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At least 883 records · Page 49

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DOE OSTI2019

Investigation of the Piezoelectric Resonance in Stoichiometric LiNbO{sub 3} Crystals at High Temperatures and Conductivities

The piezoelectric characteristics, dielectric properties, and ionic conductivity of close-to-stoichiometry LiNbO{sub 3{sub s{sub t{sub o{sub i{sub c{sub h}}}}}}} crystals have been investigated in a wide temperature range (300–850 K) with the aim of establishing the conditions of use of lithium-niobate-based piezoelectric resonators at high temperatures and, accordingly, high conductivities. It is shown that the piezoelectric phenomenon in LiNbO{sub 3{sub s{sub t{sub o{sub i{sub c{sub h}}}}}}} crystals is observed in a certain temperature range ΔT (and, correspondingly, at certain static-conductivity relaxation times Δτ{sub V}) and a frequency range Δω{sub R} at the condition τ{sub V}{sup −1}≪ ω{sub R} satisfied. Apparently, not only LiNbO{sub 3{sub s{sub t{sub o{sub i{sub c{sub h}}}}}}} crystals exhibit such regularities, but also some other piezoelectric materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Effect of Annealing on Structural, Textural, Thermal, Magnetic, and Luminescence Properties of Calcium Fluoride Nanoparticles

Mesoporous nanocrystalline CaF{sub 2} powder was produced by pulsed electron beam evaporation (PEBE) in vacuum. The specific surface area (SSA) of CaF{sub 2} nanopowder (NP) reached 88.7 m{sup 2}/g. The effect of in-air thermal annealing in the temperature range of 200–900°C on the particle size, morphology, textural, thermal, magnetic, and luminescence properties of NPs is studied. A strong deviation from stoichiometry is observed in produced nanoparticles and a significant increase in the SSA after annealing at 200°C. The obtained CaF{sub 2} NP shows ferromagnetic (FM) behavior. The FM response appearance can be explained by the formation of structural and radiation defects. An analysis of pulsed cathodoluminescence (PCL) and magnetization curves of CaF{sub 2} NPs allows conclusions about their interrelation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2025

Development of a two-zone zero-dimensional mixing model for actively fueled prechamber engines

In this numerical work, a zero-dimensional, two-zone mixing model was developed and validated to capture the mixture preparation process of an actively fueled prechamber engine. The model was developed for ethanol-gasoline fuel blends but is applicable to various fuels of interest relevant to prechamber applications. The model was exercised to demonstrate the effects of boundary conditions, fuel composition, and residual content on the mixture stoichiometry predictions. The 0D model showed reasonable agreement in prechamber equivalence ratio predictions with higher fidelity computational fluid dynamics modeling, but the accuracy of model was constrained to the governing assumptions of the injection process. The modeling assumptions surrounding the non-dimensional injection of mass into the prechamber were scrutinized to identify key areas of model improvement. The results indicate heat transfer effects play a crucial role in the evaporation of the fuel within the confined auxiliary chamber, especially when considering fuels with high latent heat of vaporization. Additionally, the presence of fuel films that collect on the prechamber surfaces complicated the modeled evaporative cooling loses as the modeling suggests the films evaporate primarily by means of conduction from the boundary. Furthermore, the developed model serves as a simplified framework to generate calibration maps of prechamber fueling or run real time as an open loop control strategy such that desired prechamber mixture proportions are effectively targeted.

Zero-dimensional↗

DOE OSTI2012

Mass spectrometry in biomarker applications: from untargeted discovery to targeted verification, and implications for platform convergence and clinical application

