bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of Uranium Phosphate Phases and Potential Retardation Effects on Spent Fuel Radionuclide Migration
Authors: Turner A. S. , Wronkiewicz D. J. 
Published: April 2011

ABSTRACTThe UO2 in spent nuclear fuel is unstable in the oxidizing conditions within the volcanic tuffs at the proposed nuclear repository at Yucca Mountain, Nevada. Over time, the UO2 will oxidize and corrode, releasing actinides and fission products to the surrounding environment. However, uranyl (U6+) phosphates (autunite, phurcalite, sodium autunite, etc.) are stable in such an oxidizing environment. The mobility of released radionuclides may be greatly retarded if they can be incorporated into these naturally stable phosphate phases, while the complex structures, variable chemical compositions, and natural analogue occurrences of the uranyl phosphates suggests such a process is favorable. Current tests have focused on synthesizing such phases by reacting uranium oxynitrate or UO3 with a calcium, sodium, or potassium phosphate and a base (if necessary) in a Teflon reaction vessel. Excess water is added, and the solution is heated at 90°C for 7, 35, or 182 days. SEM analyses have confirmed that various uranium phosphate crystalline solids have formed. XRD results indicate that tests using two different calcium phosphorus source materials, Ca2P2O7 and Ca10(OH)2(PO4)6, have both created synthetic phosphuranylite, Ca(UO2)[(UO2)3(OH)2(PO4)2] 2*12H2O. The formation of this phase is appears to be kinetically favored over other similar phases. Results utilizing sodium phosphates, NaH2(PO4)*H2O and Na2HPO4, have produced sodium autunite (NaUO2PO4*2H2O), but other phases are probably also present. Test results utilizing potassium phosphate, K3PO4, were inconclusive. Experiments using surrogate radionuclides are currently being performed in order to determine whether radionuclides, such as 239Pu, 137Cs, and 99Tc, released from corroded spent nuclear fuel can become incorporated into the crystalline structure of specific uranium phosphate phases, effectively limiting any further migration.
Host Phases for Actinide Elements in the Metallic Waste Form
Authors: Janney D. E. 
Published: April 2011

ABSTRACTArgonne National Laboratory has developed an electrometallurgical process for conditioning spent sodium-bonded metallic reactor fuel prior to disposal. A waste stream from this process consists of stainless steel cladding hulls that contain undissolved metal fission products such as Tc, Ru, Rh, Pd, and Ag; a small amount of undissolved actinides (U, Np, Pu) also remains with the hulls. These wastes will be immobilized in a waste form whose baseline composition is stainless steel alloyed with 15 wt% Zr (SS-15Zr). Scanning electron microscope (SEM) observations of simulated metal waste forms (SS-15Zr with up to 11 wt% actinides) show eutectic intergrowths of Fe-Zr-Cr-Ni intermetallic phases with steels. The actinide elements are almost entirely in the intermetallics, where they occur in concentrations ranging from 1–20 at%. Neutron- and electron-diffraction studies of the simulated waste forms show materials with structures similar to those of Fe2Zr and Fe23Zr6.Dissolution experiments on simulated waste forms show that normalized release rates of U, Np, and Pu differ from each other and from release rates of other elements in the sample, and that release rates for U exceed those for any other element (including Fe). This paper uses transmission electron microscope (TEM) observations and results from energy-dispersive X-ray spectroscopy (EDX) and selected-area electron-diffraction (SAED) to characterize relationships between structural and chemical data and understand possible reasons for the observed dissolution behavior.Transmission electron microscope observations of simulated waste form samples with compositions SS-15Zr-2Np, SS-15Zr-5U, SS-15Zr-11U-0.6Rh-0.3Tc-0.2Pd, and SS-15Zr-10Pu suggest that the major actinide-bearing phase in all of the samples has a structure similar to that of the C15 (cubic, MgCu2-type) polymorph of Fe2Zr, and that materials with this structure exhibit significant variability in chemical compositions. Material whose structure is similar to that of the C36 (dihexagonal, MgNi2-type) polymorph of Fe2Zr was also observed, and it exhibits less chemical variability than that displayed by material with the C15 structure. The TEM data also demonstrate a range of actinide concentrations in materials with the Fe23Zr6 (cubic, Mn23Th6-type) structure.Microstructures similar to those produced during experimental deformation of Fe-10 at% Zr alloys were observed in intermetallic materials in all of the simulated waste form samples. Stacking faults and associated dislocations are common in samples with U, but rarely observed in those with Np and Pu, while twins occurred in all samples. The observed differences in dissolution behavior between samples with different actinides may be related to increased defect-assisted dissolution in samples with U.
Stability and Aging of Candidate Alloys for the Yucca Mountain Project: CALPHAD Results
Authors: Turchi P. E. A. , Kaufman L. , Liu Zi-Kui 
Published: April 2011

