structure Module in a Coastal Ocean Model to Assess the Hydrodynamic Impact of Seawater Uranium Extraction Technology

Directory of Open Access Journals (Sweden)

Taiping Wang

2014-02-01

Full Text Available With the rapid growth of global energy demand, interest in extracting uranium from seawater for nuclear energy has been renewed. While extracting seawater uranium is not yet commercially viable, it serves as a “backstop” to the conventional uranium resources and provides an essentially unlimited supply of uranium resource. With recent technology advances, extracting uranium from seawater could be economically feasible only when the extraction devices are deployed at a large scale (e.g., several hundred km2. There is concern however that the large scale deployment of adsorbent farms could result in potential impacts to the hydrodynamic flow field in an oceanic setting. In this study, a kelp-type structure module based on the classic momentum sink approach was incorporated into a coastal ocean model to simulate the blockage effect of a farm of passive uranium extraction devices on the flow field. The module was quantitatively validated against laboratory flume experiments for both velocity and turbulence profiles.Model results suggest that the reduction in ambient currents could range from 4% to 10% using adsorbent farm dimensions and mooring densities previously described in the literature and with typical drag coefficients.
Market outlook for Australian uranium producers

International Nuclear Information System (INIS)

Lindsay, M.

2001-01-01

Recent improvements in the uranium market and political changes in Australia presented the uranium producers with their best opportunity in over 15 years. The removal of the well known 'three mines policy' by the current government has encouraged Australian producers to develop new development plans. With the expansion of the existing operations at Ranger and Olympic Dam, and the potential operations of Jabiluka, Kintyre, Koongara, Honeymoon and Beverley, Australia expects to increase annual production to 11630 t U 3 O 8 by the end of the decade. It will then join Canada as a major supplier of uranium to the world's nuclear power utilities in the 21st century. Uranium exploration, which has been virtually nonexistent over the past 15 years, has once again been reactivated. This occurred because of the change in the Government, but also because the Aboriginal groups are once more allowing exploration on their land. (author)
Design and reactivity of mono- and polymetallic complexes of low valent f-elements

International Nuclear Information System (INIS)

Camp, Clement

2013-01-01

Beyond its importance in nuclear industry the redox chemistry uranium is attracting increasing interest because complexes of low-valent uranium can promote unusual reductive chemistry through unusual reaction pathways, including attractive examples of CO, CO 2 , N 2 , arenes and azides activation in mild condition. Due to the unique coordination and bonding properties of uranium, its compounds could provide an attractive alternative to transition metals for the catalytic transformation of small molecules. However, metal-based multi-electron processes remain uncommon in uranium chemistry especially in comparison with the d-block metals, the chemistry of low-valent uranium being dominated by single-electron transfers. In this context, the first aim of this project was to investigate the association of low-valent uranium to a non-innocent ligand acting as an independent electron reservoir at a same molecule. Accordingly, we interrogated the use of highly p-delocalized Schiff bases ligands for supporting low-valent uranium chemistry. This led to the isolation of electron-rich complexes which are stabilized by storing electrons on the ligands through the formation of C-C bonds. Interestingly, these C-C bonds can be cleaved by oxidizing agents and the electrons released to participate in multi-electron redox reactions. This process was observed within different Schiff-base ligand scaffolds, allowing a tuning of the properties of the compounds. The second part of this work was dedicated to the synthesis of novel trivalent uranium complexes supported by siloxy ligands and the study of their redox reactivity and coordination properties. Novel dinuclear highly-reactive low-valent uranium assemblies were developed. The study of their limited stability revealed that these compounds are spontaneously decomposing through the cleavage of tBu groups from the supporting ligands resulting in the formation of U(IV) species. In parallel, a mononuclear trivalent uranium complex was
Reactivity margins in heavy water moderated production reactors

International Nuclear Information System (INIS)

Benton, F.D.

1981-11-01

The design of the reactor core and components of the heavy water moderated reactors at the Savannah River Plant (SFP) can be varied to produce a number of isotopes. For the past decade, the predominant reactor core design has been the enriched-depleted lattice. In this lattice, fuel assemblies of highly enriched uranium and target assemblies of depleted uranium, which produce plutonium, occupy alternate lattice positions. This heterogeneous lattice arrangement and a nonuniform control rod distribution result in a reactor core that requires sophisticated calculational methods for accurate reactivity margin and power distribution predictions. For maximum accuracy, techniques must exist to provide a base of observed data for the calculations. Frequent enriched-depleted lattice design changes are required as product demands vary. These changes provided incentive for the development of techniques to combine the results of calculations and observed reactivity data to accurately and conveniently monitor reactivity margins during operation
Measurement of reactivity worths of burnable poison rods in enriched uranium graphite-moderated core simulated to high temperature gas cooled reactor

International Nuclear Information System (INIS)

Akino, Fujiyoshi; Takeuchi, Motoyoshi; Kitadate, Kenji; Yoshifuji, Hisashi; Kaneko, Yoshihiko

1980-11-01

As the core design for the Experimental Very High Temperature Gas Cooled Reactor progresses, evaluation of design precision has become increasingly important. For a high precision design, it is required to have adequate group constants based on accurate nuclear data, as well as calculation methods properly describing the physical behavior of neutrons. We, therefore, assembled a simulation core for VHTR, SHE-14, using a graphite-moderated 20%-enriched uranium Semi-Homogeneous Experimental Critical Facility (SHE), and obtained useful experimental data in evaluating the design precision. The VHTR is designed to accommodate burnable poison and control rods for reactivity compensation. Accordingly, the experimental burnable poison rods which are similar to those to be used in the experimental reactor were prepared, and their reactivity values were measured in the SHE-14 core. One to three rods of the above experimental burnable poison rods were inserted into the central column of the SHE-14 core, and the reactivity values were measured by the period and fuel rod substitution method. The results of the measurements have clearly shown that due to the self-shielding effect of B 4 C particles the reactivity value decreases with increasing particle diameter. For the particle diameter, the reactivity value is found to increase linearly with the logarithm of boron content. The measured values and those calculated are found to agree with each other within 5%. These results indicate that the reactivity of the burnable poison rod can be estimated fairly accurately by taking into account the self-shielding effect of B 4 C particles and the heterogeneity of the lattice cell. (author)
Large-Scale Reactive Atomistic Simulation of Shock-induced Initiation Processes in Energetic Materials

Science.gov (United States)

Thompson, Aidan

2013-06-01

Initiation in energetic materials is fundamentally dependent on the interaction between a host of complex chemical and mechanical processes, occurring on scales ranging from intramolecular vibrations through molecular crystal plasticity up to hydrodynamic phenomena at the mesoscale. A variety of methods (e.g. quantum electronic structure methods (QM), non-reactive classical molecular dynamics (MD), mesoscopic continuum mechanics) exist to study processes occurring on each of these scales in isolation, but cannot describe how these processes interact with each other. In contrast, the ReaxFF reactive force field, implemented in the LAMMPS parallel MD code, allows us to routinely perform multimillion-atom reactive MD simulations of shock-induced initiation in a variety of energetic materials. This is done either by explicitly driving a shock-wave through the structure (NEMD) or by imposing thermodynamic constraints on the collective dynamics of the simulation cell e.g. using the Multiscale Shock Technique (MSST). These MD simulations allow us to directly observe how energy is transferred from the shockwave into other processes, including intramolecular vibrational modes, plastic deformation of the crystal, and hydrodynamic jetting at interfaces. These processes in turn cause thermal excitation of chemical bonds leading to initial chemical reactions, and ultimately to exothermic formation of product species. Results will be presented on the application of this approach to several important energetic materials, including pentaerythritol tetranitrate (PETN) and ammonium nitrate/fuel oil (ANFO). In both cases, we validate the ReaxFF parameterizations against QM and experimental data. For PETN, we observe initiation occurring via different chemical pathways, depending on the shock direction. For PETN containing spherical voids, we observe enhanced sensitivity due to jetting, void collapse, and hotspot formation, with sensitivity increasing with void size. For ANFO, we
Uranium migration in a podzol. The role of colloids in the non-saturated zone and the phreatic water: application to the Landes de Gascogne area

International Nuclear Information System (INIS)

Crancon, P.

2001-01-01

The non-saturated zone of a soil represents the interface between the atmosphere and the phreatic water. The confinement efficiency of the non-saturated zone above the phreatic water depends on the fastness of water transfers and on the type of pollutant transport mechanisms. Uranium (VI) can combine with humid acids to form very stable complexes. The aggregates of the absorbing complex are highly sensible to the variations of the ionic force of the environment. This sensitiveness can be at the origin of a strong remobilization of the colloid humic compounds of the soil, and of their migration towards the underground water. In this situation, the uranium complexed by humic compounds can rapidly migrate in the soil. The comparative reactive transport of the total uranium and its isotopes has been studied in a site, the Landes de Gascogne podzol (SW France), where metallic uranium has been sprinkled on the surface of the soil. The field study has been completed with an experimental column transport study using uranium isotopes tracer techniques. The field study shows that most of uranium is trapped in the very first cm of the soil. However, anomalous high uranium concentrations are observed in underground waters, more than 2 km away from the contaminated areas. This demonstrates that a fast and long distance transport process exists for uranium in the unsaturated zone. In the sandy soil of the study area, natural argillo-humic colloids migrate with the velocity of water but can be delayed when the ionic force of the underground waters increases. It is shown that uranium is strongly linked with the thin grain size fraction ( 233 U allows to discriminate between the uranium transported through the sand in a non-reactive way, and the uranium desorbed from the argillo-humic aggregates and the sand grain coatings. A fast reduction of the ionic force of the environment during the tests shows an important remobilization of uranium from the soil. When the complex relations
A full-scale porous reactive wall for prevention of acid mine drainage

International Nuclear Information System (INIS)

Benner, S.G.; Blowes, D.W.; Ptacek, C.J.

1997-01-01

The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problems is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years
Field-scale model for the natural attenuation of uranium at the Hanford 300 area using high performance computing

Energy Technology Data Exchange (ETDEWEB)

Lichtner, Peter C [Los Alamos National Laboratory; Hammond, Glenn E [PNNL

2009-01-01

Three-dimensional reactive flow and transport simulations are carried out to better understand the persistence of uranium [U(VI)] at the Hanford 300 Area bordering the Columbia River. The massively parallel code PFLOTRAN developed under a DOE SciDAC-2 project is employed in the simulations. The calculations were carried out on 4096 processor cores on ORNL's Jaguar XT4 & 5 Cray supercomputers with run times on the order of 6 hours, equivalent to several years if performed on a single processor with sufficient memory. A new conceptual model is presented for understanding present-day and future attenuation rates of U(VI) at the 300 Area site. Unique to the conceptual model is the recognition of three distinct phases in the evolution of the site corresponding to: (I) initial emplacement of waste; (II) present-day conditions of slow leaching of U(VI) from the Hanford sediments; and (III) the complete removal of non-labile U(VI) from the source region. This work focuses on Phase II. Both labile and non-labile forms of U(VI) are included in the model as sorbed and mineralized forms of U(VI), respectively. The non-labile form plays an important role in providing a long-term source of U(VI) as it slowly leaches out of the Hanford sediment. Rapid fluctuations in the Columbia River stage on hourly, weekly and seasonal time scales are found to' playa major role in determining the migration behavior of U(VI). The calculations demonstrate that U(VI) is released into the Columbia River at a highly fluctuating rate in a ratchet-like behavior with nonzero U(VI) flux occurring only during flow from contaminated sediment into the river. The cumulative flux, however, is found to increase approximately linearly with time. The flow rate and U(VI) flux into the Columbia River predicted by the model is highly sensitive to the value used in the conductance boundary condition at the river-sediment interface. By fitting the conductance to the measured piezometric head at well 399
Uranium accompanying recovery from copper ores

International Nuclear Information System (INIS)

Golynko, Z.Sh.; Laskorin, B.N.

1981-01-01

In the search for new raw material sources for nuclear power engineering a review of the technique of uranium accompaning recovery from copper ores reprocessing products in some countries is presented. In the USA a sorption method of uranium extraction by means of strongly basic ion exchange resins from solutions upon copper case- hardening with subsequent extraction from eluates by solutions of tertiary amines is realized. Elution is realized with sulphuric acid. In South Africa an extraction reprocessing of gravitational concentrate extracted from copper sulphide flotation tailings is organized. In India the uranium extraction from copper ores flotation enrichment tailings is organized on a commerical scale. Presented are data on the scale of uranium recovery, various conditions of its recovery as well as block diagrams of the processes. It is shown that copper ores become an additional source of uranium recovery [ru
Evaluation of the oxide and silicide fuels reactivity in the RSG-GAS core

International Nuclear Information System (INIS)

S, Tukiran; M S, Tagor; S, Lily; Pinem, S.

2000-01-01

Fuel exchange of The RSG-GAS reactor core from uranium oxide to uranium silicide in the same loading, density, and enrichment, that is, 250 gr, 2.98 gr/cm 3 , and 19.75 % respectively, will be performed in-step wise. In every cycle of exchange with 5/l mode, it is needed to evaluate the parameter of reactor core operation. One of the important operation parameters is fuel reactivity that gives effect to the core reactivity. The experiment was performed at core no. 36, BOC, low power which exist 2 silicide fuels. The evaluation was done based on the RSG-GAS control rod calibration consisting of 40 fuels and 8 control rod.s. From 40 fuels in the core, there are 2 silicide fuels, RI-225/A-9 and RI-224/C-3. For inserting 2 silicide fuels, the reactivity effect to the core must be know. To know this effect , it was performed fuels reactivity experiment, which based on control rod calibration. But in this case the RSG-GAS has no other fresh oxide fuel so that configuration of the RSG-GAS core was rearranged by taking out the both silicide fuels and this configuration is used as reference core. Then silicide fuel RI-224 was inserted to position F-3 replacing the fresh oxide fuel RI-260 so the different reactivity of the fuels is obtained. The experiment result showed that the fuel reactivity change is in amount of 12.85 cent (0.098 % ) The experiment result was compared to the calculation result, using IAFUEL code which amount to 13.49 cent (0.103 %) The result showed that the reactivity change of oxide to silicide fuel is small so that the fuel exchange from uranium oxide to uranium silicide in the first step can be done without any significant change of the operation parameter
Development of the Children's Scale of Hostility and Aggression: Reactive/Proactive (C-SHARP)

Science.gov (United States)

Farmer, Cristan A.; Aman, Michael G.

2009-01-01

Whereas some scales exist for assessing aggression in typically developing children, they do not give a detailed analysis, and none is available for populations with developmental disabilities (DD). Parents of 365 children with DD completed the Children's Scale of Hostility and Aggression: Reactive/Proactive (C-SHARP), which surveys the severity…

Uranium hexafluoride - chemistry and technology of a raw material of the nuclear fuel cycle

International Nuclear Information System (INIS)

Bacher, W.; Jacob, E.

1986-01-01

Uranium hexafluoride exhibits an unusual combination of properties: UF 6 is both a large-scale industrial product, and also one of the most reactive compounds known. Its industrial application arises from the need to use enriched uranium with up to 4% 235 U as fuel in light water reactors. Enrichment is performed in isotope separation plants with UF 6 as the working gas. Its volatility and thermal stability make UF 6 suitable for this application. UF 6 handling is difficult because of its high reactivity and its radioactivity, and special experience and equipment are required which are not commonly available in laboratories or industrial facilities. The chemical reactions of UF 6 are characterized by its marked fluorination efficiency which is similar to that of F 2 . Of special importance in connection with the handling of UF 6 is its extreme sensitivity to hydrolysis. Because they all use UF 6 , the isotope separation processes currently in use (gas diffusion, gas centrifuge, separation nozzle process) have a number of common features. For instance, they are all beset by the problem of formation of solid UF 6 decomposition products, e.g. by radiolysis of UF 6 molecules induced by its own radiation. Reconversion of UF 6 into UO 2 is achieved by three well-known methods (ADU, AUC, IDP-process). To produce uranium metal, UF 6 is first reduced to UF 4 , which is subsequently reduced by Ca 6 or Mg metal. 158 refs
Criticality safety evaluation for the Advanced Test Reactor enhanced low enriched uranium fuel elements

Energy Technology Data Exchange (ETDEWEB)

Montierth, Leland M. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-07-19

The Global Threat Reduction Initiative (GTRI) convert program is developing a high uranium density fuel based on a low enriched uranium (LEU) uranium-molybdenum alloy. Testing of prototypic GTRI fuel elements is necessary to demonstrate integrated fuel performance behavior and scale-up of fabrication techniques. GTRI Enhanced LEU Fuel (ELF) elements based on the ATR-Standard Size elements (all plates fueled) are to be fabricated for testing in the Advanced Test Reactor (ATR). While a specific ELF element design will eventually be provided for detailed analyses and in-core testing, this criticality safety evaluation (CSE) is intended to evaluate a hypothetical ELF element design for criticality safety purposes. Existing criticality analyses have analyzed Standard (HEU) ATR elements from which controls have been derived. This CSE documents analysis that determines the reactivity of the hypothetical ELF fuel elements relative to HEU ATR elements and whether the existing HEU ATR element controls bound the ELF element. The initial calculations presented in this CSE analyzed the original ELF design, now referred to as Mod 0.1. In addition, as part of a fuel meat thickness optimization effort for reactor performance, other designs have been evaluated. As of early 2014 the most current conceptual designs are Mk1A and Mk1B, that were previously referred to as conceptual designs Mod 0.10 and Mod 0.11, respectively. Revision 1 evaluates the reactivity of the ATR HEU Mark IV elements for a comparison with the Mark VII elements.
Criticality safety evaluation for the Advanced Test Reactor enhanced low enriched uranium fuel elements

International Nuclear Information System (INIS)

Montierth, Leland M.

2016-01-01

The Global Threat Reduction Initiative (GTRI) convert program is developing a high uranium density fuel based on a low enriched uranium (LEU) uranium-molybdenum alloy. Testing of prototypic GTRI fuel elements is necessary to demonstrate integrated fuel performance behavior and scale-up of fabrication techniques. GTRI Enhanced LEU Fuel (ELF) elements based on the ATR-Standard Size elements (all plates fueled) are to be fabricated for testing in the Advanced Test Reactor (ATR). While a specific ELF element design will eventually be provided for detailed analyses and in-core testing, this criticality safety evaluation (CSE) is intended to evaluate a hypothetical ELF element design for criticality safety purposes. Existing criticality analyses have analyzed Standard (HEU) ATR elements from which controls have been derived. This CSE documents analysis that determines the reactivity of the hypothetical ELF fuel elements relative to HEU ATR elements and whether the existing HEU ATR element controls bound the ELF element. The initial calculations presented in this CSE analyzed the original ELF design, now referred to as Mod 0.1. In addition, as part of a fuel meat thickness optimization effort for reactor performance, other designs have been evaluated. As of early 2014 the most current conceptual designs are Mk1A and Mk1B, that were previously referred to as conceptual designs Mod 0.10 and Mod 0.11, respectively. Revision 1 evaluates the reactivity of the ATR HEU Mark IV elements for a comparison with the Mark VII elements.
Criticality of mixtures of plutonium and high enriched uranium

International Nuclear Information System (INIS)

Grolleau, E.; Lein, M.; Leka, G.; Maidou, B.; Klenov, P.

2003-01-01

This paper presents a criticality evaluation of moderated homogeneous plutonium-uranium mixtures. The fissile media studied are homogeneous mixtures of plutonium and high enriched uranium in two chemical forms: aqueous mixtures of metal and mixtures of nitrate solutions. The enrichment of uranium considered are 93.2wt.% 235 U and 100wt.% 235 U. The 240 Pu content in plutonium varies from 0wt.% 240 Pu to 12wt.% 240 Pu. The critical parameters (radii and masses of a 20 cm water reflected sphere) are calculated with the French criticality safety package CRISTAL V0. The comparison of the calculated critical parameters as a function of the moderator-to-fuel atomic ratio shows significant ranges in which high enriched uranium systems, as well as plutonium-uranium mixtures, are more reactive than plutonium systems. (author)
Major geological events and uranium metallogenesis in South-west China

International Nuclear Information System (INIS)

Zhang Chengjiang; Xu Zhengqi; Ni Shijun; Chen Youliang

2012-01-01

Uranium is widely distributed in South-west China, with all types but on a not-so-large scale. South-west China is located on the combining site of several large tectonic elements and every tectonic movement has different effects on different regions. To study and clarify the correlation between the major geological events in South-west China and the Uranium metallogenesis, comprehensive research and field investigation are made besides collecting a lot of materials. Through analysis and research on the major geological events in South-west China, the evolution of those e vents is basically clarified and the events closely related with uranium mineralization are determined. It is discovered that there are several ore-forming geologic events in the geological history of South-west China; almost every major tectonic movement cycle is accompanied with uranium metallogenesis, from Jinning Movement to Chengjiang Movement, to Hercynian Movement, to Indosinian Movement. to Yanshan Movement. to Himalayan movement. Even though every major tectonic cycle is accompanied with uranium mineralization, three major geological events are generally obviously related with uranium metallogenesis, i.e. the Rodinian supercontinent breakup even in Jinning-Chengjiang Period, Yanshan Movement and Himalayan movement, in which the first one is the process of uranium pre-enrichment and provides the source of uranium. Yanshan Movement and Himalayan movement are the important processes for mineralization, mainly the hydrothermal superimposed mineralization. (authors)
Uranium dioxide calcining apparatus

International Nuclear Information System (INIS)

Cole, E.A.; Peterson, R.S.

1978-01-01

This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO 2 ) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO 2 , means for cooling the UO 2 to a temperature of below 100 deg C and conveying the cooled UO 2 to storage or to subsequent UO 2 processing apparatus where it finally comes into contact with air, the means for receiving cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO 2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO 2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means. (author)
New interpretation of the dominant ore-controlling factor of the uranium ore field No. 322

International Nuclear Information System (INIS)

Liu Xiang; Yang Chongqiu

1996-01-01

The NE-trending fault structures in ore field NO. 322 are characterized by compress-shearing, left-Lateral left-slipping, having an obvious control over the Localisation of the ore field No. 322, and are the dominant ore-controlling factor of the ore field NO.322. Resulting from the sinistral displacement of the NE-trending fault, there is a pull-apart basin in the Feng Zhou area. The formation and evolution of the NE-trending fault zone and the Feng Zhou basin control the formation of uranium deposits of ore field No. 322
Risk evaluation of uranium mining: A geochemical inverse modelling approach

Science.gov (United States)

Rillard, J.; Zuddas, P.; Scislewski, A.

2011-12-01

It is well known that uranium extraction operations can increase risks linked to radiation exposure. The toxicity of uranium and associated heavy metals is the main environmental concern regarding exploitation and processing of U-ore. In areas where U mining is planned, a careful assessment of toxic and radioactive element concentrations is recommended before the start of mining activities. A background evaluation of harmful elements is important in order to prevent and/or quantify future water contamination resulting from possible migration of toxic metals coming from ore and waste water interaction. Controlled leaching experiments were carried out to investigate processes of ore and waste (leached ore) degradation, using samples from the uranium exploitation site located in Caetité-Bahia, Brazil. In experiments in which the reaction of waste with water was tested, we found that the water had low pH and high levels of sulphates and aluminium. On the other hand, in experiments in which ore was tested, the water had a chemical composition comparable to natural water found in the region of Caetité. On the basis of our experiments, we suggest that waste resulting from sulphuric acid treatment can induce acidification and salinization of surface and ground water. For this reason proper storage of waste is imperative. As a tool to evaluate the risks, a geochemical inverse modelling approach was developed to estimate the water-mineral interaction involving the presence of toxic elements. We used a method earlier described by Scislewski and Zuddas 2010 (Geochim. Cosmochim. Acta 74, 6996-7007) in which the reactive surface area of mineral dissolution can be estimated. We found that the reactive surface area of rock parent minerals is not constant during time but varies according to several orders of magnitude in only two months of interaction. We propose that parent mineral heterogeneity and particularly, neogenic phase formation may explain the observed variation of the
Uranium hexafluoride purification

International Nuclear Information System (INIS)

Araujo, Eneas F. de

1986-01-01

Uranium hexafluoride might contain a large amount of impurities after manufacturing or handling. Three usual methods of purification of uranium hexafluoride were presented: selective sorption, sublimation, and distillation. Since uranium hexafluoride usually is contaminated with hydrogen fluoride, a theoretical study of the phase equilibrium properties was performed for the binary system UF 6 -HF. A large deviation from the ideal solution behaviour was observed. A purification unity based on a constant reflux batch distillation process was developed. A procedure was established in order to design the re boiler, condenser and packed columns for the UF 6 -HF mixture separation. A bench scale facility for fractional distillation of uranium hexafluoride was described. Basic operations for that facility and results extracted from several batches were discussed. (author)
A review of the environmental behavior of uranium derived from depleted uranium alloy penetrators

Energy Technology Data Exchange (ETDEWEB)

Erikson, R.L.; Hostetler, C.J.; Divine, J.R.; Price, K.R.

1990-01-01

The use of depleted uranium (DU) penetrators as armor-piercing projectiles in the field results in the release of uranium into the environment. Elevated levels of uranium in the environment are of concern because of radioactivity and chemical toxicity. In addition to the direct contamination of the soil with uranium, the penetrators will also chemically react with rainwater and surface water. Uranium may be oxidized and leached into surface water or groundwater and may subsequently be transported. In this report, we review some of the factors affecting the oxidation of the DU metal and the factors influencing the leaching and mobility of uranium through surface water and groundwater pathways, and the uptake of uranium by plants growing in contaminated soils. 29 refs., 10 figs., 3 tabs.
Study on integrated evaluation of sandstone-hosted uranium metallogenic potential in southern Yili basin

International Nuclear Information System (INIS)

Han Shaoyang; Ke Dan; Xu Jianguo; Zheng Enjiu; Li Shengxiang

2008-01-01

Plenty of geological data have been accumulated during mineral resource survey in China; under the guidance of new metallogenic theories, it is an important task of how to use these data most effectively for the new cycle uranium survey. In this paper, the flow of establishing the integrated mineral deposits prospecting model for sandstone-hosted uranium deposits is put forward. Based on studying geologic, hydrogeologic and regional geophysical field characteristics of representative uranium deposits No. 512 in southern Yili basin, its multi-source information descriptive model has been established, from which 512-type integrated prospecting models of sandstone-hosted uranium orefield and deposits are summarized. According to the established integrated prospecting models, the metallogenic information extraction of sandstone-hosted uranium deposits has completed in the study area. Finally, the integrated quantitative evaluation of sandstone-hosted uranium metallogenic potential is performed by using the evidence weighing method to integrate middle scale multi-source metallogenic information in the southern Yili basin, and good prediction effect is obtained. (authors)
Situation analysis in the field of control and management of uranium tailings in Kyrgyzstan

International Nuclear Information System (INIS)

Tolongutov, B.

2012-01-01

This article is devoted to situation analysis in the field of control and management of uranium tailings in Kyrgyzstan. The basic sites for control in Kyrgyzstan are: HMP P C 'KGRK', specialized on uranium oxide production (status operating) RSH; storage for low-activity waste (tailings and rock piles) former uranium industry; site for disposal of ionizing radiation sources and radioactive waste in Bishkek city; ionizing radiation sources; medical institutions (X-rays diagnostics, radiotherapy); natural anomaly (local sites with high radiation background). It was concluded that: in existing legislative basis there is a necessity to amend requirements for accepting regulatory provisions on radiation safety; it is necessary to continue working on combination of country's policy and strategy with Fundamental Safety Principles and with International instruments, agreements, codes which were ratified by State; legislative basis documental hierarchy on radiation safety issues is not a complete system, significant number of gaps are defined (more than 60 % from the whole system), basically, related to low stages of hierarchical structure (rules, norms, regulations, instructions and etc.); it is necessary to review existing leading documents with the purpose of inaccuracy correcting, especially in the field of safety statements (especially, it relates to new basic regulation on radiation safety, where contradicting to each other criteria are available, mixing to one 'pile' the concepts of 'dose threshold' and 'dose limits', incomplete and scrappy Radioactive Wastes classification, absence of instructions on ionizing radiation sources categorization and etc.
Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation; Langzeitverhalten von elementarem Eisen und Hydroxylapatit zur Uranrueckhaltung in permeablen reaktiven Waenden bei der Grundwassersanierung

Energy Technology Data Exchange (ETDEWEB)

Biermann, V.

2007-11-21

Elemental iron (Fe{sup 0}) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using {sup 237}U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}OH, 99 % < 0.42 mm) supplied by Che-mische Fabrik Budenheim CFB, Germany. Both materials exhibited uranium retention of more than 99.9% and sorption capacities of up to 28.3 mg U/g HAP and more than 38.4 mg U/g Fe{sup 0} (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe{sup 0} columns with effluent uranium con-centrations being below the detection limit of 10 {mu}g/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe{sup 0} columns with 200 PV of uranium free AGW. However, columns with high Fe{sup 0} content ({>=} 50%) suffered from severe loss of permeability when AGW with {>=} 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 {mu}g/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing
Uranium disequilibrium investigation of the Las Cruces East Mesa Geothermal Field

International Nuclear Information System (INIS)

Gross, J.; Cochran, J.; Icerman, L.

1985-03-01

The concentration of dissolved uranium in 33 thermal and nonthermal groundwaters was found to vary from less than 1 part per billion to 285 parts per billion. The uranium-234 to uranium-238 alpha activity ratio of the 33 samples varied from 0.8 to 4.6. Young waters in the recharge area of the Jornada del Muerto Basin are characterized by low uranium concentrations and high activity ratios. Uranium concentrations of groundwaters increase down hydraulic gradient. Concentrations and activity ratios of dissolved uranium in Mesilla Valley groundwater exhibit wide variation and appear to be related to both short-term and long-term removal of groundwater from storage. Geothermal waters exhibit low uranium concentrations and activity ratios. The water produced from New Mexico State University geothermal wells appears to be a mixture of deep upwelling geothermal water and shallow Jornada del Muerto Basin water. The low activity ratio of water from an 800 meter geothermal well may be the result of thermally-induced isotopic equilibration. Isotopic equilibration suggests that higher temperatures may be found deeper within the reservoir
Characterization of single crystal uranium-oxide thin films grown via reactive-gas magnetron sputtering on yttria-stabilized zirconia and sapphire

Energy Technology Data Exchange (ETDEWEB)

Strehle, Melissa M.; Heuser, Brent J., E-mail: bheuser@illinois.edu; Elbakhshwan, Mohamed S.; Han Xiaochun; Gennardo, David J.; Pappas, Harrison K.; Ju, Hyunsu

2012-06-30

The microstructure and valence states of three single crystal thin film systems, UO{sub 2} on (11{sup Macron }02) r-plane sapphire, UO{sub 2} on (001) yttria-stabilized zirconia, and U{sub 3}O{sub 8} on (11{sup Macron }02) r-plane sapphire, grown via reactive-gas magnetron sputtering are analyzed primarily with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). XRD analysis indicates the growth of single crystal domains with varying degrees of mosaicity. XPS and UPS analyses yield U-4f, U-5f, O-1s, and O-2p electron binding energies consistent with reported bulk values. A change from p-type to n-type semiconductor behavior induced by preferential sputtering of oxygen during depth profile analysis was observed with both XPS and UPS. Trivalent cation impurities (Nd and Al) in UO{sub 2} lower the Fermi level, shifting the XPS spectral weight. This observation is consistent with hole-doping of a Mott-Hubbard insulator. The uranium oxide-(11{sup Macron }02) sapphire system is unstable with respect to Al interdiffusion across the film-substrate interface at elevated temperature. - Highlights: Black-Right-Pointing-Pointer Single crystal uranium-oxides grown on sapphire and yttria-stabilized zirconia. Black-Right-Pointing-Pointer Anion and cation valence states studied by photoelectron emission spectroscopy. Black-Right-Pointing-Pointer Trivalent Nd and Al impurities lower the Fermi level. Black-Right-Pointing-Pointer Uranium-oxide films on sapphire found to be unstable with respect to Al interdiffusion.
Speciation of uranium with respect to hydrogeological aspects

International Nuclear Information System (INIS)

Meinrath, G.

1997-01-01

Until 1991, eastern Germany has been third largest uranium producer in the world. After the cease of uranium production, larger areas remained contaminated by uranium mining debris, mill-tailings and mining areas. Since 1991 these areas are in the process of remediation by intervention. In Germany, legal stipulations require the prognosis of the likely mid-term impact of an intervention. The benefit of a planned remediation procedure must be evident against the Zero option (doing nothing) and alternative actions. Thermodynamic data of geochemically relevant reactions for uranium under conditions of natural aqueous solution serve as important input data into geochemical reactive transport codes. Especially hydrolysis and carbonato complexation of hexavalent uranium influence the geochemical behaviour of uranium. The first part of the report report summarizes the fundamental chemical facts on mineralogy, electronic structure, UV-Vis and emission spectroscopy of hexavalent uranium. A second part reports in depth the experimental and numerical procedures to study the hydrolytic and carbonate complexation behaviour of hexavalent uranium. The evaluation of single component spectra of the relevant uranium species is discussed. Spectral curves are quantitatively deconcoluted into single components. In all cases the associated uncertainties are given. Thermodynamic data on hydrolysis and carbonato species derived from these experiments are compared to existing data in the literature. (orig.)
Geochemical exploration for uranium

International Nuclear Information System (INIS)

1988-01-01

This Technical Report is designed mainly to introduce the methods and techniques of uranium geochemical exploration to exploration geologists who may not have had experience with geochemical exploration methods in their uranium programmes. The methods presented have been widely used in the uranium exploration industry for more than two decades. The intention has not been to produce an exhaustive, detailed manual, although detailed instructions are given for a field and laboratory data recording scheme and a satisfactory analytical method for the geochemical determination of uranium. Rather, the intention has been to introduce the concepts and methods of uranium exploration geochemistry in sufficient detail to guide the user in their effective use. Readers are advised to consult general references on geochemical exploration to increase their understanding of geochemical techniques for uranium
Fission track method for uranium ore exploration

International Nuclear Information System (INIS)

Guo Shilun; Deng Xinlu; Sun Shengfen; Meng Wu; Zhang Pengfa; Hao Xiuhong

1986-01-01

The uranium concentrations in natural water collected in the fields of uranium ore exploration with fission track method have been determined. It shows that the results of fission track method are consistent with that of fluoro-colorimetry and laser fluorometry for the same samples of water with uranium concentration in the region of 10 -4 to 10 -8 g/l. For water samples with lower uranium concentration (≤10 -8 g/l), the fission track method can still give accurate or referential results, but the other two methods failed. The reproducibility of fission track method was checked and discussed by using samples collected in the same fields of uranium ore exploration. The effects of the concentration of the impurities in natural water on determination of uranium concentration were analysed and discussed as well
Reactive solute transport in physically and chemically heterogeneous porous media with multimodal reactive mineral facies: the Lagrangian approach.

Science.gov (United States)

Soltanian, Mohamad Reza; Ritzi, Robert W; Dai, Zhenxue; Huang, Chao Cheng

2015-03-01

Physical and chemical heterogeneities have a large impact on reactive transport in porous media. Examples of heterogeneous attributes affecting reactive mass transport are the hydraulic conductivity (K), and the equilibrium sorption distribution coefficient (Kd). This paper uses the Deng et al. (2013) conceptual model for multimodal reactive mineral facies and a Lagrangian-based stochastic theory in order to analyze the reactive solute dispersion in three-dimensional anisotropic heterogeneous porous media with hierarchical organization of reactive minerals. An example based on real field data is used to illustrate the time evolution trends of reactive solute dispersion. The results show that the correlation between the hydraulic conductivity and the equilibrium sorption distribution coefficient does have a significant effect on reactive solute dispersion. The anisotropy ratio does not have a significant effect on reactive solute dispersion. Furthermore, through a sensitivity analysis we investigate the impact of changing the mean, variance, and integral scale of K and Kd on reactive solute dispersion. Copyright © 2014 Elsevier Ltd. All rights reserved.
Molybdenum from uranium solutions

International Nuclear Information System (INIS)

Gardner, H.E.

1981-01-01

A method of removing molybdenum from a uranium bearing solution is claimed. It comprises adding sufficient reactive lead compound to supply at least 90 percent of the stoichiometric quantity of lead ion required to fully react with the molybdenum present to form insoluble lead molybdate and continuing the reaction with agitation until the desired percentage of the molybdenum present has reacted with the lead ion

Reactive Force Field for Liquid Hydrazoic Acid with Applications to Detonation Chemistry

Science.gov (United States)

Furman, David; Dubnikova, Faina; van Duin, Adri; Zeiri, Yehuda; Kosloff, Ronnie

The development of a reactive force field (ReaxFF formalism) for Hydrazoic acid (HN3), a highly sensitive liquid energetic material, is reported. The force field accurately reproduces results of density functional theory (DFT) calculations. The quality and performance of the force field are examined by detailed comparison with DFT calculations related to uni, bi and trimolecular thermal decomposition routes. Reactive molecular dynamics (RMD) simulations are performed to reveal the initial chemical events governing the detonation chemistry of liquid HN3. The outcome of these simulations compares very well with recent results of tight-binding DFT molecular dynamics and thermodynamic calculations. Based on our RMD simulations, predictions were made for the activation energies and volumes in a broad range of temperatures and initial material compressions. Work Supported by The Center of Excellence for Explosives Detection, Mitigation and Response, Department of Homeland Security.
Uranium fluoride chemistry. Part 1. The gas phase reaction of uranium hexafluoride with alcohols

International Nuclear Information System (INIS)

Schnautz, N.G.; Venter, P.J.