It is really only in the last ten years that mass spectrometry (MS) has had a truly significant (but still small) impact on biomedical research. Much of this impact can be attributed to proteomics and its more basic applications. Early biomedical applications have included a number of efforts aimed at developing new biomarkers; however, the success of these endeavors to date have been quite modest - essentially confined to preclinical applications - and have often suffered from combinations of immature technology and hubris. Now that MS-based proteomics is reaching adolescence, it is appropriate to ask if and when biomarker-related applications will extend to the clinical realm, and what developments will be essential for this transition. Biomarker development can be described as a multistage process consisting of discovery, qualification, verification, research assay optimization, validation, and commercialization (1). From a MS perspective, it is possible to 'bin' measurements into 1 of 2 categories - those aimed at discovering potential protein biomarkers and those seeking to verify and validate biomarkers. Approaches in both categories generally involve digesting proteins (e.g., with trypsin) as a first step to yield peptides that can be effectively detected and identified with MS. Discovery-based approaches use broad 'unbiased' or 'undirected' measurements that attempt to cover as many proteins as possible in the hope of revealing promising biomarker candidates. A key challenge with this approach stems from the extremely large dynamic range (i.e., relative stoichiometry) of proteins of potential interest in biofluids such as plasma and the expectation that biomarker proteins of the greatest clinical value for many diseases may very well be present at low relative abundances (2). Protein concentrations in plasma extend from approximately 10{sup 10} pg/mL for albumin to approximately 10 pg/mL and below for interleukins and other cytokines.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2015

SOLTHERM Thermodynamic Database for Geochemical Modeling

This data submission is a link to a thermodynamic database maintained by the University of Oregon. The data at this link are not 'data results' from sampling. The data at this link comprise a thermodynamic database for aqueous species, minerals, and gases, including data for stoichiometry, equilibrium constants log K(T,P), aqueous activity coefficients, fugacity coefficients, and water enthalpy. These data are derived from SOLTHERM as a reference for the user, showing balanced reactions and equilibrium constants log K(T,P) along the liquid-vapor saturation curve only, up to 350 degrees C, for aqueous species and minerals including REE, and gases. These data include REE aqueous species and minerals. These data are used by programs SOLVEQ-XPT, CHIM-XPT, and GEOCAL-XPT.

15 GEOTHERMAL ENERGY↗

DOE OSTI2011

Energy Frontier Research Center, Center for Materials Science of Nuclear Fuels

The Office of Science, Basic Energy Sciences, has funded the INL as one of the Energy Frontier Research Centers in the area of material science of nuclear fuels. This document is the required annual report to the Office of Science that outlines the accomplishments for the period of May 2010 through April 2011. The aim of the Center for Material Science of Nuclear Fuels (CMSNF) is to establish the foundation for predictive understanding of the effects of irradiation-induced defects on thermal transport in oxide nuclear fuels. The science driver of the center’s investigation is to understand how complex defect and microstructures affect phonon mediated thermal transport in UO2, and achieve this understanding for the particular case of irradiation-induced defects and microstructures. The center’s research thus includes modeling and measurement of thermal transport in oxide fuels with different levels of impurities, lattice disorder and irradiation-induced microstructure, as well as theoretical and experimental investigation of the evolution of disorder, stoichiometry and microstructure in nuclear fuel under irradiation. With the premise that thermal transport in irradiated UO2 is a phonon-mediated energy transport process in a crystalline material with defects and microstructure, a step-by-step approach will be utilized to understand the effects of types of defects and microstructures on the collective phonon dynamics in irradiated UO2. Our efforts under the thermal transport thrust involved both measurement of diffusive phonon transport (an approach that integrates over the entire phonon spectrum) and spectroscopic measurements of phonon attenuation/lifetime and phonon dispersion. Our distinct experimental efforts dovetail with our modeling effort involving atomistic simulation of phonon transport and prediction of lattice thermal conductivity using the Boltzmann transport framework.

