bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling The Dissolution Behavior of Defense Waste Glass in A Salt Repository Environment
Authors: McGrail B. P. 
Published: March 2011

AbstractA mechanistic model describing a dynamic mass balance between the production and consumption of dissolved silica was found to describe the dissolution behavior of SRL-165 defense waste glass in a high-magnesium brine (PBB3) at a temperature of 90°C. The synergistic effect of the waste package container on the glass dissolution rate was found to depend on a precipitation reaction for a ferrous silicate mineral.The model predicted that the ferrous silicate precipitate should be variable in composition where the iron/silica stoichiometry depended on the metal/glass surface area ratio used in the experiment. This prediction was confirmed experimentally by the variable iron/silica ratios observed in filtered leachates. However, the interaction between dissolved silica and iron corrosion products needs to be much better understood before the model can be used with confidence in predicting radionuclide release rates for a salt repository.
Geochemical Simulation of Dissolution of West Valley and Dnpf Glasses in J-13 Water at 90°C
Authors: Bruton Carol J. 
Published: March 2011

AbstractDissolution of West Valley and Defense Waste Product Facility (DWPF) glasses in J-13 water at 90°C at the candidate Yucca Mountain, Nevada repository was simulated using the EQ316 computer code package. The objectives of the study were to attempt to predict the concentrations of radionuclides and other glass components in solution resulting from glass dissolution, and to identify potential precipitates that sequester glass components.Modified projected inventories of 10,000 year-old Nest Valley and DNPF SRL-165 frit glasses were used as starting glass compositions. J-13 water was considered to be representative of groundwater at Yucca Mountain. A total of 10 grams of each glass was assumed to dissolve congruently into a kilogram of J-13 water in a closed system. No inhibitions to precipitation, except for crystalline SiO2 polymorphs, were assumed to exist. Radiolysis and materials interactions were not considered.Simulation results predict that radionuclides and other glass components precipitate predominantly in the form of oxides and hydroxides, together with carbonates, silicates and phosphates. Precipitates appear to be effective in limiting the concentrations of radionuclides and other elements in solution. The general compositional trends in precipitates and solution chemistry are the same in the West Valley and DMPF simulations, except for variations arising from differences in glass chemistry.Concentrations of elements released from glass increase until the solution reaches saturation with respect to solids that contain these elements. Elemental concentrations are then predicted to remain constant, increase or decrease depending on: 1) whether the reaction between the dominant aqueous species of the element in solution and its precipitate is pH and/or Eh-dependent; 2) whether the species distribution of the element in solution changes significantly in response to changes in pH, Eh, or other factors; and 3) the competition with other phases for elements required to form the precipitate. pH increases from 7.3 to 9.8 and from 7.2 to 10 in the West Valley and DWPF simulations, respectively. Eh decreases abruptly from about 0.5 to 0.3 volts after dissolution of 3.4 and 5.8 grams of glass in the Nest Valley and DMPF simulations, respectively, because of depletion of dissolved oxygen in solution. Complexing of aqueous species has a significant impact on radionuclide concentrations in solution; predicted concentrations of U in solution, for example, are controlled by the presence or absence of P in solution because H2PO4 is an extremely effective complexing agent for U.
Slag-Based Saltstone Formulations
Authors: Langton C. A. 
Published: March 2011