1992-01-01

The reaction between uranium hexafluoride (UF 6 ) and simple alcohols in the gas phase was observed to proceed by way of three possible reaction pathways involving dehydration, deoxygenative fluorination, and ether formation. These reactions can best be explained by assuming that alcohols first react with UF 6 to afford the alkoxy uranium pentafluoride intermediate ROUF 5 , which reacts further to give the dehydration, deoxygenative fluorination, and ether products. In each of the above three reaction pathways, UF 6 is transformed to UOF 4 , which being as reactive toward alcohols as UF 6 , reacts further with the alcohol in question to finally afford the unreactive uranyl fluoride (UO 2 F 2 ). 6 refs., 2 tabs
Uranium project DINAMIGE-BRGM

International Nuclear Information System (INIS)

Pirelli, H.

1982-01-01

This Uranium review was carried out in the frame work of Uranium prospecting programme between (DINAMIGE-BRGM) from February to June 1982. It was included radimetric cutting in sedimentaries and crystallines ground (gondwanic basin of the NE).The task was developed (1.300.000 scale) in Cunapiru, Carrillada, Vichadero, Minas de Corrales, Paso Mazangano and Yaguari zones.
Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour.

Science.gov (United States)

Martin, T L; Coe, C; Bagot, P A J; Morrall, P; Smith, G D W; Scott, T; Moody, M P

2016-07-12

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.
Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

Science.gov (United States)

Martin, T. L.; Coe, C.; Bagot, P. A. J.; Morrall, P.; Smith, G. D. W.; Scott, T.; Moody, M. P.

2016-07-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (~5 nm) interfacial layer of uranium hydride was observed at the oxide-metal interface. Exposure to deuterated water vapour produced an equivalent deuteride signal at the metal-oxide interface, confirming the hydride as originating via the water vapour oxidation mechanism. Hydroxide ions were detected uniformly throughout the oxide, yet showed reduced prominence at the metal interface. These results support a proposed mechanism for the oxidation of uranium in water vapour environments where the transport of hydroxyl species and the formation of hydride are key to understanding the observed behaviour.
Metallization of uranium oxide powders by lithium reduction

International Nuclear Information System (INIS)

Kim, I. S.; Seo, J. S.; Oh, S. C.; Hong, S. S.; Lee, W. K.

2002-01-01

Laboratory scale experiments on the reduction of uranium oxide powders into metal by lithium were performed in order to determine the equipment setup and optimum operation conditions. The method of filtration using the porous magnesia filter was introduced to recover uranium metal powders produced. Based on the laboratory scale experimental results, mock-up scale (20 kg U/batch) metallizer was designed and made. The applicability to the metallization process was estimated with respect to the thermal stability of the porous magnesia filter in the high temperature molten salt, the filtration of the fine uranium metal powders, and the operability of the equipment
Study on the relationship between uranium and phosphor in deposit No.60

International Nuclear Information System (INIS)

Zhang Wanliang

1997-01-01

The deposit No.60 is a large uranium-phosphor one located at the eastern margin of the volcanic basin No.65, and controlled by the stratigraphic horizon of the middle-lower part of the third member of the Ehuling Formation composed of volcaniclastic and terrigeneous classic rocks. Uranium and phosphor were preliminarily concentrated together during the formation of ore-hosting layer, and then reactivated, transported and reprecipitated together under the action of tectonothermal process, leading to the concentration of uranium in cellophane in the adsorption state. Uranium and phosphor are closely associated with the correlation coefficient of up to 0.8-0.9
Situation analysis in the field of control and management of uranium tailings in Kyrgyzstan

International Nuclear Information System (INIS)

Tolongutov, B.

2012-01-01

This article is devoted to situation analysis in the field of control and management of uranium tailings in Kyrgyzstan. The basic sites for control in Kyrgyzstan are: HMP P C 'KGRK', specialized on uranium oxide production (status operating) RSH; storage for low-activity waste (tailings and rock piles) former uranium industry; site for disposal of ionizing radiation sources and radioactive waste in Bishkek city; ionizing radiation sources; medical institutions (X-rays diagnostics, radiotherapy); natural anomaly (local sites with high radiation background). It was concluded that: in existing legislative basis there is a necessity to amend requirements for accepting regulatory provisions on radiation safety; it is necessary to continue working on combination of country's policy and strategy with Fundamental Safety Principles and with International instruments, agreements, codes which were ratified by State; legislative basis documental hierarchy on radiation safety issues is not a complete system, significant number of gaps are defined (more than 60 % from the whole system), basically, related to low stages of hierarchical structure (rules, norms, regulations, instructions and etc.); it is necessary to review existing leading documents with the purpose of inaccuracy correcting, especially in the field of safety statements (especially, it relates to new basic regulation on radiation safety, where contradicting to each other criteria are available, mixing to one 'pile' the concepts of 'dose threshold' and 'dose limits', incomplete and scrappy Radioactive Wastes classification, absence of instructions on ionizing radiation sources categorization and etc.
Laser-induced breakdown spectroscopy measurements of uranium and thorium powders and uranium ore

Energy Technology Data Exchange (ETDEWEB)

Judge, Elizabeth J. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Barefield, James E., E-mail: jbarefield@lanl.gov [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Berg, John M. [Manufacturing Engineering and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Clegg, Samuel M.; Havrilla, George J.; Montoya, Velma M.; Le, Loan A.; Lopez, Leon N. [Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-05-01

Laser-induced breakdown spectroscopy (LIBS) was used to analyze depleted uranium and thorium oxide powders and uranium ore as a potential rapid in situ analysis technique in nuclear production facilities, environmental sampling, and in-field forensic applications. Material such as pressed pellets and metals, has been extensively studied using LIBS due to the high density of the material and more stable laser-induced plasma formation. Powders, on the other hand, are difficult to analyze using LIBS since ejection and removal of the powder occur in the laser interaction region. The capability of analyzing powders is important in allowing for rapid analysis of suspicious materials, environmental samples, or trace contamination on surfaces since it most closely represents field samples (soil, small particles, debris etc.). The rapid, in situ analysis of samples, including nuclear materials, also reduces costs in sample collection, transportation, sample preparation, and analysis time. Here we demonstrate the detection of actinides in oxide powders and within a uranium ore sample as both pressed pellets and powders on carbon adhesive discs for spectral comparison. The acquired LIBS spectra for both forms of the samples differ in overall intensity but yield a similar distribution of atomic emission spectral lines. - Highlights: • LIBS analysis of mixed actinide samples: depleted uranium oxide and thorium oxide • LIBS analysis of actinide samples in powder form on carbon adhesive discs • Detection of uranium in a complex matrix (uranium ore) as a precursor to analyzing uranium in environmental samples.
Uranium migration in a podzol. The role of colloids in the non-saturated zone and the phreatic water: application to the Landes de Gascogne area; Migration de l'uranium dans un podzol. Le role des colloides dans la zone non saturee et la nappe: application aux Landes de Gascogne

Energy Technology Data Exchange (ETDEWEB)

Crancon, P

2001-01-01

The non-saturated zone of a soil represents the interface between the atmosphere and the phreatic water. The confinement efficiency of the non-saturated zone above the phreatic water depends on the fastness of water transfers and on the type of pollutant transport mechanisms. Uranium (VI) can combine with humid acids to form very stable complexes. The aggregates of the absorbing complex are highly sensible to the variations of the ionic force of the environment. This sensitiveness can be at the origin of a strong remobilization of the colloid humic compounds of the soil, and of their migration towards the underground water. In this situation, the uranium complexed by humic compounds can rapidly migrate in the soil. The comparative reactive transport of the total uranium and its isotopes has been studied in a site, the Landes de Gascogne podzol (SW France), where metallic uranium has been sprinkled on the surface of the soil. The field study has been completed with an experimental column transport study using uranium isotopes tracer techniques. The field study shows that most of uranium is trapped in the very first cm of the soil. However, anomalous high uranium concentrations are observed in underground waters, more than 2 km away from the contaminated areas. This demonstrates that a fast and long distance transport process exists for uranium in the unsaturated zone. In the sandy soil of the study area, natural argillo-humic colloids migrate with the velocity of water but can be delayed when the ionic force of the underground waters increases. It is shown that uranium is strongly linked with the thin grain size fraction (< 8 {mu}m) of the sand, and more particularly with the argillo-humic composite colloids. In the stable geochemical conditions of the experimental columns, more than 70% of uranium is trapped in the first 2 cm of the sand, even after the circulation of 100 volumes of water inside the column. This shows the strong trapping capacity of the Landes sand
Upscaling of U (VI) desorption and transport from decimeter‐scale heterogeneity to plume‐scale modeling

Science.gov (United States)

Curtis, Gary P.; Kohler, Matthias; Kannappan, Ramakrishnan; Briggs, Martin A.; Day-Lewis, Frederick D.

2015-01-01

Scientifically defensible predictions of field scale U(VI) transport in groundwater requires an understanding of key processes at multiple scales. These scales range from smaller than the sediment grain scale (less than 10 μm) to as large as the field scale which can extend over several kilometers. The key processes that need to be considered include both geochemical reactions in solution and at sediment surfaces as well as physical transport processes including advection, dispersion, and pore-scale diffusion. The research summarized in this report includes both experimental and modeling results in batch, column and tracer tests. The objectives of this research were to: (1) quantify the rates of U(VI) desorption from sediments acquired from a uranium contaminated aquifer in batch experiments;(2) quantify rates of U(VI) desorption in column experiments with variable chemical conditions, and(3) quantify nonreactive tracer and U(VI) transport in field tests.
Atomic-scale Studies of Uranium Oxidation and Corrosion by Water Vapour

OpenAIRE

T. L. Martin; C. Coe; P. A. J. Bagot; P. Morrall; G. D. W Smith; T. Scott; M. P. Moody

2016-01-01

Understanding the corrosion of uranium is important for its safe, long-term storage. Uranium metal corrodes rapidly in air, but the exact mechanism remains subject to debate. Atom Probe Tomography was used to investigate the surface microstructure of metallic depleted uranium specimens following polishing and exposure to moist air. A complex, corrugated metal-oxide interface was observed, with approximately 60 at.% oxygen content within the oxide. Interestingly, a very thin (∼5 nm) interfacia...
Determination of irradiated uranium in far-field contaminated areas of Belarus

International Nuclear Information System (INIS)

Mironov, V.; Pribylev, S.; Hotchkis, M.; Child, D.

2006-01-01

The possibility of using U 236 as an indicator for irradiated uranium is shown. The sensitivity of AMS is high enough for measurements of 236 U/ 238 U ratios down to 10 -9 on micrograms of uranium and therefore for the detection of Chernobyl originated uranium in the remote regions of radioactive fallout. (authors)
The geochemical characteristics of alkali metasomatic ore and its ore-forming significance at Zoujiashan deposit, Xiangshan uranium field

International Nuclear Information System (INIS)

Wang Yun; Hu Baoqun; Sun Zhanxue; Li Xueli; Guo Guolin; Rao Minghui

2012-01-01

Alkaline metasomatites are widely distributed in Zoujiashan uranium deposit and have close relation with uranium mineralization. Based on the study of field geological survey, petrographic methods, element chemical analysis and EPMA, etc, the alteration in alkaline metasomatic ore was found in the order of sodium metasomatism, potassium metasomatism and silica metasomatism. The alkaline hydrothermal fluid of mineralization is rich in Na at first and then rich in K, and quite similar in other chemical composition, but the K rich one is more favourite for the metallization. Compared with the normal porphyroclastic lava, the alkaline metasomatic ores in lower in SiO 2 , but higher in K 2 O or Na 2 O, Al 2 O 3 , Fe 2 O 3 , MgO, P 2 O 5 , CaO and U, Th, Zr, Hf, Sm, Ti, REE. Compared with potassium metasomatic ore, the sodium metasomatic ore is with high ΣLREE/ΣHREE ratio and lower Rb and REE. Because alkaline metasomatism is beneficial to release uranium from accessory mineral and bring out uranium from rocks, therefore it is very important to the migration and precipitation of uranium. (authors)
Unique advantages of organometallic supporting ligands for uranium complexes

Energy Technology Data Exchange (ETDEWEB)

Diaconescu, Paula L. [Univ. of California, Los Angeles, CA (United States); Garcia, Evan [Univ. of California, Los Angeles, CA (United States)

2014-05-31

The objective of our research project was to study the reactivity of uranium complexes supported by ferrocene-based ligands. In addition, this research provides training of graduate students as the next generation of actinide scientists.
Unique advantages of organometallic supporting ligands for uranium complexes

International Nuclear Information System (INIS)

Diaconescu, Paula L.; Garcia, Evan

2014-01-01

The objective of our research project was to study the reactivity of uranium complexes supported by ferrocene-based ligands. In addition, this research provides training of graduate students as the next generation of actinide scientists.
A regional multi-scale 3-D geological model of the Eastern Sub-Athabasca Basement, Canada: Implications for vectoring towards unconformity-type uranium deposits

International Nuclear Information System (INIS)

Annesley, I.; Reilkoff, B.; Takacs, E.; Hajnal, Z.; Pandit, B.

2014-01-01

The Proterozoic Athabasca Basin of northern Saskatchewan is one of the most important mining districts in Canada; hosting the world’s highest grade uranium deposits and prospects. In the basin, many of the near-surface deposits have been discovered; hence new ore deposits at greater depths need to be discovered. To help make new discoveries, 3D geological modelling is being carried out. Here, we present our multidisciplinary approach, whereby a 3D geological model of the eastern sub- Athabasca basement of northern Saskatchewan (i.e. the eastern and western Wollaston domains, the Wollaston-Mudjatik Transition Zone (WMTZ), and the Mudjatik Domain) was developed in the common earth environment. The project was directed towards building a robust 3D model(s) of the upper 3-5 km of the Earth’s crust in three different scales: deposit-, district-, and regional-scale, using the GOCAD software platform (Paradigm). Our eastern sub-Athabasca basement model is constrained by both geological studies and geophysical techniques, such as topographic, outcrop, drill hole, petrophysical, and petrological data, along with geophysical potential field, electrical, and highresolution regional seismic data, in order to better understand the regional- to district-scale tectonics and controls on the uranium mineral system(s) operating pre-, syn-, and post-Athabasca deposition. The resulting data were interpreted and visualized as 3D-surfaces and bodies in GOCAD. This model reveals a framework of key lithological contacts, major high-strain zones, and the setting of unconformity-type uranium deposits. As a result, this new knowledge is being used to identify key exploration vectoring criteria for unconformity-type, magmatic, and metamorphic/ metasomatic uranium deposits and to delineate new exploration targets in the basin. Hence, this regional-scale 3D GOCAD model can be utilized as a guide for exploration activities within the region (e.g. picking new drill targets). As well, this 3D
Industrial scale salt-free reactive dyeing of cationized cotton fabric with different reactive dye chemistry.

Science.gov (United States)

Nallathambi, Arivithamani; Venkateshwarapuram Rengaswami, Giri Dev

2017-10-15

Dyeing of knitted cotton goods in the industry has been mostly with reactive dyes. Handling of salt laden coloured effluent arising out of dyeing process is one of the prime concerns of the industry. Cationization of cotton is one of the effective alternative to overcome the above problem. But for cationization to be successful at industrial scale it has to be carried out by exhaust process and should be adoptable for the various dye chemistries currently practiced in the industry. Hence, in the present work, industrial level exhaust method of cationization process was carried out with concentration of 40g/L and 80g/L. The fabrics were dyed with dyes of three different dye chemistry and assessed for its dyeing performance without the addition of salt. Dye shades ranging from medium to extra dark shades were produced without the addition of salt. This study will provide industries the recipe that can be adopted for cationized cotton fabric for the widely used reactive dyes at industrial level. Copyright © 2017 Elsevier Ltd. All rights reserved.
Parallel computation of multigroup reactivity coefficient using iterative method

Science.gov (United States)

Susmikanti, Mike; Dewayatna, Winter

2013-09-01

One of the research activities to support the commercial radioisotope production program is a safety research target irradiation FPM (Fission Product Molybdenum). FPM targets form a tube made of stainless steel in which the nuclear degrees of superimposed high-enriched uranium. FPM irradiation tube is intended to obtain fission. The fission material widely used in the form of kits in the world of nuclear medicine. Irradiation FPM tube reactor core would interfere with performance. One of the disorders comes from changes in flux or reactivity. It is necessary to study a method for calculating safety terrace ongoing configuration changes during the life of the reactor, making the code faster became an absolute necessity. Neutron safety margin for the research reactor can be reused without modification to the calculation of the reactivity of the reactor, so that is an advantage of using perturbation method. The criticality and flux in multigroup diffusion model was calculate at various irradiation positions in some uranium content. This model has a complex computation. Several parallel algorithms with iterative method have been developed for the sparse and big matrix solution. The Black-Red Gauss Seidel Iteration and the power iteration parallel method can be used to solve multigroup diffusion equation system and calculated the criticality and reactivity coeficient. This research was developed code for reactivity calculation which used one of safety analysis with parallel processing. It can be done more quickly and efficiently by utilizing the parallel processing in the multicore computer. This code was applied for the safety limits calculation of irradiated targets FPM with increment Uranium.
Uranium Processing Research in Australia [Processing of Low-Grade Uranium Ores

Energy Technology Data Exchange (ETDEWEB)

Stewart, J R [Australian Atomic Energy Commission, Coogee, N.S.W. (Australia)

1967-06-15

Uranium processing research in Australia has included studies of flotation, magnetic separation, gravity separation, heavy medium separation, atmospheric leaching, multi-stage leaching, alkali leaching, solar heating of leach pulps, jigged-bed resin-in-pulp and solvent-in-pulp extraction. Brief details of the results obtained are given. In general, it can be said that gravity, magnetic and flotation methods are of limited usefulness in the treatment of Australian uranium ores. Alkali leaching seldom gives satisfactory recoveries and multi-stage leaching is expensive. Jigged-bed resin-in-pulp and packed tower solvent-in-pulp extraction systems both show promise, but plant-scale development work is required. Bacterial leaching may be useful in the case of certain low-grade ores. The main difficulties to be overcome, either singly or in combination, in the case of Australian uranium ores not currently considered economically exploitable, are the extremely finely divided state of the uranium mineral, the refractory nature of the uranium mineral and adverse effects due to the gangue minerals present. With respect to known low-grade ores, it would be possible in only a few cases to achieve satisfactory recovery of uranium at reasonable cost by standard treatment methods. (author)

Study for electrochemical behavior of uranium oxide in a molten LiCl-Li2O system

International Nuclear Information System (INIS)

Park, Sung Bin; Park, Byung Heung; Seo, Chung Seok; Jung, Ki Jung; Park, Seong Won

2005-01-01

Interest in the electrolytic reduction of uranium oxide is increasing in the treatment of spent fuel oxides. With complicated and expensive procedures many reactive metals can be prepared in a pure metal form, the electrochemical reduction of a metal oxide has been recently proposed in metallurgy. The electrochemical reduction process is simple and rapid when compared to the conventional processes. The process can reduce the production costs and be applicable to a wide range of metal oxides. Chen et al. proposed the direct electrochemical reduction of titanium dioxide to titanium in a molten calcium chloride. Argonne National Laboratory (ANL) has reported the experimental results of an electrochemical reduction of the uranium oxide fuel in a bench-scale apparatus with a cyclic voltammetry, and has designed high-capacity reduction (HCR) cells and conducted three kg-scale UO 2 reduction runs. Gourishankar et al. classified the mechanisms of the electrolytic reduction of the metal oxides in a LiCl-Li 2 O molten salt system into two types; the simultaneous reduction and the direct electrochemical reduction. The uranium oxide in LiCl-Li 2 O molten salt was converted to uranium metal according to two mechanisms. Korea Atomic Energy Research Institute (KAERI) has developed the Advanced Spent Fuel Conditioning Process (ACP) to be an innovative technology in handling the PWR spent fuel. As part of ACP, the electrolytic reduction process (ER process) is the electrochemical reduction process of uranium oxide to uranium metal in molten salt. The ER process has advantages in a technical stability, an economic potential and a good proliferation resistance. KAERI has reported on the good experimental results of an electrochemical reduction of the uranium oxide in a 20 kg HM/batch lab-scale. In this work, cyclic voltammograms for a LiCl-3 wt% Li 2 O system and an U 3 O 8 -LiCl-3 wt% Li 2 O system with the integrated cathode assembly have been obtained. From the cyclic
Uranium migration in a podzol. The role of colloids in the non-saturated zone and the phreatic water: application to the Landes de Gascogne area; Migration de l'uranium dans un podzol. Le role des colloides dans la zone non saturee et la nappe: application aux Landes de Gascogne

Energy Technology Data Exchange (ETDEWEB)

Crancon, P

2001-01-01

The non-saturated zone of a soil represents the interface between the atmosphere and the phreatic water. The confinement efficiency of the non-saturated zone above the phreatic water depends on the fastness of water transfers and on the type of pollutant transport mechanisms. Uranium (VI) can combine with humid acids to form very stable complexes. The aggregates of the absorbing complex are highly sensible to the variations of the ionic force of the environment. This sensitiveness can be at the origin of a strong remobilization of the colloid humic compounds of the soil, and of their migration towards the underground water. In this situation, the uranium complexed by humic compounds can rapidly migrate in the soil. The comparative reactive transport of the total uranium and its isotopes has been studied in a site, the Landes de Gascogne podzol (SW France), where metallic uranium has been sprinkled on the surface of the soil. The field study has been completed with an experimental column transport study using uranium isotopes tracer techniques. The field study shows that most of uranium is trapped in the very first cm of the soil. However, anomalous high uranium concentrations are observed in underground waters, more than 2 km away from the contaminated areas. This demonstrates that a fast and long distance transport process exists for uranium in the unsaturated zone. In the sandy soil of the study area, natural argillo-humic colloids migrate with the velocity of water but can be delayed when the ionic force of the underground waters increases. It is shown that uranium is strongly linked with the thin grain size fraction (< 8 {mu}m) of the sand, and more particularly with the argillo-humic composite colloids. In the stable geochemical conditions of the experimental columns, more than 70% of uranium is trapped in the first 2 cm of the sand, even after the circulation of 100 volumes of water inside the column. This shows the strong trapping capacity of the Landes sand
Unconventional uranium resources in China

International Nuclear Information System (INIS)

Qi Fucheng; Zhang Zilong; Li Zhixing; Wang Zhiming; He Zhongbo; Wang Wenquan

2011-01-01

Unconventional uranium resources in China mainly include black-rock series, peat, salt lake and evaporitic rocks. Among them, uraniferous black-rock series, uraniferous phosphorite and uranium-polymetallic phosphorite connected with black-rock series are important types for the sustainable support of uranium resources in China. Down-faulting and epocontinental rift in continental margin are the most important and beneficial ore-forming environment for unconventional uranium resources of black-rock series in China and produced a series of geochemistry combinations, such as, U-Cd, U-V-Mo, U-V-Re, U-V-Ni-Mo and U-V-Ni-Mo-Re-Tl. Unconventional uranium resources of black-rock series in China is related to uranium-rich marine black-rock series which are made up of hydrothermal sedimentary siliceous rocks, siliceous phospheorite and carbonaceous-siliceous-pelitic rock and settled in the continental margin down-faulting and epicontinental rift accompanied by submarine backwash and marine volcano eruption. Hydrothermal sedimentation or exhalation sedimentary is the mechanism to form unconventional uranium resources in black-rock series or large scale uranium-polymetallic mineralization in China. (authors)
Hydrothermal uranium vein deposits in Marysvale volcanic field, Utah

International Nuclear Information System (INIS)

Rasmussen, J.D.; Cunningham, C.G.; Steven, T.A.; Rye, R.O.; Romberger, S.B.

1984-01-01

Hydrothermal uranium veins are exposed over a 300 m (980 ft) vertical range in mines of the Central Mining area, near Marysvale, Utah. They cut 23 Ma quartz monzonite, 21 Ma granite, and 19 Ma rhyolite ash-flow tuff. The veins formed 18-19 Ma, in an area 1 km (0.6 mi) across, above the center of a composite magma chamber at least 12 x 6 km across that fed a sequence of 21-14 Ma hypabyssal granitic stocks, and rhyolitic lava flows, ash-flow tuffs, and volcanic domes. Intrusive pressure uplifted and fractured the roof; molybdenite-bearing, uranium-rich glassy dikes were intruded; and a breccia pipe and uranium-bearing veins were formed. The veins appear to have been deposited near the surface above a concealed rhyolite stock, where they filled high-angle fault zones and flat-lying to concave-downward pull-apart fractures. Low pH and fO 2 hydrothermal fluids at temperatures near 200 0 C (392 0 F) permeated the fractured rocks; these fluids were rich in fluorine and potassium, and contained uranium as uranous-fluoride complexes. Fluid-wall rock interaction increased fluid pH, causing precipitation of uranium minerals. At the deepest exposed levels, wall rocks were altered to kaolinite and sericite, and uraninite, coffinite, jordisite, fluorite, molybdenite, quartz, and pyrite (with delta 34 S near zero per mil) were deposited. The fluids were progressively oxidized higher in the system; iron in the wall rocks was oxidized to hematite, and sooty uraninite and umohoite were deposited
Uranium mines of Tajikistan

International Nuclear Information System (INIS)

Razykov, Z.A; Gusakov, E.G.; Marushenko, A.A.; Botov, A.Yu.; Yunusov, M.M.

2002-12-01

The book describes location laws, the main properties of geological structure and industrial perspectives for known uranium mines of the Republic of Tajikistan. Used methods of industrial processing of uranium mines are described. The results of investigations of technological properties of main types of uranium ores and methods of industrial processing of some of them are shown. Main properties of uranium are shortly described as well as problems, connected with it, which arise during exploitation, mining and processing of uranium ores. The main methods of solution of these problems are shown. The book has interest for specialists of mining, geological, chemical, and technological fields as well as for students of appropriate universities. This book will be interested for usual reader, too, if they are interested in mineral resources of their country [ru
Geophysical methods in uranium mining

International Nuclear Information System (INIS)

Koehler, K.

1989-01-01

In uranium prospecting, exploration, milling, and mining there is an urgent need to have information on the concentration of uranium at all steps of handling uranium containing materials. To gain this information in an effective way modern geophysical methods have to be applied. Publications of the IAEA and NEA in this field are reviewed in order to characterize the state of the art of these methods. 55 refs
All heavy metals closed-cycle analysis on water-cooled reactors of uranium and thorium fuel cycle systems

International Nuclear Information System (INIS)

Permana, Sidik; Sekimoto, Hiroshi; Waris, Abdul; Takaki, Naoyuki

2009-01-01

Uranium and Thorium fuels as the basis fuel of nuclear energy utilization has been used for several reactor types which produce trans-uranium or trans-thorium as 'by product' nuclear reaction with higher mass number and the remaining uranium and thorium fuels. The utilization of recycled spent fuel as world wide concerns are spent fuel of uranium and plutonium and in some cases using recycled minor actinide (MA). Those fuel schemes are used for improving an optimum nuclear fuel utilization as well to reduce the radioactive waste from spent fuels. A closed-cycle analysis of all heavy metals on water-cooled cases for both uranium and thorium fuel cycles has been investigated to evaluate the criticality condition, breeding performances, uranium or thorium utilization capability and void reactivity condition. Water-cooled reactor is used for the basic design study including light water and heavy water-cooled as an established technology as well as commercialized nuclear technologies. A developed coupling code of equilibrium fuel cycle burnup code and cell calculation of SRAC code are used for optimization analysis with JENDL 3.3 as nuclear data library. An equilibrium burnup calculation is adopted for estimating an equilibrium state condition of nuclide composition and cell calculation is performed for calculating microscopic neutron cross-sections and fluxes in relation to the effect of different fuel compositions, different fuel pin types and moderation ratios. The sensitivity analysis such as criticality, breeding performance, and void reactivity are strongly depends on moderation ratio and each fuel case has its trend as a function of moderation ratio. Heavy water coolant shows better breeding performance compared with light water coolant, however, it obtains less negative or more positive void reactivity. Equilibrium nuclide compositions are also evaluated to show the production of main nuclides and also to analyze the isotopic composition pattern especially
Uranium extraction from phosphoric acid

International Nuclear Information System (INIS)

Lounis, A.

1983-05-01

A study has been carried out for the extraction of uranium from phosphoric acid produced in Algeria. First of all, the Algerian phosphoric acid produced in Algeria by SONATRACH has been characterised. This study helped us to synthesize a phosphoric acid that enabled us to pass from laboratory tests to pilot scale tests. We have then examined extraction and stripping parameters: diluent, DZEPHA/TOPO ratio and oxidising agent. The laboratory experiments enabled us to set the optimum condition for the choice of diluent, extractant concentration, ratio of the synergic mixture, oxidant concentration, redox potential. The equilibrium isotherms lead to the determination of the number of theoretical stages for the uranium extraction and stripping of uranium, then the extraction from phosphoric acid has been verified on a pilot scale (using a mixer-settler)
A melt refining method for uranium-contaminated aluminum

International Nuclear Information System (INIS)

Uda, T.; Iba, H.; Hanawa, K.

1986-01-01

Melt refining of uranium-contaminated aluminum which has been difficult to decontaminate because of the high reactivity of aluminum, was experimentally studied. Samples of contaminated aluminum and its alloys were melted after adding various halide fluxes at various melting temperatures and various melting times. Uranium concentration in the resulting ingots was determined. Effective flux compositions were mixtures of chlorides and fluorides, such as LiF, KCl, and BaCl 2 , at a fluoride/chloride mole ratio of 1 to 1.5. The removal of uranium from aluminum (the ''decontamination effect'') increased with decreasing melting temperature, but the time allowed for reaction had little influence. Pure aluminum was difficult to decontaminate from uranium; however, uranium could be removed from alloys containing magnesium. This was because the activity of the aluminum was decreased by formation of the intermetallic compound Al-Mg. With a flux of LiF-KCl-BaCl 2 and a temperature of 800 0 C, uranium added to give an initial concentration of 500 ppm was removed from a commercial alloy of aluminum, A5056, which contains 5% magnesium, to a final concentration of 0.6 ppm, which is near that in the initial aluminum alloy
Analysis of geological condition of uranium mineralization in the Xiangshan northern uranium orefield in central region of Jiangxi Province

International Nuclear Information System (INIS)

Zhou Yulong; Liu Yunlang; Gao Yan

2013-01-01

According to the basic conditions of 'source, guide, transportation, storage' for uranium mineralization in strata and different types of geological structure, departure from the condition, the coupling effect of stratigraphy, lithology and structure are studied in the process of uranium mineralization in northern Xiangshan volcanic basin. Studies show that the northern ore field are of good metallogenic geological conditions and the uranium rich ancient land mass and uranium rich magma generated by the melting of deep metamorphic rocks. The main geologic events are volcanic eruptions, accompanied by repeated subvolcanic magma intrusion and strong faults and nappe tectonics which result in volcanic collapse and volcanic ring structures. These ore-forming geological condition control the structural frame for the formation of main uranium deposit type-subvolcanic rocks in northern Xiangshan ore field. (authors)
Strategy and perspective for uranium exploration in Egypt

International Nuclear Information System (INIS)

Hassan, M.A.; Salman, A.B.; Assaf, H.S.; Mahdy, M.M.

1995-01-01

Uranium exploration started in Egypt about three decades ago. This was performed by applying integrated airborne and ground radiometric prospecting. The latter was conducted upon selected areas having rather favorable geological criteria. These activities resulted in the discovery of great numbers of radiometric anomalies, with several uranium occurrences in various geologic environments in granitic and sedimentary rocks. Some of these uranium occurrences show good potential for developing into workable uranium deposits. Small-scale exploratory tunnelling and drilling works have been carried out at some of these occurrences. Leaching studies and pilot experiments were carried out on technological samples to evaluate ore's suitability for uranium extraction. However, no assured reserves of uranium have been reached yet. The demands for uranium to satisfy the near future Egyptian nuclear power generation necessitates some development in the national strategy for uranium exploration. This will be achieved through intense programmes for ground geophysics and drilling from surface and underground mining works, in addition to radon emanometry and logging of oil and gas wells. Moreover, non conventional procedures for uranium extraction such as heap-leaching may be followed to exploit small-scale uranium deposits. In this developed strategy, the present uranium occurrences are modellized and categorized following the IAEA classification. The characteristics of the present uranium occurrences will be utilized in prospecting new areas. Subsidiary resources in phosphorites, black sands and rare metal deposits could supply additional quantities of uranium, in addition to thorium and rare earth elements. (author). 34 refs, 4 figs, 1 tab
Metallogenic hydrothermal solution system of post volcanic magma in Xiangshan ore field

International Nuclear Information System (INIS)

Xu Hengli; Shao Fei; Zou Maoqin

2009-01-01

This paper has systematically described uranium metallogenic characteristics of Xiangshan ore field.Sources of metallogenic materials are discussed in different temporal and spatial scale. Combining with background analysis of metallogenic tectonic-magmatic-geodynamics, formation and evolution of metallogenic hydrothermal solution system in Xiangshan volcanic basin are studied. Metallogenic hydrothermal solution system in Xiangshan ore field is considered as the objective product of systematic evolution of hydrothermal solution in post volcanic magma constrained by regional tectonic environment. In time scale, metallogenic hydrothermal solution system developed for about 50 Ma, but its active spaces varied in different time domains. So temporal and spatial distribution of uranium mineralization is constrained. Further exploration for the ore field is also suggested in this paper. (authors)
Uranium Newsletter. No. 1

International Nuclear Information System (INIS)

1987-03-01

The new Uranium Newsletter is presented as an IAEA annual newsletter. The organization of the IAEA and its involvement with uranium since its founding in 1957 is described. The ''Red Book'' (Uranium Resources, Production and Demand) is mentioned. The Technical Assistance Programme of the IAEA in this field is also briefly mentioned. The contents also include information on the following meetings: The Technical Committee Meeting on Uranium Deposits in Magmatic and Metamorphic Rocks, Advisory Group Meeting on the Use of Airborne Radiometric Data, and the Technical Committee Meeting on Metallogenesis. Recent publications are listed. Current research contracts in uranium exploration are mentioned. IAEA publications on uranium (in press) are listed also. Country reports from the following countries are included: Australia, Brazil, Canada, China (People's Republic of), Denmark, Finland, Germany (Federal Republic of), Malaysia, Philippines, Portugal, South Africa (Republic of), Spain, Syrian Arab Republic, United Kingdom, United States of America, Zambia, and Greece. There is also a report from the Commission of European Communities
Feasibility studies on electrochemical separation and recovery of uranium by using domestic low grade uranium resources

International Nuclear Information System (INIS)

Oh, Won Zin; Jung, Chong Hun; Lee, Kune Woo; Won, Hui Jun; Choi, Wang Kyu; Kim, Gye Nam; Lee, Yu Ri; Lee, Joong Moung

2005-12-01

The up-to-date electrochemical uranium separation technology has been developed for uranium sludge waste treatment funded by a long term national nuclear technology development program. The objective of the studies is to examine applicability of the uranium separation technology to making use of the low grade uranium resources in the country. State of the arts of uranium separation and recovery from the low grade national uranium resources. - The amount of the high grade uranium resources(0.1 % U 3 O 8 contents) in the world is 1,750,000MTU and that of the low grade uranium resources(0.04 % U 3 O 8 contents) in the country is 340,000MTU. - The world uranium price will be increase to more than 30$/l0b in 10 years, so that the low grade uranium in the country become worth while to recover. - The conventional uranium recovery technologies are based on both acidic - The ACF electrochemical uranium separation technology is the state of the art technology in the world and the adsorption capability of 690 mgU/g is several ten times higher than that of a conventional zeolite and the uranium stripping efficiency by desorption is more than 99%. So, this technology is expected to replace the existing solvent extraction technology. Feasibility of the ACF electrochemical uranium separation technology as an uranium recovery method. Lab scale demonstration of uranium separation and recovery technologies have been carried out by using an ACF electrochemical method
Biological reduction of uranium-From the laboratory to the field

International Nuclear Information System (INIS)

Dullies, Frank; Lutze, Werner; Gong, Weiliang; Nuttall, H. Eric

2010-01-01

The chemical and biological processes underlying in situ bioremediation of uranium-contaminated groundwater have been studied in the laboratory and in the field. This article focuses on the long-term stability of uraninite (UO 2 ) in the underground. A large tailings pond, 'Daenkritz 1' in Germany, was selected for this investigation. A single-pass flow-through experiment was run in a 100-liter column: bioremediation for 1 year followed by infiltration of tap water (2.5 years) saturated with oxygen, sufficient to oxidize the precipitated uraninite in two months. Instead, only 1 wt.% uraninite was released over 2.4 years at concentrations typically less than 20 μg/L. Uraninite was protected against oxidation by the mineral mackinawite (FeS 0.9 ), a considerable amount of which had formed, together with uraninite. A confined field test was conducted adjacent to the tailings pond, which after bio-stimulation showed similarly encouraging results as in the laboratory. Taking Daenkritz 1 as an example we show that in situ bioremediation can be a viable option for long-term site remediation, if the process is designed based on sufficient laboratory and field data. The boundary conditions for the site in Germany are discussed.
Depleted uranium plasma reduction system study

International Nuclear Information System (INIS)

Rekemeyer, P.; Feizollahi, F.; Quapp, W.J.; Brown, B.W.

