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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

An economic analysis of a light and heavy water moderated reactor synergy: burning americium using recycled uranium

An economic analysis is presented for a proposed synergistic system between 2 nuclear utilities, one operating light water reactors (LWR) and another running a fleet of heavy water moderated reactors (HWR). Americium is partitioned from LWR spent nuclear fuel (SNF) to be transmuted in HWRs, with a consequent averted disposal cost to the LWR operator. In return, reprocessed uranium (RU) is supplied to the HWRs in sufficient quantities to support their operation both as power generators and americium burners. Two simplifying assumptions have been made. First, the economic value of RU is a linear function of the cost of fresh natural uranium (NU), and secondly, plutonium recycling for a third utility running a mixed oxide (MOX) fuelled reactor fleet has been already taking place, so that the extra cost of americium recycling is manageable. We conclude that, in order for this scenario to be economically attractive to the LWR operator, the averted disposal cost due to partitioning americium from LWR spent fuel must exceed 214 dollars per kg, comparable to estimates of the permanent disposal cost of the high level waste (HLW) from reprocessing spent LWR fuel. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Dissolution of metal oxides and separation of uranium from lanthanides and actinides in supercritical carbon dioxide

This paper investigates the feasibility of extracting and separating uranium from lanthanides and other actinides by using supercritical fluid carbon dioxide (sc-CO{sub 2}) as a solvent modified with tri-n-butylphosphate (TBP) for the development of a counter current stripping technique, which would be a more efficient and environmentally benign technology for spent nuclear fuel reprocessing compared to traditional solvent extraction. Several actinides (U, Pu, and Np) and europium were extracted in sc-CO{sub 2} modified with TBP over a range of nitric acid concentrations and then the actinides were exposed to reducing and complexing agents to suppress their extractability. According to this study, uranium/europium and uranium/plutonium extraction and separation in sc-CO{sub 2} modified with TBP is successful at nitric acid concentrations of less than 6 M and at nitric acid concentrations of less than 3 M with acetohydroxamic acid or oxalic acid, respectively. A scheme for recycling uranium from spent nuclear fuel by using sc-CO{sub 2} and counter current stripping columns is presented. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Uranium and Beryllium Decontamination and Decommissioning in a Developed Neighborhood - 17494

In September 2008, the United States Environmental Protection Agency (EPA), Region 1, issued an Administrative Order by Consent (AOC) that required the completion of a Non-Time-Critical Removal Action for the Nuclear Metals, Inc. Site (Site), which is located in Concord, Massachusetts. The AOC required decontamination and demolition of the site buildings and structures. The Site was originally used for radiological research and production, and included foundry equipment for melting metals, extrusion presses and metal working equipment, pickling and etching tanks, and electroplating equipment. In the 1970's, Nuclear Metals, Inc. developed a large scale depleted uranium manufacturing, operation, which included the manufacturing of penetrators, or bullets, from depleted uranium (DU) as a defense contractor for the U.S. Army. Later operations included production of beryllium alloy materials. The Site included a two-story, five-section interconnected building, a tank house, a hydrogen peroxide tank house, two gas cylinder storage huts, and four 'Butler' metal storage buildings, which had a combined footprint of approximately 17,000 square meters (185,000 square feet). The buildings were principally contaminated with DU and beryllium dust, along with asbestos, PCBs, lead and other constituents. The required removal action at the Site consisted of building stabilization activities to remove flammable materials, install temporary utilities and control dust to create a safe work environment within the buildings for site workers; removal of hazardous materials; demolition of all structures and equipment; and off-site disposal of waste materials. The Decontamination and Decommissioning (D and D) activities and highlights of some of the public involvement work required to complete building D and D work in a residential community are discussed. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

The Little Engine That Could: No Project is too Small for Sustainable Remediation Moab Uranium Mill Tailings Removal Project - 16427