ABSTRACTThe CALPHAD approach is applied to the study of stability and aging of several Ni-Cr-Mo alloys similar to those considered for use in waste disposal containers for the Yucca Mountain Project (YMP). The stability of occurring phases in the as-fabricated materials must be investigated since their precipitation with time at temperature can reduce their corrosion resistance and mechanical properties. We first show that excellent agreement exists between assessed and calculated phase diagrams for the three major binary alloys, Ni-Cr, Ni-Mo, and Cr-Mo, and for the ternary Ni-Cr-Mo alloy. Then we present a comparative study of phase fractions versus temperature for the nominal composition of several multi-component Ni-Cr-Mo alloys. Finally we discuss the aging properties of the Ni2Cr-ordered phase in Ni-Cr and in Ni-Cr-Mo alloys, and of the complex P phase in Alloy 22.
Extension of the Modified Associate Species Thermochemical Model for High-Level Nuclear Waste: Inclusion of Chromia
Authors: Besmann Theodore M. , Spear Karl E. , Vienna John D. 
Published: April 2011

ABSTRACTThe successful thermochemical model based on the modified associate species approach for the Na2O-Al2O3-B2O3-SiO2 base glass system has been extended to include a critical constituent, Cr2O3. This includes the Cr2O3-Al2O3 solid solution. For the liquid, and potentially glass phase when undercooling is allowed to occur, the model uses the relative simple, modified associate species method to allow accurate determination of phase relations, including liquidus surfaces. It also allows prediction of chemical activities and vapor pressures, which can be important in both processing and in modeling long-term waste form stability.
Dissolution Behavior and Fission Product Release from Irradiated Thoria-Urania Fuel in Groundwater at 90°C
Authors: Jerden James L. , Cunnane J. C. 
Published: April 2011

ABSTRACTThe dissolution behavior and fission-product release from irradiated thoria-urania fuel was studied by immersing fuel samples in J-13 well water at 90°C. The samples are from the Shippingport Light Water Breeder Reactor and consist of binary solid solutions of (U,Th)O2 with UO2 contents varying from 2.0 to 5.2 Wt.%. The post-irradiation U isotopic composition of the samples used in our experiments is: 87.3% 233U, 10.4% 234U, 1.8% 235U, and <0.5% 238U, 236U, 232U. Burn up values for the samples range from 22.3 to 40.9 megawatt-days per kg-metal. Our tests were performed on polished disks and on crushed and sieved samples in stainless-steel reaction vessels with air-filled head-space. After 196 days of reaction, samples showed no evidence for corrosion at the micrometer scale. Concentration ranges (μgL-1) of key radionuclides in filtered (∼5 nm pore size) leachates were: 0.1 – 15 90Sr, 0.9 – 7.0 99Tc, 0.1 – 35.2 137Cs,<0.2 – 0.8 233U, <0.1 – 0.7 232Th. Concentrations of 237Np, 239Pu, 240Pu and 241Am were all <0.2 μgL-1. The relatively high concentrations of the fission products 90Sr and 137Cs occur early during leaching and decrease for later samplings. Matrix dissolution rates for the irradiated thoria-urania samples range from ∼3x10-3 to <3×10-5 mg m-2day-1 and are at least two orders of magnitude lower than those measured for UO2 spent fuels under similar experimental conditions.
Microstereolithography: a Review
Authors: Bertsch Arnaud , Jiguet Sébastien , Bernhard Paul , Renaud Philippe 
Published: April 2011

