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DOE OSTI2021

Effects of Al:Si and (Al + Na):Si ratios on the properties of the international simple glass, part I: Physical properties

Understanding composition-structure-property relationships of high-alumina nuclear waste glasses are important for vitrification of nuclear waste at the Hanford Site. Two series of glasses were designed, one with varying Al:Si ratios and the other with (Al+Na):Si ratios based on the International Simple Glass (ISG, a simplified nuclear waste model glass), with Al2O3 ranging from 0 to 23 mol % (0 to 32 wt. %). The glasses were synthesized and characterized using electron probe microanalysis, X-ray photoelectron spectroscopy, small angle X-ray scattering, high temperature oxide melt solution calorimetry, and infrared spectroscopy. Glasses were crystal free, and the lowest Na2O and Al2O3 glass formed an immiscible glass phase. Evolution of various properties - glass transition temperature, percentage of 4-coordinated B, enthalpy of glass formation - and infrared spectroscopy results indicate that structural effects differ based on the glass series.

Nuclear Waste Glass↗

DOE OSTI2025

Harvesting uranium from nuclear waste streams

Nuclear-fuel-cycle wastewater contains a considerable amount of uranium that must be removed. Here, a new electron-buffering adsorbent provides an economically efficient means of recycling uranium to address remediation and fuel resource needs.

Wiechert, Alexander I. [Oak Ridge National Laborat↗

DOE OSTI2022

Comprehensive Study of the Potential of Extracting and Processing Critical Minerals from Coal-Based Resources - Phase I

The Phase I report prepared for the Department of Energy addresses U.S. Executive Order 13817 titled A Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals, issued on December 20, 2017, that lists 35 critical minerals that are vulnerable to supply disruption. A comprehensive review of each of the minerals was conducted to determine the criticality based primarily on extractability from coal-based resources. Several other factors were also considered such as gaps in supply and demand, use in current technology, and the existence of viable substitutes. It was determined that the critical minerals that show highest potential for extraction from coal-based resources are lithium, rare earth elements (REEs), cobalt, and manganese. All four of the critical minerals listed serve an important role in the technology industry, have few substitutes, and have a heavy import reliance. Most notably are lithium, which is widely used in the electric vehicle industry, and the REEs which can be found in virtually all electronic devices. The research of critical mineral extraction from coal-based resources was completed using a combination of literature review from public sources as well as cooperation from coal mines and power plants across the United States. Samples collected from six different geographical locations across the U.S. were subjected to sample preparation (i.e., pH measurement, moisture content, particle size analysis) and characterization studies using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) and Scanning Electron Microscopy, Energy Dispersive X-Ray Spectroscopy (SEM-EDX) instruments. 27 samples of coal waste materials such as refuse, sludge, and fly ash were tested to characterize the rare earth element concentration by total rare earth elements (TREEs), heavy rare earth elements (HREEs), and light rare earth elements (LREEs). Of the 27 samples tested, 22 contained a TREE concentration higher than the threshold of 300 ppm, which is considered a viable feedstock material. 3 samples contained less than 300 ppm of TREEs; however, they were within 20 ppm of the threshold, and could potentially be considered viable sources in the future pending the advancement of more efficient extraction technologies. 2 of the 27 samples had significantly low TREE concentrations, which does not imply any potential for being a source for REEs. For the minerals identified as most critical in the literature review, a conceptual process flow diagram (PFD) was developed for their extraction from different coal-based feedstocks. The process targets selective recovery of one commodity (i.e., rare earths, lithium, cobalt, and manganese) via several hydrometallurgical separation methods. By identifying potentially extractable coal-based critical mineral resources, a study of the current and future market environments for each critical mineral, and a review of current processing methodologies for critical mineral extraction from coal-based resources, the foundation has been laid to further characterize and explore new resources and extraction techniques. As reliance on technologies in industries such as the production of electronic devices, batteries, and alloys containing critical minerals utilizing critical minerals continues to increase, a sound understanding of our nation’s dependence on and even the global criticality of certain critical minerals, will serve as a catalyst for innovation in virtually all fields of science.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2020