1994-12-01

A system life-cycle cost study was conducted of a preliminary design concept for a plasma reduction process for converting depleted uranium to uranium metal and anhydrous HF. The plasma-based process is expected to offer significant economic and environmental advantages over present technology. Depleted Uranium is currently stored in the form of solid UF 6 , of which approximately 575,000 metric tons is stored at three locations in the U.S. The proposed system is preconceptual in nature, but includes all necessary processing equipment and facilities to perform the process. The study has identified total processing cost of approximately $3.00/kg of UF 6 processed. Based on the results of this study, the development of a laboratory-scale system (1 kg/h throughput of UF6) is warranted. Further scaling of the process to pilot scale will be determined after laboratory testing is complete
International training course on uranium exploration

International Nuclear Information System (INIS)

Barretto, P.M.C.

1978-01-01

Full text: As part of its Technical Assistance Programme for developing countries, the IAEA has conducted a series of training courses in prospecting for nuclear raw materials for example, in 1974 a regional course on uranium and thorium prospecting was held in India, and an interregional training course on uranium geochemical prospecting methods was held in Austria in 1975. In September 1977, another interregional training course on uranium geochemical prospecting methods was held at Skofja Loka, Slovenia, Yugoslavia. Twenty-four delegates from Afghanistan, Algeria, Argentina, Bolivia, Chile, Colombia, Czechoslovakia, India, Indonesia, Malaysia, Philippines, Portugal, Sri Lanka, Turkey, Venezuela and Yugoslavia participated in the four-week training course. The Federal Republic of Yugoslavia acted as host for the course. The Skofja Loka area was selected because it contains sedimentary rocks with known uranium mineralization, and presented ideal conditions (soil, drainage and topography) for Uranium geochemical surveys. In addition, the participants could benefit from a technical visit to a very interesting type of uranium mineralization near the town of Gorenje Vaz. Several well-known geologists, such as Dr. A. Grimbert (France) and Prof. Ian Nichol (Canada) were present as guest lecturers. In the first week the lectures dealt with the basic concepts of geochemical exploration for uranium, as well as preparing the participants for the field work. In addition to specific topics on geochemistry and uranium behaviour in the natural environment, the lectures also covered other topics of interest, such as world uranium resources and demand, types of uranium deposits and technical advances in exploration equipment. A visit to the Zirovski Vrh uranium mine was made, where the participants saw different techniques for mining ore bodies with complex structure and rapid change in grade concentration. At the end of the mine tour, there was a lengthy discussion of
Exploration for uranium and other nuclear materials

International Nuclear Information System (INIS)

Hernandez, E.C.

1975-05-01

Prospecting and exploration for uranium and other nuclear minerals have one advantage over prospecting for other metals because of their inherent radioactivity. Radioactivity in the earth is not confined solely to these elements but also to radiations coming from cosmic rays and from fallouts from large-scale atomic and nuclear explosions. The primary uranium mineral is uranimite, however, concentrations of other uranium minerals may also lead to an economic deposit. Thorium is about three times more abundant than uranium in the earth's crust. Uranium is practically found in many types of geologic environment it being ubiquitous and very mobile. Uranium deposits are classified in a descriptive manner, owing to lack of basic information as to its origin. These classifications are peneconcordant, for deposits as conglomerates and sandstones, discordant for vein pegmatite and contact metamorphic deposits, concordant for deposits in shales and phosphate rocks, and miscellaneous for deposits in beach and placer sands containing mostly thorium minerals. The different exploration techniques and their associated instrumentations are discussed from a regional scale survey to a detailed survey. To date, only the Larap copper-molybdenum-magnetite deposit at the Paracale district, Camarines Norte in the Philippines, has been found to contain uranium as discrete uraninite grains in the ore mineral assemblage of the deposit
Investigation of ore processing to recover uranium concentrate from sandstone of Pa Lua area on scale of 2 tons of ore per batch

International Nuclear Information System (INIS)

Cao Hung Thai; Dinh Manh Thang; Tran Van Son; Le Quang Thai; Bui Dang Hanh; Hoang Bich Ngoc; Nguyen Hong Ha; Phung Vu Phong; Nguyen Khac Tuan

2003-01-01

Based on the laboratory results, a system for testing on scale of 2 tons uranium ore per batch including following parts was established: equipment for crushing and grinding, equipment for acid leaching, equipment for impurity precipitation and filtration and drying. the results of testing by 2 tons ore per batch scale shown that uranium recovery in the leach circuit were achieved of at least 90% under following conditions: The supplying rate of leach agent 50-701/m 2 .h, sandstone is mixed or incubated with acid before the percolation. About 23 kg filter cake per m 3 solution were disposed as tailings. Flocculants N101, A101 (TOAGOSEL, Japan) were used for improvement of filtration and washing capacity of impurity precipitation. Uranium peroxide was precipitated with addition of hydrogen peroxide. The underflow solids were filtered and calcined. The product contained min. 76% U 3 O 8 . The water recycle was successfully tested. That results in minimization of water addition to only 0.3m 3 /ton of ore. Experimental results on 2 tons scale showed that the proposed processing flow sheet using direct precipitation can meet all environmental and technical objectives. (CHT)
The role of uranium-arene bonding in H2O reduction catalysis

Science.gov (United States)

Halter, Dominik P.; Heinemann, Frank W.; Maron, Laurent; Meyer, Karsten

2018-03-01

The reactivity of uranium compounds towards small molecules typically occurs through stoichiometric rather than catalytic processes. Examples of uranium catalysts reacting with water are particularly scarce, because stable uranyl groups form that preclude the recovery of the uranium compound. Recently, however, an arene-anchored, electron-rich uranium complex has been shown to facilitate the electrocatalytic formation of H2 from H2O. Here, we present the precise role of uranium-arene δ bonding in intermediates of the catalytic cycle, as well as details of the atypical two-electron oxidative addition of H2O to the trivalent uranium catalyst. Both aspects were explored by synthesizing mid- and high-valent uranium-oxo intermediates and by performing comparative studies with a structurally related complex that cannot engage in δ bonding. The redox activity of the arene anchor and a covalent δ-bonding interaction with the uranium ion during H2 formation were supported by density functional theory analysis. Detailed insight into this catalytic system may inspire the design of ligands for new uranium catalysts.

Recovery of uranium from uranium mine waters and copper ore leaching solutions

Energy Technology Data Exchange (ETDEWEB)

George, D R; Ross, J R [Salt Lake City Metallurgy Research Center, Salt Lake City, UT (United States)

1967-06-15

Waters pumped from uranium mines in New Mexico are processed by ion exchange to recover uranium. Production is approximately 200 lb U{sub 3}O{sub 8}/d from waters containing 5 to 15 ppm U{sub 3}O{sub 8}. Recoveries range from 80 to 90%. Processing plants are described. Uranium has been found in the solutions resulting from the leaching of copper-bearing waste rock at most of the major copper mines in western United States. These solutions, which are processed on a very large scale for recovery of copper, contain 2 to 12 ppm U{sub 3}O{sub 8}. Currently, uranium is not being recovered, but a potential production of up to 6000 lb U{sub 3}O{sub 8}/d is indicated. Ion exchange and solvent extraction research studies are described. (author)
Operating conditions of T.B.P. line uranium purification plant, for uranium dioxide production

International Nuclear Information System (INIS)

Vardich, R.N.; La Gamma, A.M.; Anasco, R.; Soler, S.M.G. de; Isnardi, E.; Gea, V.; Chiaraviglio, R.; Matyjasczyk, E.; Aramayo, R.

1992-01-01

In this contribution are presented the operative conditions and the results obtained step of the Uranium dioxide production plant of Argentina. The refining step involve the Uranium concentrate dissolution, the silica ageing, the filtration and liquid - liquid extraction with n-tributyl phosphate solution in kerosene. The established operative conditions allow to obtain Uranyl nitrate solutions of nuclear purity in industrial scale. (author)
Uranium Mill Tailings Remedial Action Project Safety Advancement Field Effort (SAFE) Program

Energy Technology Data Exchange (ETDEWEB)

1994-02-01

In 1992, the Uranium Mill Tailings Remedial Action (UMTRA) Project experienced several health and safety related incidents at active remediation project sites. As a result, the U.S. Department of Energy (DOE) directed the Technical Assistance Contractor (TAC) to establish a program increasing the DOE`s overall presence at operational remediation sites to identify and minimize risks in operations to the fullest extent possible (Attachments A and B). In response, the TAC, in cooperation with the DOE and the Remedial Action Contractor (RAC), developed the Safety Advancement Field Effort (SAFE) Program.
Uranium Mill Tailings Remedial Action Project Safety Advancement Field Effort (SAFE) Program

International Nuclear Information System (INIS)

1994-02-01

In 1992, the Uranium Mill Tailings Remedial Action (UMTRA) Project experienced several health and safety related incidents at active remediation project sites. As a result, the U.S. Department of Energy (DOE) directed the Technical Assistance Contractor (TAC) to establish a program increasing the DOE's overall presence at operational remediation sites to identify and minimize risks in operations to the fullest extent possible (Attachments A and B). In response, the TAC, in cooperation with the DOE and the Remedial Action Contractor (RAC), developed the Safety Advancement Field Effort (SAFE) Program
Induced polarization and electromagnetic field surveys of sedimentary uranium deposits

International Nuclear Information System (INIS)

Campbell, D.L.; Smith, B.D.

1985-01-01

Induced polarization (IP) and electromagnetic (EM) geophysical surveys were made over three areas of sedimentary uranium deposits in the western United States. The EM techniques were sometimes useful for investigating general structural settings, but not for finding uranium deposits per se. IP techniques were useful to help pinpoint zones of disseminated pyrite associated with the uranium deposits. In one case no clear differences were seen between the IP signatures of oxidized and reduced ground. Spectral (multi-frequency) IP showed no particular advantages over conventional IP for exploration applications. A sediment mineralization factor is introduced comparable to the ''metal factor'' used to detect porphyry copper mineralization. (author)
Existing and new techniques in uranium exploration

International Nuclear Information System (INIS)

Bowie, S.H.U.; Cameron, J.

1976-01-01

The demands on uranium exploration over the next 25 years will be very great indeed and will call for every possible means of improvement in exploration capability. The first essential is to increase geological knowledge of the mode of occurrence of uranium ore deposits. The second is to improve existing exploration techniques and instrumentation while, at the same time, promoting research and development on new methods to discover uranium ore bodies on the earth's surface and at depth. The present symposium is an effort to increase co-operation and the exchange of information in the critical field of uranium exploration techniques and instrumentation. As an introduction to the symposium a brief review is presented, firstly of what can be considered as existing techniques and, secondly, of techniques which have not yet been used on an appreciable scale. Some fourteen techniques used over the last 30 years are identified and their appropriate application, advantages and limitations are briefly summarized and the possibilities of their further development considered. The aim of future research on new techniques, in addition to finding new ways and means of identifying surface deposits, should be mainly directed to devising methods and instrumentation capable of detecting buried ore bodies that do not give a gamma signal at the surface. To achieve this aim, two contributory factors are essential: adequate financial support for research and development and increased specialized training in uranium exploration and instrumentation design. The papers in this symposium describe developments in the existing techniques, proposals for future research and development and case histories of exploration programmes
Conversion of the Worcester Polytechnic Institute nuclear reactor to low enriched uranium

International Nuclear Information System (INIS)

Newton, T.H. Jr.

1991-01-01

The Training Reactor was converted to Low-Enriched Uranium (LEU) aluminide fuel in 1988 and 1989. Tests on the Highly-Enriched Uranium (HEU) core and LEU cores were performed and comparisons made. The testing consisted of critical loading, thermal neutron flux distribution, excess reactivity, regulating blade reactivity worth, and temperature coefficient of reactivity measurement. Comparisons between the LEU and HEU showed that the critical loading configurations were somewhat different with the HEU core consisting of 24 elements and the LEU core consisting of 21 1/3 elements with excess reactivities of 0.24% ΔK/K for the HEU and 0.16% for the LEU. Thermal neutron flux distributions showed similar trends in both the LEU and HEU cores. The regulating blade worth showed a larger LEU value due to thermal peaking in the blade region and temperature coefficients showed a more negative LEU value due to Doppler broadening. Low induced activity of the HEU fuel permitted shipment to the Westinghouse Savannah River Facility using DOT-6M type B containers on 8 August, 1989. (orig.)
Uranium production from phosphates

International Nuclear Information System (INIS)

Ketzinel, Z.; Folkman, Y.

1979-05-01

According to estimates of the world's uranium consumption, exploitation of most rich sources is expected by the 1980's. Forecasts show that the rate of uranium consumption will increase towards the end of the century. It is therefore desirable to exploit poor sources not yet in use. In the near future, the most reasonable source for developing uranium is phosphate rock. Uranium reserves in phosphates are estimated at a few million tons. Production of uranium from phosphates is as a by-product of phosphate rock processing and phosphoric acid production; it will then be possible to save the costs incurred in crushing and dissolving the rock when calculating uranium production costs. Estimates show that the U.S. wastes about 3,000 tons of uranium per annum in phosphoric acid based fertilisers. Studies have also been carried out in France, Yugoslavia and India. In Israel, during the 1950's, a small plant was operated in Haifa by 'Chemical and Phosphates'. Uranium processes have also been developed by linking with the extraction processes at Arad. Currently there is almost no activity on this subject because there are no large phosphoric acid plants which would enable production to take place on a reasonable scale. Discussions are taking place about the installation of a plant for phosphoric acid production utilising the 'wet process', producing 200 to 250,000 tons P 2 O 5 per annum. It is necessary to combine these facilities with uranium production plant. (author)
Dependence of calculated void reactivity on film-boiling representation

International Nuclear Information System (INIS)

Whitlock, J.; Garland, W.

1992-01-01

Partial voiding of a fuel channel can lead to complicated neutronic analysis, because of highly nonuniform spatial distributions. An investigation of the distribution dependence of void reactivity in a Canada deuterium uranium (CANDU) lattice, specifically in the regime of film boiling, was done. Although the core is not expected to be critical at the time of sheath dryout, this study augments current knowledge of void reactivity in this type of lattice
New Technique for Speciation of Uranium in Sediments Following Acetate-Stimulated Bioremediation

Energy Technology Data Exchange (ETDEWEB)

2011-06-22

Acetate-stimulated bioremediation is a promising new technique for sequestering toxic uranium contamination from groundwater. The speciation of uranium in sediments after such bioremediation attempts remains unknown as a result of low uranium concentration, and is important to analyzing the stability of sequestered uranium. A new technique was developed for investigating the oxidation state and local molecular structure of uranium from field site sediments using X-Ray Absorption Spectroscopy (XAS), and was implemented at the site of a former uranium mill in Rifle, CO. Glass columns filled with bioactive Rifle sediments were deployed in wells in the contaminated Rifle aquifer and amended with a hexavalent uranium (U(VI)) stock solution to increase uranium concentration while maintaining field conditions. This sediment was harvested and XAS was utilized to analyze the oxidation state and local molecular structure of the uranium in sediment samples. Extended X-Ray Absorption Fine Structure (EXAFS) data was collected and compared to known uranium spectra to determine the local molecular structure of the uranium in the sediment. Fitting was used to determine that the field site sediments did not contain uraninite (UO{sub 2}), indicating that models based on bioreduction using pure bacterial cultures are not accurate for bioremediation in the field. Stability tests on the monomeric tetravalent uranium (U(IV)) produced by bioremediation are needed in order to assess the efficacy of acetate-stimulation bioremediation.
Uranium-mediated electrocatalytic dihydrogen production from water

Science.gov (United States)

Halter, Dominik P.; Heinemann, Frank W.; Bachmann, Julien; Meyer, Karsten

2016-02-01

Depleted uranium is a mildly radioactive waste product that is stockpiled worldwide. The chemical reactivity of uranium complexes is well documented, including the stoichiometric activation of small molecules of biological and industrial interest such as H2O, CO2, CO, or N2 (refs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11), but catalytic transformations with actinides remain underexplored in comparison to transition-metal catalysis. For reduction of water to H2, complexes of low-valent uranium show the highest potential, but are known to react violently and uncontrollably forming stable bridging oxo or uranyl species. As a result, only a few oxidations of uranium with water have been reported so far; all stoichiometric. Catalytic H2 production, however, requires the reductive recovery of the catalyst via a challenging cleavage of the uranium-bound oxygen-containing ligand. Here we report the electrocatalytic water reduction observed with a trisaryloxide U(III) complex [((Ad,MeArO)3mes)U] (refs 18 and 19)—the first homogeneous uranium catalyst for H2 production from H2O. The catalytic cycle involves rare terminal U(IV)-OH and U(V)=O complexes, which have been isolated, characterized, and proven to be integral parts of the catalytic mechanism. The recognition of uranium compounds as potentially useful catalysts suggests new applications for such light actinides. The development of uranium-based catalysts provides new perspectives on nuclear waste management strategies, by suggesting that mildly radioactive depleted uranium—an abundant waste product of the nuclear power industry—could be a valuable resource.
Uranium dioxide calcining apparatus and method

International Nuclear Information System (INIS)

Cole, E.A.; Peterson, R.S.

1978-01-01

This invention relates to an improved continuous calcining apparatus for consistently and controllably producing from calcinable reactive solid compounds of uranium, such as ammonium diuranate, uranium dioxide (UO 2 ) having an oxygen to uranium ratio of less than 2.2. The apparatus comprises means at the outlet end of a calciner kiln for receiving hot UO 2 , means for cooling the UO 2 to a temperature of below 100 0 C and conveying the cooled UO 2 to storage or to subsequent UO 2 processing apparatus where it finally comes into contact with air, the means for receiving, cooling and conveying being sealed to the outlet end of the calciner and being maintained full of UO 2 and so operable as to exclude atmospheric oxygen from coming into contact with any UO 2 which is at elevated temperatures where it would readily oxidize, without the use of extra hydrogen gas in said means
Uranium chemistry research unit

International Nuclear Information System (INIS)

Anon.

1978-01-01

The initial field of research of this Unit, established in 1973, was the basic co-ordination chemistry of uranium, thorium, copper, cobalt and nickel. Subsequently the interest of the Unit extended to extractive metallurgy relating to these metals. Under the term 'co-ordination chemistry' is understood the interaction of the central transition metal ion with surrounding atoms in its immediate vicinity (within bonding distance) and the influence they have on each other - for example, structural studies for determining the number and arrangement of co-ordinated atoms and spectrophotometric studies to establish how the f electron energy levels of uranium are influenced by the environment. New types of uranium compounds have been synthesized and studied, and the behaviour of uranium ions in non-aqueous systems has also received attention. This work can be applied to the development and study of extractants and new extractive processes for uranium
Uranium enrichment

International Nuclear Information System (INIS)

Rae, H.K.; Melvin, J.G.

1988-06-01

Canada is the world's largest producer and exporter of uranium, most of which is enriched elsewhere for use as fuel in LWRs. The feasibility of a Canadian uranium-enrichment enterprise is therefore a perennial question. Recent developments in uranium-enrichment technology, and their likely impacts on separative work supply and demand, suggest an opportunity window for Canadian entry into this international market. The Canadian opportunity results from three particular impacts of the new technologies: 1) the bulk of the world's uranium-enrichment capacity is in gaseous diffusion plants which, because of their large requirements for electricity (more than 2000 kW·h per SWU), are vulnerable to competition from the new processes; 2) the decline in enrichment costs increases the economic incentive for the use of slightly-enriched uranium (SEU) fuel in CANDU reactors, thus creating a potential Canadian market; and 3) the new processes allow economic operation on a much smaller scale, which drastically reduces the investment required for market entry and is comparable with the potential Canadian SEU requirement. The opportunity is not open-ended. By the end of the century the enrichment supply industry will have adapted to the new processes and long-term customer/supplier relationships will have been established. In order to seize the opportunity, Canada must become a credible supplier during this century
Recent advances in study of uranium surface chemistry in China

International Nuclear Information System (INIS)

Luo, Lizhu; Lai, Xinchun; Wang, Xiaolin

2014-01-01

Uranium is very important in nuclear energy industry; however, uranium and its alloys corrode seriously in various atmospheres because of their chemical reactivities. In China, continuous investigations focused on surface chemistry have been carried out for a thorough understanding of uranium in order to provide technical support for its engineering applications. Oxidation kinetics of uranium and its alloys in oxidizing atmospheres are in good agreement with those in the literature. In addition to the traditional techniques, non-traditional methods have been applied for oxidation kinetics of uranium, and it has been verified that spectroscopic ellipsometry and X-ray diffraction are effective and nondestructive tools for in situ kinetic studies. The inhibition efficiency of oxidizing gas impurities on uranium hydrogenation is found to follow the order CO 2 > CO > O 2 , and the broadening of XPS shoulders with temperature in depth profile of hydrogenated uranium surface is discussed, which is not mentioned in the literature. Significant progress on surface chemistry of alloyed uranium (U-Nb and U-Ti) in hydrogen atmosphere is reported, and it is revealed that the hydrating nucleation and subsequent growth of alloyed uranium are closely connected with the surface states, underlying metal matrix, and it is microstructure-dependent. In this review, the recent advances in uranium surface chemistry in China, published so far mostly in Chinese language, are briefly summarized. Suggestions for further study are made. (orig.)
Breakdown coefficients and scaling properties of rain fields

Directory of Open Access Journals (Sweden)

D. Harris

1998-01-01

Full Text Available The theory of scale similarity and breakdown coefficients is applied here to intermittent rainfall data consisting of time series and spatial rain fields. The probability distributions (pdf of the logarithm of the breakdown coefficients are the principal descriptor used. Rain fields are distinguished as being either multiscaling or multiaffine depending on whether the pdfs of breakdown coefficients are scale similar or scale dependent, respectively. Parameter estimation techniques are developed which are applicable to both multiscaling and multiaffine fields. The scale parameter (width, σ, of the pdfs of the log-breakdown coefficients is a measure of the intermittency of a field. For multiaffine fields, this scale parameter is found to increase with scale in a power-law fashion consistent with a bounded-cascade picture of rainfall modelling. The resulting power-law exponent, H, is indicative of the smoothness of the field. Some details of breakdown coefficient analysis are addressed and a theoretical link between this analysis and moment scaling analysis is also presented. Breakdown coefficient properties of cascades are also investigated in the context of parameter estimation for modelling purposes.
In situ mobility of uranium in the presence of nitrate following sulfate-reducing conditions.

Science.gov (United States)

Paradis, Charles J; Jagadamma, Sindhu; Watson, David B; McKay, Larry D; Hazen, Terry C; Park, Melora; Istok, Jonathan D

2016-04-01

Reoxidation and mobilization of previously reduced and immobilized uranium by dissolved-phase oxidants poses a significant challenge for remediating uranium-contaminated groundwater. Preferential oxidation of reduced sulfur-bearing species, as opposed to reduced uranium-bearing species, has been demonstrated to limit the mobility of uranium at the laboratory scale yet field-scale investigations are lacking. In this study, the mobility of uranium in the presence of nitrate oxidant was investigated in a shallow groundwater system after establishing conditions conducive to uranium reduction and the formation of reduced sulfur-bearing species. A series of three injections of groundwater (200 L) containing U(VI) (5 μM) and amended with ethanol (40 mM) and sulfate (20 mM) were conducted in ten test wells in order to stimulate microbial-mediated reduction of uranium and the formation of reduced sulfur-bearing species. Simultaneous push-pull tests were then conducted in triplicate well clusters to investigate the mobility of U(VI) under three conditions: 1) high nitrate (120 mM), 2) high nitrate (120 mM) with ethanol (30 mM), and 3) low nitrate (2 mM) with ethanol (30 mM). Dilution-adjusted breakthrough curves of ethanol, nitrate, nitrite, sulfate, and U(VI) suggested that nitrate reduction was predominantly coupled to the oxidation of reduced-sulfur bearing species, as opposed to the reoxidation of U(IV), under all three conditions for the duration of the 36-day tests. The amount of sulfate, but not U(VI), recovered during the push-pull tests was substantially more than injected, relative to bromide tracer, under all three conditions and further suggested that reduced sulfur-bearing species were preferentially oxidized under nitrate-reducing conditions. However, some reoxidation of U(IV) was observed under nitrate-reducing conditions and in the absence of detectable nitrate and/or nitrite. This suggested that reduced sulfur-bearing species may not be fully effective at
Reactivity of uranium(IV) bridged chalcogenido complexes UIV–E–UIV (E = S, Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

OpenAIRE

Franke, Sebastian M.; Heinemann, Frank W.; Meyer, Karsten

2014-01-01

We report the syntheses, electronic properties, and molecular structures of a series of polychalcogenido-bridged dinuclear uranium species. These complexes are supported by the sterically encumbering but highly flexible, single N-anchored tris(aryloxide) chelator (AdArO)3N3−. Reaction of an appropriate uranium precursor, either the U(III) starting material, [((AdArO)3N)U(DME)], or the dinuclear mono-chalcogenido-bridged uranium(IV/IV) compounds [{((AdArO)3N)U(DME)}2(μ-E)] (E = S, Se), with el...
Permeable reactive barriers for pollutant removal from groundwater

International Nuclear Information System (INIS)

Simon, F.G.; Meggyes, T.

2001-01-01

The removal of pollutants from the groundwater using permeable reactive barriers is a novel in-situ groundwater remediation technology. The most relevant decontamination processes used are chemical reduction, oxidation, precipitation and sorption, for which examples are given. Some common organic pollutants are halogenated hydrocarbons, aromatic and nitroaromatic compounds which can be treated in reactive barriers successfully. Lead, chromium and, in particular, uranium are dealt with in great detail among inorganic pollutants because of their occurrence in many European countries. Construction methods for cut-off walls and reactive barriers exhibit similar features. Apart from conventional methods, drilling, deep soil mixing, jet technology, arrays of wells, injected systems and biobarriers are applied to construct permeable reactive barriers. Permeable reactive barriers bear great potential for the future in remediation engineering. (orig.)
Uranium production in Sweden

International Nuclear Information System (INIS)

Bergh, S.

1994-01-01

The history of uranium production in Sweden is reviewed in the article. The World War II led to an exploitation of the Swedish alum shale on a large scale. In the last phase of the war it also became obvious that the shale might be used for energy production of quite another kind than oil. In 1947 AB Atom energy was founded, an enterprise with one of its purposes to extract uranium for peaceful use. A plant with a yearly capacity of 120 tons of uranium was erected at Ranstad and ready for production by 1965. From the start in Ranstad and for many years to come there was hardly any interest in an immediate large uranium production. It was decided to use the plant for studies on its more effective exploitation in case of an expansion in the future, bearing in mind the reactor programme. In the course of time economical reasons began to speak against the project. The shale seemed to have a future neither as oil nor as uranium resource. The complete termination of the work on uranium production from shale occurred in 1989

The Streltsovskoye uranium district

International Nuclear Information System (INIS)

Ischukova, L.P.

1997-01-01

This paper describes the geology of the Streltsovskoye uranium district located in south-eastern Zabaikalie region, Chita Province, Siberia, Russia. This district hosts Russia's only currently active uranium production centre. The uranium ore was discovered from 1963 to 1967 by drilling below fluorite veins which had minor associated uranium mineralization and radioactive anomalies. The uranium occurs as large scale vein stockwork deposits of hydrothermal origin within a volcano-tectonic caldera formed by continental volcanism of Late Mesozoic age. Rocks occurring in the caldera include basalt and trachydacite, overlain by rhyolite, and with associated interbedded sediments. The ore bodies occur in steeply dipping faults, with the greatest concentrations located where faults along the margins of the caldera intersect steeply dipping, cross cutting, northeasterly and northwesterly striking faults. The Streltsovskoye caldera extends over an area of 150 km 2 and is underlain by a large batholith. The 19 identified uranium deposits occurred in structural features that cut through the caldera sequence and extend into the basement rocks. The caldera has a maximum thickness of 1400 metres. Details of several deposits are given, including descriptions of mineralization and associated alteration. (author). 10 figs
Description of an engineering-scale facility for uranium fluorination studies

International Nuclear Information System (INIS)

Yagi, Eiji; Saito, Shinichi; Horiuchi, Masato

1976-03-01

In the research program of power reactor fuel reprocessing by fluoride volatility process, the engineering facility was constructed to establish the techniques of handling kilogram quantities of fluorine and uranium hexafluoride and to obtain engineering data on the uranium fluidized-bed oxidation and fluorination. This facility is designed for a capacity of 5 kg per batch. Descriptions on the facility and equipment are given, including design philosophy, safety and its analysis. (auth.)
Biomonitoring a human population inhabiting nearby a deactivated uranium mine

International Nuclear Information System (INIS)

Lourenço, J.; Pereira, R.; Pinto, F.; Caetano, T.; Silva, A.; Carvalheiro, T.

2013-01-01

Highlights: ► Human population environmentally exposed to uranium mining wastes. ► Significantly higher levels of manganese and uranium in peripheral blood samples. ► Significant DNA damages detected by the comet assay. ► Significant decrease of NK and T lymphocytes counts in exposed individuals. ► Concerns on the risks of human populations living nearby uranium mining areas. - Abstract: Environmental exposure to uranium and its daughter radionuclides, has been linked to several negative effects such as those related with important physiological processes, like hematopoiesis, and may also be associated with genotoxicity effects. Herein, genotoxic effects, immunotoxicity, trace elements and C reactive protein (CRP) analyses, were performed in peripheral blood samples collected from individuals of a population living near a deactivated uranium mine. C reactive protein analysis was performed to exclude candidates with active inflammatory processes from further evaluations. DNA damage and immunotoxicity (immunophenotyping and immune cell counts) were evaluated by comet assay and flow cytometry, respectively. Significant DNA damage was observed in the peripheral blood samples from volunteers living in the Cunha Baixa village. A significant decrease of NK and T lymphocytes counts were observed in the individuals from the Cunha Baixa village, when compared with individuals from the reference site. Uranium and manganese levels were significantly higher in the Cunha Baixa village inhabitants. On the other hand, zinc levels were significantly lower in those individuals when compared with the volunteers from the control village. Results suggest that inhabitants from Cunha Baixa have a higher risk of suffering from serious diseases such as cancer, since high DNA damages were observed in peripheral blood leukocytes and also decreased levels of NK and T cells, which play an essential role in the defense against tumor growth
Synthesis, reactivity, and electronic structure of molecular uranium nitrides

OpenAIRE

Cleaves, Peter A.

2016-01-01

The study of metal-ligand multiple bonding offers insight into the electronic structure and bond of metal systems. Until recently, for uranium, such systems were limited to uranyl, and terminal chalcogenide, imide and carbene complexes. In 2012, this was extended to nitrides with the first preparation of a uranium–nitride (U≡N) species isolable under standard conditions, namely [U(TrenTIPS)(N)][Na(12C4)2] (52), which is prepared by the two-electron reduction of sodium azide with a trivalent u...
The discovery of hornblende-garnet-zoisite hornfels in the metamorphic basement of Xiangshan uranium ore field

International Nuclear Information System (INIS)

Jiang Zhenpin; Dong Yongjie; Yu Jianfa; Hu Rongquan; Wu Shuilin

2007-01-01

Some vein rocks are found among mica schist in the metamorphic rock area of the Xiangshan uranium ore field. They are petrologically denominated as hornblende-garnet-zoisite hornfels. The primitive rocks are basic vein rocks. The hornfels are formed under thermal metamorphism with the temperature about 640 degree C and belong to low-pressure faces. This is closed to the form condition of EarlyMiddle Proterozoic metamorphic rocks in the area. The metamorphism forming the hornfels means that the Early-Middle Proterozoic metamorphic rocks was superimposed to another thermal metamorphism and produced the second phase metamorphic minerals such as staurolite, almandine and biotite. The lattice of the second phase metamorphic mineral developed continuously with the first phase minerals. The overlapping metamorphism made the first phase metamorphic mineral suffer recrystallization, auto purification and idiomorphism. The discovery of hornfelsed basic rock veins discloses that strong geologic process with the activity of fault, magma and metamorphism were still taken placed in Paleozoic era within the metamorphic basement of the Xiangshan uranium ore field. (authors)
Theoretical study of the structure and the reactivity of lanthanides and actinides complexes: Activation of small molecules

International Nuclear Information System (INIS)

Castro, Ludovic

2012-01-01

This PhD thesis presents a theoretical study of the structure and the reactivity of organometallic complexes of lanthanides and actinides at the DFT level. After a general introduction of the methods of theoretical chemistry used for the modelling of organometallic reactivity, a study of the participation of 5f electrons in uranium(IV) reactivity is presented. The results show that the large core ECP can be used safely in order to treat the actinide and so that 5f electrons can be treated implicitly. Then, the reactivity of uranium(III) complexes with CO 2 and other analogous molecules is studied via multiple examples from the literature. These studies show that the steric nature of the ligands is very important and controls the reactivity. This study is then extended to samarium(II) complex. Eventually, the reactivity of a hydride complex of cerium(III) with MeOSO 2 Me is investigated and theoretical results are compared with experimental observations. (author) [fr
Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

Science.gov (United States)

Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

2017-12-01

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.
Experimental Plan: Uranium Stabilization Through Polyphosphate Injection 300 Area Uranium Plume Treatability Demonstration Project

Energy Technology Data Exchange (ETDEWEB)

Wellman, Dawn M.; Fruchter, Jonathan S.; Vermeul, Vince R.

2006-09-20

This Test Plan describes a laboratory-testing program to be performed at Pacific Northwest National Laboratory (PNNL) in support of the 300-FF-5 Feasibility Study (FS). The objective of the proposed treatability test is to evaluate the efficacy of using polyphosphate injections to treat uranium contaminated groundwater in situ. This study will be used to: (1) Develop implementation cost estimates; (2) Identify implementation challenges; and (3) Investigate the technology's ability to meet remedial objectives These activities will be conducted in parallel with a limited field investigation, which is currently underway to more accurately define the vertical extent of uranium in the vadose zone, and in the capillary fringe zone laterally throughout the plume. The treatability test will establish the viability of the method and, along with characterization data from the limited field investigation, will provide the means for determining how best to implement the technology in the field. By conducting the treatability work in parallel with the ongoing Limited Field Investigation, the resulting Feasibility Study (FS) will provide proven, site-specific information for evaluating polyphosphate addition and selecting a suitable remediation strategy for the uranium plume within the FS time frame at an overall cost savings.
Theoretical study of the structure and reactivity of lanthanide and actinide based organometallic complexes

International Nuclear Information System (INIS)

Barros, N.

2007-06-01

In this PhD thesis, lanthanide and actinide based organometallic complexes are studied using quantum chemistry methods. In a first part, the catalytic properties of organo-lanthanide compounds are evaluated by studying two types of reactions: the catalytic hydro-functionalization of olefins and the polymerisation of polar monomers. The reaction mechanisms are theoretically determined and validated, and the influence of possible secondary non productive reactions is envisaged. A second part focuses on uranium-based complexes. Firstly, the electronic structure of uranium metallocenes is analysed. An analogy with the uranyl compounds is proposed. In a second chapter, two isoelectronic complexes of uranium IV are studied. After validating the use of DFT methods for describing the electronic structure and the reactivity of these compounds, it is shown that their reactivity difference can be related to a different nature of chemical bonding in these complexes. (author)
Porous reactive wall for prevention of acid mine drainage: Results of a full-scale field demonstration

International Nuclear Information System (INIS)

Benner, S.G.; Blowes, D.W.; Ptacek, C.J.

1997-01-01

A porous reactive wall was installed in August, 1995, to treat mine drainage flowing within an aquifer at the Nickel Rim mine site, near Sudbury, Ontario. The reactive mixture was designed to maximize removal of metals and acid generating capacity from the groundwater by enhancing sulfate reduction and metal sulfide precipitation. The installed structure, composed of a mixed organic substrate, is 15 meters long, 3.6 meters deep and the flow path length (wall width) is 4 meters. Results of sampling nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing the chemistry of water entering the wall to treated water exiting the wall nine months after installation: SO 4 concentrations decrease by >50% (from 2400-4800 mg/L to 60-3600 mg/L), Fe concentrations decrease by >95% (from 260-1300 mg/L to 1.0-40 mg/L), pH increased from 5.8 to 7.0 and alkalinity increased from 0-60 mg/L to 700-3200 mg/L as CaCO 3 . After passing through the reactive wall, the net acid generating potential of the aquifer water was converted from acid producing to acid consuming
Interest of uranium complexes for the mechanism study of the McMurry reaction; Interet des complexes de l`uranium pour l`etude du mecanisme de la reaction de McMurry

Energy Technology Data Exchange (ETDEWEB)

Maury, O

1997-07-04

The reducing coupling reactions of ketones in diols and olefins are generally carried out with titanium or samarium compounds. In this work uranium complexes have been used. They have allowed to study the chemical reaction mechanism. This thesis is divided into three parts: 1) the reduction mechanism of uranium tetrachloride by cyclic voltametry has been studied at first. It has been shown that this reduction is followed by a transfer reaction of chlorides between the reduced specie of the higher electronic density and UCl . 2) In the second part is described: the synthesis, the crystal structure, the reactivity of the chemical agents, the stereochemistry of diols and alkenes formation and the pinacolisation reaction catalysis. 3) In the last part, the limits of the McMurry reaction are given by the study of the aromatic ketones pinacolisation reaction by-products. The obtained results show that the complexes of the metals which present a high reducing and oxo-philic (Ti, Sm, U..) character react in a similar way with the carbonyl compounds. If the uranium compounds are less used than those of the titanium in the field of the organic synthesis applications, they are precious auxiliaries and excellent models for reactions mechanisms study and for the synthesis methods optimization. (O.M.). 284 refs.
Reactive transport modelling of groundwater chemistry in a chalk aquifer at the watershed scale.