ABSTRACTMicrostereolithography is a technology at the interface of the microengineering and rapid prototyping domains. It has evolved from the stereolithography technique, and is also based on a light-induced layer-stacking manufacturing. As the resolution of the microstereolithography technique is far better than the one of rapid prototyping technologies, this technique is of particular interest in the microengineering domain where its 3D capability allows the production of components no other microfabrication technique can create.The first developments of the microstereolithography technique have started in 1993 and different research teams have developed machines since, using different approaches. This paper reviews the major microstereolithography processes developed until now.Microstereolithography is starting to be a commercially available manufacturing process. As the market for miniaturized products grows rapidly, there is an increasing need for highresolution small size prototype parts. If the production of small mechanical components is the first commercial application of microstereolithography, this technology can also produce useful components for the microrobotic, microfluidic, microsystems and biomedical fields. Current research in the microstereolithography field is focused on using ceramic composites as material to manufacture complex three-dimensional parts that can be sintered to produce pure alumina microcomponents.
Direct Fabrication of Patterned Functional Ceramic Films by Soft Solution Processing without Post-Firing
Authors: Yoshimura Masahiro , Watanabe Tomoaki , Fujiwara Takeshi , Teranishi Ryo 
Published: April 2011

ABSTRACTWe are proposing an innovative concept and technology, Soft Solution Processing (SSP) for ceramics, which aims to achieve direct fabrication of shaped, sized, located, oriented ceramic materials from solutions without firing and/or sintering. We have successfully fabricated thin and thick films of BaTiO3, SrTiO3, BaWO4, SrMoO4, LiCoO2, and LiNiO2 by SSP in aqueous solutions from room temperature to 200 °C. In these experiments, interfacial reactions between a solid reactant (substrate) and component(s) in a solution have been designed and realized. By locally activating the reaction and moving the reaction point dynamically in these reactions, we can produce patterned ceramics directly in solution without masking, etching, pattern forming, or any post-heating such as firing or sintering. In this paper we present recent results for patterned ceramic films of PbS, CdS, and LiCoO2. The processes used to produce these films are entirely new, and represent the first examples of successful direct patterning of ceramics from solutions. In previous reports, heating processes have been essential for synthesis and/or sintering of powders and precursors to obtain patterns in ceramic materials. Such processes inevitably cost environmentally and economically. In contrast, our method, where no firing is needed, provides an environmentally and economically less expensive alternative.
Direct-Write Process for UV-Curable Epoxy Materials by Inkjet Technology
Authors: Voit W. , Rao K. V. , Zapka W. 
Published: April 2011

ABSTRACTWe demonstrate drop-on-demand inkjet printing technique to be a high throughput method for the patterned deposition of UV-curable epoxy materials. Different multi-nozzle printheads have been used to produce epoxy droplets with controlled volume in the range from 15 to 180 pl, and to apply the droplets with high placement accuracy. For a large dot grid pattern, which was printed by addressing 126 individual ink channels, standard deviations of σx = 2.3 μm and σy = 2.6 μm have been achieved for the error in dot placement. The deposited epoxy dots were found to form planar convex lenses with a focal length of 142 μm. In addition, we have successfully printed magnetic nanoparticles in a carrier fluid with the drop-on-demand printheads, as a step towards the production of composites.
Fabrication Of Mesoscale Energy Storage Systems By Laser Direct-Write
Authors: Arnold Craig B. , Wartena Ryan C. , Swider-Lyons Karen E. , Piqué Alberto 
Published: April 2011

ABSTRACTOver the last two decades, there has been a trend towards the development of smaller and more autonomous electronic devices, yet the question of how to power these microdevices with correspondingly small power sources remains. To address this problem, we employ a laser forward-transfer process in combination with ultraviolet laser micromachining, to fabricate mesoscale electrochemical power sources, such as microbatteries and micro-ultracapacitors. This direct-write laser-engineering approach enables the deposition of battery materials (hydrous ruthenium oxide, manganese oxide, lithium cobalt oxide, etc.) under ambient temperature and atmospheric conditions, resulting in films with the desired morphological and electrochemical properties. Planar and stacked cell configurations are produced and tested for their energy storage and power delivery capabilities and exhibit favorable performance in comparison to current battery technology.
Laser Direct-Write Of Alkaline Microbatteries
Authors: Arnold Craig B. , Piqué Alberto 
Published: April 2011