Electrical power generation from moderate-temperature radiative thermal sources

Moderate-temperature thermal sources (100° to 400°C) which radiate waste heat are often the by-product of mechanical work, chemical or nuclear reactions, or information processing. We demonstrate conversion of thermal radiation into electrical power using a bipolar grating-coupled complementary metal-oxide-silicon (CMOS) tunnel diode. A two-step photon-assisted tunneling charge pumping mechanism results in separation of charge carriers in pn-junction wells leading to a large open-circuit voltage developed across a load. Electrical power generation from a broadband blackbody thermal source has been experimentally demonstrated with converted power densities of 27 to 61 microwatts per square centimeter for thermal sources between 250° and 400°C. Scalable, efficient conversion of radiated waste heat into electrical power can be used to reduce energy consumption or to power electronics and sensors.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2023

Decision-Making Framework to Evaluate Opportunities for Recovery of Rare Earth Elements and Critical Minerals in Produced Water Networks

Oil and gas development activities require a significant amount of water. Given the environmental impacts associated with high consumption and subsequent disposal of this water, there is a need for strategies to support effective reuse of, treatment of, and/or resource recovery from this produced water. These streams can contain appreciable concentrations of rare earth elements (REE) and critical minerals (CM) (e.g., Lithium), which are critical for many important applications in electronics, technology, manufacturing, energy, and medicine [1]. Along with REE/CM present in produced water, other waste streams such as fly ash from coal-fired power plants and acid mine discharge present other potential sources for recovery of REE/CM [2-4]. And with increases in demand for REE/CM, the need for recovery from wastewater streams is becoming even more important. There is a need to develop effective decision-making tools to evaluate the economic and environmental potential for REE/CM recovery from produced water networks while supporting the needs of drilling and hydraulic fracturing activities. In this work, we present our progress in developing a decision-making framework to efficiently design and operate produced water networks for REE/CM recovery. Our approach considers REE/CM recovery from produced water streams alongside other potential wastewater sources. The models consider the location and capacity of storage and decentralized treatment processes as well as the design and operation of pipeline and transportation networks to connect different sources and effectively schedule inventories, reuse, and recovery opportunities. We focus on the evaluation of opportunities for REE/CM recovery with treatment constraints on composition and flow. We demonstrate this framework with an illustrative case study that features diverse production sites, storage facilities, transportation, and treatment sites. This proposed framework will be deployed in an open-source software package that is compatible with the PARETO framework to deliver analysis and decision-making tools that allow stakeholders to quantitatively evaluate potential opportunities for REE/CM recovery in produced water networks.

Pulsipher, Joshua↗

NASA NTRS1994

Space Station Environmental Control and Life Support Systems: An Update on Waste Water Reclamation

Since the mid-1980's, work has been ongoing In the development of the various environmental control and life support systems (ECLSS) for the space station. Part of this effort has been focused on the development of a new subsystem to reclaim waste water that had not been previously required for shuttle missions. Because of the extended manned missions proposed, reclamation of waste water becomes imperative to avoid the weight penalties associated with resupplying a crew's entire water needs for consumption and daily hygiene. Hamilton Standard, under contract to Boeing Aerospace and Electronics, has been designing the water reclamation system for space station use. Since June of 1991, Hamilton Standard has developed a combined water processor capable of reclaiming potable quality water from waste hygiene water, used laundry water, processed urine, Shuttle fuel cell water, humidity condensate and other minor waste water sources. The system was assembled and then tested with over 27,700 pounds of 'real' waste water. During the 1700 hours of system operation required to process this waste water, potable quality water meeting NASA and Boeing specifications was produced. This paper gives a schematic overview of the system, describes the test conditions and test results and outlines the next steps for system development.