Executive Order 13693, 'Planning for Federal Sustainability in the Next Decade', mandates the reduction of energy use and cost and greenhouse gas emissions, and the search for renewable or alternative energy solutions. DOE EM manages the Moab Uranium Mill Tailings Remedial Action Project in Utah that involves relocating a 16-million-ton uranium mill tailings pile and associated contaminated materials at the former Atlas mill site to a permanent disposal cell constructed near Crescent Junction, Utah, predominantly by rail. Project personnel strive to support the Executive Order in making preparations for the impacts of climate change. Meeting the goals of the Executive Order in light of the remote location and limited resources of the Project sites often requires an innovative approach and perseverance. The Moab Project is a 'Small Site' within EM and has a comparatively short-term completion date. As a result, large-scale sustainability projects, such as retrofits or remodels, do not offer a cost benefit over this period. Instead, less dramatic process changes are achievable. The Project purchases renewable wind energy through the local power provider to reduce Scope 2 (purchased electricity) greenhouse gas emissions. Toward its ambitious goal of achieving zero landfill waste, the Project has diverted over 50 percent of its nonhazardous solid waste from the local landfill through composting and recycling efforts. In particular, electronics must meet various sustainable criteria prior to purchase, and be recycled through donations and certified recyclers, diverting it from the waste stream. The Project has received multiple Green Buy Awards from DOE by reaching leadership goals for purchasing energy-efficient, water-efficient, bio-based, and recycled-content products. In fiscal year 2014, in response to President Obama's June 2014 memorandum, 'Sustainable Practices for Designed Landscapes and Supporting Pollinators on Federal Landscapes', the Project decided to take a proactive approach and work with a local pollinator group, hosting two beehives in a revegetation area on the Moab site. An increase in plant growth and blossoming plants in the revegetation area has been observed and is believed to be related to the added pollinators. The Project has previously seeded disturbed areas mainly with native drought-resistant species to reduce water usage. Storm water collected in sediment basins at the Crescent Junction site is used for dust control and compaction of mill tailings in the disposal cell. The Project worked with the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service to gain support for re-contouring a remediated area adjacent to the Colorado River, which borders the Moab site on the east, to allow the area to flood at a lower river stage. This re-contouring promotes more varied vegetation growth and river water that tops the west bank brings soil nutrients to inundated areas of the site. Ponded floodwater has been pumped into revegetation plots for irrigation, reducing freshwater usage. Innovation in sustainable practices comes in many different fashions. The Moab Project demonstrates that no project is too small to implement sustainable practices. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Tritium Recycling from Depleted Uranium Beds - 18098

Nuclear Sources and Services Inc. (NSSI) in Houston Texas houses a unique infrastructure to recover and recycle tritium from a variety of different waste streams. NSSI is licensed to operate within a 2-gram tritium inventory limit and accepts gaseous, aqueous, and tritiated-solid feedstock as sources for tritium recovery. For example, titanium-tritide foils from spent neutron generator sources are de-tritiated at 1000 deg. C in a high temperature desorption facility. Tritiated water is concentrated in a Combined Electrolysis Catalytic Exchange (CECE) system before the gas is transferred to a hydrogen isotope separator for tritium recovery. Mixed-waste liquids containing tritium and carbon-14 isotopes, typically generated in the pharmaceutical industry, are converted to tritiated water, CaC14O3, and inactive gaseous effluents using a high-temperature, two-stage, catalytic-oxidation destruction process with 99.9999% efficiency. [1-4] Depleted uranium (DU) beds are unloaded of tritium and chemically de-activated with oxygen in the bed unloading station. Recently NSSI has worked with the EPA to receive and unload tritium from a number of legacy DU beds found at a super fund site. The DU beds were un-characterized and ranged from 10 to 30 years in age. The variety and size of the beds meant that measuring the quantity of tritium by calorimetry would be prohibitively expensive. Ground disposal was problematic due to the unknown tritium inventory in the beds and the pyrophoricity of the depleted uranium. NSSI was able to unload the tritium from a representative sample of two DU beds, collect and measure the total activity of the gas destined for recycling and remove the hazardous material codes of the DU by de-activating the bed with oxygen before disposing them as low active waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Synchrotron Microdiffraction Study of Heavy-Ion-Irradiated Uranium-Molybdenum Dispersion Fuel