AbstractApproximately 400 × 106 liters of low-level alkaline salt solution will be treated at the Savannah River Plant (SRP) Defense Waste Processing Facility (DWPF) prior to disposal in concrete vaults at SRP. Treatment involves removal of Ca+and Sr+2 followed by solidification and stabilization of potential contaminants in saltstone, a hydrated ceramic waste form.Chromium, technetium, and nitrate releases from saltstone can be significantly reduced by substituting hydraulic blast furnace slag for portland cement in the formulation designs. Slag-based mixes are also compatible with Class F fly ash used in saltstone as a functional extender to control heat of hydration and reduce permeability. (Class F fly ash is locally available at SRP.)A monolithic waste form is produced by the hydration of the slag and fly ash. Soluble ion release (NO3−) is controlled by the saltstone microstructure (bulk porosity and pore size and connectivity). Chromium and technetium are 103−104 times less leachable from slag mixes than from cement-based waste forms. Results suggest that chemical stabilization rather than physical entrapment, as in the case of nitrate is responsible for this improved leaching. Reduction of Cr+6 and Tc+7 to Cr+3 and Tc+4 by ferrous iron or Mn+2 in the slag and subsequent precipitation of the relatively insoluble phses Cr(OH)3 and TcO2 are proposed as the stabilizing reactions.
The Performance Of Actinide-Containing Srl 165 Type Glass In Unsaturated Conditions
Authors: Bates John K. , Gerding Thomas J. 
Published: March 2011

AbstractAs part of the effort by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project to evaluate the volcanic tuff beds of Yucca Mountain, Nevada, as a repository for the permanent storage of high-level nuclear waste, the interaction of actinide-doped Savannah River Laboratory (SRL) 165 type glass with the unsaturated repository environment has been studied. The NNWSI Unsaturated Test method has been used, and the results from batch and continuous tests completed through 18 months demonstrate that several interactions are important for controlling both the reaction of the glass and the release of radionuclides. These interactions include (1) the reaction between the glass and moist air with interludes of liquid water contact, which results in the release of alkali metals from the glass; and (2) the reaction between standing water, glass, and presensitized 304 L type stainless steel which results in breakdown of the glass matrix and the release of radionuclides from the glass-metal assemblage. A comparison of the results of the Unsaturated Test with those of parametric experiments illustrates the importance of presensitized steel in enhancing the glass reaction, and demonstrates the applicability of the Unsaturated Test to those conditions anticipated to exist in the NNWSI repository horizon.
Mineral Phase Identificaticn Along two Profiles from the LRW French Reference Glass: Use of an X-Ray Position Sensitive Detector
Authors: Caurel J. , Beaufort D. , Vernaz E. Y. 
Published: March 2011

AbstractThis study was undertaken to clarify the alteration process of French LWR synthetic glass leached by distilled water at 250 and 300°C for 28 days. The present experiments emphasize “in situ” identification of the alteration products in small areas (20 × 10−4 mm2 ) along the alteration profile by a specific X-ray diffraction technique.Experimental assembly: The sample is irradiated by an incident X-ray beam (Co k α, 40 mA, 40 Kv) focused to a 150 μ m diameter. The sample oscillates around a θ central selected position and the diffracted X-rays are detected simultaneously in a 14.5 (2 θ ) solid angle, then recorded by the linear position sensitive detector and stored in a multichannel analyzer.
Systematic Composition Studies on the Durability of Waste Glass WV205
Authors: Feng Xiangdong , Barkatt Aaron , Jiang Tian 
Published: March 2011

AbstractA systematic study of the chemical durability of glass compositions developed for the immobilization of high-level radioactive wastes at West Valley is described. Most of the compositions studied here represent variations around the nonradioactive WV205 composition. The results from this study indicate that the effectiveness of the various oxides tested in increasing the durability of WV205, when considered in terms of 2% additions by weight to the central composition, decreases in the following order: A12O3>ZrO2>SiO2>Cr2O3>Fe2O3>TiO2>CuO>ZnO>NiO. The addition of 2–6% Cr2O3 or NiO to WV205 was observed to cause extensive crystallization. The addition of 2% or 6% ZnO or 2% TiO2, CuO or NiO to the glass actually enhances corrosion rates. A12O3 and ZrO2 are the best additives in terms of increasing the durability. The additions of ThO2 and U3O8 slightly increase the durability. The effects of various oxides on the durability of WV-205-based glasses with ThO2 and U3O8 were found to be very similar to the effects of these oxides on the durability of the corresponding glasses which did not contain ThO2 and U3O8. This study also showed that Fe2O3 has little effect on the durability. However, FeO greatly enhances the corrosion rates of WV205-based glasses. Much less pronounced effects of the redox state of iron were found in the case of more durable base glass compositions.
Annealing and Leaching Studies With Natural and Artificial Obsidian Glass
Authors: MÄrk T. D. , Walder G. 
Published: March 2011