Ferner, Kathleen M.↗

DOE OSTI2023

Effect of Ligand Chemistry on the Electronic Properties and Reactivity of Cobalt Acetate Autoxidation Catalysts

Autoxidation chemistry catalyzed by cobalt(II) acetate is an industrial pathway for converting hydrocarbons into oxygenated compounds and has promising potential applications in plastic waste deconstruction. However, the chemical properties of the Co acetate-based catalysts and their roles in the reaction mechanism are poorly understood, and as a result, attempts to redesign the autoxidation chemical process for novel applications lack clear direction. In this work, we investigate the structure and electronic properties of a series of multinuclear Co(III) compounds that have been proposed as active participants in catalytic autoxidation. Through a combination of X-ray spectroscopic measurements [Co K-edge X-ray absorption spectroscopy (XAS), extended X-ray absorption fine structure (EXAFS), Kβ X-ray emission spectroscopy (XES), and high-energy resolution fluorescence detection (HERFD) XAS] and theoretical methods, we characterize the interactions of Co with acetate and hydroxyl ligands in these compounds. Here we show that the substitution of acetate ligands with hydroxyls in these compounds causes an increase in the electron density on Co, driven by the loss of a π back-bonding interaction between Co and acetate and an increase in electron donation to Co from the hydroxyl ligands. We further classify the bonding between Co and acetate based on the orbital overlap and show that the experimental absorption and emission spectra are well-described by the resulting molecular orbitals. Finally, we predict the impacts of acetate/hydroxyl ligand exchange on autoxidation catalytic properties, showing that the reaction free energies for key Co oxidation and reduction steps are extremely sensitive to metal-ligand bonding interactions and thus have meaningful impacts on overall reactivity. The results of this study constitute an important set of design criteria for developing novel homogeneous autoxidation catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS2014

Bacterial Degradation of Plastics

Plastics are not only a major component of societies on Earth but also those in Space. After use, plastics can accumulate and become difficult to recycle or reuse. Finding ways to degrade and recycle synthetic plastics would provide a way to reduce the upmass of Space Travel, create a closed-loop system of resources and even benefit life on Earth. The purpose of this project is to identify and characterize bacterial species that can degrade and recycle plastics. It has been suggested that bacteria can use plastics, like polyethylene and polystyrene, as a carbon source. These plastics are broken down into intermediary molecules which can then be used in the bacterium's metabolism. Environmental samples were collected from various locations rich in plastic waste. These samples are currently being used to culture bacteria in M9 minimal media containing polyethylene and polystyrene beads as the sole carbon source. High Performance Liquid Chromatography (HPLC), Scanning Electron Microscopy (SEM), and DNA sequencing are among the various methods that will be used identify and characterize bacteria that can degrade plastics. The results from these experiments will provide methods to reduce waste of plastics and ultimately improve sustainability for long-term space exploration.

plastic conversion↗

NASA NTRS2017

Milli-Watt Radioisotope Power to Enable Small, Long-Term Robotic “Probe” Space Exploration

Milli-watt Radioisotope Power Systems (RPS) based on Radioisotope Heater Units (RHUs) could be an ideal power source for certain spacecraft that cannot use solar power due to large distances from the sun, or other environmental constraints, and where they enable or significantly enhance the ability of a mission to meet its scientific or operational goals. Various modular, compact RHU-based thermoelectric (TE) generator concepts developed or derived from current NASA Small Business Innovation Research (SBIR) projects satisfying this need have been investigated. These modular, compact and low mass power systems could support small, highly-mobile robotic exploration packages, and could be incorporated into different robotic package concepts, spacecraft or satellites. Current modular RPS design concepts with 40mW, 80mW and 120mW power levels use RHUs and Bi2Te3 TE converters. Skutterudites materials could be used in the future if new higher thermal energy output and higher temperature miniature heat sources were developed, for example, using technologies currently in the General Purpose Heat Source (GPHS) used in higher electric power output RTGs. Small (a.k.a., “mice-like”) robotic packages could effectively utilize these RHU-driven power levels to accommodate crawling, climbing, monitoring, taking measurements, and communicating during long-term planetary missions aimed at gathering environmental and geologic data (i.e., over multiple decades). Waste heat from the cold side of the TE converter could also be directed toward the electronics and / or energy storage (e.g. batteries) to keep them within design temperature ranges. In addition to power generation and electronics / battery heating, the RHU / TE configuration could be designed to survive an external 500°C bake out procedure for critical spacecraft sterilization, environmental certification and planetary protection. Analytical studies have been performed to optimize various design configurations for power, mass, volume and robotic mobility. Specific power (mW/kg) and volumetric specific power (mW/cm3) characteristics of various design configurations will be presented and key conceptual design tradeoffs will be discussed. Hot- and cold-side thermal interfaces required to meet power and mass goals and associated design sensitivities will also be discussed. RHU / TE systems must overcome critical design challenges to survive high-g loadings in some robotic applications and we will examine the mass impacts required to satisfy various dynamic loading environments up to 10,000 g’s. Power can be generated for a minimum of 30 years or more using plutonium-238 dioxide heat sources (given that Pu-238 has an 87.7 year half-life) with some reduction in power as the heat source naturally degrades.