36 MATERIALS SCIENCE↗

DOE OSTI2011

SCIX IMPACT ON DWPF CPC

A program was conducted to systematically evaluate potential impacts of the proposed Small Column Ion Exchange (SCIX) process on the Defense Waste Processing Facility (DWPF) Chemical Processing Cell (CPC). The program involved a series of interrelated tasks. Past studies of the impact of crystalline silicotitanate (CST) and monosodium titanate (MST) on DWPF were reviewed. Paper studies and material balance calculations were used to establish reasonable bounding levels of CST and MST in sludge. Following the paper studies, Sludge Batch 10 (SB10) simulant was modified to have both bounding and intermediate levels of MST and ground CST. The SCIX flow sheet includes grinding of the CST which is larger than DWPF frit when not ground. Nominal ground CST was not yet available, therefore a similar CST ground previously in Savannah River National Laboratory (SRNL) was used. It was believed that this CST was over ground and that it would bound the impact of nominal CST on sludge slurry properties. Lab-scale simulations of the DWPF CPC were conducted using SB10 simulants with no, intermediate, and bounding levels of CST and MST. Tests included both the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles. Simulations were performed at high and low acid stoichiometry. A demonstration of the extended CPC flowsheet was made that included streams from the site interim salt processing operations. A simulation using irradiated CST and MST was also completed. An extensive set of rheological measurements was made to search for potential adverse consequences of CST and MST and slurry rheology in the CPC. The SCIX CPC impact program was conducted in parallel with a program to evaluate the impact of SCIX on the final DWPF glass waste form and on the DWPF melter throughput. The studies must be considered together when evaluating the full impact of SCIX on DWPF. Due to the fact that the alternant flowsheet for DWPF has not been selected, this study did not consider the impact of proposed future alternative DWPF CPC flowsheets. The impact of the SCIX streams on DWPF processing using the selected flowsheet need to be considered as part of the technical baseline studies for coupled processing with the selected flowsheet. In addition, the downstream impact of aluminum dissolution on waste containing CST and MST has not yet been evaluated. The current baseline would not subject CST to the aluminum dissolution process and technical concerns with performing the dissolution with CST have been expressed. Should this option become feasible, the downstream impact should be considered. The main area of concern for DWPF from aluminum dissolution is an impact on rheology. The SCIX project is planning for SRNL to complete MST, CST, and sludge rheology testing to evaluate any expected changes. The impact of ground CST transport and flush water on the DWPF CPC feed tank (and potential need for decanting) has not been defined or studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2011

Studies of the structure and function of Mms6, a bacterial protein that promotes the formation of magnetic nanoparticles

Here we report structural and functional studies of Mms6, a biomineralization protein that can promote the formation in vitro of magnetic nanoparticles with sizes and morphologies similar to the magnetites synthesized by magnetotactic bacteria. We found the binding pattern of Mms6 to ferric ion to be two-phase and multivalent. We quantatively determined that Mms6 binds one Fe 3+ with a very high affinity (K d = 10 16 M). The second phase of iron binding is multivalent and cooperative with respect to iron with a K d in the μM range and a stoichiometry of about 20 ferric ion per protein molecule. We found that Mms6 exists in large particles of two sizes, one consisting of 20-40 monomeric units and the other of 200 units. From proteolytic digestion, ultracentrifugation and liposome fusion studies, we found that Mms6 forms a large micellar quaternary structure with the N-terminal domain self-assembling into a uniformly sized micelle and the C-terminal domain on the surface. The two-phase iron-binding pattern may be relevant to iron crystal formation. We propose that the first high affinity phase may stabilize a new conformation of the C-terminal domain that allows interaction with other C-terminal domains leading to a structural change in the multimeric protein complex that enables the second low affinity iron binding phase to organize iron and initiate crystal formation. We also observed a dimeric apparent molecular mass of the Mms6 C-terminal peptide (C21Mms6). We speculate that the C-terminal domain may form higher order quaternary arrangements on the surface of the micelle or when anchored to a membrane by the N-terminal domain. The change in fluorescence quenching in the N-terminal domain with iron binding suggests a structural integrity between the C- and N-terminal domains. The slow change in trp fluorescence as a function of time after adding iron suggests a very slow conformational change in the protein that involves both N- and C-terminal domains. We interpret these results to mean that there is a coordinated global change in Mms6 structure that involves multiple Mms6 monomers. Based on our observations, we propose a mechanism by which Mms6 can promote the formation of crystalline nanoparticles. Upon binding ferric iron at very high affinity with a molar ratio of 1, the C-terminal domains undergo a conformational change, coordinated with the N-terminal domain that initiates a slow rearrangement of the multiprotein complex to create a surface on which many iron atoms can organize. This slow rearrangement allows the initiation of a crystal that is propagated on the protein surface to form a crystal seed. We also observed that Mms6 undergoes a periodical structural change with increasing molar ratios of iron to protein. The observed structural change occurs in the N-terminal domain, but reflects iron binding by the C-terminal domain. A mutant Mms6 that does not promote the formation of superparamagnetic magnetite also does not undergo the periodic structural change. The correlation between the ability to form magnetic nanoparticles and the ability to undergo the periodic structural change suggests that this structural change might participate in the mechanism of magnetite formation. Analysis of the quaternary structure of Mms6 protein and its C-terminal domain reveals that the C-terminal domain contributes to the overall stability of the quaternary structure of Mms6. The C-terminal domain of Mms6 displays ferric reductase activity that is diminished in the mutant C-terminus. Although it does not play a role in the in vitro formation of magnetite during which both ferrous and ferric forms of iron are provided, this reductase activity may participate in magnetite formation in vivo. Our results suggest that the iron binding properties and quaternary structure of Mms6 is responsible for formation of magnetic nanoparticles. The ability for Mms6 protein to form a quaternary structure and the ability of that structure to change as iron is incorporated into a crystal may be fundamental aspects of the mechanism by which a small protein such as Mms6 can promote the formation of magnetite crystals.