Science.gov (United States)

Mangeret, A; De Windt, L; Crançon, P

2012-09-01

This study investigates thermodynamics and kinetics of water-rock interactions in a carbonate aquifer at the watershed scale. A reactive transport model is applied to the unconfined chalk aquifer of the Champagne Mounts (France), by considering both the chalk matrix and the interconnected fracture network. Major element concentrations and main chemical parameters calculated in groundwater and their evolution along flow lines are in fair agreement with field data. A relative homogeneity of the aquifer baseline chemistry is rapidly reached in terms of pH, alkalinity and Ca concentration since calcite equilibrium is achieved over the first metres of the vadose zone. However, incongruent chalk dissolution slowly releases Ba, Mg and Sr in groundwater. Introducing dilution effect by rainwater infiltration and a local occurrence of dolomite improves the agreement between modelling and field data. The dissolution of illite and opal-CT, controlling K and SiO(2) concentrations in the model, can be approximately tackled by classical kinetic rate laws, but not the incongruent chalk dissolution. An apparent kinetic rate has therefore been fitted on field data by inverse modelling: 1.5×10(-5) mol(chalk)L (-1) water year (-1). Sensitivity analysis indicates that the CO(2) partial pressure of the unsaturated zone is a critical parameter for modelling the baseline chemistry over the whole chalk aquifer. Copyright © 2012 Elsevier B.V. All rights reserved.
Analysis on deep metallogenic trace and simulation experiment in xiangshan large-scale volcanic hydrothermal type uranium deposit

International Nuclear Information System (INIS)

Liu Zhengyi; Liu Zhangyue; Wen Zhijian; Du Letian

2010-01-01

Based on series experiments on field geologic analysis, and associated with deep metallogenic trace experiment model transformed from establishment of field deep metallogenic trace model, this paper come to the conclusion that distribution coefficients of U and Th first domestic from the magmatic experiment, and then discuss the geochemical behaviors of U, Th, K during magmatic evolution stage. The experiment shows that close relationship between U and Na during the hydrothermal alteration stage; and relationship between U and K during metallogenic stage, which prove that U and K are incompatible and regularity of variation between K and Na. The conclusion of uranium dissolving ability increased accompany with pressure increasing in basement metamorphic rocks and host rocks, is obtained from this experiment, which indicate a good deep metallogenic prospect. Furthermore, Pb, Sr, Nd, He isotopes show that the volcanic rocks and basement rocks are ore source beds; due to the combined functions of volcanic hydrothermal and mantle ichor, uranium undergo multi-migration and enrichment and finally concentrated to large rich deposit. (authors)
History of the use of uranium

International Nuclear Information System (INIS)

Miettinen, J.K.

1989-01-01

Uranium was found 200 years ago, though the first use for it - in colouring glass yellow, orange or green - was only found 40 years later. When its radioactivity was discovered in 1896, interest in research into uranium increased and for a brief period it was used for improving the ductility of steel. The isolation of radium from uranium ore in 1904 caused a boom for uranium mining for radium. It found use in healing skin cancer, for various 'health' preparations like radon-containing water, and for making self-luminous paints. The discovery of fission 50 years ago increased the use of uranium into large industrial-scale applications. For fission weapons highly enriched U-235 and Pu-239 were needed. Today the main use is for uranium enriched to about 3 per cent U-235 for light water power reactors. Other important uses are for submarines, icebreakers and satellites
Quantum electrodynamics at strong electric fields. The ground state Lamb shift in hydrogenlike uranium

Energy Technology Data Exchange (ETDEWEB)

Gumberidze, A.; Stoehlker, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Frankfurt Univ. (Germany). Inst. fuer Kernphysik; Banas, D. [Pedagogical Univ., Kielce (PL). Inst. of Phys.] [and others

2005-05-01

X-ray spectra following radiative recombination of free electrons with bare uranium ions (U{sup 92+}) were measured at the electron cooler of the ESR storage ring. The most intense lines observed in the spectra can be attributed to the characteristic Lyman ground-state transitions and to the recombination of free electrons into the K-shell of the ions. Our experiment was carried out by utilizing the deceleration technique which leads to a considerable reduction of the uncertainties associated with Doppler corrections. This, in combination with the 0 observation geometry, allowed us to determine the ground-state Lamb shift in hydrogen-like uranium (U{sup 91+}) from the observed X-ray lines with an accuracy of 1%. The present result is about 3 times more precise than the most accurate value available up to now and provides the most stringent test of bound-state quantum electrodynamics for one-electron systems in the strong-field regime. (orig.)
A note on the heritability of reactivity assessed at field tests for Danish Warmblood horses

DEFF Research Database (Denmark)

Rothmann, Janne; Christensen, Ole F.; Søndergaard, Eva

2014-01-01

Temperament traits in horses, especially reactivity, are an important trait in relation to human–horse accidents and the welfare of the horses. However, so far, temperament is often not included in many horse breeding programs. Most of the behavioral genetic studies in horses have been based on i......, a high standard error was untainted. Nevertheless, results suggested a genetic variation of reactivity when assessed at field tests, but further research is needed before reactivity can be incorporated as a selection criteria into a breeding program....
Brazilian uranium reserves

International Nuclear Information System (INIS)

Marques, J.P.M.

1981-01-01

Due to a growing demand of electric power to support Brasil's development, the use of nuclear energy will be indispensable. The nuclear fuel cycle for the production of energy, starts with the uranium exploration. The work performed in this field led to the discovery of several deposits in the country, which to-date totalize a reserve of 236,300t of U 308 , ranking Brazil in the 6th place among the nations of the western world holding uranium reserves. (Author) [pt
NURE uranium deposit model studies

International Nuclear Information System (INIS)

Crew, M.E.

1981-01-01

The National Uranium Resource Evaluation (NURE) Program has sponsored uranium deposit model studies by Bendix Field Engineering Corporation (Bendix), the US Geological Survey (USGS), and numerous subcontractors. This paper deals only with models from the following six reports prepared by Samuel S. Adams and Associates: GJBX-1(81) - Geology and Recognition Criteria for Roll-Type Uranium Deposits in Continental Sandstones; GJBX-2(81) - Geology and Recognition Criteria for Uraniferous Humate Deposits, Grants Uranium Region, New Mexico; GJBX-3(81) - Geology and Recognition Criteria for Uranium Deposits of the Quartz-Pebble Conglomerate Type; GJBX-4(81) - Geology and Recognition Criteria for Sandstone Uranium Deposits in Mixed Fluvial-Shallow Marine Sedimentary Sequences, South Texas; GJBX-5(81) - Geology and Recognition Criteria for Veinlike Uranium Deposits of the Lower to Middle Proterozoic Unconformity and Strata-Related Types; GJBX-6(81) - Geology and Recognition Criteria for Sandstone Uranium Deposits of the Salt Wash Type, Colorado Plateau Province. A unique feature of these models is the development of recognition criteria in a systematic fashion, with a method for quantifying the various items. The recognition-criteria networks are used in this paper to illustrate the various types of deposits
Uranium industry seminar

International Nuclear Information System (INIS)

1980-01-01

The tenth annual Uranium Industry Seminar, sponsored by the US Department of Energy's (DOE) Grand Junction Office, was held in Grand Junction, Colorado, on October 22 and 23, 1980. There were 700 registered attendees as compared to 833 attending the previous year. The attendees were drawn largely from uranium and other energy resource companies, electric utility firms, energy consultants and service companies, and governmental agencies. In addition, there were representatives present from Indian tribes, universities, the media, DOE laboratories, and foreign countries and organizations. There were 14 papers presented at the seminar by speakers from the Department of Energy, US Geological Survey, and Bendix Field Engineering Corporation which is the on-site prime contractor for DOE's Grand Junction Office. The topics the papers dealt with were uranium policies, exploration, respources, supply, enrichment, and market conditions. There also were papers describing the National Uranium Resource Evaluation program and international activities. All 14 papers in this Proceedings have been abstracted and indexed
Recent International R&D Activities in the Extraction of Uranium from Seawater

Energy Technology Data Exchange (ETDEWEB)

Rao, Linfeng

2010-03-15

A literature survey has been conducted to collect information on the International R&D activities in the extraction of uranium from seawater for the period from the 1960s till the year of 2010. The reported activities, on both the laboratory scale bench experiments and the large scale marine experiments, were summarized by country/region in this report. Among all countries where such activities have been reported, Japan has carried out the most advanced large scale marine experiments with the amidoxime-based system, and achieved the collection efficiency (1.5 g-U/kg-adsorbent for 30 days soaking in the ocean) that could justify the development of industrial scale marine systems to produce uranium from seawater at the price competitive with those from conventional uranium resources. R&D opportunities are discussed for improving the system performance (selectivity for uranium, loading capacity, chemical stability and mechanical durability in the sorption-elution cycle, and sorption kinetics) and making the collection of uranium from seawater more economically competitive.

Uranium ore mining in the future

International Nuclear Information System (INIS)

Ertle, H.J.; Schmid, K.

1979-01-01

Since energy supply has to be secured in the long term (hardly without a uranium contribution), the disparate laws governing the uranium market need a closer lock, taking into account the economic advantages or uranium as compared with other energies, the strategic importance, market fluctuations and price formation. Regarding costs, the paper highlights the imbalance between the modest increase in uranium reserves and the steadily growing production costs over the last four years. In this context, the pattern of exploration outlays of a number of countries active in the uranium field since 1972 and the size of the main uranium reserves of the Western World are relevant. Lastly, an attempt is made to estimate uranium availability, production and demand for the period 1985 to 1990 on the basis of two scenarios, one based on a moderate rate of nuclear power development and one on an accelerated rate. (orig./HS) [de
Bioremediation of uranium contaminated Fernald soils

International Nuclear Information System (INIS)

Delwiche, M.E.; Wey, J.E.; Torma, A.E.

1994-01-01

This study investigated the use of microbial bioleaching for removal of uranium from contaminated soils. The ability of bacteria to assist in oxidation and solubilization of uranium was compared to the ability of fungi to produce complexing compounds which have the same effect. Biosorption of uranium by fungi was also measured. Soil samples were examined for changes in mineralogical properties due to these processes. On the basis of these laboratory scale studies a generalized flow sheet is proposed for bioremediation of contaminated Fernald soils
Uranium removal from soils: An overview from the Uranium in Soils Integrated Demonstration program

International Nuclear Information System (INIS)

Francis, C.W.; Brainard, J.R.; York, D.A.; Chaiko, D.J.; Matthern, G.

1994-01-01

An integrated approach to remove uranium from uranium-contaminated soils is being conducted by four of the US Department of Energy national laboratories. In this approach, managed through the Uranium in Soils Integrated Demonstration program at the Fernald Environmental Management Project, Fernald, Ohio, these laboratories are developing processes that selectively remove uranium from soil without seriously degrading the soil's physicochemical characteristics or generating waste that is difficult to manage or dispose of. These processes include traditional uranium extractions that use carbonate as well as some nontraditional extraction techniques that use citric acid and complex organic chelating agents such as naturally occurring microbial siderophores. A bench-scale engineering design for heap leaching; a process that uses carbonate leaching media shows that >90% of the uranium can be removed from the Fernald soils. Other work involves amending soils with cultures of sulfur and ferrous oxidizing microbes or cultures of fungi whose role is to generate mycorrhiza that excrete strong complexers for uranium. Aqueous biphasic extraction, a physical separation technology, is also being evaluated because of its ability to segregate fine particulate, a fundamental requirement for soils containing high levels of silt and clay. Interactions among participating scientists have produced some significant progress not only in evaluating the feasibility of uranium removal but also in understanding some important technical aspects of the task
Proteomic analysis reveals contrasting stress response to uranium in two nitrogen-fixing Anabaena strains, differentially tolerant to uranium

Energy Technology Data Exchange (ETDEWEB)

Panda, Bandita; Basu, Bhakti; Acharya, Celin; Rajaram, Hema; Apte, Shree Kumar, E-mail: aptesk@barc.gov.in

2017-01-15

Highlights: • Response of two native cyanobacterial strains to uranium exposure was studied. • Anabaena L-31 exhibited higher tolerance to uranium as compared to Anabaena 7120. • Uranium exposure differentially affected the proteome profiles of the two strains. • Anabaena L-31 showed better sustenance of photosynthesis and carbon metabolism. • Anabaena L-31 displayed superior oxidative stress defense than Anabaena 7120. - Abstract: Two strains of the nitrogen-fixing cyanobacterium Anabaena, native to Indian paddy fields, displayed differential sensitivity to exposure to uranyl carbonate at neutral pH. Anabaena sp. strain PCC 7120 and Anabaena sp. strain L-31 displayed 50% reduction in survival (LD{sub 50} dose), following 3 h exposure to 75 μM and 200 μM uranyl carbonate, respectively. Uranium responsive proteome alterations were visualized by 2D gel electrophoresis, followed by protein identification by MALDI-ToF mass spectrometry. The two strains displayed significant differences in levels of proteins associated with photosynthesis, carbon metabolism, and oxidative stress alleviation, commensurate with their uranium tolerance. Higher uranium tolerance of Anabaena sp. strain L-31 could be attributed to sustained photosynthesis and carbon metabolism and superior oxidative stress defense, as compared to the uranium sensitive Anabaena sp. strain PCC 7120. Significance: Uranium responsive proteome modulations in two nitrogen-fixing strains of Anabaena, native to Indian paddy fields, revealed that rapid adaptation to better oxidative stress management, and maintenance of metabolic and energy homeostasis underlies superior uranium tolerance of Anabaena sp. strain L-31 compared to Anabaena sp. strain PCC 7120.
Uranium from sea water

International Nuclear Information System (INIS)

Westermark, T.; Forsberg, S.

1980-01-01

The prevalent situation in the field of uranium extraction from the oceans was reviewed from a scientific and technological standpoint and as to legality too. No international convention seems to limit the access to dissolved or suspended matter in free area of the oceans. All publications received through 1979 point to adsorption as the method of choice, at some form of hydrated titanium ''oxide'' as the most promising sorbent, and, generally spoken, at the cost of pumping water through the contacting system as a huge economical problem. A recent Swedish invention may circumvent the pumping problem by making available, in a previously unknown manner, some kind of self-renewing energy from the oceans. A simple economic calculus has resulted in costs from two to six times the present world market price of crude uranium oxide (which is assumed to be US dollar 43.-/1b), with a possibility to compete really after some technical and systematic developments. Results from a small-scale adsorption experiment in genuine sea water are presented: During a few weeks sea water was pumped through tiny, 10 cm high beds of sodium titanate ion exchangers, partly in the hydrogen form. The grain size was 250-500 μm, the flow rate 0.15-0.61 m/min. About 5% of the total amount of uranium passing the columns was retained, resulting in 8-11 μg/Ug. Also, large amounts of manganese, strontium, vanadium and zink were retained. Some of these elements and plankton as well may perhaps be recovered with an economic gain
Exploring the conformational and reactive dynamics of biomolecules in solution using an extended version of the glycine reactive force field

DEFF Research Database (Denmark)

Monti, Susanna; Corozzi, Alessandro; Fristrup, Peter

2013-01-01

In order to describe possible reaction mechanisms involving amino acids, and the evolution of the protonation state of amino acid side chains in solution, a reactive force field (ReaxFF-based description) for peptide and protein simulations has been developed as an expansion of the previously rep...
Interest of uranium complexes for the mechanism study of the McMurry reaction

International Nuclear Information System (INIS)

Maury, O.

1997-01-01

The reducing coupling reactions of ketones in diols and olefins are generally carried out with titanium or samarium compounds. In this work uranium complexes have been used. They have allowed to study the chemical reaction mechanism. This thesis is divided into three parts: 1) the reduction mechanism of uranium tetrachloride by cyclic voltametry has been studied at first. It has been shown that this reduction is followed by a transfer reaction of chlorides between the reduced specie of the higher electronic density and UCl . 2) In the second part is described: the synthesis, the crystal structure, the reactivity of the chemical agents, the stereochemistry of diols and alkenes formation and the pinacolisation reaction catalysis. 3) In the last part, the limits of the McMurry reaction are given by the study of the aromatic ketones pinacolisation reaction by-products. The obtained results show that the complexes of the metals which present a high reducing and oxo-philic (Ti, Sm, U..) character react in a similar way with the carbonyl compounds. If the uranium compounds are less used than those of the titanium in the field of the organic synthesis applications, they are precious auxiliaries and excellent models for reactions mechanisms study and for the synthesis methods optimization. (O.M.)
Impact of colloids on uranium transport in groundwater applied to the Aube radioactive waste disposal

International Nuclear Information System (INIS)

Le Cointe, Pierre

2011-01-01

The presence of colloids, known vectors of radionuclides and chemical contaminants in groundwater, has been identified in groundwater at the Aube radioactive waste disposal in 2004. This thesis aims to characterize these colloids, and to determine their potential impact in the transport of Uranium, chosen as the element of interest for this study. The identified 60 nm in diameter clay colloids and the fulvic and humic acids can move in Aptian groundwater, as indirectly evidenced by column experiments. A feasibility study of a in situ test has been done through a transport modeling to confirm the colloid mobility at the field scale. Using the conditions of the study, the clay colloids do not influence Uranium transport. Even with the greatest concentration assumed on site, they have a very limited impact on the mobilization of Uranium, in the pH range measured on site. On the contrary, the organic colloids, despite their low concentration, can facilitate Uranium transport, the uranyl - organic acid chemical bond being exceptionally strong. Therefore their low concentration in groundwater makes their impact on uranium mobility equally insignificant. (author)
Recent advances in study of uranium surface chemistry in China

Energy Technology Data Exchange (ETDEWEB)

Luo, Lizhu; Lai, Xinchun [Science and Technology on Surface Physics and Chemistry Laboratory, Sichuan (China); Wang, Xiaolin [China Academy of Engineering Physics, Sichuan (China)

2014-04-01

Uranium is very important in nuclear energy industry; however, uranium and its alloys corrode seriously in various atmospheres because of their chemical reactivities. In China, continuous investigations focused on surface chemistry have been carried out for a thorough understanding of uranium in order to provide technical support for its engineering applications. Oxidation kinetics of uranium and its alloys in oxidizing atmospheres are in good agreement with those in the literature. In addition to the traditional techniques, non-traditional methods have been applied for oxidation kinetics of uranium, and it has been verified that spectroscopic ellipsometry and X-ray diffraction are effective and nondestructive tools for in situ kinetic studies. The inhibition efficiency of oxidizing gas impurities on uranium hydrogenation is found to follow the order CO{sub 2} > CO > O{sub 2}, and the broadening of XPS shoulders with temperature in depth profile of hydrogenated uranium surface is discussed, which is not mentioned in the literature. Significant progress on surface chemistry of alloyed uranium (U-Nb and U-Ti) in hydrogen atmosphere is reported, and it is revealed that the hydrating nucleation and subsequent growth of alloyed uranium are closely connected with the surface states, underlying metal matrix, and it is microstructure-dependent. In this review, the recent advances in uranium surface chemistry in China, published so far mostly in Chinese language, are briefly summarized. Suggestions for further study are made. (orig.)
Uranium metallogenic model related to CO2 and hydrocarbon in granite type uranium deposits

International Nuclear Information System (INIS)

Ou Guangxi; Chen Anfu; Cui Jianyong; Xu Yinhuan; Wang Chunhua; Xu Yan

2001-01-01

The report is concerned with the inseparable connections between the uranium migration, enrichment rule and the geochemical characteristics of CO 2 and hydrocarbon gas, as well as the relations between the deposit locations and the gas abnormal distribution in rocky body, which are based on the analysis of some data and phenomena in 11 typical deposits in 2 granite type uranium ore fields, including the observations of 250 rocky fluid inclusion sections and the analyzed data of which 2470 are in gas composition, 200 in uranium content, 50 in thermometry. All the conclusions are drawn from different angles for the first time and this new exploration and advancement fills up the blank of gas geochemistry study in uranium deposits or other metal deposits
Extraction of uranium from seawater: evaluation of uranium resources and plant siting

International Nuclear Information System (INIS)

Rodman, M.R.; Gordon, L.I.; Chen, A.C.T.

1979-02-01

This report deals with the evaluation of U.S. coastal waters as a uranium resource and with the selection of a suitable site for construction of a large-scale plant for uranium extraction. Evaluation of the resource revealed that although the concentration of uranium is quite low, about 3.3 ppB in seawater of average oceanic salinity, the amount present in the total volume of the oceans is very great, some 4.5 billion metric tons. Of this, perhaps only that uranium contained in the upper 100 meters or so of the surface well-mixed layer should be considered accessible for recovery, some 160 million tonnes. The study indicated that open ocean seawater acquired for the purpose of uranium extraction would be a more favorable resource than rivers entering the sea, cooling water of power plants, or the feed or effluent streams of existing plants producing other products such as magnesium, bromine, or potable and/or agricultural water from seawater. Various considerations led to the selection of a site for a pumped seawater coastal plant at a coastal location. Puerto Yabucoa, Puerto Rico was selected. Recommendations are given for further studies. 21 figures, 8 tables
Extraction of uranium from seawater: evaluation of uranium resources and plant siting

Energy Technology Data Exchange (ETDEWEB)

Rodman, M.R.; Gordon, L.I.; Chen, A.C.T.

1979-02-01

This report deals with the evaluation of U.S. coastal waters as a uranium resource and with the selection of a suitable site for construction of a large-scale plant for uranium extraction. Evaluation of the resource revealed that although the concentration of uranium is quite low, about 3.3 ppB in seawater of average oceanic salinity, the amount present in the total volume of the oceans is very great, some 4.5 billion metric tons. Of this, perhaps only that uranium contained in the upper 100 meters or so of the surface well-mixed layer should be considered accessible for recovery, some 160 million tonnes. The study indicated that open ocean seawater acquired for the purpose of uranium extraction would be a more favorable resource than rivers entering the sea, cooling water of power plants, or the feed or effluent streams of existing plants producing other products such as magnesium, bromine, or potable and/or agricultural water from seawater. Various considerations led to the selection of a site for a pumped seawater coastal plant at a coastal location. Puerto Yabucoa, Puerto Rico was selected. Recommendations are given for further studies. 21 figures, 8 tables.
Geology of the Sievi, Kuru and Askola sites. Uranium mineralogy at Askola

International Nuclear Information System (INIS)

Markovaara-Koivisto, M.; Read, D.; Lindberg, A.; Siitari-Kauppi, M.; Togneri, L.

2009-01-01

The natural geochemical retardation systems of radioactive elements in the Finnish bedrock are of great relevance to the Finnish nuclear waste disposal programme. It indicates the likely fate of radionuclides released from the deep repository when the chemical environment is oxidizing within its operating stage or in the event of glacial melt water percolates to the repository. In these conditions the uranium occurs in its state, and it is reactive and mobile. Studying uranium migration and retention in oxidizing conditions is thus justified. Uranium migration and retention are studied with samples taken from a natural uranium deposit at Askola. Likewise the uranium migration is studied with laboratory tests. The naturally uranium-rich samples are taken from shallow depths at Askola, and thus the behaviour of uranium can be studied in oxidising conditions. In the laboratory tests uranium is released from a depleted uranium disc and allowed to migrate and retain in Kuru grey granite and Sievi altered tonalite. The uranium is expected to migrate into the rock and to precipitate there as secondary phases. The rate of uranium migration and age of the precipitates in the laboratory experiments are known, but not in the case of the natural analogue studies. The observations from both the natural analogue and the laboratory tests will be used as input data for the coupled geochemical model for uranium migration and retention. (orig.)
National Uranium Resource Evaluation: Wichita Falls Quadrangle, Texas and Oklahoma

International Nuclear Information System (INIS)

Edwards, M.B.; Andersen, R.L.

1982-08-01

The uranium favorability of the Wichita Falls Quadrangle, Texas and Oklahoma, was determined by using National Uranium Resource Evaluation criteria; by subsurface studies of structure, facies distribution, and gamma-ray anomalies in well logs to a depth of 1500 m; and by surface studies involving extensive field sampling and radiometric surveying. These were supplemented by both aerial radiometric and hydrogeochemical and stream-sediment reconnaissance studies. Favorable environments were identified in fluviodeltaic to fan-delta sandstones in the upper Strawn, Canyon, and Cisco Groups (Pennsylvania to Lower Permian), which occur exclusively in the subsurface. Evaluation was based on the presence of a good uranium source, abundant feldspar, good hydrogeologic characteristics, association with carbonaceous shales, presence of coal and oil fields, and anomalies in gamma logs. Additional favorable environments include deltaic to alluvial sandstones in the Wichita-Albany Group (Lower Permian), which crops out widely and occurs in the shallow subsurface. Evaluation was based on high uranium values in stream-sediment samples, a small uranium occurrence located during the field survey, anomalous gamma logs, good uranium source, and hydrogeologic characteristics. Unfavorable environments include Cambrian to Permian limestones and shales. Pennsylvanian to Permian fluviodeltaic systems that have poor uranium sources, and Permian, Cretaceous, and Pleistocene formations that lack features characteristic of known uranium occurrences
Extraction of Uranium from Seawater: Design and Testing of a Symbiotic System

Energy Technology Data Exchange (ETDEWEB)

Slocum, Alex [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

2018-02-22

The U.S. Department of Energy in October 2014 awarded the Massachusetts Institute of Technology (MIT) a Nuclear Energy University Program grant (DE-NE0008268) to investigate the design and testing of a symbiotic system to harvest uranium from seawater. As defined in the proposal, the goals for the project are: 1. Address the design of machines for seawater uranium mining. 2. Develop design rules for a uranium harvesting system that would be integrated into an offshore wind power tower. 3. Fabricate a 1/50th size scale prototype for bench and pool-testing to verify initial analysis and theory. 4. Design, build, and test a second 1/10th size scale prototype in the ocean for more comprehensive testing and validation. This report describes work done as part of DE-NE0008268 from 10/01/2014 to 11/30/2017 entitled, “Extraction of Uranium from Seawater: Design and Testing of a Symbiotic System.” This effort is part of the Seawater Uranium Recovery Program. This report details the publications and presentations to date on the project, an introduction to the project’s goals and background research into previous work done to achieve these goals thus far. From there, the report describes an algorithm developed during the project used to optimize the adsorption of uranium by changing mechanical parameters such as immersion time and adsorbent reuses is described. Next, a design tool developed as part of the project to determine the global feasibility of symbiotic uranium harvesting systems. Additionally, the report details work done on shell enclosures for uranium adsorption. Moving on, the results from the design, building, and testing of a 1/50th physical scale prototype of a highly feasible symbiotic uranium harvester is described. Then, the report describes the results from flume experiment used to determine the affect of enclosure shells on the uptake of uranium by the adsorbent they enclose. From there the report details the design of a Symbiotic Machine for Ocean uRanium
Communication: Relativistic Fock-space coupled cluster study of small building blocks of larger uranium complexes

International Nuclear Information System (INIS)

Tecmer, Paweł; Visscher, Lucas; Severo Pereira Gomes, André; Knecht, Stefan

2014-01-01

We present a study of the electronic structure of the [UO 2 ] + , [UO 2 ] 2 + , [UO 2 ] 3 + , NUO, [NUO] + , [NUO] 2 + , [NUN] − , NUN, and [NUN] + molecules with the intermediate Hamiltonian Fock-space coupled cluster method. The accuracy of mean-field approaches based on the eXact-2-Component Hamiltonian to incorporate spin–orbit coupling and Gaunt interactions are compared to results obtained with the Dirac–Coulomb Hamiltonian. Furthermore, we assess the reliability of calculations employing approximate density functionals in describing electronic spectra and quantities useful in rationalizing Uranium (VI) species reactivity (hardness, electronegativity, and electrophilicity)
Communication: Relativistic Fock-space coupled cluster study of small building blocks of larger uranium complexes

Science.gov (United States)

Tecmer, Paweł; Severo Pereira Gomes, André; Knecht, Stefan; Visscher, Lucas

2014-07-01

We present a study of the electronic structure of the [UO2]+, [UO2]2 +, [UO2]3 +, NUO, [NUO]+, [NUO]2 +, [NUN]-, NUN, and [NUN]+ molecules with the intermediate Hamiltonian Fock-space coupled cluster method. The accuracy of mean-field approaches based on the eXact-2-Component Hamiltonian to incorporate spin-orbit coupling and Gaunt interactions are compared to results obtained with the Dirac-Coulomb Hamiltonian. Furthermore, we assess the reliability of calculations employing approximate density functionals in describing electronic spectra and quantities useful in rationalizing Uranium (VI) species reactivity (hardness, electronegativity, and electrophilicity).
Enhancing the design of in situ chemical barriers with multicomponent reactive transport modeling

International Nuclear Information System (INIS)

Sevougian, S.D.; Steefel, C.I.; Yabusaki, S.B.

1994-11-01

This paper addresses the need for systematic control of field-scale performance in the emplacement and operation of in situ chemical treatment barriers; in particular, it addresses the issue of how the local coupling of reaction kinetics and material heterogeneities at the laboratory or bench scale can be accurately upscaled to the field. The authors have recently developed modeling analysis tools that can explicitly account for all relevant chemical reactions that accompany the transport of reagents and contaminants through a chemically and physically heterogeneous subsurface rock or soil matrix. These tools are incorporated into an enhanced design methodology for in situ chemical treatment technologies, and the new methodology is demonstrated in the ongoing design of a field experiment for the In Situ Redox Manipulation (ISRM) project at the U.S. Department of Energy (DOE) Hanford Site. The ISRM design approach, which systematically integrates bench-scale and site characterization information, provides an ideal test for the new reactive transport techniques. The need for the enhanced chemistry capability is demonstrated by an example that shows how intra-aqueous redox kinetics can affect the transport of reactive solutes. Simulations are carried out on massively parallel computer architectures to resolve the influence of multiscale heterogeneities on multicomponent, multidimensional reactive transport. The technology will soon be available to design larger-scale remediation schemes
Innovative mathematical modeling in environmental remediation

Energy Technology Data Exchange (ETDEWEB)

Yeh, Gour T. [Taiwan Typhoon and Flood Research Institute (Taiwan); National Central Univ. (Taiwan); Univ. of Central Florida (United States); Gwo, Jin Ping [Nuclear Regulatory Commission (NRC), Rockville, MD (United States); Siegel, Malcolm D. [Sandia National Laboratories, Albuquerque, NM (United States); Li, Ming-Hsu [National Central Univ. (Taiwan); ; Fang, Yilin [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Zhang, Fan [Inst. of Tibetan Plateau Research, Chinese Academy of Sciences (China); Luo, Wensui [Inst. of Tibetan Plateau Research, Chinese Academy of Sciences (China); Yabusaki, Steven B. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

2013-05-01

There are two different ways to model reactive transport: ad hoc and innovative reaction-based approaches. The former, such as the Kd simplification of adsorption, has been widely employed by practitioners, while the latter has been mainly used in scientific communities for elucidating mechanisms of biogeochemical transport processes. It is believed that innovative mechanistic-based models could serve as protocols for environmental remediation as well. This paper reviews the development of a mechanistically coupled fluid flow, thermal transport, hydrologic transport, and reactive biogeochemical model and example-applications to environmental remediation problems. Theoretical bases are sufficiently described. Four example problems previously carried out are used to demonstrate how numerical experimentation can be used to evaluate the feasibility of different remediation approaches. The first one involved the application of a 56-species uranium tailing problem to the Melton Branch Subwatershed at Oak Ridge National Laboratory (ORNL) using the parallel version of the model. Simulations were made to demonstrate the potential mobilization of uranium and other chelating agents in the proposed waste disposal site. The second problem simulated laboratory-scale system to investigate the role of natural attenuation in potential off-site migration of uranium from uranium mill tailings after restoration. It showed inadequacy of using a single Kd even for a homogeneous medium. The third example simulated laboratory experiments involving extremely high concentrations of uranium, technetium, aluminum, nitrate, and toxic metals (e.g.,Ni, Cr, Co).The fourth example modeled microbially-mediated immobilization of uranium in an unconfined aquifer using acetate amendment in a field-scale experiment. The purposes of these modeling studies were to simulate various mechanisms of mobilization and immobilization of radioactive wastes and to illustrate how to apply reactive transport models
Innovative mathematical modeling in environmental remediation

International Nuclear Information System (INIS)

Yeh, Gour T.; Gwo, Jin Ping; Siegel, Malcolm D.; Li, Ming-Hsu; Fang, Yilin; Zhang, Fan; Luo, Wensui; Yabusaki, Steven B.

2013-01-01

There are two different ways to model reactive transport: ad hoc and innovative reaction-based approaches. The former, such as the Kd simplification of adsorption, has been widely employed by practitioners, while the latter has been mainly used in scientific communities for elucidating mechanisms of biogeochemical transport processes. It is believed that innovative mechanistic-based models could serve as protocols for environmental remediation as well. This paper reviews the development of a mechanistically coupled fluid flow, thermal transport, hydrologic transport, and reactive biogeochemical model and example-applications to environmental remediation problems. Theoretical bases are sufficiently described. Four example problems previously carried out are used to demonstrate how numerical experimentation can be used to evaluate the feasibility of different remediation approaches. The first one involved the application of a 56-species uranium tailing problem to the Melton Branch Subwatershed at Oak Ridge National Laboratory (ORNL) using the parallel version of the model. Simulations were made to demonstrate the potential mobilization of uranium and other chelating agents in the proposed waste disposal site. The second problem simulated laboratory-scale system to investigate the role of natural attenuation in potential off-site migration of uranium from uranium mill tailings after restoration. It showed inadequacy of using a single Kd even for a homogeneous medium. The third example simulated laboratory experiments involving extremely high concentrations of uranium, technetium, aluminum, nitrate, and toxic metals (e.g.,Ni, Cr, Co). The fourth example modeled microbially-mediated immobilization of uranium in an unconfined aquifer using acetate amendment in a field-scale experiment. The purposes of these modeling studies were to simulate various mechanisms of mobilization and immobilization of radioactive wastes and to illustrate how to apply reactive transport models

Colloidal transport of uranium in soil: Size fractionation and characterization by field-flow fractionation-multi-detection

International Nuclear Information System (INIS)

Claveranne-Lamolere, C.; Lespes, G.; Dubascoux, St.; Potin-Gautier, M.; Claveranne-Lamolere, C.; Aupiais, J.; Pointurier, F.

2009-01-01

The aim of this study was to characterize colloids associated with uranium by using an on-line fractionation/multi-detection technique based on asymmetrical flow field-flow fractionation (As-Fl-FFF) hyphenated with UV detector, multi angle laser light scattering (MALLS) and inductively coupling plasma-mass spectrometry (ICP-MS). Moreover, thanks to the As-Fl-FFF, the different colloidal fractions were collected and characterized by a total organic carbon analyzer (TOC). Thus it is possible to determine the nature (organic or inorganic colloids), molar mass, size (gyration and hydrodynamic radii) and quantitative uranium distribution over the whole colloidal phase. In the case of the site studied, two populations are highlighted. The first population corresponds to humic-like substances with a molar mass of (1500 ± 300) g mol -1 and a hydrodynamic diameter of (2. 0 ± 0. 2) nm. The second one has been identified as a mix of carbonated nano-particles or clays with organic particles (aggregates and/or coating of the inorganic particles) with a size range hydrodynamic diameter between 30 and 450 nm. Each population is implied in the colloidal transport of uranium: maximum 1% of the uranium content in soil leachate is transported by the colloids in the site studied, according to the depth in the soil. Indeed, humic substances are the main responsible of this transport in sub-surface conditions whereas nano-particles drive the phenomenon in depth conditions. (authors)
Uranium enrichment by laser: a technology for the future

International Nuclear Information System (INIS)

Cazalet, J.