Bahrami, Poyan↗

DOE OSTI2020

Remote Radiation Sensing Using Aerial and Ground Platforms

Remote sensing of ionizing radiation has a significant role in waste management, nuclear material management and nonproliferation, and radiation safety. Robotic platforms can surpass the number of tasks that are achieved by humans. With this technique, the operator's radiation exposure can be decreased. Remote sensing allows for the evaluation and monitoring of radiological contamination. Gamma-ray and neutron sensors were integrated onto the robotic platforms. This approach allows for the radiation sensor data to be dynamically tracked and mapped thus enabling further analysis of the radiation flux in temporal and spatial domains. The goal is to complete scheduled tasks while the robot is being irradiated. To achieve this, electronic components must be shielded and radiation hardened. CZT Detector: Cadmium Zinc Telluride (CZT) detector technology has been a promising solution for gamma-ray and x-ray measurements. Detector data is transferred to the Odroid minicomputer that controls and powers the module via the USB. Robot Operating System (ROS) was utilized for data acquisition and data fusion. The Mariscotti method was employed for the spectrum analysis. A function was programmed in ROS for the automatic identification of photopeaks. CLYC Detector: A Cs{sub 2}LiYCl{sub 6}:Ce{sup 3+} (CLYC) detector was used for simultaneous medium-resolution gamma-ray measurements and neutron counting. A 2.54 cm diameter photomultiplier tube (PMT) was equipped with a high voltage supply and a miniature digitizer. Gamma-ray excitation: fast core-to-valence luminescence (CVL) with 1 ns decay constant, and prompt Ce{sup 3+} emission with 50 ns decay constant. Neutron excitation: slow cerium self-trapped excitation (Ce{sup 3+} STE), 1000 ns decay constant. Radiation Source Localization: Maximum Likelihood Estimation (MLE) and gradient-based methods were used to locate the position of a radiation source based on measured radiation intensities. Multi-Particle Transport Code FLUKA: Estimation of radiation damage of the electronic components is important in order to optimize the robot's operational time while it is irradiated. Displacement per atom (DPA) represents the radiation damage in materials exposed to the ionizing radiation. Various shielding layers of different thickness t were analyzed (< 5% statistical error). The model of the controller of the UAS was designed in FLUKA. Conclusion: CZT and CLYC detectors were integrated onto the robotic platforms. Radiation source localization and contour mapping using robotic platforms were studied. Functions for data analysis and fusion were developed in ROS. FLUKA code was utilized to analyze DPA values. Layers of low-density and high-density materials were used to shield the UAS electronics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays

The search for a reliable U.S. domestic source of rare earth elements (REE) is necessary to support the demand of advanced energy applications (e.g., catalysts, electronics, magnets). Sedimentary deposits may be sources for selectively recovering REE and critical metals—specifically the interbedded seat rock, or underclay, that underlies or forms the floor of a coal seam. This material is often a major component of coal waste fines and refuse and thus readily available. This study examines several Appalachian Basin underclays associated with actively mined coal seams as potential feedstocks for the REE. Multimodal microanalytical electron microscopy (SEM, FIB-SEM, EMPA) synchrotron-based µXRF, and image processing techniques are coupled with detailed elemental and mineral data to classify the 2D and 3D petrophysical properties of the materials. The REE contents of Appalachian Basin underclays were measured from 235–399 ppm and predominantly observed as discrete REE-bearing minerals such as monazite and xenotime on the order of 10–100 µm in size. These REE-bearing minerals typically accounted for less than 1% of the scanned areas and volumes under SEM and FIB-SEM analysis, with the exception of regions enriched in crandallite. Synchrotron-based µXRF elemental maps further identified several REE deposition environments in different underclays, including micro-scale (10–100 µm) light REEs co-localizing with Ca and P, micro-scale heavy REEs with Fe, and large-scale light REEs (>200 µm) co-localizing with Sr, Ba, Ca and P.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Investigation of Undissolved Solids from Salt Waste Processing Facility (SWPF) Salt Batches Collected via Filtration