36 MATERIALS SCIENCE↗

DOE OSTI2011

Isotope exchange kinetics in metal hydrides I : TPLUG model.

A one-dimensional isobaric reactor model is used to simulate hydrogen isotope exchange processes taking place during flow through a powdered palladium bed. This simple model is designed to serve primarily as a platform for the initial development of detailed chemical mechanisms that can then be refined with the aid of more complex reactor descriptions. The one-dimensional model is based on the Sandia in-house code TPLUG, which solves a transient set of governing equations including an overall mass balance for the gas phase, material balances for all of the gas-phase and surface species, and an ideal gas equation of state. An energy equation can also be solved if thermodynamic properties for all of the species involved are known. The code is coupled with the Chemkin package to facilitate the incorporation of arbitrary multistep reaction mechanisms into the simulations. This capability is used here to test and optimize a basic mechanism describing the surface chemistry at or near the interface between the gas phase and a palladium particle. The mechanism includes reversible dissociative adsorptions of the three gas-phase species on the particle surface as well as atomic migrations between the surface and the bulk. The migration steps are more general than those used previously in that they do not require simultaneous movement of two atoms in opposite directions; this makes possible the creation and destruction of bulk vacancies and thus allows the model to account for variations in the bulk stoichiometry with isotopic composition. The optimization code APPSPACK is used to adjust the mass-action rate constants so as to achieve the best possible fit to a given set of experimental data, subject to a set of rigorous thermodynamic constraints. When data for nearly isothermal and isobaric deuterium-to-hydrogen (D {yields} H) and hydrogen-to-deuterium (H {yields} D) exchanges are fitted simultaneously, results for the former are excellent, while those for the latter show pronounced deviations at long times. These discrepancies can be overcome by postulating the presence of a surface poison such as carbon monoxide, but this explanation is highly speculative. When the method is applied to D {yields} H exchanges intentionally poisoned by known amounts of CO, the fitting results are noticeably degraded from those for the nominally CO-free system but are still tolerable. When TPLUG is used to simulate a blowdown-type experiment, which is characterized by large and rapid changes in both pressure and temperature, discrepancies are even more apparent. Thus, it can be concluded that the best use of TPLUG is not in simulating realistic exchange scenarios, but in extracting preliminary estimates for the kinetic parameters from experiments in which variations in temperature and pressure are intentionally minimized.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2011

Raman investigation of the uranium compounds U 3 O 8 , UF 4 , UH 3 and UO 3 under pressure at room temperature

