Interracial segregation and partitioning in a polysynthetically twinned Ti-48.4 at.% Al-0.6% Zr alloy were investigated by atom probe field ion microscopy and atom probe tomography. The compositions of the {gamma} and {alpha}{sub 2} phases were determined to be Ti-47.5% Al-O.71% Zr-0.06% O and Ti-31.6% Al-0.68% Zr-2.4% O, respectively. These results indicate a high concentration of zirconium in both matrix phases, confirming a strength increase through solid-solution strengthening, but no significant zirconium partitioning to either phase. Although zirconium additions produced a refined lamellar microstructure in this material, compositional analysis of {gamma}/{gamma} and {gamma}/{alpha}{sub 2} interfaces showed no evidence of significant zirconium segregation. This suggests that zirconium additions may produce a refined lamellar microstructure, but may not be effective at providing resistance to growth and coarsening.

Seep C was a free-flowing stream of groundwater that emerged in a narrow valley below the old low-level waste (LLW) disposal trenches in Solid Waste Storage Area 5 (SWSA 5) at Oak Ridge National Laboratory (ORNL). The flow rate of the seep water was strongly influenced by rainfall, and typically ranged from 0.5 to 8 L/min. The seep water entered Melton Branch, a small stream that joins White Oak Creek before exiting the ORNL boundary. The seep water contained high concentrations of {sup 90}Sr (10,000 to 20,000 Bq/L) and, before the full-scale treatment system was installed, contributed about 25% of all the {sup 90}Sr leaving ORNL. Seep C was identified as a primary source of off-site contaminant transport and was designated for an early removal action under the Comprehensive Environmental Response and Liability Act (CERCLA). A passive flow treatment system was chosen as the most cost-effective method for treating the water.

The adhesion of alumina scales to aluminide bond coats is a life-limiting factor for some advanced thermal barrier coating systems. This study investigated the effects of aluminide bond coat sulfur and platinum contents on alumina scale adhesion and coating microstructural evolution during isothermal and cyclic oxidation testing at 1150 C. Low-sulfur NiAl and NiPtAl bond coats were fabricated by chemical vapor deposition (CVD). Lowering the sulfur contents of CVD NiAl bond coatings significantly improved scale adhesion, but localized scale spallation eventually initiated along coating grain boundaries. Further improvements in scale adhesion were obtained with Pt additions. The observed influences of Pt additions included: (1) mitigation of the detrimental effects of high sulfur levels, (2) drastic reductions in void growth along the scale-metal interface, (3) alteration of the oxide-metal interface morphology, and (4) elimination of Ta-rich oxides in the Al{sub 2}O{sub 3} scales during thermal cycling. The results of this study also suggested that the microstructure (especially the grain size) of CVD aluminide bond coatings plays a significant role in scale adhesion.

Biomass fuels are considered to be a promising renewable source of energy. However, impurities present in the fuel may cause corrosion problems with the materials used in the hot sections of gas turbines and only limited data are available so far. As part of the Advanced Turbine Systems Program initiated by the U.S. Department of Energy, the present study provides initial data on the hot corrosion resistance of different nickel-base alloys against sodium sulfate-induced corrosion as a baseline, and against salt compositions simulating biomass-derived fuel deposits. Single crystal nickel-superalloy Rene N5, a cast NiCrAlY alloy, a NiCoCrAlY alloy representing industrially used overlay compositions, and a model {beta}NiAl+Hf alloy were tested in 1h thermal cycles at 950 C with different salt coatings deposited onto the surfaces. Whereas the NiCoCrAlY alloy exhibited reasonable resistance against pure sodium sulfate deposits, the NiCrAiY alloy and Rene N5 were attacked severely. Although considered to be an ideal alumina former in air and oxygen at higher temperatures, {beta}NiAl+Hf also suffered from rapid corrosion attack at 950 C when coated with sodium sulfate. The higher level of potassium present in biomass fuels compared with conventional fuels was addressed by testing a NiCoCrAlY alloy coated with salts of …

This paper describes a life cycle analysis system (LCAS) developed to support US Department of Energy (DOE) decision-making regarding deactivation and decommissioning (D and D), pollution prevention (P2), and asset recovery, and its deployment to analyze the disposition of facilities and capital assets. Originally developed for use at the Oak Ridge East Tennessee Technology Park, this approach has been refined through application at Ohio Operations Office sites and is now being deployed at a number of DOE sites. Programs such as National Metals Recycle, the D and D Focus Area, P2, and Asset Utilization are successfully using the system to make better decisions resulting in lower cost to the taxpayer and improved environmental quality. The LCAS consists of a user-friendly, cost-effective, and analytically-sound decision-aiding process and a complementary suite of automated tools to handle data administration and multiple criteria life cycle analysis (LCA). LCA is a systematic and comprehensive process for identifying, assessing, and comparing alternatives for D and D, P2, and asset recovery at government sites, and for selecting and documenting a preferred alternative. An LCA includes all of the impacts (benefits and costs) that result from a course of action over the entire period of time affected by …