There has been an ongoing effort by the Department of Energy Office of Material Management and Minimization to convert research and test reactors from high-enriched to low-enriched uranium fuels. Uranium-molybdenum alloy fuel dispersed in an aluminum matrix (UMo-Al dispersion fuel) has emerged as the leading candidate fuel for converting the remaining high-power research reactors in Europe. One of the primary barriers to using this fuel type is the deleterious reaction of UMo with Al. Depending on the operating temperature of the reactor, this interaction layer can be amorphous under irradiation and allows for the accumulation of fission gas products in large bubbles, leading to unacceptable swelling of the fuel. Therefore, detailed characterization of the phases that form within the fuel and in the interaction layer is critical to understanding, and controlling, UMo-Al dispersion fuel behavior under irradiation. Furthermore, the phase stability of the UMo fuel is of great importance, as the alpha-UMo phase has undesirable swelling compared to the metastable gamma-UMo phase. Heavy ion irradiation was used to reproduce the interaction layer that develops in-reactor. Samples of both the fuel and interaction layer formed under ion irradiation were examined using the high-energy x-ray microdiffraction technique at the Advanced Photon Source (APS) at Argonne National Laboratory to examine the microstructure of the interaction layer. The high-resolution phase information obtained in this experiment provides a valuable basis for understanding the evolution of UMo-Al dispersion fuel under irradiation and as input for computational studies to improve predictive capabilities. Phase information for in-pile fuels can currently be determined from TEM samples (limited sample volume, limiting statistics), or by extrapolation from SEMEDS analysis. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Using Superfund Guidance and Tools for the Remediation of Uranium Mine sites - 19056

The Environmental Protection Agency (EPA) Office of Superfund Remediation and Technology Innovation (OSRTI) has primary responsibility for implementing the long-term (non-emergency) portion of a key U.S. law regulating cleanup of contaminated sites: the Comprehensive Environmental Response, Compensation and Liability Act, CERCLA, nicknamed 'Superfund.' The purpose of the Superfund program is to protect human health and the environment over the long term from releases or potential releases of hazardous substances from abandoned or uncontrolled hazardous waste sites. The focus of this paper is on the guidance and tools for addressing radioactively contaminated sites by the Superfund program that are most important when remediating uranium mine sites. This presentation will also discuss some of the key features of these tools that may have more utility at a uranium mine site. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Autonomous Radiological Survey Systems for Locating Fired Depleted Uranium Munitions - 19212

An ensemble of autonomous radiological survey platforms that utilize a suite of scintillation detectors that can be used to conduct radiological site characterization, assist with remediation efforts, or conduct site clearance in accordance with the Multi-Agency Radiologic Survey and Site Investigation Manual are described. The overall systems are composed of inorganic scintillators, light detection and ranging, global positioning, inertial guidance, wireless telemetry, and signal processing systems. Two primary designs are discussed: a three-meter wide platform and multiple half-meter-wide systems. The survey systems are used to conduct radiological surveys over large areas autonomously, without human involvement. The three-meter system has been designed to cover large, open areas free of obstacles. Smaller robotic platforms are designed to handle a large range of terrain types and to conduct surveys in areas that are plagued with obstacles, such as bushes and trees. The primary design criteria for these systems were accurate locating of fired depleted uranium (DU) munitions. Several U.S. Army facilities have remnant DU material on active firing ranges where DU rounds have been used in performance evaluations. Many ranges also have unexploded ordinance (UXO) challenges which are problematic for conducting walkover surveys. The combination of having active DU impacted firing ranges with UXO make conducting site characterization surveys very difficult and hazardous. The autonomous surveying systems allow radiological scanning data collection to be scheduled around range activities and reduces human exposure to ionizing radiation and UXO. All of the robotic platforms act independently, and are controlled by a centralized computer system via a wireless telemetry system. The central computer system is responsible for setting up survey units, survey paths, and scheduling which platform is to complete the scheduled survey. Unit selection and scheduling are completed by technicians, and the work is conducted autonomously by these survey platforms. The survey areas and survey paths are transmitted to each platform through the telemetry system. Radiological and positional data are collected by the systems and transmitted back to the central computer system in real-time. Collected data is saved to a database for post-survey analysis or can be analyzed in real-time. Analysis of the radiological data is used to construct radiation intensity and estimated DU concentration maps. Automatically generated reports for each survey unit will provide range managers with: survey coverage data maps, estimated uranium concentration maps, and a detailed list of areas that are above a user defined concentration. This paper describes the components of each of the surveying systems, their capabilities, and limitations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Prompt Neutron Decay Constants in a Highly Enriched Uranium-Lead Copper Reflected System