SRNL researchers performed six experiments wherein 0.1 μm-grade stainless steel filters were used to filter samples pulled from salt batches 6, 9B, and 11B, without the addition of monosodium titanate. Three of these experiments were performed to collect filterable solids from each salt batch and characterize trapped solids via scanning electron microscopy. The remaining three experiments were performed to collect and then dissolve the same solids using 3.5 M nitric acid (similar to that employed in the Salt Waste Processing Facility) for characterization via Inductively-coupled plasma atomic emission spectroscopy.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2020

Structural Implications of Interfacial Hydrogen Bonding in Hydrated Wyoming-Montmorillonite Clay

Montmorillonite (MMT) clay - a layered porous nanomaterial used as seals in engineered waste containment barriers for spent nuclear fuel - adopts discrete hydration/swelling states depending upon surrounding water and ion activities and confining pressure. The structure of nanoconfined water and charge-balancing counterions in the clay mineral interlayers dictate the swelling and mechanical behavior of MMT, so a molecular model for this clay with high structural fidelity is required to accurately predict the reliability of long-term nuclear waste storage. Here, we present a molecular model for MMT that is based on high resolution transmission electron microscopy of Wyoming-MMT single crystals. Imaging data unambiguously show a cis-vacant arrangement of structural hydroxyl groups in the octahedral sheet, whereas existing molecular models assume a centrosymmetric trans-vacant configuration for MMT. Furthermore, using atomistic simulations, we find that the cis-vacant arrangement of structural hydroxyl groups significantly affects the structure of adsorbed water yielding a larger population of hydrogen bonds with bridging oxygens on the tetrahedral sheet and weak hydrogen bonding between the hydroxyl groups in the octahedral sheet and water in the clay mineral interlayers. As a result, water adsorbed in the interlayer is more "ice-like", with stronger ordering and lower density, although the diffusivity of the interlayer species is not significantly diminished. Our improved structural model for MMT provides insight into the energetics of water adsorption, which ultimately dictates its pore- to macro-scale swelling, transport, and fracture properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1993

Studies on the effects of microgravity on the ultrastructure and functions of cultured mammalian cells (L-6)

The human body consists of 10(exp 13) cells. Understanding the mechanisms by which the cells sense and respond to microgravity is very important as the basis for space biology. The cells were originally isolated aseptically from mammalian bodies and cultured in vitro. A set of cell culture vessels was developed to be applied to three kinds of space flight experiments. Experiment 1 is to practice the cell culture technique in a space laboratory and obtain favorable growth of the cells. Aseptic handling in tryspin treatment and medium renewal will be tested. The cells, following space flight, will be returned to the ground and cultured continuously to investigate the effects of space flight on the cellular characteristics. Experiment 2 is to examine the cytoskeletal structure of the cells under microgravity conditions. The cytoskeletal structure plays essential roles in the morphological construction, movements, axonal transport, and differentiation of the cells. The cells fixed during space flight will be returned and the cytoskeleton and ultrastructure observed using electron microscopy and fluorescence microscopy. Experiment 3 is to study the cellular productivity of valuable substances. The waste medium harvested during space flight are returned and quantitated for the cellular products. The effects of microgravity on mammalian cells will be clarified from the various aspects.