ABSTRACTWe are developing a laser engineering approach to fabricate and optimize various types of alkaline microbatteries. Microbattery cells are produced using a laser forward transfer process that is compatible with the materials required to make the anode, cathode, separator and current collectors. The use of an ultraviolet transfer laser (wavelength = 355 nm, 30 ns FWHM) enables other operations such as surface processing, trimming and micromachining of the transferred materials and substrate and is performed in situ. Such multi-capability for adding, removing and processing material is unique to this direct-write technique and provides the ability to laser pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc-silver oxide alkaline cell by laser direct-write under ambient conditions. The microbattery cells exhibit 1.5–1.6 V open circuit potentials, as expected for the battery chemistry and show flat discharge behavior under constant current loads.
Versatile Nanodeposition of Dielectrics and Metals by Non-contact Direct-Write Technology
Authors: Wanzenboeck H. D. , Langfischer H. , Harasek S. , Basnar B. , Hutter H. , Bertagnolli E. 
Published: April 2011

ABSTRACTDirect-write techniques allow processing in the nanometer range and have become powerful methods for rapid prototyping of microelectronic circuits and micro-electro-mechanical systems (MEMS). Chemical reactions are initiated by a focused beam leading to deposition of solid material on literally any surface. We have used this method to deposit metals such as tungsten and dielectrics such as silicon oxide using a focused ion beam (FIB) with 10 to 50 kV acceleration voltage. Controlled guidance of the beam allows deposition of both metallic and dielectric material with features in the 100 nm range. The deposition of separate structures of metallic and dielectric material deposited next to each other is shown on samples of different roughness. 3-dimensional exemplary prototypes in the sub-μm range and multilayer structures demonstrate the versatility of this method for prototyping and mix-and-match approaches with commercial semiconductor devices. A characterization of the deposited material was performed to clarify chemical composition and surface morphology of deposited structures. The deposition parameters were found to influence the chemical composition and electronic properties of the material. Direct-write deposition of dielectrics and metals by FIB allows fabrication of 3-dimensional prototypes with custom-tailored material properties.
Two-Photon Laser Micro-Nano Fabrication; Understanding from Single-Voxel Level
Authors: Kawata Satoshi , Sun Hong-Bo 
Published: April 2011

ABSTRACTFor laser nanofabrication using two-photon photopolymerization, a deep understanding of the nature of focal spots that are related to two-photon excitation is essential for achieving a high spatial resolution in three dimensions. Here we report the use of a technology we call ascending scan for characterizing the three-dimensional size and shape of single polymerization elements (voxels), and introduce several features of voxels that have not been fully noticed before. These findings are important for tailoring nanofeatures according to design.
Structural and Morphological Study of Zirconia and Titania Sol-Gel Monolayered Films Supported on Soda-Lime Glass Substrates
Authors: Cueto Luisa F. , Sánchez Enrique , Torres-Martínez Leticia M. , Hirata Gustavo A. 
Published: April 2011

ABSTRACTSol-Gel, dip-coated titaniumIV and zirconiumIV dioxide monolayered films were deposited on soda-lime glass using titanium and zirconium acetylacetonates as precursors, respectively, and their structural and morphological characterization carried out. The films were heat-treated at different temperatures, 25°C, 150°C, 300°C, and 500°C and, according to Low-angle X-Ray Diffraction analyses (XRD), it was found that TiO2 (anatase) and tetragonal zirconia were present on the substrate, when heated at 500°C. Yoshida and Yajima's method, based on optical information given by the films transmittance UV-Vis spectra, was used to estimate film thickness, refractive index, and, using the Lorentz-Lorentz relationship, their volume fraction. Film thinning and phase formation with increasing temperature was observed, and both titania and zirconia films showed similar behavior during firing. Smooth films with a roughness value of around 2 nm are obtained for the two cases as indicated by Atomic Force Microscopy (AFM) of the surface. Also, formation temperature at around 500°C resulted in the optimum condition to obtain clean stoichiometric TiO2 and ZrO2 thin films on glass substrates as confirmed by X-Ray Photoelectron Spectroscopy (XPS) measurements.
Microfrictional Properties of Titanium Carbide
Authors: Ahmed Syed Imad-Uddin , Bregliozzi Giuseppe , Haefke Henry 
Published: April 2011