AbstractAnnealing kinetics of fission tracks (produced by induced fission of U235 in natural and artificial (doped) obsidian glass has been studied by etching microscopy as a function of annealing time and temperature. The observed annealing characteristics can be best decribed by a two term exponential function with an Arrhenius type temperature dependence of the annealing coefficients. The activation energies deduced are (0.94 ± 0.16)eV and (1.04 ± 0.15)eV for artificial obsidian and (0.83 ± O.13)eV and (0.60 ± 0.16)eV for natural (fossil) obsidian, respectively. In addition, leaching experiments of obsidian samples exposed to different radiation, doses and rates have been made at two different leachate temperatures. At a temperature of 60°C the leaching rate of irradiated samples is much larger than that of unirradiated samples, whereas at a temperature of 90°C observed leaching rates are similar.
Corrosion of Candidate Container Materials in Air-Steam Mixtures
Authors: Lutton James M. , Dewees D. A. , Robinson C. G. , Brehm W. F. , Anantatmula R. P. 
Published: March 2011

AbstractThe environment during the operating period of a high-level nuclear waste repository in basalt is expected to be air saturated with steam. Liquid groundwater is not expected to be in contact with the container surface during that time.The report presents corrosion findings from tests conducted for one to twenty-five months in an air-steam environment. Tests were carried out with bare metal specimens exposed to an air atmosphere containing 12% moisture in chambers maintained at temperatures between 150°C and 300°C. Cast carbon steel exhibited total penetrations less than 0.002 mm for exposures up to 25 months. A ferritic alloy steel, Fe9CrlMo, showed corrosion results very similar to cast carbon steel. Unalloyed copper materials showed essentially linear corrosion rates, with total penetrations between 0.002 mm at 150°C and 0.14 mm at 300°C in 25 months. Cupronickel 90−10 exhibited total penetrations between 0.001 mm at 150°C and 0.05 mm at 300°C in 25 months. There was a tendency for the corrosion rate to increase with time for cupronickel at 250°C and 300°C possibly because of a mid-test change in the corrosion mechanism. Limited testing of specimens surrounded with bentonite/basalt packing material indicated that the presence of packing has no strong effect on the corrosion of iron-base materials; however, copper-base and cupronickel materials corroded at higher rates in the presence of packing, with a possible shift towards the lower bare specimen corrosion rates with increasing time.
Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash
Authors: Schlorholtz Scott , Bergeson Ken , Demirel Turgut 
Published: March 2011

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.
Scientific Basis for Determining the Sulfate Resistance of Blended Cements
Authors: Mehta P. K. 
Published: March 2011

ABSTRACTThe physical and chemical processes underlying the sulfate attack on concrete are briefly reviewed with special reference to blended portland cements containing natural pozzolans, fly ash, or granulated iron blast-furnace slag. Published literature contains empirical guidelines for evaluating the suitability of blending materials for sulfate resistance; however a critical examination shows that some of the guidelines are not satisfactory. Ideas for establishing a scientific basis for determining the sulfate resistance of blended cements are presented in the paper.
Characterization of Solid Wastes from Advanced SO2 Control Technologies for Electric Utilities
Authors: Eklund A. G. , Golden D. M. 
Published: March 2011

SUMMARYAlternate approaches to conventional control of sulfur dioxide emissions from electric utilities burning coal have resulted in “advanced SO2 control technologies”, among which are furnace sorbent injection, fluid bed combustion, and the use of spray dryers. This summary is a review of laboratory-measured properties of wastes produced from these advanced SO2 control technologies. Chemical composition, leaching properties, physical characteristics, and engineering properties of these wastes were determined using standard methods. These properties were measured to aid in design strategies for subsequent disposal and/or utilization of the wastes under RP 2708, which was funded by the Electric Power Research Institute under the direction of Mr. D.M. Golden. Complete, final reports documenting the sampling and analytical protocol, waste characterization per process, and waste utilization will be published over the next two years by the Electric Power Research Institute.
Micromorphology and Mineralogy of Fly Ash and Lime Stabilized Bentonite
Authors: Ferrell Ray E. , Arman Ara , Baykal Gokhan 
Published: March 2011