The life cycle analysis toolbox is a valuable integration of decision-making tools and supporting materials developed by Oak Ridge National Laboratory (ORNL) to help Department of Energy managers improve environmental quality, reduce costs, and minimize risk. The toolbox provides decision-makers access to a wide variety of proven tools for pollution prevention (P2) and waste minimization (WMin), as well as ORNL expertise to select from this toolbox exactly the right tool to solve any given P2/WMin problem. The central element of the toolbox is a multiple criteria approach to life cycle analysis developed specifically to aid P2/WMin decision-making. ORNL has developed numerous tools that support this life cycle analysis approach. Tools are available to help model P2/WMin processes, estimate human health risks, estimate costs, and represent and manipulate uncertainties. Tools are available to help document P2/WMin decision-making and implement programs. Tools are also available to help track potential future environmental regulations that could impact P2/WMin programs and current regulations that must be followed. An Internet-site will provide broad access to the tools.

Measurements of liquid permeability in the mushy zones of AI-15.42% Cu and Al-8.68% Cu alloy samples have been performed isothermally just above the eutectic temperature, using eutectic liquid as the fluid. A modified method has been developed to determine the specific permeability, K{sub s}, as a function of time during the test from the data collected on these alloys. Factors affecting permeability measurements are discussed. Permeabilities are observed to vary throughout the experiment. This is attributed to microstructural coarsening and channeling that occurs in the sample during the experiment. The permeability is related to the microstructure of the sample using the Kozeny-Carman equation. The correlation between the measured K{sub s}, liquid fraction, g{sub L} and the specific solid surface area, S{sub v}, improves markedly when compared to previous studies in which microstructural coarsening was ignored.

Mercury was effectively removed from the oil via sorption using SAMMS.The method was demonstrated on a large scale using ORNL waste oil contaminated with mercury. This technology is ready for further demonstration and implementation when the SAMMS material is available in large quantities.

''The Murmansk Initiative - RF'' is a tri-lateral project developed to support Russia's ability to meet the London Convention's prohibition on ocean disposal of radioactive waste. The Initiative, under a tripartite agreement, has upgraded an existing low-level liquid radioactive waste treatment facility, increasing capacity from 1,200 m{sup 3}/year to 5,000 m{sup 3}/year, and expanded capability to treat liquids containing salt (up to 10 g/L). The three parties to the agreement, the Russian Federation, Norway, and the United States, have all contributed the project. All construction has been provided by Russia. Construction of mechanical systems (piping and valves, pumps, sorbent columns, settling tanks, and surge tanks) is nearing completion, with instrumentation and control (I&C) systems currently being installed. Delays to the I&C installation have occurred because changes in system specifications required additional U.S. supplied computer control equipment to be purchased, and clearance through customs (both U.S. and Russian) has been slow. Start-up testing has been limited to testing of isolated sub-systems because of the delays in the I&C installation. The current state of the Russian economy and completion of a cementation unit, which was not part of the original tri-partite agreement, have hampered final construction activities. Russian regulatory authorities have stated …

The U.S. Department of Energy will present an update and review of its programs in aluminum and magnesium for automotive and heavy-duty vehicle applications. While the main programs focused on vehicle materials are in the Office of Transportation Technologies, contributing efforts will be described in the DOE Office of Industrial Technologies and the DOE Office of Energy Research. The presentation will discuss materials for body/chassis and power train, and will highlight the considerable synergy among the efforts. The bulk of the effort is on castings, sheet, and alloys with a smaller focus on metal matrix composites. Cost reduction and energy savings are the overriding themes of the programs.

A series of bench-scale experiments were conducted to determine the optimum reaction conditions for destruction of styrene-divinyl benzene based cation resin and methylene chloride by the mediated electrochemical oxidation (MEO) process. Reaction parameters examined include choice of electron transfer mediator, reaction temperature and solvent system. For the cation exchange resins, maximum destruction efficiencies were obtained using cerium (IV) as mediator in nitric acid at a temperature of 70 C. Reasonable efficiencies were also realized with silver(II) and cobalt (III) at ambient temperature in the same solvent. Use of sulfuric acid as the solvent yielded much lower efficiencies under equivalent conditions. Methylene chloride was found to react only with silver (II) at ambient temperature in nitric acid media, cobalt (III) and cerium (IV) were totally ineffective. These results demonstrate a need to perform bench-scale experiments to determine optimum operating conditions for each organic substrate targeted for treatment by the MEO process.