1999-01-01

The SILVA (Isotopic Separation by Laser on atomic Vapor of uranium) process, developed by CEA and COGEMA, is an innovative system of production of enriched uranium, to be used as the fuel of nuclear reactors. It is a sound research program, calling on advanced technologies that are quickly changing. The goal is to cut drastically the production cost in comparison with the operating cost of the present plants based on gaseous diffusion. its industrialization is forecast for the beginning of next century. The SILVA process consists in putting a vapor of uranium through a beam of photons emitted by finely tuned lasers capable of ionising selectively the isotopes 235. The ionised isotopes are attracted on plates by an electric field, they are condensed and collected on these plates. The very high selectivity of enrichment technologies by laser, which are quite new, pave the way for compact and modular plants, which will consume little energy. Accordingly their production cost will be very low. So a new process could take a significant part of the uranium enrichment market after 2010. Even if the multinational EURODIF gaseous diffusion plant is modern and performing, it will be necessary to strengthen the French industry of uranium enrichment to maintain or improve its competitive position on the world market. This could be achieved by smoothly replacing EURODIF by a high performance laser plant. This is the common goal of CEA and COGEMA: all the efforts are concentrated on SILVA, the qualities of which (high selectivity, separation in one single step) have been demonstrated in the facilities of Saclay and Pierrelatte. 400 researchers and technicians are involved, as well as many industrial firms. The budget is equally by CEA and COGEMA through a cooperation agreement. The program includes: a phase of scientific and technical research, which has been highlighted in 1997-1998 by a demonstration of feasibility of the process; a phase of technological development, with
Accounting for the Decreasing Reaction Potential of Heterogeneous Aquifers in a Stochastic Framework of Aquifer-Scale Reactive Transport

Science.gov (United States)

Loschko, Matthias; Wöhling, Thomas; Rudolph, David L.; Cirpka, Olaf A.

2018-01-01

Many groundwater contaminants react with components of the aquifer matrix, causing a depletion of the aquifer's reactivity with time. We discuss conceptual simplifications of reactive transport that allow the implementation of a decreasing reaction potential in reactive-transport simulations in chemically and hydraulically heterogeneous aquifers without relying on a fully explicit description. We replace spatial coordinates by travel-times and use the concept of relative reactivity, which represents the reaction-partner supply from the matrix relative to a reference. Microorganisms facilitating the reactions are not explicitly modeled. Solute mixing is neglected. Streamlines, obtained by particle tracking, are discretized in travel-time increments with variable content of reaction partners in the matrix. As exemplary reactive system, we consider aerobic respiration and denitrification with simplified reaction equations: Dissolved oxygen undergoes conditional zero-order decay, nitrate follows first-order decay, which is inhibited in the presence of dissolved oxygen. Both reactions deplete the bioavailable organic carbon of the matrix, which in turn determines the relative reactivity. These simplifications reduce the computational effort, facilitating stochastic simulations of reactive transport on the aquifer scale. In a one-dimensional test case with a more detailed description of the reactions, we derive a potential relationship between the bioavailable organic-carbon content and the relative reactivity. In a three-dimensional steady-state test case, we use the simplified model to calculate the decreasing denitrification potential of an artificial aquifer over 200 years in an ensemble of 200 members. We demonstrate that the uncertainty in predicting the nitrate breakthrough in a heterogeneous aquifer decreases with increasing scale of observation.
Evaluation of uranium dioxide thermal conductivity using molecular dynamics simulations

International Nuclear Information System (INIS)

Kim, Woongkee; Kaviany, Massoud; Shim, J. H.

2014-01-01

It can be extended to larger space, time scale and even real reactor situation with fission product as multi-scale formalism. Uranium dioxide is a fluorite structure with Fm3m space group. Since it is insulator, dominant heat carrier is phonon, rather than electrons. So, using equilibrium molecular dynamics (MD) simulation, we present the appropriate calculation parameters in MD simulation by calculating thermal conductivity and application of it to the thermal conductivity of polycrystal. In this work, we investigate thermal conductivity of uranium dioxide and optimize the parameters related to its process. In this process, called Green Kubo formula, there are two parameters i.e correlation length and sampling interval, which effect on ensemble integration in order to obtain thermal conductivity. Through several comparisons, long correlation length and short sampling interval give better results. Using this strategy, thermal conductivity of poly crystal is obtained and comparison with that of pure crystal is made. Thermal conductivity of poly crystal show lower value that that of pure crystal. In further study, we broaden the study to transport coefficient of radiation damaged structures using molecular dynamics. Although molecular dynamics is tools for treating microscopic scale, most macroscopic issues related to nuclear materials such as voids in fuel materials and weakened mechanical properties by radiation are based on microscopic basis. Thus, research on microscopic scale would be expanded in this field and many hidden mechanism in atomic scales will be revealed via both atomic scale simulations and experiments
Ore-concentrating structures with telescoped uranium mineralization

International Nuclear Information System (INIS)

Shchetochkin, V.N.; Dmitriyev, V.I.; Tkachenko, I.I.

1986-01-01

Deep faults are the main controlling elements in uranium ore fields, although the immediate geologic environments may be quite varied. Within the fault zones, the uranium fields are usually associated with areas where major transverse and diagonal faults intersect or link, and with points of splitting or change in strike in disjunctive zones. Another distinctive feature of the mineralized structure is their long history, with a combination of tectonic elements differing in age and type, usually associated with retrograde dislocation metamorphism. The specific features of these structures control the uranium mineralization, which is usually localized in foci with telescoped tectonic, magmatic, hydrothermal, metasomatic, and sometimes exogenous processes. The unnamed area (in the Ukraine?) furnishes a good example of how successive stages of a complex geologic history affect the occurrence of such a highly mobile element as uranium. 12 references, 4 figures
Uranium exploration in Ecuador

International Nuclear Information System (INIS)

Severne, B.; Penaherrera, P.F.; Fiallos, V.S.

1981-01-01

The 600-km segment of the Andean Cordillera in Ecuador includes zones that can be correlated, geologically, with uranium districts elsewhere in the Andes. It is believed that these essentially unexplored zones have the potential for economic uranium mineralization. Exploration activity to date has been limited, although it has involved both geochemical and radiometric techniques to evaluate geological concepts. Minor uranium occurrences (with chemical analyses up to 100 ppm) have been encountered, which provide further incentive to commence large-scale systematic exploration. It is recognized that a very large exploration budget and considerable technical expertise will be required to ensure exploration success. Consequently, participation by groups of proven capability from other countries will be sought for Ecuador's national exploration programme. (author)
Algorithms of GPU-enabled reactive force field (ReaxFF) molecular dynamics.

Science.gov (United States)

Zheng, Mo; Li, Xiaoxia; Guo, Li

2013-04-01

Reactive force field (ReaxFF), a recent and novel bond order potential, allows for reactive molecular dynamics (ReaxFF MD) simulations for modeling larger and more complex molecular systems involving chemical reactions when compared with computation intensive quantum mechanical methods. However, ReaxFF MD can be approximately 10-50 times slower than classical MD due to its explicit modeling of bond forming and breaking, the dynamic charge equilibration at each time-step, and its one order smaller time-step than the classical MD, all of which pose significant computational challenges in simulation capability to reach spatio-temporal scales of nanometers and nanoseconds. The very recent advances of graphics processing unit (GPU) provide not only highly favorable performance for GPU enabled MD programs compared with CPU implementations but also an opportunity to manage with the computing power and memory demanding nature imposed on computer hardware by ReaxFF MD. In this paper, we present the algorithms of GMD-Reax, the first GPU enabled ReaxFF MD program with significantly improved performance surpassing CPU implementations on desktop workstations. The performance of GMD-Reax has been benchmarked on a PC equipped with a NVIDIA C2050 GPU for coal pyrolysis simulation systems with atoms ranging from 1378 to 27,283. GMD-Reax achieved speedups as high as 12 times faster than Duin et al.'s FORTRAN codes in Lammps on 8 CPU cores and 6 times faster than the Lammps' C codes based on PuReMD in terms of the simulation time per time-step averaged over 100 steps. GMD-Reax could be used as a new and efficient computational tool for exploiting very complex molecular reactions via ReaxFF MD simulation on desktop workstations. Copyright © 2013 Elsevier Inc. All rights reserved.
Chiral battery, scaling laws and magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Anand, Sampurn; Bhatt, Jitesh R.; Pandey, Arun Kumar, E-mail: sampurn@prl.res.in, E-mail: jeet@prl.res.in, E-mail: arunp@prl.res.in [Physical Research Laboratory, Ahmedabad, 380009 (India)

2017-07-01

We study the generation and evolution of magnetic field in the presence of chiral imbalance and gravitational anomaly which gives an additional contribution to the vortical current. The contribution due to gravitational anomaly is proportional to T {sup 2} which can generate seed magnetic field irrespective of plasma being chirally charged or neutral. We estimate the order of magnitude of the magnetic field to be 10{sup 30} G at T ∼ 10{sup 9} GeV, with a typical length scale of the order of 10{sup −18} cm, which is much smaller than the Hubble radius at that temperature (10{sup −8} cm). Moreover, such a system possess scaling symmetry. We show that the T {sup 2} term in the vorticity current along with scaling symmetry leads to more power transfer from lower to higher length scale as compared to only chiral anomaly without scaling symmetry.
NGSI FY15 Final Report. Innovative Sample Preparation for in-Field Uranium Isotopic Determinations

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Thomas M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meyers, Lisa [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-10

Our FY14 Final Report included an introduction to the project, background, literature search of uranium dissolution methods, assessment of commercial off the shelf (COTS) automated sample preparation systems, as well as data and results for dissolution of bulk quantities of uranium oxides, and dissolution of uranium oxides from swipe filter materials using ammonium bifluoride (ABF). Also, discussed were reaction studies of solid ABF with uranium oxide that provided a basis for determining the ABF/uranium oxide dissolution mechanism. This report details the final experiments for optimizing dissolution of U₃O₈ and UO₂ using ABF and steps leading to development of a Standard Operating Procedure (SOP) for dissolution of uranium oxides on swipe filters.
Integrated prospecting model in Jinguanchong uranium deposit

International Nuclear Information System (INIS)

Xie Yongjian

2006-01-01

Jinguanchong uranium deposit is large in scale, which brings difficulties to prospecting and researches. Based on conditions of mineral-formation, geophysics and geochemistry, this paper summarizes a few geophysical and geochemical prospecting methods applied to this deposit. The principles, characteristics, application condition and exploration phases of these prospecting methods are discussed and some prospecting examples are also given in the prospecting for Jinguanchong uranium deposit. Based on summarizing the practice and effects of different methods such as gamma and electromagnetic method, soil emanation prospecting, track etch technique and polonium method used in uranium prospecting, the author finally puts forward a primary uranium prospecting model for the further prospecting in Jinguanchong uranium deposit through combining the author's experience with practice. (authors)
Nuclear characteristics evaluation for Kyoto University Research Reactor with low-enriched uranium core

Energy Technology Data Exchange (ETDEWEB)

Nakajima, Ken; Unesaki, Hironobu [Kyoto University Research Reactor Institute, Kumatori-cho Sennan-gun Osaka (Japan)

2008-07-01

A project to convert the fuel of Kyoto University Research Reactor (KUR) from highly enriched uranium (HEU) to low-enriched uranium (LEU) is in progress as a part of RERTR program. Prior to the operation of LEU core, the nuclear characteristics of the core have been evaluated to confirm the safety operation. In the evaluation, nuclear parameters, such as the excess reactivity, shut down margin control rod worth, reactivity coefficients, were calculated, and they were compared with the safety limits. The results of evaluation show that the LEU core is able to satisfy the safety requirements for operation, i.e. all the parameters satisfy the safety limits. Consequently, it was confirmed that the LEU fuel core has the proper nuclear characteristics for the safety operation. (authors)
Uranium deposits in granitic rocks

International Nuclear Information System (INIS)

Nishimori, R.K.; Ragland, P.C.; Rogers, J.J.W.; Greenberg, J.K.

1977-01-01

This report is a review of published data bearing on the geology and origin of uranium deposits in granitic, pegmatitic and migmatitic rocks with the aim of assisting in the development of predictive criteria for the search for similar deposits in the U.S. Efforts were concentrated on the so-called ''porphyry'' uranium deposits. Two types of uranium deposits are primarily considered: deposits in pegmatites and alaskites in gneiss terrains, and disseminations of uranium in high-level granites. In Chapter 1 of this report, the general data on the distribution of uranium in igneous and metamorphic rocks are reviewed. Chapter 2 contains some comments on the classification of uranium deposits associated with igneous rocks and a summary of the main features of the geology of uranium deposits in granites. General concepts of the behavior of uranium in granites during crustal evolution are reviewed in Chapter 3. Also included is a discussion of the relationship of uranium mineralization in granites to the general evolution of mobile belts, plus the influence of magmatic and post-magmatic processes on the distribution of uranium in igneous rocks and related ore deposits. Chapter 4 relates the results of experimental studies on the crystallization of granites to some of the geologic features of uranium deposits in pegmatites and alaskites in high-grade metamorphic terrains. Potential or favorable areas for igneous uranium deposits in the U.S.A. are delineated in Chapter 5. Data on the geology of specific uranium deposits in granitic rocks are contained in Appendix 1. A compilation of igneous rock formations containing greater than 10 ppM uranium is included in Appendix 2. Appendix 3 is a report on the results of a visit to the Roessing area. Appendix 4 is a report on a field excursion to eastern Canada
Australian uranium resources

International Nuclear Information System (INIS)

Battey, G.C.; Miezitis, Y.; McKay, A.D.

1987-01-01

Australia's uranium resources amount to 29% of the WOCA countries (world outside centrally-planned-economies areas) low-cost Reasonably Assured Resources and 28% of the WOCA countries low-cost Estimated Additional Resources. As at 1 January 1986, the Bureau of Mineral Resources estimated Australia's uranium resources as: (1) Cost range to US$80/kg U -Reasonably Assured Resources, 465 000 t U; Estimated Additional Resources, 256 000 t U; (2) Cost range US$80-130/kg U -Reasonably Assured Resources, 56 000 t U; Estimated Additional Resources, 127 000 t U. Most resources are contained in Proterozoic unconformity-related deposits in the Alligator Rivers uranium field in the Northern Territory (Jabiluka, Ranger, Koongarra, Nabarlek deposits) and the Proterozoic stratabound deposit at Olympic Dam on the Stuart Shelf in South Australia
Lattice Boltzmann based multicomponent reactive transport model coupled with geochemical solver for scale simulations

NARCIS (Netherlands)

Patel, R.A.; Perko, J.; Jaques, D.; De Schutter, G.; Ye, G.; Van Breugel, K.

2013-01-01

A Lattice Boltzmann (LB) based reactive transport model intended to capture reactions and solid phase changes occurring at the pore scale is presented. The proposed approach uses LB method to compute multi component mass transport. The LB multi-component transport model is then coupled with the
Italian activities in the field of uranium enrichment

International Nuclear Information System (INIS)

Bullio, P.

1977-01-01

The Italian effort on uranium enrichment is principally developed along the two classical processes: gaseous diffusion, centrifuges. Research, development and industrial activities play different role in the two methods; a special working group (GIAU) was established by CNEN to help coordinating this activity. In the field of gaseous diffusion, research and development effort, was, from the starting of the program in 1968, mainly devoted to barriers and compressors. The aim was to gain a full understanding of the process and to demonstrate the capability to overcome the main problems of this technology. Isotope separation of UF 6 was demonstrated in 1974 at an experimental plant level. Cost sharing contracts were signed between CNEN and industries to build prototypes and ''first of a kind'' components; small production lines have been set up to evaluate economics and assess production quality: Eurodif is partially associated with the development of this activity. On the industrial level Agip Nucleare and CNEN were among the promoters of the Eurodif venture from the beginning in 1973 and now own 25% of the shares. In the field of ultracentrifugation the work is still devoted mainly to research and development on the machines. The demonstration of the separation process has been achieved in 1973 at laboratory level with a Zippe type centrifuge. Further on, work has been aimed to the development of high capacity machines and different solutions are under close scrutiny. Carbon fibers and multiple rotors machines have been mechanically tested; the first reference design of small cascade plant has been completed. In the field of laser separation, after a complete and critical survey of different process under development abroad, experimental research work is now being undertaken; experiments on basic aspects of the process are in progress [fr
Recent International R and D Activities in the Extraction of Uranium from Seawater

International Nuclear Information System (INIS)

Rao, Linfeng

2010-01-01

A literature survey has been conducted to collect information on the International R and D activities in the extraction of uranium from seawater for the period from the 1960s till the year of 2010. The reported activities, on both the laboratory scale bench experiments and the large scale marine experiments, were summarized by country/region in this report. Among all countries where such activities have been reported, Japan has carried out the most advanced large scale marine experiments with the amidoxime-based system, and achieved the collection efficiency (1.5 g-U/kg-adsorbent for 30 days soaking in the ocean) that could justify the development of industrial scale marine systems to produce uranium from seawater at the price competitive with those from conventional uranium resources. R and D opportunities are discussed for improving the system performance (selectivity for uranium, loading capacity, chemical stability and mechanical durability in the sorption-elution cycle, and sorption kinetics) and making the collection of uranium from seawater more economically competitive.
Uranium deposits of the world. Europe

Energy Technology Data Exchange (ETDEWEB)

Dahlkamp, Franz J.

2016-07-01

Uranium Deposits of the World, in three volumes, comprises an unprecedented compilation of data and descriptions of the uranium regions in Asia, USA, Latin America and Europe structured by countries. With this third, the Europe volume, Uranium Deposits of the World presents the most extensive data collection of the set. It covers about 140 uranium regions in more than 20 European countries with nearly 1000 mentioned uranium deposits. Each country and region receives an analytical overview followed by the geologically- and economically-relevant synopsis of the individual regions and fields. The presentations are structured in three major sections: (a) location and magnitude of uranium regions, districts, and deposits, (b) principal features of regions and districts, and (c) detailed characteristics of selected ore fields and deposits. This includes sections on geology, alteration, mineralization, shape and dimensions of deposits, isotopes data, ore control and recognition criteria, and metallogenesis. Beside the main European uranium regions, for example in the Czech Republic, Eastern Germany, France, the Iberian Peninsula or Ukraine, also small regions an districts to the point of singular occurrences of interest are considered. This by far the most comprehensive presentation of European uranium geology and mining would not be possible without the author's access to extensive information covering the countries of the former Eastern Bloc states, which was partly not previously available. Abundantly illustrated with information-laden maps and charts throughout, this reference work is an indispensable tool for geologists, mining companies, government agencies, and others with an interest in European key natural resources. A great help for the reader's orientation are the substantial bibliography of uranium-related publications and the indices, latter containing about 3900 entries in the geographical part alone. The three volumes of Uranium Deposits of the
Low-resolution gamma-ray measurements of uranium enrichment

International Nuclear Information System (INIS)

Sprinkle, J.K. Jr.; Christiansen, A.; Cole, R.; Collins, M.L.

1996-01-01

Facilities that process special nuclear material perform periodic inventories. In bulk facilities that process low-enriched uranium, these inventories and their audits are based primarily on weight and enrichment measurements. Enrichment measurements determine the 211 U weight fraction of the uranium compound from the passive gamma-ray emissions of the sample. Both international inspectors and facility operators rely on the capability to make in-field gamma-ray measurements of uranium enrichment. These users require rapid, portable measurement capability. Some in-field measurements have been biased, forcing the inspectors to resort to high-resolution measurements or mass spectrometry to accomplish their goals
Calculations of 3D full-scale VVER fuel assembly and core models using MCU and BIPR-7A codes

Energy Technology Data Exchange (ETDEWEB)

Aleshin, Sergey S.; Bikeev, Artem S.; Bolshagin, Sergey N.; Kalugin, Mikhail A.; Kosourov, Evgeniy K.; Pavlovichev, Aleksandr M.; Pryanichnikov, Aleksandr V.; Sukhino-Khomenko, Evgenia A.; Shcherenko, Anna I.; Shcherenko, Anastasia I.; Shkarovskiy, Denis A. [Nuclear Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation)

2015-09-15

Two types of calculations were made to compare BIPR-7A and MCU results for 3D full-scale models. First EPS (emergency protection system) efficiency and in-core power distributions were analyzed for an equilibrium fuel load of VVER-1000 assuming its operation within an 18-month cycle. Computations were performed without feedbacks and with fuel burnup distributed over the core. After 3D infinite lattices of full-scale VVER-1000 fuel assemblies (A's) with uranium fuel 4.4% enrichment and uranium-erbium fuel 4.4% enrichment and Er{sub 2}O{sub 3} 1 % wt were considered. Computations were performed with feedbacks and fuel burnup at the constant power level. For different time moments effective multiplication factor and power distribution were obtained. EPS efficiency and reactivity effects at chosen time moments were analyzed.
Discussion on some problems in uranium hydrogeochemical prospecting

International Nuclear Information System (INIS)

Shi Weijun.

1989-01-01

The requirements for sampling density in uranium hydrogeochemical prospecting are discussed in this paper. The scales for regional hydrogeochemical survey, prospetcing survey and detailed prospecting survey are 1 : 200,000 - 1 : 100,000, 1 : 50,000 - 1 : 25,000 and 1 : 10,000 - 1 : 5,000 respectively. On the basis of explanation to the geological meaning of hydrogeochemical field defined in different stage, the principle, effect and technical requirements of small-medium scale hydrogeochemical prospecting are studied. The reason and advantage of the dispersion train prospecting using in the wet and rainy regions have been suggested. The key to the dispersion train prospecting is the sensitivity and precision of analytic methods. The general indications and salinity (conductivity) should be paid attention to in hydrogeochemical prospecting

Report of the Subcommittee on Domestic Uranium Enrichment

International Nuclear Information System (INIS)

1981-01-01

A report by the Subcommittee on Domestic Uranium Enrichment to the Atomic Energy Commission is described; which covers the procedure of the domestic uranium enrichment by centrifugal process up to the commercial production, reviewing the current situation in this field. Domestic uranium enrichment is important in the aspects of securing stable enrichment service, establishing sound fuel cycle, and others. As the future target, the production around the year 2000 is set at 3,000 tons SWU per year at least. The business of uranium enrichment, which is now developed in the Power Reactor and Nuclear Fuel Development Corporation, is to be carried out by private enterprise. The contents are as follows: demand and supply balance of uranium enrichment service, significance of domestic uranium enrichment, evaluation of centrifugal uranium enrichment technology, the target of domestic uranium enrichment, the policy of domestic uranium enrichment promotion. (J.P.N.)
Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

International Nuclear Information System (INIS)

Souza, J.A.B.; Durazzo, M.

2010-01-01

IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 gU/cm 3 by using the U 3 Si 2 -Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 gU/cm 3 for the U 3 Si 2 -Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian-Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)
Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

Energy Technology Data Exchange (ETDEWEB)

Souza, Jose Antonio Batista de; Durazzo, Michelangelo, E-mail: jasouza@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 g U/c m3 by using the U{sub 3}Si{sub 2}-Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 g U/c m3 for the U{sub 3}Si{sub 2}-Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian- Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)
Heap bioleaching of uranium from low-grade granite-type ore by mixed acidophilic microbes

International Nuclear Information System (INIS)

Xuegang Wang; Zhongkui Zhou

2017-01-01

We evaluated uranium bioleaching from low-grade, granite-type uranium ore using mixed acidophilic microbes from uranium mine leachate. A 4854-ton plant-scale heap bioleaching process achieved sustained leaching with a uranium leaching efficiency of 88.3% using a pH of 1.0-2.0 and an Fe"3"+ dosage of 3.0-5.5 g/L. Acid consumption amounted to 25.8 g H_2SO_4 kg"-"1 ore. Uranium bioleaching follows a diffusion-controlled kinetic model with a correlation coefficient of 0.9136. Almost all uranium was dissolved in aqueous solution, except those encapsulated in quartz particles. Therefore, heap bioleaching by mixed acidophilic microbes enables efficient, economical, large-scale recovery of uranium from low-grade ores. (author)
A mobile-mobile transport model for simulating reactive transport in connected heterogeneous fields

Science.gov (United States)

Lu, Chunhui; Wang, Zhiyuan; Zhao, Yue; Rathore, Saubhagya Singh; Huo, Jinge; Tang, Yuening; Liu, Ming; Gong, Rulan; Cirpka, Olaf A.; Luo, Jian

2018-05-01

Mobile-immobile transport models can be effective in reproducing heavily tailed breakthrough curves of concentration. However, such models may not adequately describe transport along multiple flow paths with intermediate velocity contrasts in connected fields. We propose using the mobile-mobile model for simulating subsurface flow and associated mixing-controlled reactive transport in connected fields. This model includes two local concentrations, one in the fast- and the other in the slow-flow domain, which predict both the concentration mean and variance. The normalized total concentration variance within the flux is found to be a non-monotonic function of the discharge ratio with a maximum concentration variance at intermediate values of the discharge ratio. We test the mobile-mobile model for mixing-controlled reactive transport with an instantaneous, irreversible bimolecular reaction in structured and connected random heterogeneous domains, and compare the performance of the mobile-mobile to the mobile-immobile model. The results indicate that the mobile-mobile model generally predicts the concentration breakthrough curves (BTCs) of the reactive compound better. Particularly, for cases of an elliptical inclusion with intermediate hydraulic-conductivity contrasts, where the travel-time distribution shows bimodal behavior, the prediction of both the BTCs and maximum product concentration is significantly improved. Our results exemplify that the conceptual model of two mobile domains with diffusive mass transfer in between is in general good for predicting mixing-controlled reactive transport, and particularly so in cases where the transfer in the low-conductivity zones is by slow advection rather than diffusion.
Single well field injection test of humate to enhance attenuation of uranium and other radionuclides in an acidic plume

Energy Technology Data Exchange (ETDEWEB)

Denham, M. [Savannah River Site (SRS), Aiken, SC (United States)

2014-09-30

This report documents the impact of the injected humate on targeted contaminants over a period of 4 months and suggests it is a viable attenuation-based remedy for uranium, potentially for I-129, but not for Sr-90. Future activities will focus on issues pertinent to scaling the technology to full deployment.
Lithologic features and Uranium possibilities of the granites of ...

African Journals Online (AJOL)

Preliminary lithologic and uranium investigation conducted in Pupule and environs to investigate further the area of uranium mineralisation in the neighbouring district revealed that the area is not attractive for further uranium search. Geologic field mapping shows that the area like most other parts of the region is underlain ...
Spectroscopy and chemistry of uranium IV

International Nuclear Information System (INIS)

Folcher, G.; Rigny, P.

1980-06-01

Different fundamental research papers on uranium IV are presented, some were never edited. Molecular spectroscopy was used for identification and structural study of uranium IV in aqueous or organic solutions. The fields studied are: coordination, stereochemistry, electronic structure and chemical properties. For interpretation of results some studies were made with solid compounds or with thorium compounds or thorium complexes. Knowledge of actinides chemistry is improved, uranium and thorium being models for 5 f ions, extractive chemistry is better understood and new applications are possible [fr
Factoring uncertainty into restoration modeling of in-situ leach uranium mines

Science.gov (United States)

Johnson, Raymond H.; Friedel, Michael J.

2009-01-01

Postmining restoration is one of the greatest concerns for uranium in-situ leach (ISL) mining operations. The ISL-affected aquifer needs to be returned to conditions specified in the mining permit (either premining or other specified conditions). When uranium ISL operations are completed, postmining restoration is usually achieved by injecting reducing agents into the mined zone. The objective of this process is to restore the aquifer to premining conditions by reducing the solubility of uranium and other metals in the ground water. Reactive transport modeling is a potentially useful method for simulating the effectiveness of proposed restoration techniques. While reactive transport models can be useful, they are a simplification of reality that introduces uncertainty through the model conceptualization, parameterization, and calibration processes. For this reason, quantifying the uncertainty in simulated temporal and spatial hydrogeochemistry is important for postremedial risk evaluation of metal concentrations and mobility. Quantifying the range of uncertainty in key predictions (such as uranium concentrations at a specific location) can be achieved using forward Monte Carlo or other inverse modeling techniques (trial-and-error parameter sensitivity, calibration constrained Monte Carlo). These techniques provide simulated values of metal concentrations at specified locations that can be presented as nonlinear uncertainty limits or probability density functions. Decisionmakers can use these results to better evaluate environmental risk as future metal concentrations with a limited range of possibilities, based on a scientific evaluation of uncertainty.
Hydrology and geochemistry of the uranium mill tailings pile at Riverton, Wyoming. Part II. History matching

International Nuclear Information System (INIS)

Narasimhan, T.N.; White, A.F.; Tokunaga, T.

1985-02-01

In Part I of this series of two reports the observed fluid potential and geochemical characteristics in and around the inactive uranium mill tailings pile at Riverton, Wyoming were presented. The prupose of the present work is to attempt to simulate field observations using mathematical models. The results of the studies have not only helped identify the physicochemical mechanisms govering contaminant migration around the inactive mill tailings pile in Riverton, but also have indicated the feasibility of quantifying these mechanisms with the help of newly developed mathematical models. Much work needs to be done to validate and benchmark these models. The history-matching effort on hand involves the mathematical simulation of the observed fluid potentials within the tailings, and the observed distribution of various chemical species within and around the inactive uranium mill tailings. The simulation problem involves consideration of transient fluid flow and transient, reactive chemical transport in a variably saturated ground water system with time-dependent boundary conditions. 15 refs., 30 figs., 3 tabs
Epithermal uranium deposits in a volcanogenic context: the example of Nopal 1 deposit, Sierra de Pena Blanca, Mexico

Science.gov (United States)

Calas, G.; Angiboust, S.; Fayek, M.; Camacho, A.; Allard, T.; Agrinier, P.

2009-12-01

The Peña Blanca molybdenum-uranium field (Chihuahua, Mexico) exhibits over 100 airborne anomalies hosted in tertiary ignimbritic ash-flow tuffs (44 Ma) overlying the Pozos conglomerate and a sequence of Cretaceous carbonate rocks. Uranium occurrences are associated with breccia zones at the intersection of two or more fault systems. Periodic reactivation of these structures associated with Basin and Range and Rio Grande tectonic events resulted in the mobilization of U and other elements by meteoric fluids heated by geothermal activity. Trace element geochemistry (U, Th, REE) provides evidence for local mobilization of uranium under oxidizing conditions. In addition, O- and H-isotope geochemistry of kaolinite, smectite, opal and calcite suggests that argillic alteration proceeded at shallow depth with meteoric water at 25-75 °C. Focussed along breccia zones, fluids precipitated several generations of pyrite and uraninite together with kaolinite, as in the Nopal 1 mine, indicating that mineralization and hydrothermal alteration of volcanic tuffs are contemporaneous. Low δ34S values (~ -24.5 ‰) of pyrites intimately associated with uraninite suggest that the reducing conditions at the origin of the U-mineralization arise from biological activity. Later, the uplift of Sierra Pena Blanca resulted in oxidation and remobilization of uranium, as confirmed by the spatial distribution of radiation-induced defect centers in kaolinites. These data show that tectonism and biogenic reducing conditions can play a major role in the formation and remobilization of uranium in epithermal deposits. By comparison with the other uranium deposits at Sierra Pena Blanca and nearby Sierra de Gomez, Nopal 1 deposit is one of the few deposits having retained a reduced uranium mineralization.
The use of carbonate lixiviants to remove uranium from uranium-contaminated soils

International Nuclear Information System (INIS)

Francis, C.W.; Lee, S.Y.; Wilson, J.H.; Timpson, M.E.; Elless, M.P.

1997-01-01

The objective of this research was to design an extraction media and procedure that would selectively remove uranium without adversely affecting the soils' physicochemical characteristics or generating secondary waste forms difficult to manage or dispose of. Investigations centered around determining the best lixivant and how the various factors such as pH, time, and temperature influenced extraction efficiency. Other factors investigated included the influence of attrition scrubbing, the effect of oxidants and reductants and the recycling of lixiviants. Experimental data obtained at the bench- and pilot-scale levels indicated 80 to 95% of the uranium could be removed from the uranium-contaminated soils by using a carbonate lixiviant. The best treatment was three successive extractions with 0.25 M carbonate-bicarbonate (in presence of KMnO 4 as an oxidant) at 40 C followed with two water rinses
Sorption of uranium species from aqueous solutions by Greek zeolite Metaxades

Energy Technology Data Exchange (ETDEWEB)

Viglasova, E.; Krajnak, A.; Galambos, M.; Rosskopfova, O. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra jadrovej chemie, 84215 Bratislava (Slovakia)

2013-04-16

Uranium is naturally-occurring radioactive element, which is commonly found in very small amounts in rocks, soils, waters, plants or animals (include human body). It is harmful both through its chemical toxicity and its radioactivity (all uranium isotopes are radioactive). Exposure to uranium increases your risk of getting a variety of cancers due to its radioactivity. In case of management of radioactive waste, the adsorption of radionuclides plays significant role. Among the natural sorbents applied to the adsorption of uranium zeolites offer a number of advantages (low cost, availability, quite high sorption capacity, good hydraulic properties, thermal stability etc.) as well as no introduction of additional pollution to the environment in the case of application as permeable reactive barriers. The main aims of this work are investigations of adsorption properties of Greek zeolite Metaxades, modelling of traditional isotherms and behaviour during kinetics process, influenced by temperature. (authors)
General trends in the use of uranium in the nuclear industry

International Nuclear Information System (INIS)

Salesse, M.

1960-01-01

It can be seen from a consideration of the development of the military and civil needs for uranium that, in the long run, the main outlet for the metal will be provided by its industrial applications. The technical uncertainties concerning the best method of producing atomic energy are still numerous and in fact reflect the hesitation in choosing one of two classes of fuel: that based on the metal and that based on the oxide. Four main factors should influence the choice: - the neutron reactivity and the enrichment of the uranium; - the operating temperature; - the resistance to radiation effects; - the chemical stability; but in actual fact, when the choice for a particular use has to be made, it will be another type of factor, such as the cost price, and weight and space considerations which will determine the choice of either metallic uranium or uranium oxide reactors. (author) [fr
Modeling uranium transport in acidic contaminated groundwater with base addition

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fan [Institute of Tibetan Plateau Research, Chinese Academy of Sciences; Luo, Wensui [ORNL; Parker, Jack C. [University of Tennessee, Knoxville (UTK); Brooks, Scott C [ORNL; Watson, David B [ORNL; Jardine, Philip [University of Tennessee, Knoxville (UTK); Gu, Baohua [ORNL

2011-01-01

This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.
Modeling uranium transport in acidic contaminated groundwater with base addition

International Nuclear Information System (INIS)

Zhang Fan; Luo Wensui; Parker, Jack C.; Brooks, Scott C.; Watson, David B.; Jardine, Philip M.; Gu Baohua

2011-01-01

This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO 3 - , SO 4 2- , U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.
Modeling uranium transport in acidic contaminated groundwater with base addition

Energy Technology Data Exchange (ETDEWEB)

Zhang Fan, E-mail: zhangfan@itpcas.ac.cn [Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, P.O. Box 2871, Beijing, 100085 (China); Luo Wensui [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China); Parker, Jack C. [Institute for a Secure and Sustainable Environment, Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Brooks, Scott C.; Watson, David B. [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Jardine, Philip M. [Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN 37996 (United States); Gu Baohua [Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2011-06-15

This study investigates reactive transport modeling in a column of uranium(VI)-contaminated sediments with base additions in the circulating influent. The groundwater and sediment exhibit oxic conditions with low pH, high concentrations of NO{sub 3}{sup -}, SO{sub 4}{sup 2-}, U and various metal cations. Preliminary batch experiments indicate that additions of strong base induce rapid immobilization of U for this material. In the column experiment that is the focus of the present study, effluent groundwater was titrated with NaOH solution in an inflow reservoir before reinjection to gradually increase the solution pH in the column. An equilibrium hydrolysis, precipitation and ion exchange reaction model developed through simulation of the preliminary batch titration experiments predicted faster reduction of aqueous Al than observed in the column experiment. The model was therefore modified to consider reaction kinetics for the precipitation and dissolution processes which are the major mechanism for Al immobilization. The combined kinetic and equilibrium reaction model adequately described variations in pH, aqueous concentrations of metal cations (Al, Ca, Mg, Sr, Mn, Ni, Co), sulfate and U(VI). The experimental and modeling results indicate that U(VI) can be effectively sequestered with controlled base addition due to sorption by slowly precipitated Al with pH-dependent surface charge. The model may prove useful to predict field-scale U(VI) sequestration and remediation effectiveness.
Near-field high-temperature transport: Evidence from the genesis of the Osamu Utsumi uranium mine, Pocos de Caldas alkaline complex, Brazil

International Nuclear Information System (INIS)

Cathles, L.M.; Shea, M.E.

1990-01-01

The chemical, isotopic and mineralogical alteration which occurred during primary uranium ore deposition at the breccia pipe-hosted Osamu Utsumi mine, Pocos de Caldas, Brazil, was studied as a natural analogue for near-field radionuclide migration. Chemical and isotopic alteration models were combined with finite difference models of the convective cooling of caldera intrusives. Application of the chemical models successfully used to interpret mineralization and alteration at the Osamu Utsumi mine to the hypothetical waste repository shows that even in a worst case scenario (waste emplaced in a permeable host rock with no measures taken to inhibit flow through the repository), the amount of hydrothermal alteration in the hypothetical repository will be about 0.1% of that in the breccia pipe at the Osamu Utsumi mine. Assuming no barriers to uranium mobility, uranium precipitation above the hypothetical repository would be 0.05 ppm (rather than 50 ppm), hydrothermal alteration 0.03 wt.% (rather than 30 wt.%), etc. The analysis indicates that mineralogical alteration is extremely sensitive to thermodynamic data. Prediction of mineralogical alteration (which may be necessary to predict the migration of radionuclides other than uranium, for example) probably cannot be based directly on even very carefully collected laboratory thermodynamic data. Mineralogical complexities of the system, as well as database uncertainties, will require calibration of the thermodynamic framework against mineralogical alteration observed in the laboratory or field by procedures briefly described. (au)
Uranium

International Nuclear Information System (INIS)

Hamdoun, N.A.