Rossi-{alpha} measurements were performed on highly enriched uranium (HEU)-lead copper reflected systems to determine the prompt neutron decay constants. These constants represent an eigenvalue characteristic of these particular critical configurations, which can be experimentally measured by the Rossi-a or pulse neutron source techniques and calculated by a deterministic or Monte Carlo method. In the measurements presented in this summary, highly enriched uranium interleaved with lead plates and reflected with copper were assembled to a high multiplication and the prompt neutron decay constants were determined by the Rossi-{alpha} technique. This research intended to benchmark the lead neutron cross sections; it was a collaboration between the Japanese Atomic Energy Agency (JAEA) Fast Critical Assembly Facility (FCA) in Tokai, Japan and the Los Alamos National Laboratory (LANL) in the U.S. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2015

Minimum critical masses of heterogeneous moderated plutonium and uranium metal systems and their practical application to operation limits - 14355

In criticality safety analysis it is important to recognize the significant differences in reactivity achieved when material transitions from the solid to solution regime. However, the intermediate area of mixed heterogeneous systems (i.e. collections of small pieces) has not been well characterized. To that end, a study has been completed to determine the effect of fissile material piece size/shape on minimum critical mass of a system. The study presented represents a calculation-based investigation of moderated arrays of fissionable material to expand on established plutonium and uranium solution curves of LA-10860 to add the heterogeneous regime between pure a solid and solution of fissionable material. The analysis performed consists of parametric studies utilizing the neutron transport code MCNP6 to calculate the critical mass of systems composed of moderated arrays of varying sizes of spheres, cubes, or elongated rods (height >> diameter). The boundary of the array is increased to find the critical mass for the particular piece geometry and fissile volume density. The different shapes were then compared at points with the same fissile volume density to demonstrate that the key relationship between varying piece shape is the surface area to volume ratio. The results show that as pieces get larger (i.e. more heterogeneous) the minimum critical mass starts to increase. This effect results from the moderation of neutrons becoming less and less effective due to increased self-shielding of larger individual pieces. For plutonium pieces at a surface area to volume ratio of < 13 the reactivity increase from additional neutron moderation can no longer overcome the reactivity decrease from the reduced core density (separation of material pieces). At this point the minimum critical mass is achieved when the plutonium is in a solid metal configuration. This effect is not noticed for uranium which responds much more quickly to moderation and thus almost any sized pieces will increase in reactivity when moderation is introduced. Summarizing the results of the calculation a surface area to volume ratio vs minimum critical mass curve is generated. The curve gives analysts a practical starting minimum critical mass in analysis of heterogeneous systems with known minimum material surface area to volume ratios. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Nuclear criticality safety of pipes networks containing uranium - 14437

In nuclear facilities, the transfer of fissile material in solution, gas or powder forms between process stages requires many transfer lines (called 'pipes' in this paper) which may be laid out into bundles or networks. In Nuclear Criticality Safety evaluations, it is usual to assimilate such networks as a unique cylinder which area bounds the sum of the surface of pipes making up the network. However, even if this geometric simplification appears intuitively safe, it is not conservative in all cases. The aim of this paper is therefore to explore the validity and limitations associated to the assessment of pipes networks by a unique cylinder. This paper presents the impact on the k{sub eff} value of a detailed modeling of a pipes network compared to a unique cylinder. Variables of interest considered in such calculations are pipes diameter, composition, pitches and layout. Fissile media taken into account are uranium systems enriched from 5 % to 93.5 % in {sup 235}U. Then, the impact on reactivity of pipes material, such as stainless steel or plastic, is discussed and the minimal or maximal safe thickness of material has been determined. Finally, this paper provides guidance on the nuclear criticality safety assessment of pipes networks for uranium systems. (authors)