Our current state-of-the-art X-ray diffraction experiments are primarily sensitive to the position of the uranium atom. While the uranium - low-Z element bond (such as U-H or U-F) changes under pressure and temperature the X-ray diffraction investigations do not reveal information about the bonding or the stoichiometry. Questions that can be answered by Raman spectroscopy are (i) whether the bonding strength changes under pressure, as observed by either blue- or red-shifted peaks of the Raman active bands in the spectrum and (ii) whether the low-Z element will eventually be liberated and leave the host lattice, i.e. do the fluorine, oxygen, or hydrogen atoms form dimers after breaking the bond to the uranium atom. Therefore Raman spectra were also collected in the range where those decomposition products would appear. Raman is particularly well suited to these types of investigations due to its sensitivity to trace amounts of materials. One challenge for Raman investigations of the uranium compounds is that they are opaque to visible light. They absorb the incoming radiation and quickly heat up to the point of decomposition. This has been dealt with in the past by keeping the incoming laser power to very low levels on the tens of milliWatt range consequently affecting signal to noise. Recent modern investigations also used very small laser spot sizes (micrometer range) but ran again into the problem of heating and chemical sensitivity to the environment. In the studies presented here (in contrast to all other studies that were performed at ambient conditions only) we employ micro-Raman spectroscopy of samples situated in a diamond anvil cell. This increases the trustworthiness of the obtained data in several key-aspects: (a) We surrounded the samples in the DAC with neon as a pressure transmitting medium, a noble gas that is absolutely chemically inert. (b) Through the medium the sample is thermally heat sunk to the diamond anvils, diamond of course possessing the very best heat conductivity of any material. Therefore local heating and decomposition are avoided, a big challenge with other approaches casting doubts on their results. (c) This in turn benefits the signal/noise ratio tremendously since the Raman features of uranium-compounds are very small. The placement of the samples in DACs allows for higher laser powers to impinge on the sample spot while keeping the spot-size larger than in previous studies and keep the samples from heating up. Raman spectroscopy is a very sensitive non-invasive technique and we will show that it is even possible to distinguish the materials by their origin / manufacturer as we have studied samples from Cameco (Canada) and IBI-Labs (US-Florida) and can compare with ambient literature data for samples from Strem (US-MA) and Areva (Pierrelatte, France).

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2012

Scanning Electron Microscopy and X-Ray Diffraction Analysis of Tank 18 Samples

The F-Area Tank Farm (FTF) Performance Assessment (PA) utilizes waste speciation in the waste release model used in the FTF fate and transport modeling. The waste release modeling associated with the residual plutonium in Tank 18 has been identified as a primary contributor to the Tank 18 dose uncertainty. In order to reduce the uncertainty related to plutonium in Tank 18, a better understanding of the plutonium speciation in the Tank 18 waste (including the oxidation state and stoichiometry) is desired. Savannah River National Laboratory (SRNL) utilized Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to analyze Tank 18 samples to provide information on the speciation of plutonium in the waste material. XRD analysis of the Tank 18 samples did not identify any plutonium mineral phases in the samples. These indicates the crystalline mineral phases of plutonium are below the detection limits of the XRD method or that the plutonium phase(s) lack long range order and are present as amorphous or microcrystalline solids. SEM analysis of the Tank 18 samples did locate particles containing plutonium. The plutonium was found as small particles, usually <1 μm but ranging up to several micrometers in diameter, associated with particles of an iron matrix and at low concentration in other elemental matrices. This suggests the plutonium has an affinity for the iron matrix. Qualitatively, the particles of plutonium found in the SEM analysis do not appear to account for all of the plutonium in the sample based on concentrations determined from the chemical analysis of the Tank 18 samples. This suggests that plutonium is also distributed throughout the solids in low concentrations.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2012

Glycolic-Nitric Acid Flowsheet Demonstration of the DWPF Chemical Processing Cell with Matrix Simulants and Supernate

Savannah River Remediation (SRR) is evaluating changes to its current DWPF flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the CPC since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT and QAP). The details regarding the simulant preparation and analysis have been documented previously.

08 HYDROGEN↗

DOE OSTI2012

Draft report on melt point as a function of composition for urania-based systems

This report documents the testing of a urania (UO 2.00 ) sample as a baseline and the attempt to determine the melt point associated with 4 compositions of urania-ceria and urania-neodymia pseudo binaries provided by ORNL, with compositions of 95/5, and 80/20 and of (U/Ce)O 2.00 and (U/Nd)O 2.00 in the newly developed ceramic melt point determination system. A redesign of the system using parts fabricated from tungsten was undertaken in order to help prevent contamination and tungsten carbide formation in the crucibles. The previously developed system employed mostly graphite parts that were shown to react with the sample containment black-body crucible leading to unstable temperature readings and crucible failure, thus the redesign. Measured melt point values of UO 2.00 and U 0.95 Ce 0.05 O 2.00 , U 0.80 Ce 0.20 O 2.00 , U 0.95 Nd 0.05 O 2.00 and U 0.80 Nd 0.20 O 2.00 were measured using a 2-color pyrometer. The value measured for UO 2.00 was consistent with the published accepted value 2845°C±25°C, although a wide range of values has been published by researchers and will be discussed later in the text. For comparison, values obtained from a published binary phase diagram of UO 2 -Nd 2 O 3 were used for comparison with our measure values. No literature melt point values for comparison with the measurements performed in this study were found for (U/Ce)O 2.00 in our stoichiometry range.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2012