Sato, Atsushige↗

DOE OSTI2025

Exploring the influence of transition metals on f-element bonding

The United States aims to triple its nuclear energy production by 2050, which will result in increased uranium usage and spent nuclear fuel generation. This highlights the need for a comprehensive understanding of actinide coordination chemistry, which is crucial for the extraction, processing, purification, and fabrication of uranium-based fuels. Moreover, it is vital for the reprocessing or safe disposal of nuclear waste and effective remediation efforts. Achieving this successfully requires an in-depth understanding of f-electron behavior, as “the role of 5f electrons in bond formation remains a fundamental topic in actinide chemistry”. Introducing a second metal into the system can increase structural dimensionality and diversify structural architecture. Heterometallic systems can also alter material properties, such as magnetic and spectroscopic characteristics, luminescence, and actinide mobility. Additionally, secondary transition metals, even when present only in the second coordination sphere and not directly coordinated, can influence the electron density at the actinyl metal center. In this study, uranium heterometallic single crystals were synthesized by incorporating transition metals such as iron(III), iron(II), nickel(II), manganese(II), copper(I), and cobalt(II). The crystals were formed using 2,6-pyridine dicarboxylic acid and other structurally similar ligands with varying functional groups. The synthesized crystals were analyzed using an extensive array of analytical and computational characterization techniques, including single crystal X-ray diffraction, Raman and infrared spectroscopy, and density functional theory calculations.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗

DOE OSTI2023

Characterization of the Soluble and Insoluble Portions of Solids from the Salt Waste Processing Facility Tank 201 and Tank 202 Samples

The Salt Waste Processing Facility (SWPF) Tank 201 and Tank 202 samples have been characterized using X-ray diffraction (XRD), scanning electron microscope/energy dispersive x-ray (SEM/EDX), particle size analysis (PSA-Microtrac), Fourier transform-infrared (FT-IR) and nuclear magnetic resonance ( 1 H NMR) spectroscopic techniques to characterize and identify organic and inorganic components in Tanks 201 and 202 as part of efforts to understand the problems occurring at SWPF due to the presence of solids in the recovered solvent.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Characterization of the Soluble and Insoluble Portions of Solids from the Salt Waste Processing Facility Tank 201 and Tank 202 Samples

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2026

Epitaxy of Beta-Ga2O3 on Highly-Offcut (Greater than 10 Degrees) Substrates

Beta-Ga2O3 has emerged as a leading candidate for next-generation power electronics, radio frequency (RF) switches, and extreme environment electronics due to a wide band gap (4.6 - 4.9 eV), high dopability (approximately 40 meV activation energy for an isolated silicon donor), and melt growth characteristics resulting in commercially available 4-inch substrates and commercial demonstrations of 6-inch substrates by multiple techniques. The (100) surface of Ga2O3 is highly desirable from a device and epitaxy standpoint - bulk growth of (100) material is more scalable than (010), the surface is nearly lattice-matched to p-type partner NiO, and Al2O3 incorporates at higher concentrations without phase separation. However, the epitaxial growth rate on (100) surfaces is less than 10% of other faces due to weak bonding and favorable desorption. Recent demonstrations have shown growth rate improvements from 0.4 nm/min to 1.5 nm/min by growing on (100) wafers that are offcut 6 degrees in the -c direction.1 These films show step-flow growth from (-201) step-edges and high electron mobility. Despite these exciting results, offcuts greater than 6 degrees have not been explored due to the waste associated with grinding and polishing large offcuts. In this talk we will discuss the molecular beam epitaxy (MBE) growth and properties of Beta-Ga2O3 grown on (100) substrates offcut in the -c direction up to 13.4 degrees. These large offcuts are enabled by edge-fed film-defined growth (EFG) where the offcut is grown into the surface by pulling the crystal through the EFG die with the seed crystal rotated by the desired offcut angle. We will demonstrate that 13.4 degrees offcut substrates still exhibit a terraced (100) surface, and that a >10x increase (4.8 nm/min) in growth rate is achieved. As previously reported on lower offcuts, we observe 100% reversal of substrate twin domains around the (001) direction at the substrate-epilayer interface. We will discuss electrical properties including record-low (by MBE) unintentional doping densities of < 5E15 cm-3.

36 MATERIALS SCIENCE↗