2007-01-01

The article includes a historical preface about uranium, discovery of portability of sequential fission of uranium, uranium existence, basic raw materials, secondary raw materials, uranium's physical and chemical properties, uranium extraction, nuclear fuel cycle, logistics and estimation of the amount of uranium reserves, producing countries of concentrated uranium oxides and percentage of the world's total production, civilian and military uses of uranium. The use of depleted uranium in the Gulf War, the Balkans and Iraq has caused political and environmental effects which are complex, raising problems and questions about the effects that nuclear compounds left on human health and environment.
Effects of technological learning and uranium price on nuclear cost: Preliminary insights from a multiple factors learning curve and uranium market modeling

International Nuclear Information System (INIS)

Kahouli, Sondes

2011-01-01

This paper studies the effects of returns to scale, technological learning, i.e. learning-by-doing and learning-by-searching, and uranium price on the prospects of nuclear cost decrease. We use an extended learning curve specification, named multiple factors learning curve (MFLC). In a first stage, we estimate a single MFLC. In a second stage, we estimate the MFLC under the framework of simultaneous system of equations which takes into account the uranium supply and demand. This permits not only to enhance the reliability of the estimation by incorporating the uranium price formation mechanisms in the MFLC via the price variable, but also to give preliminary insights about uranium supply and demand behaviors and the associated effects on the nuclear expansion. Results point out that the nuclear cost has important prospects for decrease via capacity expansion, i.e. learning-by-doing effects. In contrast, they show that the learning-by-searching as well as the scale effects have a limited effect on the cost decrease prospects. Conversely, results also show that uranium price exerts a positive and significant effect on nuclear cost, implying that when the uranium price increases, the nuclear power generation cost decreases. Since uranium is characterized by important physical availability, and since it represents only a minor part in the total nuclear cost, we consider that in a context of increasing demand for nuclear energy the latter result can be explained by the fact that the positive learning effects on the cost of nuclear act in a way to dissipate the negative ones that an increase in uranium price may exert. Further, results give evidence of important inertia in the supply and demand sides as well as evidence of slow correlation between the uranium market and oil market which may limit the inter-fuels substituability effects, that is, nuclear capacity expansion and associated learning-by-doing benefits. - Highlights: → We study the prospects of nuclear cost

Criticality safety concerns of uranium deposits in cascade equipment

International Nuclear Information System (INIS)

Plaster, M.J.

1996-01-01

The Paducah and Portsmouth Gaseous Diffusion Plants enrich uranium in the 235 U isotope by diffusing gaseous uranium hexafluoride (UF 6 ) through a porous barrier. The UF 6 gaseous diffusion cascade utilized several thousand open-quotes stagesclose quotes of barrier to produce highly enriched uranium (HEU). Historically, Portsmouth has enriched the Paducah Gaseous Diffusion Plant's product (typically 1.8 wt% 235 U) as well as natural enrichment feed stock up to 97 wt%. Due to the chemical reactivity of UF 6 , particularly with water, the formation of solid uranium deposits occur at a gaseous diffusion plant. Much of the equipment operates below atmospheric pressure, and deposits are formed when atmospheric air enters the cascade. Deposits may also be formed from UF 6 reactions with oil, UF 6 reactions with the metallic surfaces of equipment, and desublimation of UF 6 . The major deposits form as a result of moist air in leakage due to failure of compressor casing flanges, blow-off plates, seals, expansion joint convolutions, and instrument lines. This report describes criticality concerns and deposit disposition
Reactive barrier technologies for treatment of contaminated groundwater at Rocky Flats

International Nuclear Information System (INIS)

Marozas, D.C.; Bujewski, G.E.; Castaneda, N.

1997-01-01

The U.S. Department of Energy (DOE) Office of Science and Technology Subsurface Contaminants Focus Area is supporting the investigation of reactive barrier technologies to mitigate the risks associated with mixed organic/radioactive waste at several DOE sites. Groundwater from a small contaminated plume at the Rocky Flats Environmental Technology Site (RFETS) is being used to evaluate passive reactive material treatment. Permeable reactive barriers which intercept contaminants and destroy the VOC component while containing radionuclides are attractive for a number of reasons relating to public and regulatory acceptance. In situ treatment keeps contaminants away from the earth's surface, there is no above-ground treatment equipment that could expose workers and the public and operational costs are expected to be lower than currently used technologies. This paper will present results from preliminary site characterization and in-field small-scale column testing of reactive materials at RFETS. Successful demonstration is expected to lead to full-scale implementation of the technology at several DOE sites, including Rocky Flats
Uranium extraction from gold-uranium ores

Energy Technology Data Exchange (ETDEWEB)

Laskorin, B.N.; Golynko, Z.Sh.

1981-01-01

The process of uranium extraction from gold-uranium ores in the South Africa is considered. Flowsheets of reprocessing gold-uranium conglomerates, pile processing and uranium extraction from the ores are presented. Continuous counter flow ion-exchange process of uranium extraction using strong-active or weak-active resins is noted to be the most perspective and economical one. The ion-exchange uranium separation with the succeeding extraction is also the perspective one.
The effects of physical separtation treatment on the removal of uranium from contaminated soils at Fernald: A bench-scale study

International Nuclear Information System (INIS)

Sadler, K.G.; Krstich, M.A.

1994-01-01

A bench-scale treatability study incorporating the use of physical separation techniques and chemical dispersants/extractants was conducted on uranium contaminated soils at the Fernald Environmental Management Project (FEMP) site. The soils contained approximately 497 and 450 milligrams per kilogram (mg/kg) of total uranium, respectively. Geotechnical characterization indicated that 77.4 and 74.6 percent of the soil was in the less that 50 micrometer (μm) size fraction for the ID-A and ID-B soils, respectively. An initial characterization effort indicated that uranium was distributed among all particle size fractions. After each soil was dispersed in water, it was noted that the uranium concentrated in the sand and clay fractions for the ID-A soil (1028 and 1475 mg kg -1 , respectively) and the clay fraction for ID-B soil (2710 mg kg -1 ). Four 1 millimolar (mM) sodium reagent solutions (sodium hydroxide, sodium carbonate, sodium bicarbonate, and a sodium citrate-bicarbonate-dithionite mixture) and potable water were evaluated for effectiveness in dispersing each soil into single grain separates and extracting total uranium from each of the resulting particle size fractions. Dilute sodium solutions were more effective than water in dispersing the soil. The use of dispersants, as compared to water, on the less than 2 mm size fraction causes a shift in the distribution of uranium out of the sand fraction and into the silt and clay fractions for ID-A soil and into the clay fraction for the ID-B soil. Attrition scrubbing tests were conducted on the less than 2 mm size fraction for the ID-A and ID-B soils using water and three alkaline extraction solutions, sodium pyrophosphate, sodium carbonate/bicarbonate, and ammonium carbonate/bicarbonate. There was little difference among the chemical extractants on their effectiveness in removing uranium from the greater than 53 μm (sand) or less than 53 μm (silt and clay) soil fraction
Sorption of uranium (VI) on homoionic sodium smectite experimental study and surface complexation modeling.

Science.gov (United States)

Korichi, Smain; Bensmaili, Aicha

2009-09-30

)-BET specific surface area, SSA(BET) (thus, total edge site concentrations). The specific surface area should be at least 80-100m(2)/g for smectite clays in order to reach convergence during the modeling. The range of 10-20% SSA(BET) was used to estimate the values of edge site surfaces that led to the convergence during modeling. An agreement between the experimental data and model predictions is found reasonable when 15% SSA(BET) was used as edge site surface. However, the predicted U (VI) adsorption underestimated and overestimated the experimental observations at the 10 and 20% of the measured SSA(BET), respectively. The dependence of uranium sorption modeling results on specific surface area and edge site surface is useful to describe and predict U (VI) retardation as a function of chemical conditions in the field-scale reactive transport simulations. Therefore this approach can be used in the environmental quality assessment.
The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

International Nuclear Information System (INIS)

Syarifah, Ratna Dewi; Suud, Zaki

2015-01-01

Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better
The prospect of uranium nitride (UN) and mixed nitride fuel (UN-PuN) for pressurized water reactor

Science.gov (United States)

Syarifah, Ratna Dewi; Suud, Zaki

2015-09-01

Design study of small Pressurized Water Reactors (PWRs) core loaded with uranium nitride fuel (UN) and mixed nitride fuel (UN-PuN), Pa-231 as burnable poison, and Americium has been performed. Pa-231 known as actinide material, have large capture cross section and can be converted into fissile material that can be utilized to reduce excess reactivity. Americium is one of minor actinides with long half life. The objective of adding americium is to decrease nuclear spent fuel in the world. The neutronic analysis results show that mixed nitride fuel have k-inf greater than uranium nitride fuel. It is caused by the addition of Pu-239 in mixed nitride fuel. In fuel fraction analysis, for uranium nitride fuel, the optimum volume fractions are 45% fuel fraction, 10% cladding and 45% moderator. In case of UN-PuN fuel, the optimum volume fractions are 30% fuel fraction, 10% cladding and 60% coolant/ moderator. The addition of Pa-231 as burnable poison for UN fuel, enrichment U-235 5%, with Pa-231 1.6% has k-inf more than one and excess reactivity of 14.45%. And for mixed nitride fuel, the lowest value of reactivity swing is when enrichment (U-235+Pu) 8% with Pa-231 0.4%, the excess reactivity value 13,76%. The fuel pin analyze for the addition of Americium, the excess reactivity value is lower than before, because Americium absorb the neutron. For UN fuel, enrichment U-235 8%, Pa-231 1.6% and Am 0.5%, the excess reactivity is 4.86%. And for mixed nitride fuel, when enrichment (U-235+Pu) 13%, Pa-231 0.4% and Am 0.1%, the excess reactivity is 11.94%. For core configuration, it is better to use heterogeneous than homogeneous core configuration, because the radial power distribution is better.
Geological-economic analysis on the exploration of backup resources for depleted mines in Lujing uranium ore-field, central-southern China

International Nuclear Information System (INIS)

Li Deping; Wang Zhicheng; Fan Shaoyun

2006-01-01

With the geological-economic evaluation program for pithead heap-leaching mining uranium deposits developed by the authors and the data of column-leaching tests and the geological reserve, the geological-economic evaluation is made to the residual geological reserves of both Lujing and Huangfengling deposit, and the geological reserves of Yangjiaonao deposit of the depleted mines in Lujing uranium ore-field, central-southern China. The results of static analysis on these reserves show that the residual geological reserves of both Lujing and Huangfengling deposit belong to sub-profitable type, but the ones of Yangjiaonao deposit is profitable with 26.56% tax-before profit. 1 tU profitable type of ore from Yangjiaonao deposit can use 2.40-3.79 tU subprofitable type of ores from Lujing and Huangfengling deposit. In order to solving the problem on scarcity of backup resources of the depleted mines in Lujing uranium ore-field and using the existing sub-profitable type of geological reserves, it is suggested that the high grade of profitable type of deposits should be explored around the exhausting mines so that the production of the mines could be profitable by the pithead heap-leaching mining method with arrangement groups of both sub-profitable and profitable type of ores. (authors)
Uranium resource evaluation project quality assurance evaluation

International Nuclear Information System (INIS)

Grimes, J.G.

1981-01-01

This evaluation was conducted over an eight-month period from February 4 through October 1, 1980. During this time, field sampling was suspended for an indefinite time period while the National Uranium Resource Evaluation (NURE) Program underwent restructuring. In addition, the Uranium Resource Evaluation (URE) Project archives are being restructured. Since it is difficult to evaluate quality assurance needs of a program that is undergoing drastic change and because sections of the evaluation were well along before these changes were announced, this evaluation reflects the situation as it was during February 1980. The following quality assurance related programs are continuing to date: (1) periodic checks of field sampling procedures by the Supervising Field Geologist and the Director of Field Operations; (2) verification of field form information and laboratory analytical data verification for all geochemical surveys; (3) URE Project laboratory quality control program (all elements routinely analyzed); and (4) Ames interlaboratory quality control program (uranium only). UCC-ND was given the responsibility of conducting a Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) survey in the Central United States (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Nebraska, North Dakota, Oklahoma, Texas, South Dakota, and Wisconsin). During 1979 and 1980, 13 detailed surveys were conducted by the URE Project in the Central and Western United States to characterize the hydrogeochemistry, stream sediment geochemistry, and/or radiometric patterns of known or potential uranium occurrences. Beginning in 1980, the HSSR surveys were modified to the Regional Hydrogeochemical and Stream Sediment (RHSS) surveys
Push-pull test: a method of evaluating formation adsorption parameters for predicting the environmental effects on in situ coal gasification and uranium recovery

International Nuclear Information System (INIS)

Drever, J.I.; McKee, C.R.

1980-11-01

The push-pull test, which is a simple injection and pumping sequence of groundwater spiked with solutes of interest, is presented as a method of determining the adsorption characteristics of a formation. Adsorption properties are necessary to predict restoration from both in situ coal gasification and in situ uranium extraction. The major problems in applying laboratory measurements to the field concern scaling the effect of particle size and obtaining representative samples. Laboratory measurements are conducted on gram to kilogram scale samples, whereas the push-pull test evaluates a sample weighing approximately 130 to 1000 metric tons, depending on volume injected and porosity. The problem in translating laboratory results to the field appear to be less severe for sedimentary uranium bodies than for coal. Laboratory measurements are useful in delineating ranges in adsorption properties and in planning the field experiment. Two field push-pull tests were conducted on uranium formations in Wyoming. Adsorption properties estimated from these tests on the basis of a simple cell model were compared to the laboratory values. In the first case, excellent agreement was observed between the values estimated from the field test and the values measured in the laboratory. In the second case, the value for K/sub d/ determined in the laboratory was five times higher than the field value. It is recommended that push-pull tests be conducted on coal formations being considered for in situ gasification in view of the great uncertainty in extrapolating laboratory adsorption properties to the field
The X-625 Groundwater Treatment Facility: A field-scale test of trichloroethylene dechlorination using iron filings for the X-120/X-749 groundwater plume

International Nuclear Information System (INIS)

Liang, L.; West, O.R.; Korte, N.E.

1997-09-01

The dehalogenation of chlorinated solvents by zero-valence iron has recently become the subject of intensive research and development as a potentially cost-effective, passive treatment for contaminated groundwater through reactive barriers. Because of its successful application in the laboratory and other field sites, the X-625 Groundwater Treatment Facility (GTF) was constructed to evaluate reactive barrier technology for remediating trichloroethylene (TCE)-contaminated groundwater at the Portsmouth Gaseous Diffusion Plant (PORTS). The X-625 GTF was built to fulfill the following technical objectives: (1) to test reactive barrier materials (e.g., iron filings) under realistic groundwater conditions for long term applications, (2) to obtain rates at which TCE degrades and to determine by-products for the reactive barrier materials tested, and (3) to clean up the TCE-contaminated water in the X-120 plume. The X-625 is providing important field-scale and long-term for the evaluation and design of reactive barriers at PORTS. The X-625 GTS is a unique facility not only because it is where site remediation is being performed, but it is also where research scientists and process engineers can test other promising reactive barrier materials. In addition, the data collected from X-625 GTF can be used to evaluate the technical and economic feasibility of replacing the activated carbon units in the pump-and-treat facilities at PORTS
Method for converting uranium oxides to uranium metal

International Nuclear Information System (INIS)

Duerksen, W.K.

1988-01-01

A method for converting uranium oxide to uranium metal is described comprising the steps of heating uranium oxide in the presence of a reducing agent to a temperature sufficient to reduce the uranium oxide to uranium metal and form a heterogeneous mixture of a uranium metal product and oxide by-products, heating the mixture in a hydrogen atmosphere at a temperature sufficient to convert uranium metal in the mixture to uranium hydride, cooling the resulting uranium hydride-containing mixture to a temperature sufficient to produce a ferromagnetic transition in the uranium hydride, magnetically separating the cooled uranium hydride from the mixture, and thereafter heating the separated uranium hydride in an inert atmosphere to a temperature sufficient to convert the uranium hydride to uranium metal
Enhanced Particle Swarm Optimization Algorithm: Efficient Training of ReaxFF Reactive Force Fields.

Science.gov (United States)

Furman, David; Carmeli, Benny; Zeiri, Yehuda; Kosloff, Ronnie

2018-05-04

Particle swarm optimization is a powerful metaheuristic population-based global optimization algorithm. However, when applied to non-separable objective functions its performance on multimodal landscapes is significantly degraded. Here we show that a significant improvement in the search quality and efficiency on multimodal functions can be achieved by enhancing the basic rotation-invariant particle swarm optimization algorithm with isotropic Gaussian mutation operators. The new algorithm demonstrates a superior performance across several nonlinear, multimodal benchmark functions compared to the rotation-invariant Particle Swam Optimization (PSO) algorithm and the well-established simulated annealing and sequential one-parameter parabolic interpolation methods. A search for the optimal set of parameters for the dispersion interaction model in ReaxFF-lg reactive force field is carried out with respect to accurate DFT-TS calculations. The resulting optimized force field accurately describes the equations of state of several high-energy molecular crystals where such interactions are of crucial importance. The improved algorithm also presents a better performance compared to a Genetic Algorithm optimization method in the optimization of a ReaxFF-lg correction model parameters. The computational framework is implemented in a standalone C++ code that allows a straightforward development of ReaxFF reactive force fields.
Multi-Scale Monitoring and Prediction of System Responses to Biostimulation

International Nuclear Information System (INIS)

Susan Hubbard; Jill Banfield; Jinsong Chen; Mark Conrad; Jenny Druhan; Andreas Englert; Andreas Kemna; LiLi; Phil Long; Michael O'Brien; Dimtrios Ntarlagiannis; Yves Personna; Steve Pride; Lee Slater; Carl Steefel; Ken William

2007-01-01

To advance solutions needed for remediation of DOE contaminated sites, approaches are needed that can elucidate and predict reactions associated with coupled biological, geochemical, and hydrological processes over a variety of spatial scales and in heterogeneous environments. Our previous laboratory experimental experiments, which were conducted under controlled and homogeneous conditions, suggest that geophysical methods have the potential for elucidating system transformations that often occur during remediation. Examples include tracking the onset and aggregation of precipitates associated with sulfate reduction using seismic and complex resistivity methods (Williams et al., 2005; Ntarlagiannis et al., 2005) as well as estimating the volume of evolved gas associated with denitrification using radar velocity. These exciting studies illustrated that geophysical responses correlated with biogeochemical changes, but also that multiple factors could impact the geophysical signature and thus a better understanding as well as integration tools were needed to advance the techniques to the point where they can be used to provide quantitative estimates of system transformations. Our current research includes theoretical, numerical, and experimental investigations, performed at the laboratory and the field scales, to determine if geophysical methods can be used to uniquely monitor system transformations. Our work is geared toward the Uranium Mill Tailings site at Rifle, CO, site (Figure 1), where ERSP-sponsored investigations are exploring the efficacy of electron-donor amendments for facilitating sustainable microbial reduction of U(VI) to U(IV) through a series of local-scale field experiments conducted in 2002-2005 (Anderson et al., 2003; Vrionis et al, 2005) Early experiments at the site showed that U(VI) loss from groundwater occurred synchronously with growth of Geobacter after acetate amendment, and illustrated the importance of maintaining iron-reducing conditions
Biotechnology based opportunities for environmental protection in the uranium mining industry

International Nuclear Information System (INIS)

Glombitza, F.; Iske, U.; Bullmann, M.; Ondruschka, J.

1992-01-01

Fluorides and a sodium paraffin sulfonate were used as biocidial substances for blocking microbial oxidation reactions due to chemolithoautotrophic microorganisms and tested in a laboratory and pilot plant scale. A treatment of uranium containing effluents by means of a biosorption process for reducing the uranium concentration was demonstrated in a pilot plant scale too. (orig.)
Reactive Transport at the Pore Scale with Applications to the Dissolution of Carbonate Rocks for CO2 Sequestration Operations

Science.gov (United States)

Boek, E.; Gray, F.; Welch, N.; Shah, S.; Crawshaw, J.

2014-12-01

In CO2 sequestration operations, CO2 injected into a brine aquifer dissolves in the liquid to create an acidic solution. This may result in dissolution of the mineral grains in the porous medium. Experimentally, it is hard to investigate this process at the pore scale. Therefore we develop a new hybrid particle simulation algorithm to study the dissolution of solid objects in a laminar flow field, as encountered in porous media flow situations. First, we calculate the flow field using a multi-relaxation-time lattice Boltzmann (LB) algorithm implemented on GPUs, which demonstrates a very efficient use of the GPU device and a considerable performance increase over CPU calculations. Second, using a stochastic particle approach, we solve the advection-diffusion equation for a single reactive species and dissolve solid voxels according to our reaction model. To validate our simulation, we first calculate the dissolution of a solid sphere as a function of time under quiescent conditions. We compare with the analytical solution for this problem [1] and find good agreement. Then we consider the dissolution of a solid sphere in a laminar flow field and observe a significant change in the sphericity with time due to the coupled dissolution - flow process. Second, we calculate the dissolution of a cylinder in channel flow in direct comparison with corresponding dissolution experiments. We discuss the evolution of the shape and dissolution rate. Finally, we calculate the dissolution of carbonate rock samples at the pore scale in direct comparison with micro-CT experiments. This work builds on our recent research on calculation of multi-phase flow [2], [3] and hydrodynamic dispersion and molecular propagator distributions for solute transport in homogeneous and heterogeneous porous media using LB simulations [4]. It turns out that the hybrid simulation model is a suitable tool to study reactive flow processes at the pore scale. This is of great importance for CO2 storage and
Geochemical features of the ore-bearing medium in uranium deposits in the Khiagda ore field

Science.gov (United States)

Kochkin, B. T.; Solodov, I. N.; Ganina, N. I.; Rekun, M. L.; Tarasov, N. N.; Shugina, G. A.; Shulik, L. S.

2017-09-01

The Neogene uranium deposits of the Khiagda ore field (KOF) belong to the paleovalley variety of the hydrogene type and differ from other deposits of this genetic type in the geological and geochemical localization conditions. The contemporary hydrogeochemical setting and microbiological composition of ore-bearing medium are discussed. The redox potential of the medium (Eh is as low as-400 mV) is much lower than those established at other hydrogenic deposits, both ancient Late Mesozoic and young Late Alpine, studied with the same methods in Russia, Uzbekistan, and southern Kazakhstan. The pH of subsurface water (6.86-8.13) differs in significant fluctuations both between neighboring deposits and within individual ore lodes. Hydrogen-forming and denitrifying bacteria are predominant in microbiological populations, whereas sulfate-reducing bacteria are low-active. The consideration of these factors allowed us to describe the mechanism of uranium ore conservation as resulting from the development of the cryolithic zone, which isolates ore lodes from the effect of the external medium. Carbonated water supplied from the basement along fault zones also participates in the formation of the present-day hydrogeochemical setting. Based on the features of the ore-bearing medium, we propose a method of borehole in situ acid leaching to increase the efficiency of mining in the Khiagda ore field.
Amplification of large-scale magnetic field in nonhelical magnetohydrodynamics

KAUST Repository

Kumar, Rohit

2017-08-11

It is typically assumed that the kinetic and magnetic helicities play a crucial role in the growth of large-scale dynamo. In this paper, we demonstrate that helicity is not essential for the amplification of large-scale magnetic field. For this purpose, we perform nonhelical magnetohydrodynamic (MHD) simulation, and show that the large-scale magnetic field can grow in nonhelical MHD when random external forcing is employed at scale 1/10 the box size. The energy fluxes and shell-to-shell transfer rates computed using the numerical data show that the large-scale magnetic energy grows due to the energy transfers from the velocity field at the forcing scales.
Modelling of uranium/plutonium splitting in purex process

International Nuclear Information System (INIS)

Boullis, B.; Baron, P.

1987-06-01

A mathematical model simulating the highly complex uranium/plutonium splitting operation in PUREX process has been achieved by the french ''Commissariat a l'Energie Atomique''. The development of such a model, which includes transfer and redox reactions kinetics for all the species involved, required an important experimental work in the field of basis chemical data acquisition. The model has been successfully validated by comparison of its results with those of specific trials achieved (at laboratory scale), and with the available results of the french reprocessing units operation. It has then been used for the design of french new plants splitting operations
Vitrification of F006 plating waste sludge by Reactive Additive Stabilization Process (RASP)

International Nuclear Information System (INIS)

Martin, H.L.; Jantzen, C.M.; Pickett, J.B.

1994-01-01

Solidification into glass of nickel-on-uranium plating wastewater treatment plant sludge (F006 Mixed Waste) has been demonstrated at the Savannah River She (SRS). Vitrification using high surface area additives, the Reactive Additive Stabilization Process (RASP), greatly enhanced the solubility and retention of heavy metals In glass. The bench-scale tests using RASP achieved 76 wt% waste loading In both soda-lime-silica and borosilicate glasses. The RASP has been Independently verified by a commercial waste management company, and a contract awarded to vitrify the approximately 500,000 gallons of stored waste sludge. The waste volume reduction of 89% will greatly reduce the disposal costs, and delisting of the glass waste is anticipated. This will be the world's first commercial-scale vitrification system used for environmental cleanup of Mixed Waste. Its stabilization and volume reduction abilities are expected to set standards for the future of the waste management Industry

Effects of high density dispersion fuel loading on the kinetic parameters of a low enriched uranium fueled material test research reactor

Energy Technology Data Exchange (ETDEWEB)

Muhammad, Farhan [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad 45650 (Pakistan)], E-mail: mfarhan_73@yahoo.co.uk; Majid, Asad [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad 45650 (Pakistan)

2008-09-15

The effects of using high density low enriched uranium on the neutronic parameters of a material test research reactor were studied. For this purpose, the low density LEU fuel of an MTR was replaced with high density LEU fuels currently being developed under the RERTR program. Since the alloying elements have different cross-sections affecting the reactor in different ways, therefore fuels U-Mo (9 w/o) which contain the same elements in same ratio were selected for analysis. Simulations were carried out to calculate core excess reactivity, neutron flux spectrum, prompt neutron generation time, effective delayed neutron fraction and feedback coefficients including Doppler feedback coefficient, and reactivity coefficients for change of water density and temperature. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the excess reactivity at the beginning of life does not increase as the uranium density of fuel. Both the prompt neutron generation time and the effective delayed neutron fraction decrease as the uranium density increases. The absolute value of Doppler feedback coefficient increases while the absolute values of reactivity coefficients for change of water density and temperature decrease.
Effects of high density dispersion fuel loading on the kinetic parameters of a low enriched uranium fueled material test research reactor

International Nuclear Information System (INIS)

Muhammad, Farhan; Majid, Asad

2008-01-01

The effects of using high density low enriched uranium on the neutronic parameters of a material test research reactor were studied. For this purpose, the low density LEU fuel of an MTR was replaced with high density LEU fuels currently being developed under the RERTR program. Since the alloying elements have different cross-sections affecting the reactor in different ways, therefore fuels U-Mo (9 w/o) which contain the same elements in same ratio were selected for analysis. Simulations were carried out to calculate core excess reactivity, neutron flux spectrum, prompt neutron generation time, effective delayed neutron fraction and feedback coefficients including Doppler feedback coefficient, and reactivity coefficients for change of water density and temperature. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the excess reactivity at the beginning of life does not increase as the uranium density of fuel. Both the prompt neutron generation time and the effective delayed neutron fraction decrease as the uranium density increases. The absolute value of Doppler feedback coefficient increases while the absolute values of reactivity coefficients for change of water density and temperature decrease
Annex 4 - Task 08/13 final report, Producing the binary uranium alloys with alloying components Al, Mo, Zr, Nb, and B

International Nuclear Information System (INIS)

Lazarevic, Dj.

1961-01-01

Due to reactivity of uranium in contact with the gasses O 2 , N 2 , H 2 , especially under higher temperatures uranium processing is always done in vacuum or inert gas. Melting, alloying and casting is done in high vacuum stoves. This report reviews the type of furnaces and includes detailed description of the electric furnace for producing uranium alloys which is available in the Institute
Report of Sectional Committee on Industrialization of Uranium Enrichment

International Nuclear Information System (INIS)

1981-01-01

In order to accelerate the development and utilization of atomic energy which is the core of the substitute energies for petroleum, it is indispensable requirement to establish independent fuel cycle as the base. In particular, the domestic production of enriched uranium is necessary to eliminate the obstacles to secure the energy supply in Japan. The construction and operation of the pilot plant for uranium enrichment by centrifugal separation method have progressed smoothly, and the technical base for the domestic production of enriched uranium is being consolidated. For the time being, the service of uranium enrichment is given by USA and France, but it is expected that the short supply will arise around 1990. The start of operation of the uranium enrichment plant in Japan is scheduled around 1990, and the scale of the plant will be expanded stepwise thereafter. The scale of production is assumed as 3000 t SWU/year in 2000. Prior to this commercial plant, the prototype plant of up to 250 t SWU/year capacity will be operated in 1986, starting the production of centrifugal separators in 1983. The production line for centrifugal separators will have the capacity of up to 125 t SWU/year. The organization for operating these plants, the home production of natural uranium conversion, the uranium enrichment by chemical method and others are described. (Kako, I.)
Uranium refining by solvent extraction

International Nuclear Information System (INIS)

Kraikaew, J.; Srinuttrakul, W.

2014-01-01

The solvent extraction process to produce higher purity uranium from yellowcake was studied in laboratory scale. Yellowcake, which the uranium purity is around 70% and the main impurity is thorium, was obtained from monazite processing pilot plant of Rare Earth Research and Development Center in Thailand. For uranium re-extraction process, the extractant chosen was Tributylphosphate (TBP) in kerosene. It was found that the optimum concentration of TBP was 10% in kerosene and the optimum nitric acid concentration in uranyl nitrate feed solution was 4 N. An increase in concentrations of uranium and thorium in feed solution resulted in a decrease in the distribution of both components in the extractant. However, the distribution of uranium into the extractant was found to be more than that of thorium. The equilibration study of the extraction system, UO_2(NO_3)/4N HNO_3 – 10%TBP/Kerosene, was also investigated. Two extraction stages were calculated graphically from 100,000 ppm uranium concentration in feed solution input with 90% extraction efficiency and the flow ratio of aqueous phase to organic phase was adjusted to 1.0. For thorium impurity scrubbing process, 10% TBP in kerosene was loaded with uranium and minor thorium from uranyl nitrate solution prepared from yellowcake and was scrubbed with different low concentration nitric acid. The results showed that at nitric acid normality was lower than 1 N, uranium distributed well to aqueous phase. As conclusion, optimum nitric acid concentration for scrubbing process should not less than 1 N and diluted nitric acid or de-ionized water should be applied to strip uranium from organic phase in the final refining process. (author)
Synthesis, characterization, and reactivity of a uranium(VI) carbene imido oxo complex

Energy Technology Data Exchange (ETDEWEB)

Lu, Erli; Cooper, Oliver J.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [Nottingham Univ. (United Kingdom). School of Chemistry; Tuna, Floriana; McInnes, Eric J.L. [Manchester Univ. (United Kingdom). School of Chemistry and Photon Science Inst.

2014-06-23

We report the uranium(VI) carbene imido oxo complex [U(BIPM{sup TMS})(NMes)(O)(DMAP){sub 2}] (5, BIPM{sup TMS}=C(PPh{sub 2}NSiMe{sub 3}){sub 2}; Mes=2,4,6-Me{sub 3}C{sub 6}H{sub 2}; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPM{sup TMS})(O){sub 2}(DMAP){sub 2}] (6).
Scale-up of mixer-settler for uranium extraction; Determinacao das relacoes de `scale-up` em misturador-decantador tipo caixa utilizado na extracao de uranio

Energy Technology Data Exchange (ETDEWEB)

Santana, A.O. de

1990-05-01

The aim of this work was to obtain scale-up relations for a box type mixer-settler used in uranium extraction process for chloridric leaches. Three box type units with different sizes and with the same geometry were used for scale-up of the mixer. The correlation between extraction rate and specific power input, D/T ratio (stirrer diameter/mixer length) and residence time were experimentally obtained. The results showed that the extraction increases with power input for a constant value of D/T equal to 1/3, remaining however independent from mixer sizes for a specific value of power input. This behavior was observed for power input values ranging from 100 to 750 w/m{sup 9}. (author). 23 refs, 22 figs, 23 tabs.
Method for converting uranium oxides to uranium metal

Science.gov (United States)

Duerksen, Walter K.

1988-01-01

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.
Uranium - the element: its occurrence and uses

International Nuclear Information System (INIS)

Awan, I. Z.

2015-01-01

Uranium metal and its compounds have been of great interest to physicists and chemists due to its use for both civil and military applications, e.g. production of electricity, use in the medical field and for making nuclear weapons. This review paper describes the occurrence, chemistry and metallurgy of the element 'uranium', its conversion to stable compounds such as yellow cake, uranium tetrafluoride and uranium hexafluoride and the enrichment technologies and uses for both civil and military purposes. The paper is meant for ready reference for students and teachers in connection with the recent spate of interest shown in nuclear power generation in Pakistan and abroad. (author)
Solubilities of uranium for TILA-99

International Nuclear Information System (INIS)

Ollila, K.; Ahonen, L.

1998-11-01

This report presents the evaluation of the uranium solubilities in the reference waters of TILA-99. The behaviour of uranium has been discussed separately in the near-field and far-field conditions. The bentonite/groundwater interactions have been considered in the compositions of the fresh and saline near-field reference waters. The far-field groundwaters' compositions include fresh, brackish, saline and very saline, almost brine-type compositions. The pH and redox conditions, as the main parameters affecting the solubilities, are considered. A literature study was made in order to obtain information on the recent dissolution and leaching experiments of UO 2 and spent fuel. The latest literature includes studies on UO 2 solubility under anoxic conditions, in which the methods for simulating the reducing conditions of deep groundwater have been improved. Studies on natural uraninite and its alteration products give a valuable insight into the long-term behaviour of spent fuel. Also the solubility equilibria for some relevant poorly known uranium minerals have been determined. The solubilities of the selected solubility-limiting phases were calculated using the geochemical code, EQ3/6. The NEA database for uranium was the basis for the modelling. The recently extended and updated SR '97 database was used for comparison. The solubility products for uranophane were taken from the latest literature. The recommended values for solubilities were given after a comparison between the calculated solubilities, experimental information and measured concentrations in natural groundwaters. The experiments include several UO 2 dissolution studies in synthetic groundwaters with compositions close to the reference groundwaters. (author)
Solubilities of uranium for TILA-99

Energy Technology Data Exchange (ETDEWEB)

Ollila, K. [VTT Chemical Technology, Espoo (Finland); Ahonen, L. [Geological Survey of Finland, Espoo (Finland)

1998-11-01

This report presents the evaluation of the uranium solubilities in the reference waters of TILA-99. The behaviour of uranium has been discussed separately in the near-field and far-field conditions. The bentonite/groundwater interactions have been considered in the compositions of the fresh and saline near-field reference waters. The far-field groundwaters` compositions include fresh, brackish, saline and very saline, almost brine-type compositions. The pH and redox conditions, as the main parameters affecting the solubilities, are considered. A literature study was made in order to obtain information on the recent dissolution and leaching experiments of UO{sub 2} and spent fuel. The latest literature includes studies on UO{sub 2} solubility under anoxic conditions, in which the methods for simulating the reducing conditions of deep groundwater have been improved. Studies on natural uraninite and its alteration products give a valuable insight into the long-term behaviour of spent fuel. Also the solubility equilibria for some relevant poorly known uranium minerals have been determined. The solubilities of the selected solubility-limiting phases were calculated using the geochemical code, EQ3/6. The NEA database for uranium was the basis for the modelling. The recently extended and updated SR `97 database was used for comparison. The solubility products for uranophane were taken from the latest literature. The recommended values for solubilities were given after a comparison between the calculated solubilities, experimental information and measured concentrations in natural groundwaters. The experiments include several UO{sub 2} dissolution studies in synthetic groundwaters with compositions close to the reference groundwaters. (author) 81 refs.
Development and performance of on-line uranium analyzers

International Nuclear Information System (INIS)

Ofalt, A.E.; O'Rourke, P.E.