Cameco UO 3 Materials Analysis

Uranium trioxide (UO 3 ) was characterized using a variety of techniques to better understand its physical properties. Scanning electron microscope (SEM) images were collected to examine particle morphology, which consisted of semi-spherical particles that tended to agglomerate before sonication. Particle size analysis revealed a singular mode distribution with a mean particle size of 43.0 {micro}m. After sonication a bimodal distribution was produced with peak particle sizes at 0.226 μm and 9.43 μm. The O/U ratio was measured to be 3.09 by Cameco in 2009, by gravimetric analysis. X-ray diffraction (XRD) showed that the sample was mostly Υ-UO 3 (87.1%) with a small amount of UO 3 ̣ 0.80 H 2 O (12.9%). Bulk and tap densities were determined to be 3.678 ±} 0.2 and 4.81 ± 0.2 g/cm 3 }, respectively (crystalline density is 7.3 g/cm 3 ). The stoichiometry was measured to be 2.99 in 2012.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2012

Glycolic-Nitric Acid Flowsheet Demonstration of the DWPF Chemical Process Cell with Sludge and Supernate Simulants

Savannah River Remediation (SRR) is evaluating changes to its current Defense Waste Processing Facility (DWPF) flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the Chemical Process Cell (CPC) since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT&QAP). The details regarding the simulant preparation and analysis have been documented previously.

08 HYDROGEN↗

DOE OSTI2015

Supplying materials needed for grain growth characterizations of nano-grained UO 2

This activity is supported by the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) Fuels Product Line (FPL) and aims at providing experimental data for the validation of the mesoscale simulation code MARMOT. MARMOT is a mesoscale multiphysics code that predicts the coevolution of microstructure and properties within reactor fuel during its lifetime in the reactor. It is an important component of the Moose-Bison-Marmot (MBM) code suite that has been developed by Idaho National Laboratory (INL) to enable next generation fuel performance modeling capability as part of the NEAMS Program FPL. In order to ensure the accuracy of the microstructure based materials models being developed within the MARMOT code, extensive validation efforts must be carried out. In this report, we summarize our preliminary synchrotron radiation experiments at APS to determine the grain size of nanograin UO 2 . The methodology and experimental setup developed in this experiment can directly apply to the proposed in-situ grain growth measurements. The investigation of the grain growth kinetics was conducted based on isothermal annealing and grain growth characterization as functions of duration and temperature. The kinetic parameters such as activation energy for grain growth for UO 2 with different stoichiometry are obtained and compared with molecular dynamics (MD) simulations.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2015

Synchrotron characterization of nanograined UO 2 grain growth

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

Implementation of flowsheet change to minimize hydrogen and ammonia generation during chemical processing of high level waste in the Defense Waste Processing Facility

Testing was completed to develop a chemical processing flowsheet for the Defense Waste Processing Facility (DWPF), designed to vitrify and stabilize high level radioactive waste. DWPF processing uses a reducing acid (formic acid) and an oxidizing acid (nitric acid) to rheologically thin the slurry and complete the necessary acid base and reduction reactions (primarily mercury and manganese). Formic acid reduces mercuric oxide to elemental mercury, allowing the mercury to be removed during the boiling phase of processing through steam stripping. In runs with active catalysts, formic acid can decompose to hydrogen and nitrate can be reduced to ammonia, both flammable gases, due to rhodium and ruthenium catalysis. Replacement of formic acid with glycolic acid eliminates the generation of rhodium- and ruthenium-catalyzed hydrogen and ammonia. In addition, mercury reduction is still effective with glycolic acid. Hydrogen, ammonia and mercury are discussed in the body of the report. Ten abbreviated tests were completed to develop the operating window for implementation of the flowsheet and determine the impact of changes in acid stoichiometry and the blend of nitric and glycolic acid as it impacts various processing variables over a wide processing region. Three full-length 4-L lab-scale simulations demonstrated the viability of the flowsheet under planned operating conditions. The flowsheet is planned for implementation in early 2017.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