42 ENGINEERING↗
DOE OSTI2025

LDRD conclusion poster - Synthesizing Heterometallic Uranium Single Crystals to Understand the Influence of the Secondary Metals on Uranyl Axial Bond Strength

Understanding how transition metals influenced the chemistry of lanthanide and actinide (f-element) materials is critical for advancing separation technologies, materials design, and coordination chemistry. This project examined how incorporating first-row transition metals affected the structural and spectroscopic properties of f-element coordination polymers. In uranium(VI)-based systems synthesized with 2,6-pyridinedicarboxylic acid (PDC) ligands, single-crystal X-ray diffraction and Raman spectroscopy revealed that the presence of transition metals shortened the uranyl axial bond and induced a blue shift in its symmetric stretching vibration—evidence of increased bond strength. Electronic structure analysis, including Density of States (DOS) calculations using density functional theory (DFT), revealed altered orbital overlaps and highlighted the role of transition metal d-orbitals in modulating bonding. Raman modes were modeled using truncated structural fragments in collaboration with the University of Notre Dame, and although the predicted frequencies were lower than experimental values, they remained within expected ranges. In parallel, similar experiments with cerium (Ce) in the presence of cobalt (Co) and PDC demonstrated multi-step single-crystal-to-single-crystal transformations—behavior not observed in the uranium systems. Initial products included light yellow, orange, and polycrystalline materials. Single-crystal X-ray diffraction studies, conducted in collaboration with the Colorado School of Mines, identified the yellow phase as monometallic Ce(PDC)2(H2O)2·4H2O and the orange phase as heterometallic Ce2Co(PDC)4(H2O)6. After standing in solution for one week, both phases fully transformed into a dark yellow crystalline phase, [Ce3(PDC)5(H2O)8].6(H2O). Remarkably, this transformation was reversible—disturbing the equilibrium by removing some crystals caused reversion to the initial Ce(PDC)2(H2O)2·4H2O phase, highlighting dynamic behavior. All three structures were previously unreported. Solid-state UV-visible and Raman spectroscopy further distinguished these phases, revealing ligand-to-metal charge transfer involving Ce and characteristic d–d transitions from Co(II). The precise mechanism driving these transformations remained unclear; however, pH-dependent experiments confirmed that the transformation did not occur when the pH decreased. Overall, the project demonstrated that transition metals could be employed to tune bonding interactions, structural dimensionality, and optical properties in f-element materials, establishing new pathways for designing functional heterometallic systems. The work resulted in several novel structural discoveries and fostered productive collaborations with the University of Notre Dame and the Colorado School of Mines.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2026

Irradiation Impact on Uranium Recovery Under Direct Extraction Conditions

Reducing the quantity of high-level radioactive waste is essential for minimizing environmental impact and improving efficiency of using natural resources for nuclear power. The current standard, Plutonium Uranium Solvent EXtraction (PUREX), uses tributyl phosphate (TBP) ligands to extract complexes of uranium and plutonium from a nitric acid (HNO3) phase. Although this method is effective, large volumes of HNO3 and the non-incinerable phosphate ligands increase the amount of hazardous waste produced. Alternative extractants and flowsheets have been proposed that allow for more selective extraction of radioactive metals, reduced nitric acid use, and easier incineration by only containing carbon, hydrogen, oxygen, and nitrogen (CHON). One candidate, N,N-di(2-ethylhexyl)-isobutyramide (DEHiBA) exhibits promising properties for direct extraction. A HNO3 pre-equilibrated DEHiBA phase selectively extracts U(VI), leaving plutonium, transuranics, and fission products behind as precipitate and reducing the volume of radioactive HNO3 produced.