ABSTRACTCompacted fly ash, lime, bentonite and water mixtures were cured at 23° and 50°C, for 1, 28, 90 and 180 days. Cementitious products and microstructure were observed by scanning electron microscopy, energy dispersive x-ray spectrometry and x-ray diffractometry. Unconfined compressive strength changes are correlated to the formation of new mineral phases. For bentonite-limefly ash mixtures, strength increased from 1050 kPa (I day) to 2,300 kPa (90 days) and then slightly increased to 2,400 kPa after 180 days at ∼ 230C. Ettringite is the most abundant mineral associated with the increased compressive strength.New minerals identified in the 23°C mixtures include calcium silicate hydrate - Type 1, afwillite and ettringite. Acicular crystals of these and other minerals were formed by the hydration of lime and fly ash in the montmorillonitic clay. The cementitious phases create a rigid framework joining spheres and clay aggregates. Continued reaction dissolves some of the spheres and slightly reduces the rigidity of the cured samples.
Fundamental Approach for Predicting Pore-Water Composition in Fossil Fuel Combustion Wastes
Authors: Rai Dhanpat , Mattigod S. V. , Eary L. E. , Ainsworth C. C. 
Published: March 2011

ABSTRACTAn application of a fundamental thermochemical approach that relates the aqueous concentrations of elements to specific chemical reactions in waste/water systems is described. The approach involves the concept of waste as consisting of mixtures of discrete solids (pure solid phases and solid solution phases) that control aqueous concentrations of individual solutes through their solubilization or adsorption/desorption characteristics. Thermochemical data can then be used in conjunction with knowledge of the specific solid phases present in the wastes to calculate the aqueous concentrations of elements. This approach does not explicitly consider specific rates of kinetically controlled reactions but does incorporate empirical knowledge of the relative rates of several reaction types. Overall, the thermochemical approach is applicable to all waste types and environments, and is appropriate because (1) most waste solids that either are present or are expected to form during weathering have relatively rapid precipitation/dissolution kinetics, and (2) experimental results, enrichment of many constituents on particle surfaces, and the large specific surface areas of wastes suggest that many of the constituents present in the wastes are accessible to solution attack and are mobilized fairly rapidly. Supporting evidence for the successful application of this approach to predicting pore-water concentrations of several major and trace elements in utility wastes is discussed.
Preparation of Zeolites for TEM Using Microtomy
Authors: Csencsits Roseann , Gronsky Ronald 
Published: March 2011

ABSTRACTThe application of microtomy to Transmission Electron Microscopy (TEM) specimen preparation of zeolite catalysts is explained. Using a new acrylic resin (LR White®) thin sections (≤60 nm) may be cut with relative ease. Although the details described are specific to catalysts, microtomy and the use of the acrylic resin are applicable to any hard ceramic powder sample.
In Situ High-Temperature Cross-Sectional TEM Specimen Preparation
Authors: Fiore Eric M. , Herring Rodney A. 
Published: March 2011

ABSTRACTWe describe a technique for preparing transmission electron microscope (TEM) cross-sectional specimens for observation during in situ annealing to high temperatures. The process utilizes a ceramic adhesive that is stable to a temperature of 1650°C. The technique, which was successfully used to observe the recrystallization of amorphized silicon, is being applied to high-energy ion-implanted silicon in an attempt to better understand the amorphous-to-crystalline phase transformation and defect formation mechanisms resulting from thermal processing.
Preparation of Crazed Specimens of Rubber-Toughened Glassy Polymers for Transmission Electron Microscopy
Authors: Gebizlioglu O. S. , Argon A. S. , Cohen R. E. 
Published: March 2011