1985-10-01

A diode-array spectrophotometer and and x-ray fluorescence analyzer were installed online in a full-scale prototype facility to monitor uranium loading and breakthrough of ion exchange columns. Uranium concentrations of 10 ppM in uranyl nitrate solutions can be detected online to improve process control and material accountability. 9 figs
Inherently safe in situ uranium recovery

International Nuclear Information System (INIS)

Krumhansl, James Lee; Beauheim, Richard Louis; Brady, Patrick Vane; Arnold, Bill Walter; Kanney, Joseph F.; McKenna, Sean Andrew

2009-01-01

Expansion of uranium mining in the United States is a concern to some environmental groups and sovereign Native American Nations. An approach which may alleviate some problems is to develop inherently safe in situ uranium recovery ('ISR') technologies. Current ISR technology relies on chemical extraction of trace levels of uranium from aquifers that, once mined, can still contain dissolved uranium and other trace metals that are a health concern. Existing ISR operations are few in number; however, high uranium prices are driving the industry to consider expanding operations nation-wide. Environmental concerns and enforcement of the new 30 ppb uranium drinking water standard may make opening new mining operations more difficult and costly. Here we propose a technological fix: the development of inherently safe in situ recovery (ISISR) methods. The four central features of an ISISR approach are: (1) New 'green' leachants that break down predictably in the subsurface, leaving uranium, and associated trace metals, in an immobile form; (2) Post-leachant uranium/metals-immobilizing washes that provide a backup decontamination process; (3) An optimized well-field design that increases uranium recovery efficiency and minimizes excursions of contaminated water; and (4) A combined hydrologic/geochemical protocol for designing low-cost post-extraction long-term monitoring. ISISR would bring larger amounts of uranium to the surface, leave fewer toxic metals in the aquifer, and cost less to monitor safely - thus providing a 'win-win-win' solution to all stakeholders.
URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

Energy Technology Data Exchange (ETDEWEB)

S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

2006-04-01

Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit.
URANIUM-SERIES CONSTRAINTS ON RADIONUCLIDE TRANSPORT AND GROUNDWATER FLOW AT NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, MEXICO

International Nuclear Information System (INIS)

S. J. Goldstein, S. Luo, T. L. Ku, and M. T. Murrell

2006-01-01

Uranium-series data for groundwater samples from the vicinity of the Nopal I uranium ore deposit are used to place constraints on radionuclide transport and hydrologic processes at this site, and also, by analogy, at Yucca Mountain. Decreasing uranium concentrations for wells drilled in 2003 suggest that groundwater flow rates are low (< 10 m/yr). Field tests, well productivity, and uranium isotopic constraints also suggest that groundwater flow and mixing is limited at this site. The uranium isotopic systematics for water collected in the mine adit are consistent with longer rock-water interaction times and higher uranium dissolution rates at the front of the adit where the deposit is located. Short-lived nuclide data for groundwater wells are used to calculate retardation factors that are on the order of 1,000 for radium and 10,000 to 10,000,000 for lead and polonium. Radium has enhanced mobility in adit water and fractures near the deposit
Laboratory scale micro-seismic monitoring of rock faulting and injection-induced fault reactivation

Science.gov (United States)

Sarout, J.; Dautriat, J.; Esteban, L.; Lumley, D. E.; King, A.

2017-12-01

The South West Hub CCS project in Western Australia aims to evaluate the feasibility and impact of geosequestration of CO2 in the Lesueur sandstone formation. Part of this evaluation focuses on the feasibility and design of a robust passive seismic monitoring array. Micro-seismicity monitoring can be used to image the injected CO2plume, or any geomechanical fracture/fault activity; and thus serve as an early warning system by measuring low-level (unfelt) seismicity that may precede potentially larger (felt) earthquakes. This paper describes laboratory deformation experiments replicating typical field scenarios of fluid injection in faulted reservoirs. Two pairs of cylindrical core specimens were recovered from the Harvey-1 well at depths of 1924 m and 2508 m. In each specimen a fault is first generated at the in situ stress, pore pressure and temperature by increasing the vertical stress beyond the peak in a triaxial stress vessel at CSIRO's Geomechanics & Geophysics Lab. The faulted specimen is then stabilized by decreasing the vertical stress. The freshly formed fault is subsequently reactivated by brine injection and increase of the pore pressure until slip occurs again. This second slip event is then controlled in displacement and allowed to develop for a few millimeters. The micro-seismic (MS) response of the rock during the initial fracturing and subsequent reactivation is monitored using an array of 16 ultrasonic sensors attached to the specimen's surface. The recorded MS events are relocated in space and time, and correlate well with the 3D X-ray CT images of the specimen obtained post-mortem. The time evolution of the structural changes induced within the triaxial stress vessel is therefore reliably inferred. The recorded MS activity shows that, as expected, the increase of the vertical stress beyond the peak led to an inclined shear fault. The injection of fluid and the resulting increase in pore pressure led first to a reactivation of the pre
lithologic features and uranium possibilities of the granites of pupule

African Journals Online (AJOL)

Preliminary lithologic and uranium investigation conducted in Pupule and environs to investigate further the area of uranium mineralisation in the neighbouring district revealed that the area is not attractive for further uranium search. Geologic field mapping shows that the area like most other parts of the region is underlain ...
Determination of uranium by an amperometric method

International Nuclear Information System (INIS)

John, Mary; Venkataramana, P.; Vaidyanathan, S.; Natarajan, P.R.

1981-01-01

An amperometric method has been standardised for the determination of uranium. Uranium is reduced to its quadrivalent state in concentrated phosphoric acid medium with ferrous iron. The excess iron is destroyed with nitric acid in presence of Mo(VI). The medium is diluted and U(IV) is titrated with standard potassium dichromate to an amperometric end point using a pair of identical plantinum wires as electrodes. The reagent volumes and uranium quantities have been scaled down to 30 ml. and 2-5 mg of uranium in the present work with a view to minimising the problems associated with recovery of plutonium. The results are quantitative with an R.S.D. of 0.2% in the present version of weight based titrations. (author)
Uranium

International Nuclear Information System (INIS)

Poty, B.; Cuney, M.; Bruneton, P.; Virlogeux, D.; Capus, G.

2010-01-01

With the worldwide revival of nuclear energy comes the question of uranium reserves. For more than 20 years, nuclear energy has been neglected and uranium prospecting has been practically abandoned. Therefore, present day production covers only 70% of needs and stocks are decreasing. Production is to double by 2030 which represents a huge industrial challenge. The FBR-type reactors technology, which allows to consume the whole uranium content of the fuel, is developing in several countries and will ensure the long-term development of nuclear fission. However, the implementation of these reactors (the generation 4) will be progressive during the second half of the 21. century. For this reason an active search for uranium ores will be necessary during the whole 21. century to ensure the fueling of light water reactors which are huge uranium consumers. This dossier covers all the aspects of natural uranium production: mineralogy, geochemistry, types of deposits, world distribution of deposits with a particular attention given to French deposits, the exploitation of which is abandoned today. Finally, exploitation, ore processing and the economical aspects are presented. Contents: 1 - the uranium element and its minerals: from uranium discovery to its industrial utilization, the main uranium minerals (minerals with tetravalent uranium, minerals with hexavalent uranium); 2 - uranium in the Earth's crust and its geochemical properties: distribution (in sedimentary rocks, in magmatic rocks, in metamorphic rocks, in soils and vegetation), geochemistry (uranium solubility and valence in magmas, uranium speciation in aqueous solution, solubility of the main uranium minerals in aqueous solution, uranium mobilization and precipitation); 3 - geology of the main types of uranium deposits: economical criteria for a deposit, structural diversity of deposits, classification, world distribution of deposits, distribution of deposits with time, superficial deposits, uranium
Review of international classification systems for uranium resources

International Nuclear Information System (INIS)

Wang Wenyou

2007-01-01

The two primary classification systems for uranium resources in common use in the whole world are described. These uranium resource classification systems were developed under two distinct philosophies, it implies two very different processes, criteria, terms and definitions from which the systems evolved and were implemented. However, the two primary systems are all based on two considerations: the degree of geological confidence and the degree of economic attractiveness based on cost of producing the resource. The uranium resource classification methods currently used in most major uranium producing countries have all a bearing on the two aforesaid classification systems. The disparity exists only in the way or practice of classifying and estimating the uranium resources for reasons of different political and economical systems in various countries. The harmonization of these resource classification systems for uranium can be realized with the economic integration on a global scale. (authors)

National Uranium Resource Evaluation: Harrisburg Quadrangle, Pennsylvania

International Nuclear Information System (INIS)

Popper, G.H.P.

1982-08-01

The Harrisburg Quadrangle, Pennsylvania, was evaluated to identify geologic environments and delineate areas favorable for uranium deposits. The evaluation, based primarily on surface reconnaissance, was carried out for all geologic environments within the quadrangle. Aerial radiometric and hydrogeochemical and stream-sediment reconnaissance surveys provided the supplementary data used in field-work followup studies. Results of the investigation indicate that environments favorable for peneconcordant sandstone uranium deposits exist in the Devonian Catskill Formation. Near the western border of the quadrangle, this environment is characterized by channel-controlled uranium occurrences in basal Catskill strata of the Broad Top syncline. In the east-central portion of the quadrangle, the favorable environment contains non-channel-controlled uranium occurrences adjacent to the Clarks Ferry-Duncannon Members contact. All other geologic environments are considered unfavorable for uranium deposits
Surface characterization of uranium metal and uranium dioxide using X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Allen, G.C.; Trickle, I.R.; Tucker, P.M.

1981-01-01

X-ray photoelectron spectra of pure uranium metal and stoichiometric uranium dioxide have been obtained using an AEI ES300 spectrometer. Binding energy values for core and valence electrons have been determined using an internally calibrated energy scale and monochromatic Al Kα radiation. Satellite peaks observed accompanying certain principal core ionizations are discussed in relation to the mechanisms by which they arise. Confirmation is obtained that for stoichiometric UOsub(2.00) a single shake-up satellite is observed accompanying the U 4fsub(7/2,5/2) principal core lines, separated by 6.8 eV to higher binding energy. (author)
Research on using depleted uranium as nuclear fuel for HWR

International Nuclear Information System (INIS)

Zhang Jiahua; Chen Zhicheng; Bao Borong

1999-01-01

The purpose of our work is to find a way for application of depleted uranium in CANDU reactor by using MOX nuclear fuel of depleted U and Pu instead of natural uranium. From preliminary evaluation and calculation, it was shown that MOX nuclear fuel consisting of depleted uranium enrichment tailings (0.25% 235 U) and plutonium (their ratio 99.5%:0.5%) could replace natural uranium in CANDU reactor to sustain chain reaction. The prospects of application of depleted uranium in nuclear energy field are also discussed
Oblique reactivation of lithosphere-scale lineaments controls rift physiography - the upper-crustal expression of the Sorgenfrei-Tornquist Zone, offshore southern Norway

Science.gov (United States)

Phillips, Thomas B.; Jackson, Christopher A.-L.; Bell, Rebecca E.; Duffy, Oliver B.

2018-04-01

Pre-existing structures within sub-crustal lithosphere may localise stresses during subsequent tectonic events, resulting in complex fault systems at upper-crustal levels. As these sub-crustal structures are difficult to resolve at great depths, the evolution of kinematically and perhaps geometrically linked upper-crustal fault populations can offer insights into their deformation history, including when and how they reactivate and accommodate stresses during later tectonic events. In this study, we use borehole-constrained 2-D and 3-D seismic reflection data to investigate the structural development of the Farsund Basin, offshore southern Norway. We use throw-length (T-x) analysis and fault displacement backstripping techniques to determine the geometric and kinematic evolution of N-S- and E-W-striking upper-crustal fault populations during the multiphase evolution of the Farsund Basin. N-S-striking faults were active during the Triassic, prior to a period of sinistral strike-slip activity along E-W-striking faults during the Early Jurassic, which represented a hitherto undocumented phase of activity in this area. These E-W-striking upper-crustal faults are later obliquely reactivated under a dextral stress regime during the Early Cretaceous, with new faults also propagating away from pre-existing ones, representing a switch to a predominantly dextral sense of motion. The E-W faults within the Farsund Basin are interpreted to extend through the crust to the Moho and link with the Sorgenfrei-Tornquist Zone, a lithosphere-scale lineament, identified within the sub-crustal lithosphere, that extends > 1000 km across central Europe. Based on this geometric linkage, we infer that the E-W-striking faults represent the upper-crustal component of the Sorgenfrei-Tornquist Zone and that the Sorgenfrei-Tornquist Zone represents a long-lived lithosphere-scale lineament that is periodically reactivated throughout its protracted geological history. The upper-crustal component of
A process for uranium recovery in phosphoric acid

International Nuclear Information System (INIS)

Duarte Neto, J.

1984-01-01

Results are presented about studies carried out envisaging the development of a process for uranium recovery from phosphoric acid, produced from the concentrate obtained from phosphorus-uraniferous mineral from Itataia mines (CE, Brazil). This process uses a mixture of DEPA-TOPO as extractant and the extraction cycle involves the following stages: acid pre-treatment; adjustment of the oxidation potential so to ensure that all uranium is hexavalent; extraction of uranium from the acid; screening of the solvent to remove undesirable impurities; uranium re-extraction and precipitation; solvent recovery. A micro-pilot plant for continuous processing was built up. Data collected showed that uranium can be recovered with an yield greater than 99%, thus proving the feasibility of the process and encouraging the construction of a bigger scale plant. (Author) [pt
Monte Carlo criticality analysis of simple geometries containing tungsten-rhenium alloys engrained with uranium dioxide and uranium mononitride

International Nuclear Information System (INIS)

Webb, Jonathan A.; Charit, Indrajit

2011-01-01

Highlights: → The addition of rhenium to the tungsten matrix within W-UO 2 and W-UN CERMET materials can help reduce the risk of submersion criticality accidents while increasing the strength and ductility of tungsten based nuclear fuel elements. → The addition of rhenium up to 30 at.% to simple geometries containing W-UO 2 mixtures can increase the critical mass by 65 kg. → The addition of rhenium up to 30 at.% to simple geometries containing W-UN mixtures can increase the critical mass by 22 kg. → The addition of rhenium by up to 30 at.% to simple geometries containing W-UO 2 mixtures can reduce the change in reactivity change due to water submersion by $5.07. → The addition of rhenium by up to 30 at.% to simple geometries containing W-UN mixtures can reduce the change in reactivity due to water submersion by $3.24. - Abstract: The critical mass and dimensions of simple geometries containing highly enriched uranium dioxide (UO 2 ) and uranium mononitride (UN) encapsulated in tungsten-rhenium alloys are determined using MCNP5 criticality calculations. Spheres as well as cylinders with length to radius ratios of 1.82 are computationally built to consist of 60 vol.% fuel and 40 vol.% metal matrix. Within the geometries, the uranium is enriched to 93 wt.% uranium-235 and the rhenium content within the metal alloy was modeled over the range of 0-30 at.%. The spheres containing UO 2 were determined to have a critical radius of 18.29-19.11 cm and a critical mass ranging from 366 kg to 424 kg. The cylinders containing UO 2 were found to have a critical radius ranging from 17.07 cm to 17.84 cm with a corresponding critical mass of 406-471 kg. Spheres engrained with UN were determined to have a critical radius ranging from 14.82 cm to 15.19 cm and a critical mass between 222 kg and 242 kg. Cylinders which were engrained with UN were determined to have a critical radius ranging from 13.81 cm to 14.15 cm and a corresponding critical mass of 245-267 kg. The critical
Determining uranium speciation in contaminated soils by molecular spectroscopic methods: Examples from the Uranium in Soils Integrated Demonstration

International Nuclear Information System (INIS)

Allen, P.G.; Berg, J.M.; Chisholm-Brause, C.J.; Conradson, S.D.; Donohoe, R.J.; Morris, D.E.; Musgrave, J.A.; Tait, C.D.

1994-01-01

The US Department of Energy's former uranium production facility located at Fernald, OH (18 mi NW of Cincinnati) is the host site for an Integrated Demonstration for remediation of uranium-contaminated soils. A wide variety of source terms for uranium contamination have been identified reflecting the diversity of operations at the facility. Most of the uranium contamination is contained in the top ∼1/2 m of soil, but uranium has been found in perched waters indicating substantial migration. In support of the development of remediation technologies and risk assessment, we are conducting uranium speciation studies on untreated and treated soils using molecular spectroscopies. Untreated soils from five discrete sites have been analyzed. We have found that ∼80--90% of the uranium exists as hexavalent UO 2 2+ species even though many source terms consisted of tetravalent uranium species such as UO 2 . Much of the uranium exists as microcrystalline precipitates (secondary minerals). There is also clear evidence for variations in uranium species from the microscopic to the macroscopic scale. However, similarities in speciation at sites having different source terms suggest that soil and groundwater chemistry may be as important as source term in defining the uranium speciation in these soils. Characterization of treated soils has focused on materials from two sites that have undergone leaching using conventional extractants (e.g., carbonate, citrate) or novel chelators such as Tiron. Redox reagents have also been used to facilitate the leaching process. Three different classes of treated soils have been identified based on the speciation of uranium remaining in the soils. In general, the effective treatments decrease the total uranium while increasing the ratio of U(IV) to U(VI) species
The concentrations of uranium in marine organisms

Energy Technology Data Exchange (ETDEWEB)

Matsuba, Mitsue; Ishii, Toshiaki; Nakahara, Motokazu; Nakamura, Ryoichi; Watabe, Teruhisa; Hirano, Shigeki [National Inst. of Radiological Sciences, Hitachinaka, Ibaraki (Japan). Laboratory for Radioecology

2000-07-01

Determination of uranium in sixty-one species of marine organisms was carried out by inductively coupled plasma mass spectrometry to obtain concentration factors and to estimate the internal radiation dose. The concentrations of uranium in soft tissues of marine animals were ranged from 0.077 to 5040 ng/g wet wt. Especially, the branchial heart of cephalopod molluscs showed the specific accumulation of uranium. The concentration factor of the branchial heart of Octopus vulgaris, which indicated the highest value, was calculated to be about 1.6 x 10{sup 3}, comparing with that (3.1 ng/ml) in coastal seawaters of Japan. The concentrations of uranium in hard tissues of marine invertebrates such as clam and sea urchin were similar to those in soft tissues. In contrast, hard tissues like bone, scale, fin, etc. of fishes showed much higher concentrations of uranium than soft tissues like muscle. The concentrations of uranium of twenty-two species of algae were ranged from 2 to 310 ng/g wet wt. Particularly, the brown alga Undaria pinnatifida showed the highest value of the uranium content in the algae and its concentration factor was calculated to be 10{sup 2}. (author)
The concentrations of uranium in marine organisms

International Nuclear Information System (INIS)

Matsuba, Mitsue; Ishii, Toshiaki; Nakahara, Motokazu; Nakamura, Ryoichi; Watabe, Teruhisa; Hirano, Shigeki

2000-01-01

Determination of uranium in sixty-one species of marine organisms was carried out by inductively coupled plasma mass spectrometry to obtain concentration factors and to estimate the internal radiation dose. The concentrations of uranium in soft tissues of marine animals were ranged from 0.077 to 5040 ng/g wet wt. Especially, the branchial heart of cephalopod molluscs showed the specific accumulation of uranium. The concentration factor of the branchial heart of Octopus vulgaris, which indicated the highest value, was calculated to be about 1.6 x 10 3 , comparing with that (3.1 ng/ml) in coastal seawaters of Japan. The concentrations of uranium in hard tissues of marine invertebrates such as clam and sea urchin were similar to those in soft tissues. In contrast, hard tissues like bone, scale, fin, etc. of fishes showed much higher concentrations of uranium than soft tissues like muscle. The concentrations of uranium of twenty-two species of algae were ranged from 2 to 310 ng/g wet wt. Particularly, the brown alga Undaria pinnatifida showed the highest value of the uranium content in the algae and its concentration factor was calculated to be 10 2 . (author)
Strategies for measuring flows of reactive nitrogen at the landscape scale

DEFF Research Database (Denmark)

Theobald, M.R.; Akkal, N.; Bienkowski, J.

2011-01-01

Within a rural landscape there are flows of reactive nitrogen (Nr) through and between the soil, vegetation, atmosphere and hydrological systems as well as transfer as a result of agricultural activities. Measurements of these flows and transfers have generally been limited to individual media (e.......g., hydrological flows) or the interface between two media (e.g., exchange between the soil and the atmosphere). However, the study of flows of Nr at the landscape scale requires a more integrated approach that combines measurement techniques to quantify the flows from one medium to the next. This paper discusses...
Uranium in groundwater--Fertilizers versus geogenic sources.

Science.gov (United States)

Liesch, Tanja; Hinrichsen, Sören; Goldscheider, Nico

2015-12-01

Due to its radiological and toxicological properties even at low concentration levels, uranium is increasingly recognized as relevant contaminant in drinking water from aquifers. Uranium originates from different sources, including natural or geogenic, mining and industrial activities, and fertilizers in agriculture. The goal of this study was to obtain insights into the origin of uranium in groundwater while differentiating between geogenic sources and fertilizers. A literature review concerning the sources and geochemical processes affecting the occurrence and distribution of uranium in the lithosphere, pedosphere and hydrosphere provided the background for the evaluation of data on uranium in groundwater at regional scale. The state of Baden-Württemberg, Germany, was selected for this study, because of its hydrogeological and land-use diversity, and for reasons of data availability. Uranium and other parameters from N=1935 groundwater monitoring sites were analyzed statistically and geospatially. Results show that (i) 1.6% of all water samples exceed the German legal limit for drinking water (10 μg/L); (ii) The range and spatial distribution of uranium and occasional peak values seem to be related to geogenic sources; (iii) There is a clear relation between agricultural land-use and low-level uranium concentrations, indicating that fertilizers generate a measurable but low background of uranium in groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.
Potential uranium provinces in some arabian countries

Energy Technology Data Exchange (ETDEWEB)

Salman, A A [Nuclear materials authority, El Maadi, Cairo, (Egypt)

1995-10-01

This work represents an attempt to delineate potential uranium provinces in some Arabian countries using various related recognition criteria. Definition of these provinces is based on the available geologic and tectonic setting beside geochronological sequence and some geochemical characteristics. This trial would be of a great help for interchanging the ideas and necessary data for the development in the fields of uranium exploration and production. As a result of this study, a number of promising potential uranium provinces are recommended in some arabian countries. 5 figs.
Potential uranium provinces in some arabian countries

International Nuclear Information System (INIS)

Salman, A.A.

1995-01-01

This work represents an attempt to delineate potential uranium provinces in some Arabian countries using various related recognition criteria. Definition of these provinces is based on the available geologic and tectonic setting beside geochronological sequence and some geochemical characteristics. This trial would be of a great help for interchanging the ideas and necessary data for the development in the fields of uranium exploration and production. As a result of this study, a number of promising potential uranium provinces are recommended in some arabian countries. 5 figs
Uranium enrichment. Technology, economics, capacity

International Nuclear Information System (INIS)

Voigt, W.R. Jr.; Saire, D.E.; Gestson, D.K.; Peske, S.E.; Vanstrum, P.R.

1983-01-01

Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R+D efforts on various processes. (author)
Uranium enrichment: technology, economics, capacity

Energy Technology Data Exchange (ETDEWEB)

Voigt, Jr., W. R.; Vanstrum, P. R.; Saire, D. E.; Gestson, D. K.; Peske, S. E.

1982-08-01

Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R and D efforts on various processes.
Uranium enrichment: technology, economics, capacity

International Nuclear Information System (INIS)

Voigt, W.R. Jr.; Vanstrum, P.R.; Saire, D.E.; Gestson, D.K.; Peske, S.E.

1982-01-01

Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R and D efforts on various processes
Responses of microbial community functional structures to pilot-scale uranium in situ bioremediation

Energy Technology Data Exchange (ETDEWEB)

Xu, M.; Wu, W.-M.; Wu, L.; He, Z.; Van Nostrand, J.D.; Deng, Y.; Luo, J.; Carley, J.; Ginder-Vogel, M.; Gentry, T.J.; Gu, B.; Watson, D.; Jardine, P.M.; Marsh, T.L.; Tiedje, J.M.; Hazen, T.C.; Criddle, C.S.; Zhou, J.

2010-02-15

A pilot-scale field test system with an inner loop nested within an outer loop was constructed for in situ U(VI) bioremediation at a US Department of Energy site, Oak Ridge, TN. The outer loop was used for hydrological protection of the inner loop where ethanol was injected for biostimulation of microorganisms for U(VI) reduction/immobilization. After 2 years of biostimulation with ethanol, U(VI) levels were reduced to below drinking water standard (<30 {micro}gl{sup -1}) in the inner loop monitoring wells. To elucidate the microbial community structure and functions under in situ uranium bioremediation conditions, we used a comprehensive functional gene array (GeoChip) to examine the microbial functional gene composition of the sediment samples collected from both inner and outer loop wells. Our study results showed that distinct microbial communities were established in the inner loop wells. Also, higher microbial functional gene number, diversity and abundance were observed in the inner loop wells than the outer loop wells. In addition, metal-reducing bacteria, such as Desulfovibrio, Geobacter, Anaeromyxobacter and Shewanella, and other bacteria, for example, Rhodopseudomonas and Pseudomonas, are highly abundant in the inner loop wells. Finally, the richness and abundance of microbial functional genes were highly correlated with the mean travel time of groundwater from the inner loop injection well, pH and sulfate concentration in groundwater. These results suggest that the indigenous microbial communities can be successfully stimulated for U bioremediation in the groundwater ecosystem, and their structure and performance can be manipulated or optimized by adjusting geochemical and hydrological conditions.
Uranium resource processing. Secondary resources

International Nuclear Information System (INIS)

Gupta, C.K.; Singh, H.

2003-01-01

This book concentrates on the processing of secondary sources for recovering uranium, a field which has gained in importance in recent years as it is environmental-friendly and economically in tune with the philosophy of sustainable development. Special mention is made of rock phosphate, copper and gold tailings, uranium scrap materials (both natural and enriched) and sea water. This volume includes related area of ore mineralogy, resource classification, processing principles involved in solubilization followed by separation and safety aspects
Micro-distribution of uranium in bone after contamination: new insight into its mechanism of accumulation into bone tissue

Energy Technology Data Exchange (ETDEWEB)

Bourgeois, Damien [ICSM, LHYS, Bagnols-sur-Ceze (France); Burt-Pichat, Brigitte [INSERM, UMR 1033 Lyon (France); Lyon Univ. (France); Le Goff, Xavier [ICSM, L2ME, Bagnols-sur-Ceze (France)

2015-09-15

After internal contamination, uranium rapidly distributes in the body; up to 20 % of the initial dose is retained in the skeleton, where it remains for years. Several studies suggest that uranium has a deleterious effect on the bone cell system, but little is known regarding the mechanisms leading to accumulation of uranium in bone tissue. We have performed synchrotron radiation-based micro-X-ray fluorescence (SR μ-XRF) studies to assess the initial distribution of uranium within cortical and trabecular bones in contaminated rats' femurs at the micrometer scale. This sensitive technique with high spatial resolution is the only method available that can be successfully applied, given the small amount of uranium in bone tissue. Uranium was found preferentially located in calcifying zones in exposed rats and rapidly accumulates in the endosteal and periosteal area of femoral metaphyses, in calcifying cartilage and in recently formed bone tissue along trabecular bone. Furthermore, specific localized areas with high accumulation of uranium were observed in regions identified as micro-vessels and on bone trabeculae. These observations are of high importance in the study of the accumulation of uranium in bone tissue, as the generally proposed passive chemical sorption on the surface of the inorganic part (apatite) of bone tissue cannot account for these results. Our study opens original perspectives in the field of exogenous metal bio-mineralization.
A laboratory-scale pretreatment and hydrolysis assay for determination of reactivity in cellulosic biomass feedstocks.

Science.gov (United States)

Wolfrum, Edward J; Ness, Ryan M; Nagle, Nicholas J; Peterson, Darren J; Scarlata, Christopher J

2013-11-14

The rapid determination of the release of structural sugars from biomass feedstocks is an important enabling technology for the development of cellulosic biofuels. An assay that is used to determine sugar release for large numbers of samples must be robust, rapid, and easy to perform, and must use modest amounts of the samples to be tested.In this work we present a laboratory-scale combined pretreatment and saccharification assay that can be used as a biomass feedstock screening tool. The assay uses a commercially available automated solvent extraction system for pretreatment followed by a small-scale enzymatic hydrolysis step. The assay allows multiple samples to be screened simultaneously, and uses only ~3 g of biomass per sample. If the composition of the biomass sample is known, the results of the assay can be expressed as reactivity (fraction of structural carbohydrate present in the biomass sample released as monomeric sugars). We first present pretreatment and enzymatic hydrolysis experiments on a set of representative biomass feedstock samples (corn stover, poplar, sorghum, switchgrass) in order to put the assay in context, and then show the results of the assay applied to approximately 150 different feedstock samples covering 5 different materials. From the compositional analysis data we identify a positive correlation between lignin and structural carbohydrates, and from the reactivity data we identify a negative correlation between both carbohydrate and lignin content and total reactivity. The negative correlation between lignin content and total reactivity suggests that lignin may interfere with sugar release, or that more mature samples (with higher structural sugars) may have more recalcitrant lignin. The assay presented in this work provides a robust and straightforward method to measure the sugar release after pretreatment and saccharification that can be used as a biomass feedstock screening tool. We demonstrated the utility of the assay by

Magnetic separation of uranium from magnesium fluoride

International Nuclear Information System (INIS)

Hoegler, J.M.

1987-01-01

The attraction or repulsion of particles by a magnetic gradient, based on the respective susceptibilities, provides the basis for physical separation of particles that are comprised predominantly of uranium from those that are predominantly magnesium fluoride (MgF 2 ). To determine the effectiveness of this approach, a bench-scale magnetic separator from the S.G. Frantz Co., Inc. was used. In the Frantz Model L-1, particles are fed through a funnel onto a vibration tray and through a magnetic field. The specific design of the Frantz magnet causes the magnetic field strength to vary along the width of the magnet, setting up a gradient. The tray in the magnetic field is split at a point about half way down its length so that the separated material does not recombine. A schematic is presented of Frantz Model L-1 CN - the same magnet configured for high gradient magnetic separation of liquid-suspended particles. Here different pole pieces create a uniform magnetic field, and stainless steel wood in the canister between the pole pieces creates the high gradient. 1 ref., 6 figs., 2 tabs
General trends in the use of uranium in the nuclear industry; Tendances generales d'emploi de l'uranium dans les industries nucleaires

Energy Technology Data Exchange (ETDEWEB)

Salesse, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

It can be seen from a consideration of the development of the military and civil needs for uranium that, in the long run, the main outlet for the metal will be provided by its industrial applications. The technical uncertainties concerning the best method of producing atomic energy are still numerous and in fact reflect the hesitation in choosing one of two classes of fuel: that based on the metal and that based on the oxide. Four main factors should influence the choice: - the neutron reactivity and the enrichment of the uranium; - the operating temperature; - the resistance to radiation effects; - the chemical stability; but in actual fact, when the choice for a particular use has to be made, it will be another type of factor, such as the cost price, and weight and space considerations which will determine the choice of either metallic uranium or uranium oxide reactors. (author) [French] D'apres le developpement des besoins militaires ou civils en uranium, on voit que les usages industriels de ce metal constituent, a long terme, le debouche essentiel. Les incertitudes techniques, sur le procede optimum pour faire de l'energie nucleaire, restent nombreuses, et se traduisent finalement par une hesitation entre deux grandes classes de combustibles: ceux a base de metal et ceux a base d'oxyde: la preference a l'une ou l'autre de ces deux categories doit s'inspirer de quatre considerations: - la reactivite neutronique et l'enrichissement de l'uranium; - la temperature de fonctionnement; - la resistance aux effets du rayonnement; - la stabilite chimique; mais en definitive, lorsqu'il s'agira d'une application determinee, ce seront des considerations d'un autre ordre, comme le prix de revient, le poids et l'encombrement, qui determineront le choix entre piles a uranium metallique et piles a oxyde d'uranium. (auteur)
Recovery of uranium in mine waters

International Nuclear Information System (INIS)

Sugier, P.

1967-01-01

In a brief introductory survey the author indicates the date on which leaching was first observed in the CEA mines and lists the main factors necessary for, or favourable to, the solubilization of uranium in mines. Information is given on the various sources of this type at present identified in France and the methods used to recover uranium in mines situated near ore-concentration plants. An explanation is given for the use of the calcium precipitation technique in connection with waters produced in mines not situated near ore-concentration plants. Data are given on the results of laboratory tests carried out on waters containing uranium, together with a description of an industrial-scale facility built in consequence of these tests. Details are given of the statistical results obtained. The author concludes by outlining the programme which will be implemented in the near future with a view to increasing the tonnage of uranium produced by in situ leaching and indicates that the CEA engineers are very optimistic about the prospects of this new low-cost method of producing uranium. (author) [fr
Uranium project DINAMIGE-BRGM; Proyecto Uranio DINAMIGE-BRGM

Energy Technology Data Exchange (ETDEWEB)

Pirelli, H

1982-07-01

This Uranium review was carried out in the frame work of Uranium prospecting programme between (DINAMIGE-BRGM) from February to June 1982. It was included radimetric cutting in sedimentaries and crystallines ground (gondwanic basin of the NE).The task was developed (1.300.000 scale) in Cunapiru, Carrillada, Vichadero, Minas de Corrales, Paso Mazangano and Yaguari zones.
Water Treatment for Uranium at the U.S. Department of Energy's Legacy Management Sites

International Nuclear Information System (INIS)

Dayvault, J.; Bush, R.; Ribeiro, T.; Surovchak, S.; Powell, J.; Bartlett, T.; Carpenter, C.; Jacobson, C.; Miller, D.; Morrison, S.; Boylan, J.; Broberg, K.; Glassmeyer, C.; Hertel, W.

2009-01-01

The U.S. Department of Energy's Legacy Management (LM) Program is responsible for 82 sites as of September 30, 2008, more than 30 of which contain uranium contamination in the ground water. The compliance strategy for some of the uranium-contaminated ground-water systems is monitored natural attenuation (MNA); however, five sites have active ground-water remediation systems for uranium. Active remediation methods, goals, and scales vary widely among sites. This paper discusses and contrasts methods used to treat ground water contaminated with uranium at LM sites. At a former uranium milling site in Monticello, Utah, uranium-contaminated ground water is pumped through two reaction vessels containing a total of 7.6 cubic meters (m 3 ) of a mixture of gravel and zero-valent iron (ZVI). The flow rate is typically about 38 liters per minute (lpm), and the influent uranium concentration is about 300 micrograms per liter (μg/L). About 5.9 kilograms (kg) of uranium is removed from the aquifer per year. The system is monitored by a telemetry system and requires minimal maintenance; however, the reactive media requires replacement every 1 to 2 years. Some treated ground water is discharged back to the aquifer to enhance MNA, and some is discharged to a nearby creek. At the Rocky Flats Site near Denver, Colorado, contaminated ground water is collected in subsurface drains and pumped through a reaction vessel containing 136 m3 of a mixture of sawdust and ZVI, followed by a second reactor containing 40 m 3 of a mixture of gravel and ZVI. Microbial activity in the sawdust/ZVI reactor removes nitrate and some uranium, and the ZVI/gravel reactor removes the remainder of the uranium. The flow rate is typically about 1.9 lpm. The typical influent uranium concentration is about 40 μg/L, and the effluent concentration is less than 5 μg/L. Treated water is discharged to an infiltration gallery that feeds to a nearby creek. The system is removing approximately 0.05 kg of uranium per
Temperature/electric field scaling in Ferroelectrics

Energy Technology Data Exchange (ETDEWEB)

Hajjaji, Abdelowahed, E-mail: Hajjaji12@gmail.co [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Guyomar, Daniel; Pruvost, Sebastien [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Touhtouh, Samira [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco); Yuse, Kaori [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Boughaleb, Yahia [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco)

2010-07-01

The effects of the field amplitude (E) and temperature on the polarization and their scaling relations were investigated on rhombohedral PMN-xPT ceramics. The scaling law was based on the physical symmetries of the problem and rendered it possible to express the temperature variation ({Delta}{theta}) as an electric field equivalent {Delta}E{sub eq}=({alpha}+2{beta}xP(E,{theta}{sub 0}))x{Delta}{theta}. Consequently, this was also the case for the relationship between the entropy ({Gamma}) and polarization (P). Rhombohedral Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.75}Ti{sub 0.25}O{sub 3} ceramics were used for the verification. It was found that such an approach permitted the prediction of the maximal working temperature, using only purely electrical measurements. It indicates that the working temperature should not exceed 333 K. This value corresponds to the temperature maximum before the dramatic decrease of piezoelectric properties. Reciprocally, the polarization behavior under electrical field can be predicted, using only purely thermal measurements. The scaling law enabled a prediction of the piezoelectric properties (for example, d{sub 31}) under an electrical field replacing the temperature variation ({Delta}{theta}) by {Delta}E/({alpha}+2{beta}xp(E,{theta}{sub 0})). Inversely, predictions of the piezoelectric properties (d{sub 31}) as a function of temperature were permitted using purely only electrical measurements.
Temperature/electric field scaling in Ferroelectrics

International Nuclear Information System (INIS)

Hajjaji, Abdelowahed; Guyomar, Daniel; Pruvost, Sebastien; Touhtouh, Samira; Yuse, Kaori; Boughaleb, Yahia

2010-01-01

The effects of the field amplitude (E) and temperature on the polarization and their scaling relations were investigated on rhombohedral PMN-xPT ceramics. The scaling law was based on the physical symmetries of the problem and rendered it possible to express the temperature variation (Δθ) as an electric field equivalent ΔE eq =(α+2βxP(E,θ 0 ))xΔθ. Consequently, this was also the case for the relationship between the entropy (Γ) and polarization (P). Rhombohedral Pb(Mg 1/3 Nb 2/3 ) 0.75 Ti 0.25 O 3 ceramics were used for the verification. It was found that such an approach permitted the prediction of the maximal working temperature, using only purely electrical measurements. It indicates that the working temperature should not exceed 333 K. This value corresponds to the temperature maximum before the dramatic decrease of piezoelectric properties. Reciprocally, the polarization behavior under electrical field can be predicted, using only purely thermal measurements. The scaling law enabled a prediction of the piezoelectric properties (for example, d 31 ) under an electrical field replacing the temperature variation (Δθ) by ΔE/(α+2βxp(E,θ 0 )). Inversely, predictions of the piezoelectric properties (d 31 ) as a function of temperature were permitted using purely only electrical measurements.
Uranium in situ leach mining in the United States. Information circular

International Nuclear Information System (INIS)

Larson, W.C.