38 - RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCL↗
DOE OSTI2016

Comparison of femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for uranium isotopic measurements

Feasibility tests were conducted using femtosecond and nanosecond laser ablation inductively coupled plasma mass spectrometry for rapid uranium isotopic measurements. The samples used in this study consisted of a range of pg quantities of known 235/238 U solutions as dried spot residues of 300 pL drops on silicon substrates. The samples spanned the following enrichments of 235 U: 0.5, 1.5, 2, 3, and 15.1%. In this direct comparison using these particular samples both pulse durations demonstrated near equivalent data can be produced on either system with respect to accuracy and precision. There is no question that either LA-ICP-MS method offers the potential for rapid, accurate and precise isotopic measurements of U10Mo materials whether DU, LEU or HEU. The LA-ICP-MS equipment used for this work is commercially available. The program is in the process of validating this work for large samples using center samples strips from Y-12 MP-1 LEU-Mo Casting #1.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Purification of Regenerated Uranium Hexafluoride by Removal of {sup 232,234}U in a Centrifuge Cascade with Prescribed Concentration of One of the Isotopes {sup 232,234,235}U

Schemes are proposed for purifying regenerated uranium hexafluoride by removal of {sup 232,234}U in an optimal centrifuge cascade with prescribed external concentration of one of the isotopes {sup 232,234,235}U. The cascade is optimized according to the criterion of minimum total number of centrifuges. The purification effect is achieved in the waste flow of the cascade when the feed point is shifted toward the product. The number of steps in the cascade is determined by a preliminary calculation of an R-cascade with different key components. The product parameters and the desirable number of the feed step are picked on the basis of the limit {sup 235}U concentration 5–20%. Calculations showing the possibility of cascades with different degrees of purification by removal of {sup 232,234}U were performed.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Infrared spectroscopic method for uranium isotopic analysis

A high performance infrared (HPIR) system was developed and demonstrated for the infrared absorption analysis of {sup 235}U and {sup 238}U isotopes in uranium hexafluoride gas samples. Sweeping the quantum cascade laser light source over the spectral range and sampling via a high-rate analog-to-digital converter provided 0.0005 cm-1 spectral resolution, which allowed for high-precision measurements of the isotopic peak shift. A data analysis method was developed using principal component analysis to predict the isotope weight % content of {sup 235}U. The HPIR precision, accuracy, and error were evaluated for a wide range of isotopic ratio samples (0.287 – 93.7 weight % {sup 235}U), and the results were compared to the International Target Values (ITVS) set forth by the International Atomic Energy Agency (IAEA) for non-destructive and destructive analytical techniques. The method meets or surpasses the IAEA ITVs for non-destructive analysis of samples with isotopic content of depleted to highly enriched. The results also demonstrated the capability of the HPIR system to correctly predict the {sup 235}U weight % content of a mislabeled sample whose isotopic distribution was validated by mass spectroscopic measurements. The HPIR measurement is nondestructive and, thus, allows for confirmatory analyses of the exact sample at a designated IAEA lab if higher-resolution or a certified analysis is needed. (author)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

Isolation of a TMTAA-Based Radical in Uranium bis-TMTAA Complexes

Here, we report the synthesis, characterization, and electronic structure studies of a series of thorium(IV) and uranium(IV) bis-tetramethyltetraazaannulene complexes. These sandwich complexes show remarkable stability towards air and moisture, even at elevated temperatures. Electrochemical studies show the uranium complex to be stable in three different oxidation states; isolation of the oxidized species reveals a rare case of a non-innocent tetramethyltetraazaannulene (TMTAA) ligand.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Homoleptic Aryl Complexes of Uranium (IV)

Abstract The synthesis and characterization of sterically unencumbered homoleptic organouranium aryl complexes containing U−C σ‐bonds has been of interest to the chemical community for over 70 years. Reported herein are the first structurally characterized, sterically unencumbered homoleptic uranium (IV) aryl‐ate species of the form [U(Ar) 6 ] 2− (Ar=Ph, p ‐tolyl, p ‐Cl‐Ph). Magnetic circular dichroism (MCD) spectroscopy and computational studies provide insight into electronic structure and bonding interactions in the U−C σ‐bond across this series of complexes. Overall, these studies solve a decades‐long challenge in synthetic uranium chemistry, enabling new insight into electronic structure and bonding in organouranium complexes.

Wolford, Nikki J.↗