ABSTRACTUpon staining with OsO4, crazes in rubber-toughened themplastics show inverted contrast in microscopy of ultra-thin sections and the details of the craze microstructure are masked. This report presents a method of specimen preparation for obtaining correct contrast of light crazes in a darker background.
Preparation of Semiconductor Cross Sections by Cleaving
Authors: Hetherington Crispin J. D. 
Published: March 2011

ABSTRACTThe practical details are presented for preparing cross-sectional samples of semiconductor epitaxial layers by cleaving. Examples of results are shown and a number of possible applications for the samples are discussed. A variation of the method can be used to prepare a TEM sample of a high Tcsuperconductor.
The Art of the Possible: An Overview of Catalyst Specimen Preparation Techniques for TEM Studies
Authors: Rice Stephen B. , Treacy Michael M. J. 
Published: March 2011

ABSTRACTObtaining useful microstructural information about catalysts requires appropriate procedures for preparing specimens for the transmission electron microscope. Unfortunately, most descriptions of catalyst specimen preparation are scattered throughout numerous journal articles or are unavailable. Traditional techniques for preparing heterogeneous catalyst powders include primarily dilute dispersion and ultramicrotomy. The advantages and disadvantages of these will be discussed in terms of information obtainable and possible artifacts. In addition, techniques for preparing layered materials, as well as some novel approaches and model systems, will be presented. With these, as with more traditional approaches, the best method for a specific material will be arrived at only through experimentation. Our aim is to describe a variety of possibilities for getting an already synthesized catalyst into the microscope suitably neat, thin, and artifactfree.
Microstructural Changes Produced by Ion-Beam Thinning in Al-Li-Cu Alloys
Authors: Singh A. K. , Imam M. A. , Michel D. J. , Sadananda K. 
Published: March 2011

ABSTRACTThin specimens for transmission electron microscopy examination may be prepared by several techniques, such as electropolishing and ion-beam thinning. Ion-beam thinning, which employs the use of an argon ion-beam at high voltage (e.g. 6kV) to bombard the specimen, is a commonly used technique for preparing and/or cleaning thin foil specimens. The experimental results show that even short-time thinning of Al-Li-Cu alloys with argon ion-beams introduce dramatic microstructural changes. Interesting observations concerning the effect of the ion-beam on quasi-crystals in Al-Li-Cu alloys during the thinning process are presented. The results and causes of the ion-beam thinning in Al-Li-Cu alloys are discussed.
Developments in the Tem Examination Of Pu and Pu Alloys
Authors: Zocco T. G. , Rohr D. L. 
Published: March 2011

ABSTRACTMicrostructural characterization of plutonium utilizing Transmission Electron Microscopy (TEN) has previously been difficult because of the extreme toxicity and high oxidation rate of plutonium metal. Recent developments in plutonium sample preparation have shown that foils of both alpha and delta phases of plutonium may be prepared for TEN without the use of inert atmospheric systems or complex preparation devices. Samples may be produced, using standard electropolishing techniques, that yield important microstructural data on plutonium and plutonium alloys.
Techniques for the Study of the Initial Stages of Electrocrystallization Using TEM
Authors: Hanson K. J. , Gibson J. M. , McDonald M. L. 
Published: March 2011

ABSTRACTA cell to permit in-situ imaging of the electrodeposition of silver on gold <100> from a polymer electrolyte by TEM is described. The extremely thin electrochemical cells were composed of a layer of polyethylene oxide containing a silver salt between evaporated silver and gold electrodes. Observations from preliminary in-situ TEM experiments include the nucleation and growth, and coalescence of silver islands oriented epitaxially to the gold electrode.
A Microscopic Marker Technique For Documenting Interface Motion in Corrosion Scales Using TEM
Authors: Fan Shou-Kong , Hobbs Linn W. 
Published: March 2011

ABSTRACTWe report here on a microscopic marker technique designed for use with cross-section TEM examination of corrosion scales. The technique involves microphotolithographic methods for sputter deposition of inert markers and has been used to document substrate/scale interface motion during high-temperature oxidation of Ni and Ni-base alloys.