1978-01-01

This report discusses uranium in situ leach mining in the United States; the purpose of which is to acquaint the reader with an overview of this emerging mining technology. This report is not a technical discussion of the subject matter, but rather should be used as a reference source for information on in situ leaching. An in situ leaching bibliography is included as well as engineering data tables for almost all of the active pilot-scale and commercial uranium in situ leaching operators. These tables represent a first attempt at consolidating operational data in one source, on a regional scale. Additional information is given which discusses the current Bureau of Mines uranium in situ leaching research program. Also included is a listing of various State and Federal permitting agencies, and a summary of the current uranium in situ leaching operators. Finally, a glossary of terms has been added, listing some of the more common terms used in uranium in situ leach mining
International uranium market

International Nuclear Information System (INIS)

Neff, T.L.; Jacoby, H.D.

1980-12-01

Discussed in this report are 1) how one might think about uranium demand, resources and supply, 2) how producers and consumers see the market and are likely to behave, including specifics about export and import commitments, and 3) how these actors are brought together in the international market. The general conclusion is that much of current anxiety about future uranium supply results primarily from a brief but difficult period in the mid- to late-1970's; and that current conditions and trends are favorable (at least to consumers) that there is now little basis for concern. Inventories contractual positions and producer commitments--when compared with realistic (or even unrealistic) demand estimates--imply a buyer's market for at least the next decade. The result will be considerable increases in market flexibility and resilience to shock, and real prices that are low relative to those of the past few years. There is a need to reconsider assumptions about desired directions of technological development, for many current programs were planned in an era of pessimism about uranium supply and process. Similar questions must be raided about nonproliferation policies that depend on some level of control of fuel supplies by the industrial nations. With a soft and more diversified uranium market, leverage that may have existed in the past is rapidly being eroded. Finally, as world prices turn soft, there may be significant problems created for U.S. uranium producers, who have relatively high costs in relation to several large-scale foreign suppliers
Study On The Choice Of Leaching System For Thanh My, Quang Nam Province Uranium Ores Treatment

International Nuclear Information System (INIS)

Than Van Lien; Nguyen Dinh Van; Tran The Dinh

2011-01-01

In order to implement the plan of peaceful uses of atomic energy, the Radioactive and Rare Earth Geology Division have been carried out the uranium ores exploitation project in Thanh My area of Quang Nam province since 2010. The treatment uranium ores samples is one of works of this project. In order to preparing for uranium ores samples treatment, the Institute for Technology of Radioactive and Rare Elements have been studied and have chosen the heap leaching method for Thanh My uranium ore treatment. The ore, which contained less than 0.07% U, was crushed to -1 cm before being placed in the heap. The acid consumption for this heap leach operation was approximately ranged 40 kg - 45 kg of H 2 SO 4 per tonne of ore, and oxidant 4 kg of MnO 2 per tonne of ore. The entire treatment cycle required 20-25 days, the recovery exceeded 80%, the leached tails contained less than 0.01% U. The experimental results were comparable with those obtained in the field scale heap leaching in the world. (author)
Preliminary discussion on deep-sourced uranium metallogenesis and deep prospecting

International Nuclear Information System (INIS)

Huang Shijie

2006-01-01

Prospecting for hydrothermal type uranium deposits should be aimed at medium-to large-sized deposits, and be guided by mantle-sourced, superimposed, deep-sourced metallogenic theory and the establishment of a multifactor, composite, deep-sourced metallogenic model. The author suggests that hydrothermal uranium deposits may be classified into three genetic types, i.e. hydrothermal circulation concentration, postmagmatic hydrothermal and mantle fluid concentration. These types of uranium deposits are characterized by their own metallogenic features and are concentrated in the same mineralization-concentrated area forming a metallogenic series. Large-sized uranium ore fields and rich-large uranium deposits are usually closely associated with mantle-sourced metallogenesis and the formation of such uranium ore fields and deposits is characterized by specific and unique regional geologic environments. Recognition criteria of mantle-sourced metallogenesis are preliminarily proposed in the paper. It is pointed out that prospecting in the future should follow the metallogenic model proper for the specific genetic type, and the establishment of operable prospecting model to realize the model-guided prospecting. (authors)
Uranium conversion

International Nuclear Information System (INIS)

Oliver, Lena; Peterson, Jenny; Wilhelmsen, Katarina

2006-03-01

FOI, has performed a study on uranium conversion processes that are of importance in the production of different uranium compounds in the nuclear industry. The same conversion processes are of interest both when production of nuclear fuel and production of fissile material for nuclear weapons are considered. Countries that have nuclear weapons ambitions, with the intention to produce highly enriched uranium for weapons purposes, need some degree of uranium conversion capability depending on the uranium feed material available. This report describes the processes that are needed from uranium mining and milling to the different conversion processes for converting uranium ore concentrate to uranium hexafluoride. Uranium hexafluoride is the uranium compound used in most enrichment facilities. The processes needed to produce uranium dioxide for use in nuclear fuel and the processes needed to convert different uranium compounds to uranium metal - the form of uranium that is used in a nuclear weapon - are also presented. The production of uranium ore concentrate from uranium ore is included since uranium ore concentrate is the feed material required for a uranium conversion facility. Both the chemistry and principles or the different uranium conversion processes and the equipment needed in the processes are described. Since most of the equipment that is used in a uranium conversion facility is similar to that used in conventional chemical industry, it is difficult to determine if certain equipment is considered for uranium conversion or not. However, the chemical conversion processes where UF 6 and UF 4 are present require equipment that is made of corrosion resistant material
Synthesis, characterization, and reactivity of a uranium(VI) carbene imido oxo complex

Energy Technology Data Exchange (ETDEWEB)

Lu, Erli; Cooper, Oliver J.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.; Liddle, Stephen T. [School of Chemistry, University of Nottingham (United Kingdom); Tuna, Floriana; McInnes, Eric J.L. [School of Chemistry and Photon Science Institute, University of Manchester (United Kingdom)

2014-06-23

We report the uranium(VI) carbene imido oxo complex [U(BIPM{sup TMS})(NMes)(O)(DMAP){sub 2}] (5, BIPM{sup TMS}=C(PPh{sub 2}NSiMe{sub 3}){sub 2}; Mes=2,4,6-Me{sub 3}C{sub 6}H{sub 2}; DMAP=4-(dimethylamino)pyridine) which exhibits the unprecedented arrangement of three formal multiply bonded ligands to one metal center where the coordinated heteroatoms derive from different element groups. This complex was prepared by incorporation of carbene, imido, and then oxo groups at the uranium center by salt elimination, protonolysis, and two-electron oxidation, respectively. The oxo and imido groups adopt axial positions in a T-shaped motif with respect to the carbene, which is consistent with an inverse trans-influence. Complex 5 reacts with tert-butylisocyanate at the imido rather than carbene group to afford the uranyl(VI) carbene complex [U(BIPM{sup TMS})(O){sub 2}(DMAP){sub 2}] (6). (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Organic tissues, graphite, and hydrocarbons in host rocks of the Rum Jungle Uranium Field, northern Australia

Science.gov (United States)

Foster, C.B.; Robbins, E.I.; Bone, Y.

1990-01-01

The Rum Jungle Uranium field consists of at least six early Proterozoic deposits that have been mined either for uranium and/or the associated base and precious metals. Organic matter in the host rocks of the Whites Formation and Coomalie Dolomite is now predominantly graphite, consistent with the metamorphic history of these rocks. For nine samples, the mean total organic carbon content is high (3.9 wt%) and ranged from 0.33 to 10.44 wt%. Palynological extracts from the host rocks include black, filamentous, stellate (Eoastrion-like), and spherical morphotypes, which are typical of early Proterozoic microbiota. The colour, abundance, and shapes of these morphotypes reflect the thermal history, organic richness, and probable lacustrine biofacies of the host rocks. Routine analysis of rock thin sections and of palynological residues shows that mineral grains in some of the host rocks are coated with graphitized organic matter. The grain coating is presumed to result from ultimate thermal degradation of a petroleum phase that existed prior to metamorphism. Hydrocarbons are, however, still present in fluid inclusions within carbonates of the Coomalie Dolomite and lower Whites Formation. The fluid inclusions fluoresce dull orange in blue-light excitation and their hydrocarbon content is confirmed by gas chromatography of whole-rock extracts. Preliminary analysis of the oil suggests that it is migrated, and because it has escaped graphitization through metamorphism it is probably not of early Proterozoic age. The presence of live oil is consistent with fluid inclusion data that suggest subsequent, low-temperature brine migration through the rocks. The present observations support earlier suggestions that organic matter in the host formations trapped uranium to form protore. Subsequent fluid migrations probably brought additional uranium and other metals to these formations, and the organic matter provided a reducing environment for entrapment. ?? 1990.
Spectrophotometric determination of uranium with arsenazo previous liquid-liquid extraction and colour development in organic medium

International Nuclear Information System (INIS)

Palomares Delgado, F.; Vera Palomino, J.; Petrement Eguiluz, J. C.

1964-01-01

The determination of uranium with arsenazo is hindered by a great number of cation which form stable complexes with the reactive and may given rise to serious interferences. By studying the optimum conditions of uranium the extraction be means of tributylphosphate solutions dissolved in methylisobuthylketone, under conditions for previous masking of the interfering cations, an organic extract was obtained containing all the uranium together with small amounts of iron. The possible interference derived from the latter element is avoided by reduction with hydroxylammoniumchlorid followed by complex formation of the Fe(II)-ortophenantroline compound in alcoholic medium. (Author) 17 refs
Scaling of Anomalous Hall Effects in Facing-Target Reactively Sputtered Fe4N Films

KAUST Repository

Zhang, Yan

2015-05-13

Anomalous Hall effect (AHE) in the reactively sputtered epitaxial and polycrystalline γ′-Fe4N films is investigated systematically. The Hall resistivity is positive in the entire temperature range. The magnetization, carrier density and grain boundaries scattering have a major impact on the AHE scaling law. The scaling exponent γ in the conventional scaling of is larger than 2 in both the epitaxial and polycrystalline γ′-Fe4N films. Although γ>2 has been found in heterogeneous systems due to the effects of the surface and interface scattering on AHE, γ>2 is not expected in homogenous epitaxial systems. We demonstrated that γ>2 results from residual resistivity (ρxx0) in γ′-Fe4N films. Furthermore, the side-jump and intrinsic mechanisms are dominant in both epitaxial and polycrystalline samples according to the proper scaling relation.
Soil treatment to remove uranium and related mixed radioactive contaminants. Final report September 1992--October 1995

International Nuclear Information System (INIS)

1996-07-01

A research and development project to remove uranium and related radioactive contaminants from soil by an ultrasonically-aided chemical leaching process began in 1993. The project objective was to develop and design, on the basis of bench-scale and pilot-scale experimental studies, a cost-effective soil decontamination process to produce a treated soil containing less than 35 pCi/g. The project, to cover a period of about thirty months, was designed to include bench-scale and pilot-scale studies to remove primarily uranium from the Incinerator Area soil, at Fernald, Ohio, as well as strontium-90, cobalt-60 and cesium-137 from a Chalk River soil, at the Chalk River Laboratories, Ontario. The project goal was to develop, design and cost estimate, on the basis of bench-scale and pilot-scale ex-situ soil treatment studies, a process to remove radionuclides form the soils to a residual level of 35 pCi/g of soil or less, and to provide a dischargeable water effluent as a result of soil leaching and a concentrate that can be recovered for reuse or solidified as a waste for disposal. In addition, a supplementary goal was to test the effectiveness of in-situ soil treatment through a field study using the Chalk River soil
Present condition of uranium exploration and the prospecting direction in southwest China

International Nuclear Information System (INIS)

Ni Shijun; Zhang Chengjiang; Xu Zhengqi; Chen Youliang

2012-01-01

Southwest China is one of the important areas where uranium is distributed. After exploration and research of 50 years, the metallogenic conditions for uranium deposits in Southwest China have been studied more deeply. It is found that uranium ore in Southwest China has more complete types, less deposits and more mineral occurrences, and the amount of uranium resources is disproportionate to the area of Southwest China. Researches of years show that Southwest China is characterized by thick crust. thick sedimentary cover, weak crust-mantle interaction, weak deep flu id activity in shallow strata, strong dynamic formation in shallow strata and obvious deep geologic process on block mar- gins. In this paper, the control of deep geologic process and evolution in uranium metallogenesis in Southwest China is studied by employing new theories and thoughts on the fundamental concept that deep geologic process and evolution has important control on super-large scale deposits. The study focuses on the crust-mantle structure and evolution with uranium metallogenesis, structural and magmatic activity and deep fluid activity with uranium metallogenesis, and ore-con- trolling role of penetrating faults on block edges and inside the blocks. To offer theoretic basis for large-scale uranium deposit prospecting in Southwest China, the key research on uranium deposit in Southwest China in future should be on the deep geologic evolution and uranium metallogenesis in Western Qinling Region, the uranium metallogenesis of iron oxide copper gold deposits on Kangdian axis, the uranium metallogenesis in Yunnan-Guizhou contiguous area, the hydrothermal uranium metallogenesis in Eastern Tibet and Western Sichuan, and the connection between sandstone type uranium deposit and magmatic activity. Meanwhile, the above regions are also the key ones for uranium deposit prospecting in Southwest China in a rather long period in future. (authors)
Machining of uranium and uranium alloys

International Nuclear Information System (INIS)

Morris, T.O.

1981-01-01

Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures
Process for extracting uranium from phosphoric acid solutions

International Nuclear Information System (INIS)

1977-01-01

The description is given of a method for extracting uranium from phosphoric acid solutions whereby the previously oxided acid is treated with an organic solvent constituted by a mixture of dialkylphosphoric acid and trialkylphosphine oxide in solution in a non-reactive inert solvent so as to obtain de-uraniated phosphoric acid and an organic extract constituted by the solvent containing most of the uranium. The uranium is then separated from the extract as uranyl ammonium tricarbonate by reaction with ammonia and ammonium carbonate and the extract de-uraniated at the extraction stage is recycled. The extract is treated in a re-extraction apparatus comprising not less than two stages. The extract to be treated is injected at the top of the first stage. At the bottom of the first stage, ammonia is introduced counter current as gas or as an aqueous solution whilst controlling the pH of the first stage so as to keep it to 8.0 or 8.5 and at the bottom of the last stage an ammonium carbonate aqueous solution is injected in a quantity representing 50 to 80% of the stoichiometric quantity required to neutralize the dialkylphosphoric acid contained in the solvent and transform the uranium into uranyl ammonium tricarbonate [fr

Uranium mineralization in the Bohemian Massif and its exploration

International Nuclear Information System (INIS)

Matolin, M.; Pluskal, O.; Rene, M.

1981-01-01

Long-term systematic and planned uranium survey including airborne, carborne, ground, logging and laboratory radiometric measurements as well as geological and geochemical investigations have shown a difference in radioactivity of two regional geological units in Czechoslovakia. The higher regional radioactivity of the Variscan granitoid rocks of the Bohemian Massif differs from that of the West Carpathians and is associated with more frequent uranium mineralization. Endogenous vein-type uranium mineralization has a spatial association with high-radioactivity granitoids in the Bohemian Massif. Airborne prospection defined rock radioactivity features on a regional scale while surface and subsurface radiometric and geological investigations using various techniques localized important uranium deposits. Complex statistical evaluation of numerous geophysical and geological data was studied in order to delineate uranium-favourable areas. (author)
Uranium, depleted uranium, biological effects; Uranium, uranium appauvri, effets biologiques

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

Physicists, chemists and biologists at the CEA are developing scientific programs on the properties and uses of ionizing radiation. Since the CEA was created in 1945, a great deal of research has been carried out on the properties of natural, enriched and depleted uranium in cooperation with university laboratories and CNRS. There is a great deal of available data about uranium; thousands of analyses have been published in international reviews over more than 40 years. This presentation on uranium is a very brief summary of all these studies. (author)
Biamperometric estimation of uranium in input KMP samples of spent fuel reprocessing plant: field experience

International Nuclear Information System (INIS)

Gurba, P.B.; Dhakras, S.P.; Chaugule, G.A.; Venugopal, A.K.; Singh, R.K.; Bajpai, D.D.; Nair, P.R.; Xavier, Mary; Aggarwal, S.K.

2000-01-01

Feasibility of simple, precise and accurate biamperometric determination of uranium at about 0.1 mg level was earlier established using simulated uranium standards. To evaluate the usefulness of this method for accurate determination of uranium in spent fuel dissolver solution samples, analytical work was carried out
Current uranium activities in Pakistan

International Nuclear Information System (INIS)

Moghal, M.Y.

2001-01-01

The rocks of Siwaliks group in Pakistan, extending from Kashmir in the east through Potwar Plateau, Bannu Basin and Sulaiman range up to the Arabian Sea in the west have been extensively explored for uranium. The Dhok Pathan Formation, which is younger member of the middle Siwaliks has been aeroradiometrically surveyed and extensively prospected on foot. A large number of anomalies were encountered in Kashmir, Potwar Plateau, Bannu Basin and Sulaiman range. While exploratory work in Sulaiman range and Bannu Basin yielded a few workable deposits, none of the anomalous areas yielded an ore grade concentration in Potwar Plateau. As conventional exploration activities in Potwar Plateau did not yield any ore grade concentration therefore a resource potential evaluation programme through geological modeling was started under the guidance of an IAEA expert. The volcanic material found in the middle Siwaliks is considered to be the main source of uranium and siliceous cement in the sandstones. These findings have considerably increased uranium potential in Siwaliks. The tectonic deformation during and after the deposition of Siwaliks is considered to be the main reason for mobilization of uranium, while permeability barriers and upward movement of oil products may provide trappings for the mobilized uranium. Through this survey south western part of Potwar Plateau being relatively less deformed is considered to provide conducive environments for concentration of uranium. Low grade uranium concentrations have also been discovered in carbonatites in northern part of Pakistan. Preliminary exploration in Sallai Patti carbonatite through drilling supplemented by trenching, pitting and aditing, subsurface continuation of surface concentrations has been confirmed. The ore contains about 200 ppm of uranium and 3 to 4% phosphate in addition to magnetite, rare metals and rare earths. It has been demonstrated on laboratory/pilot scale that the concentrations of uranium and phosphate
Calculation of research reactor RA power at uncontrolled reactivity changes

International Nuclear Information System (INIS)

Cupac, S.

1978-01-01

The safety analysis of research reactor RA involves also the calculation of reactor power at uncontrolled reactivity changes. The corresponding computer code, based on Point Kinetics Model has been made. The short review of method applied for solving kinetic equations is given and several examples illustrating the reactor behaviour at various reactivity changes are presented. The results already obtained are giving rather rough picture of reactor behaviour in considered situations. This is the consequence of using simplified feed back and reactor cooling models, as well as temperature reactivity coefficients, which do not correspond to the actual reactor RA structure (which is now only partly fulfilled with 80% enriched uranium fuel). (author) [sr
Mineralization mechanism and geodynamic setting of No. 337 deposit in Xiazhuang uranium orefield

International Nuclear Information System (INIS)

Zhang Zhanshi; Wu Jianhua; Liu Shuai; Hua Renmin

2009-01-01

Uranium deposit No.337 in Xiazhuang uranium orefield has been regarden as a representative of the earliest forming, relatively high temperature and short time gap between the formation of pluton and the mineralization. But the latest study revealed that the formation age of the Maofeng pluton, which is the most important uranium host granite in Xiazhuang uranium orefield, is 206-238.2 Ma by LA-ICP-MS zircon dating, while the secondary origin muscovite in Maofeng pluton has the age of 131-136 Ma by 40 Ar/ 39 Ar dating which correspond to the main mineralization age of 130.3-138 Ma in uranium deposit No.337. In Guidong granitic complex, Maofeng pluton shown some unique characteristics. It has the Al 2 O 3 /TiO 2 ratio that infers the lowest forming temperature, the lowest ΣREE and it is the only pluton which presents typical tetrad effects of REE, it is also shown a varying δ 18 O values and the lowest( 87 Sr/ 86 Sr) i values. According to the above findings, a concept model of uranium mineralization and geodynamic setting for No.337 uranium deposit might be presented: in late or post-collision stage of Indosinian orogeny, strongly peraluminous granite of Maofeng pluton formed from partial melting of uranium rich formations. Intrusion of maficdyke in late Yanshanian Period(<140 Ma), caused large fluid movement. Uranium was reactivated and extracted from the altered granite,and precipitated in some favorite places to form uranium ore bodies. Uranium deposit No.337 is the typical representative of the first stage uranium mineralization in Xiazhuang uranium orefield. (authors)
Bioleaching - an alternate uranium ore processing technology for India

International Nuclear Information System (INIS)

Abilash; Mehta, K.D.; Kumar, V.; Pandey, B.D.; Tamarakar, P.K.

2010-01-01

Meeting the feed supply of uranium fuel in the present and planned nuclear reactors calls for huge demand of uranium, which at the current rate of production, shows a mismatch. The processing methods at UCIL (DAE) needs to be modified/changed or re-looked into because of its very suitability in near future for low-index raw materials which are either unmined or stacked around if mined. There is practically no way to process tailings with still some values. Efforts were made to utilize such resources (low-index ore of Turamdih mines, containing 0.03% U 3 O 8 ) by NML in association with UCIL as a national endeavor. In this area, the R and D work showed the successful development of a bioleaching process from bench scale to lab scale columns and then finally to the India's first ever large scale column, from the view point of harnessing such a processing technology as an alternative for the uranium industry and nuclear sector in the country. The efforts culminated into the successful operation of large scale trials at the 2 ton level column uranium bioleaching that was carried out at the site of UCIL, Jaduguda yielding a maximum recovery of 69% in 60 days. This achievement is expected to pave the way for scaling up the activity to a 100T or even more heap bioleaching trials for realization of this technology, which needs to be carried out with the support of the nuclear sector in the country keeping in mind the national interest. (author)
Epigenetic zonation and fluid flow history of uranium-bearing fluvial aquifer systems, south Texas uranium province. Report of Investigations No. 119

International Nuclear Information System (INIS)

Galloway, W.E.

1982-01-01

The Oligocene-Miocene fluvial uranium host aquifers of the South Texas uranium province were deposited principally as syndepositionally oxidized sands and muds. Early intrusion of reactive sulfide-enriched waters produced large intrastratal islands of epigenetic sulfidic alteration, which contain isotopically heavy pyrite exhibiting unique replacement textures. The only known reservoir containing such sulfidic waters is the deeply buried Mesozoic carbonate section beneath the thick, geopressured Tertiary basin fill. Thermobaric waters were expulsed upward along major fault zones into shallow aquifers in response to a pressure head generated by compaction and dehydration in the abyssal ground-water regime. Vertical migration of gaseous hydrogen sulfide was less important. Repeated flushing of the shallow aquifers by oxidizing meteoric waters containing anomalous amounts of uranium, selenium, and molybdenum alternating with sulfidic thermobaric waters caused cyclic precipitation and oxidation of iron disulfide. Uranium deposits formed along hydrologically active oxidation interfaces separating epigenetic sulfidic and epigenetic oxidation zones. Multiple epigenetic events are recorded in imperfectly superimposed, multiple mineralization fronts, in regional and local geometric relations between different alteration zones, and in the bulk matrix geochemistry and mineralogy of alteration zones. The dynamic mineralization model described in this report may reflect processes active in many large, depositionally active basins
Mineral solubility and free energy controls on microbial reaction kinetics: Application to contaminant transport in the subsurface

Energy Technology Data Exchange (ETDEWEB)

Taillefert, Martial [Georgia Inst. of Technology, Atlanta, GA (United States); Van Cappellen, Philippe [Univ. of Waterloo, ON (Canada)

2016-11-14

Recent developments in the theoretical treatment of geomicrobial reaction processes have resulted in the formulation of kinetic models that directly link the rates of microbial respiration and growth to the corresponding thermodynamic driving forces. The overall objective of this project was to verify and calibrate these kinetic models for the microbial reduction of uranium(VI) in geochemical conditions that mimic as much as possible field conditions. The approach combined modeling of bacterial processes using new bioenergetic rate laws, laboratory experiments to determine the bioavailability of uranium during uranium bioreduction, evaluation of microbial growth yield under energy-limited conditions using bioreactor experiments, competition experiments between metabolic processes in environmentally relevant conditions, and model applications at the field scale. The new kinetic descriptions of microbial U(VI) and Fe(III) reduction should replace those currently used in reactive transport models that couple catabolic energy generation and growth of microbial populations to the rates of biogeochemical redox processes. The above work was carried out in collaboration between the groups of Taillefert (batch reactor experiments and reaction modeling) at Georgia Tech and Van Cappellen (retentostat experiments and reactive transport modeling) at University of Waterloo (Canada).
Uranium Oxide Rate Summary for the Spent Nuclear Fuel (SNF) Project (OCRWM)

Energy Technology Data Exchange (ETDEWEB)

PAJUNEN, A.L.

2000-09-20

The purpose of this document is to summarize the uranium oxidation reaction rate information developed by the Hanford Spent Nuclear Fuel (SNF) Project and describe the basis for selecting reaction rate correlations used in system design. The selection basis considers the conditions of practical interest to the fuel removal processes and the reaction rate application during design studies. Since the reaction rate correlations are potentially used over a range of conditions, depending of the type of evaluation being performed, a method for transitioning between oxidation reactions is also documented. The document scope is limited to uranium oxidation reactions of primary interest to the SNF Project processes. The reactions influencing fuel removal processes, and supporting accident analyses, are: uranium-water vapor, uranium-liquid water, uranium-moist air, and uranium-dry air. The correlation selection basis will consider input from all available sources that indicate the oxidation rate of uranium fuel, including the literature data, confirmatory experimental studies, and fuel element observations. Trimble (2000) summarizes literature data and the results of laboratory scale experimental studies. This document combines the information in Trimble (2000) with larger scale reaction observations to describe uranium oxidation rate correlations applicable to conditions of interest to the SNF Project.
Uranium Oxide Rate Summary for the Spent Nuclear Fuel (SNF) Project (OCRWM)

International Nuclear Information System (INIS)

PAJUNEN, A.L.

2000-01-01

The purpose of this document is to summarize the uranium oxidation reaction rate information developed by the Hanford Spent Nuclear Fuel (SNF) Project and describe the basis for selecting reaction rate correlations used in system design. The selection basis considers the conditions of practical interest to the fuel removal processes and the reaction rate application during design studies. Since the reaction rate correlations are potentially used over a range of conditions, depending of the type of evaluation being performed, a method for transitioning between oxidation reactions is also documented. The document scope is limited to uranium oxidation reactions of primary interest to the SNF Project processes. The reactions influencing fuel removal processes, and supporting accident analyses, are: uranium-water vapor, uranium-liquid water, uranium-moist air, and uranium-dry air. The correlation selection basis will consider input from all available sources that indicate the oxidation rate of uranium fuel, including the literature data, confirmatory experimental studies, and fuel element observations. Trimble (2000) summarizes literature data and the results of laboratory scale experimental studies. This document combines the information in Trimble (2000) with larger scale reaction observations to describe uranium oxidation rate correlations applicable to conditions of interest to the SNF Project
Technique for large-scale structural mapping at uranium deposits i in non-metamorphosed sedimentary cover rocks

International Nuclear Information System (INIS)

Kochkin, B.T.

1985-01-01

The technique for large-scale construction (1:1000 - 1:10000), reflecting small amplitude fracture plicate structures, is given for uranium deposits in non-metamorphozed sedimentary cover rocks. Structure drill log sections, as well as a set of maps with the results of area analysis of hidden disturbances, structural analysis of iso-pachous lines and facies of platform mantle horizons serve as sour ce materials for structural mapplotting. The steps of structural map construction are considered: 1) structural carcass construction; 2) reconstruction of structure contour; 3) time determination of structure initiation; 4) plotting of an additional geologic load
Uranium resources evaluation model as an exploration tool

International Nuclear Information System (INIS)

Ruzicka, V.

1976-01-01

Evaluation of uranium resources, as conducted by the Uranium Resources Evaluation Section of the Geological Survey of Canada, comprises operations analogous with those performed during the preparatory stages of uranium exploration. The uranium resources evaluation model, simulating the estimation process, can be divided into four steps. The first step includes definition of major areas and ''unit subdivisions'' for which geological data are gathered, coded, computerized and retrieved. Selection of these areas and ''unit subdivisions'' is based on a preliminary appraisal of their favourability for uranium mineralization. The second step includes analyses of the data, definition of factors controlling uranium minearlization, classification of uranium occurrences into genetic types, and final delineation of favourable areas; this step corresponds to the selection of targets for uranium exploration. The third step includes geological field work; it is equivalent to geological reconnaissance in exploration. The fourth step comprises computation of resources; the preliminary evaluation techniques in the exploration are, as a rule, analogous with the simplest methods employed in the resource evaluation. The uranium resources evaluation model can be conceptually applied for decision-making during exploration or for formulation of exploration strategy using the quantified data as weighting factors. (author)
Event classification related to overflow of solvent containing uranium according to the INES scale (International Nuclear and Radiological Event Scale); Classificacao do evento de transbordamento de solvente contendo uranio segundo a escala INES (International Nuclear and Radiological Event Scale)

Energy Technology Data Exchange (ETDEWEB)

Dourado, Eneida R.G.; Assis, Juliana T. de; Lage, Ricardo F., E-mail: cneida@inb.gov.br, E-mail: julianateixeira@inb.gov.br, E-mail: rlage@inb.gov.br [lndustrias Nucleares do Brasil S/A (CLISE.P/INB), Rio de Janeiro, RJ (Brazil). Coordenacao de Licenciamento Nuclear e Ambiental, Saude e Seguranca; Lopes, Karina B., E-mail: karina@inb.gov.br [lndustrias Nucleares do Brasil S/A (CPRAD/INB), Rio de Janeiro, RJ (Brazil). Coordenacao de Protecao Radiologica

2013-11-01

This paper aims to frame the event overflow organic solvent rich in uranium, from a decanter of ore beneficiation plant, caused by the fall in the supply of electricity, according to the criteria established by the International Nuclear Event Scale and radiological (INES), facilitating the understanding of the occurrence and communication with the public regarding the radiation safety aspects involved. With the fall of electricity, routine procedures in situations of installation stop were performed, however, due to operational failure, the valve on the transfer line liquor was not closed. Thus, the mixer continued being fed with liquor, that led the consequent leakage of solvent loaded with uranium. It reached the drainage system, and the box of rainwater harvesting of the plant. However, immediately after the detection of the event, corrective actions were initiated and the overflow was contained. Regulatory agencies followed the removal of the solvent and on the results of the analysis of environmental monitoring, found that the event did not provide exposure to workers or any other impact. Therefore, comparing the characteristics of the event and the guidelines proposed by the INES scale, it is concluded that the classification of the event is below scale/level 0, confirming the absence of risk to the local population, workers and the environment.
Morphology of uranium electrodeposits on cathode in electrorefining process: A phase-field simulation

International Nuclear Information System (INIS)

Shibuta, Yasushi; Sato, Takumi; Suzuki, Toshio; Ohta, Hirokazu; Kurata, Masaki

2013-01-01

Morphology of uranium electrodeposits on cathode with respect to applied voltage, zirconium concentration in the molten salt and the size of primary deposit during pyroprocessing is systematically investigated by the phase-field simulation. It is found that there is a threshold zirconium concentration in the molten salt demarcating planar and cellular/needle-like electrodeposits, which agrees with experimental results. In addition, the effect of size of primary deposits on the morphology of electrodeposits is examined. It is then confirmed that cellular/needle-like electrodeposits are formed from large primary deposits at all applied voltages considered, whereas both the planar and cellular/needle-like electrodeposits are formed from the primary deposits of 10 μm and less
Preliminary study of the uranium mineralization in the Eastern Belt, San Ramon, Oxapampa

International Nuclear Information System (INIS)

Valencia, Jacinto

2013-01-01

Permotriasic intrusive magmatic rocks of the eastern belt, consisting of San Ramon and Oxapampa granites, have a good favorability as fertile uranium rocks, one facie of red granite called monzo-granite; this condition is the result of the execution the cooperation project IPEN IAEA PER 2/16, ‘Improving the uranium potential of Peru’. The field work consisted of geological and radiometric review, with sampling of outcrop intrusive. The field radiometry and chemical analysis of the rock samples indicate the presence of radiometric and uranium anomalies, the petro-mineragraphyc study identified the presence of uranium ore, a phosphate hydrated uranium and copper, torbernite type, secondary mineral formed from leaching of primary uranium minerals in granite, the mineralization is found both in the granite and sedimentary rock contact. (author).
Selected bibliography for the extraction of uranium from seawater: evaluation of uranium resources and plant siting

Energy Technology Data Exchange (ETDEWEB)

Chen, A.C.T.; Gordon, L.I.; Rodman, M.R.; Binney, S.E.

1979-02-06

This bibliography contains 471 references pertaining to the evaluation of U.S. territorial ocean waters as a potential uranium resource and to the selection of a site for a plant designed for the large scale extraction of uranium from seawater. This bibliography was prepared using machine literature retrieval, bibliographic, and work processing systems at Oregon State University. The literature cited is listed by author with indices to the author's countries, geographic areas of study, and to a set of keywords to the subject matter.
Selected bibliography for the extraction of uranium from seawater: evaluation of uranium resources and plant siting

International Nuclear Information System (INIS)

Chen, A.C.T.; Gordon, L.I.; Rodman, M.R.; Binney, S.E.

1979-01-01

This bibliography contains 471 references pertaining to the evaluation of U.S. territorial ocean waters as a potential uranium resource and to the selection of a site for a plant designed for the large scale extraction of uranium from seawater. This bibliography was prepared using machine literature retrieval, bibliographic, and work processing systems at Oregon State University. The literature cited is listed by author with indices to the author's countries, geographic areas of study, and to a set of keywords to the subject matter
Treating water-reactive wastes

International Nuclear Information System (INIS)

Lussiez, G.W.

1993-01-01

Some compounds and elements, such as lithium hydride, magnesium, sodium, and calcium react violently with water to generate much heat and produce hydrogen. The hydrogen can ignite or even form an explosive mixture with air. Other metals may react rapidly only if they are finely divided. Some of the waste produced at Los Alamos National Laboratory includes these metals that are contaminated with radioactivity. By far the greatest volume of water-reactive waste is lithium hydride contaminated with depleted uranium. Reactivity of the water-reactive wastes is neutralized with an atmosphere of humid nitrogen, which prevents the formation of an explosive mixture of hydrogen and air. When we adjust the temperature of the nitrogen and the humidifier, the nitrogen can be more or less humid, and the rate of reaction can be adjusted and controlled. Los Alamos has investigated the rates of reaction of lithium hydride as a function of the temperature and humidity, and, as anticipated, they in with in temperature and humidity. Los Alamos will investigate other variables. For example, the nitrogen flow will be optimized to conserve nitrogen and yet keep the reaction rates high. Reaction rates will be determined for various forms of lithium waste, from small chips to powder. Bench work will lead to the design of a skid-mounted process for treating wastes. Other water-reactive wastes will also be investigated
300 Area Treatability Test: Laboratory Development of Polyphosphate Remediation Technology for In Situ Treatment of Uranium Contamination in the Vadose Zone and Capillary Fringe

Energy Technology Data Exchange (ETDEWEB)

Wellman, Dawn M.; Pierce, Eric M.; Bacon, Diana H.; Oostrom, Martinus; Gunderson, Katie M.; Webb, Samuel M.; Bovaird, Chase C.; Cordova, Elsa A.; Clayton, Eric T.; Parker, Kent E.; Ermi, Ruby M.; Baum, Steven R.; Vermeul, Vincent R.; Fruchter, Jonathan S.

2008-09-30

This report presents results from bench-scale treatability studies conducted under site-specific conditions to optimize the polyphosphate amendment for implementation of a field-scale technology demonstration to stabilize uranium within the 300 Area vadose and smear zones of the Hanford Site. The general treatability testing approach consisted of conducting studies with site sediment and under site conditions, to develop an effective chemical formulation and infiltration approach for the polyphosphate amendment under site conditions. Laboratory-scale dynamic column tests were used to 1) quantify the retardation of polyphosphate and its degradation products as a function of water content, 2) determine the rate of polyphosphate degradation under unsaturated conditions, 3) develop an understanding of the mechanism of autunite formation via the reaction of solid phase calcite-bound uranium and aqueous polyphosphate remediation technology, 4) develop an understanding of the transformation mechanism, the identity of secondary phases, and the kinetics of the reaction between uranyl-carbonate and -silicate minerals with the polyphosphate remedy under solubility-limiting conditions, and 5) quantify the extent and rate of uranium released and immobilized based on the infiltration rate of the polyphosphate remedy and the effect of and periodic wet-dry cycling on the efficacy of polyphosphate remediation for uranium in the vadose zone and smear zone.

Some links on this page may take you to non-federal websites. Their policies may differ from this site.