ABSTRACTThe tribological issues associated with silicon-based microelectromechanical systems (MEMS) are well known. A popular solution to improve the tribological behavior is to apply different kinds of thin films. One film material, shown to have favorable properties in specialty applications, and which may also be suited for MEMS, is titanium carbide (TiC).This paper examines the microfrictional properties of titanium carbide surfaces with two surface roughnesses sliding against polished 2 mm diameter TiC counterbodies. A comparison of the microfrictional behavior is made with various other surfaces sliding against the same material. Results indicate that the microfriction of smooth TiC sliding against a smooth TiC surface is low and similar to silicon or TiC sliding against a hydrophobic self-assembled monolayer. However, friction increases when the polished TiC ball slides against a rough TiC surface. Experiments at various relative humidities show that friction increases with increase in the relative humidity for two smooth TiC surfaces sliding against one another, but is reduced at higher relative humidity if the surface of one of the sliding partners is considerably rough.This microfrictional study shows that TiC is well suited for microtribological applications. However, for optimal performance, the surface characteristics need to be tailored to the operating conditions.
Corrosion Protection of Materials by Applying Nanotechnology Associated Studies
Authors: Asmatulu Ramazan , Claus Richard O. 
Published: April 2011

ABSTRACTCorrosion usually takes place and degrades material surfaces based on environmental chemistry. There are several popular ways of decreasing corrosion rates to improve the lifetime of materials and devices. As recently determined, some methods may incorporate nanostructured materials processing approaches. These include surface treatment methods, nanocomposite thin film coatings, top layer coatings and thermal barrier coatings. Test results show that the corrosion performance of materials is significantly improved as compared to materials processed using conventional methods. In the present paper, some of these studies will be analyzed, and the obtained corrosion results will be evaluated in detail for the future of corrosion processes.
Fe3O4 Ultrafine Particles with Narrow Size Distribution from Polymer-Metal Complex Gels
Authors: Huang Cheng , Yang C. Z. , Chen L. 
Published: April 2011

ABSTRACTAlthough studies on the Fe3O4 magnetic particle formation have been markedly advanced by the strenuous efforts of numerous researchers, the preparation and formation of ultrafine Fe3O4 particles with narrow size distribution still remain as an open area due to their broad applications, especially in biomedical fields such as target drug delivery and medical imaging. A new method for the titled template-mediated synthesis of Fe3O4 ultrafine magnetite particles (several tens of nanometers) with narrow size distribution from a polymer matrix has been investigated. Hydrazine hydrate was used as a reducing agent to prepare the poly(itaconic acid-co-acrylic acid) gel-supported iron metallic nanoclusters, which served as nuclei, and were later transferred into ultrafine iron oxide powders in NaOH base solution. The morphology, particle size, structure and magnetic properties, as well as the formation of the particles with narrow size distribution, were investigated by means of transmission electron microscopy, selected area electron diffraction, laser light scattering, wide-angle X-ray diffraction, Fourier-transform infrared spectroscopy, and electron spectroscopy for chemical analysis, as well as magnetic measurements, respectively. It was revealed that the Fe3O4 ultrafine particles prepared from the Fe3+-poly(itaconic acid-co-acrylic acid) complex gel system kept narrow size distribution, which originated from the oxidation and aggregation growth of the primary particles, and the metallic iron nanoclusters would act as “templates” in the later magnetite particles growth stage. This new attempt of template-mineralization of Fe3O4 ultrafine particles in our preparation was proved to be effective for preparing template-mediated ultrafine magnetite particles with narrow size distribution quickly, which could also be used to prepare other kinds of inorganic particles.