In spite of recent advances in the mathematical modeling of fluid dynamics for materials processing applications, no significant advances have been made in the numerical discretization of these equations. In this work, the application of two-step projection methods for the numerical simulation of interdendritic flows is, discussed. Unlike previous methods, the methods presented here are constructed for the exact equations which are characterized by variable density and volumetric fraction of the liquid. The drag terms, which describe the momentum loss due to the flow around and through the dendrite structures, are treated implicitly. Numerical examples for shrinkage-induced flow during solidification of an AI-4.5% Cu alloy bar is used to illustrate the effectiveness of the proposed algorithm.

The authors have developed several different types of tools for sampling from sealed containers. These tools allow the user to rapidly drill into a closed container, extract a sample of its contents (gas, liquid, or free-flowing powder), and permanently reseal the point of entry. This is accomplished without exposing the user or the environment to the container contents, even while drilling. The entire process is completed in less than 15 seconds for a 55 gallon drum. Almost any kind of container can be sampled (regardless of the materials) with wall thicknesses up to 1.3 cm and internal pressures up to 8 atm. Samples can be taken from the top, sides, or bottom of a container. The sampling tools are inexpensive, small, and easy to use. They work with any battery-powered hand drill. This allows considerable safety, speed, flexibility, and maneuverability. The tools also permit the user to rapidly attach plumbing, a pressure relief valve, alarms, or other instrumentation to a container. Possible applications include drum venting, liquid transfer, container flushing, waste characterization, monitoring, sampling for archival or quality control purposes, emergency sampling by rapid response teams, counter-terrorism, non-proliferation and treaty verification, and use by law enforcement personnel during drug or …

Experiments are described in which a focused pulsed-excimer laser beam is used either to ablate a graphite target and deposit hydrogen-free amorphous carbon films, or to directly texture a silicon surface and produce arrays of high-aspect-ratio silicon microcolumns. In the first case, diamond-like carbon (or tetrahedral amorphous carbon, ta-C) films were deposited with the experimental conditions selected so that the masses and kinetic energies of incident carbon species were reasonably well controlled. Striking systematic changes in ta-C film properties were found. The sp{sup 3}-bonded carbon fraction, the valence electron density, and the optical (Tauc) energy gap ail reach their maximum values in films deposited at a carbon ion kinetic energy of {approximately}90 eV. Tapping-mode atomic force microscope measurements also reveal that films deposited at 90 eV are extremely smooth (rms roughness {approximately}1 {angstrom} over several hundred nm) and relatively free of particulate, while the surface roughness increases in films deposited at significantly lower energies. In the second set of experiments, dense arrays of high-aspect-ratio silicon microcolumns {approximately}20-40 {micro}m tall and {approximately}2 {micro}m in diameter were formed by cumulative nanosecond pulsed excimer laser irradiation of silicon wafers in air and other oxygen-containing atmospheres. It is proposed that microcolumn growth occurs through …

Over the last few years, there has been a growing interest in self-amplified spontaneous emission (SASE) free-electron lasers (FELs) as a means for achieving a fourth-generation light source. In order to correctly and easily simulate the many configurations that have been suggested, such as multi-segmented wigglers and the method of high-gain harmonic generation, we have developed a robust three-dimensional code. The specifics of the code, the comparison to the linear theory as well as future plans will be presented.

This paper presents a finite element evaluation of residual stress in a thread form generated by a cold rolling process. Included in this evaluation area mesh development study, methodology sensitivity studies, and the effects of applied loads on the stress in a rolled thread root. A finite element analysis of the thread forming process using implicit modeling methodology, incremental large deformation, elastic-plastic material properties, and adaptive meshing techniques was performed. Results of the study indicate the axial component of the residual stress in the thread root of the fastener is highly compressive. Results also indicate that a rolled threaded fastener loaded to an average tensile stress equal to yield through the cross-section will retain compressive stresses in the thread root. This compressive stress state will be advantageous when evaluating fasteners for fatigue and environmental concerns.

Recent advances in novel technologies (including chirped-pulse amplification, femtosecond laser systems operating in the TW-PW range, high-gradient rf photoinjectors, and synchronized relativistic electron bunches with subpicosecond durations and THz bandwidths) allow experimentalists to study the interaction of relativistic electrons with ultrahigh-intensity photon fields. Ponderomotive scattering can accelerate these electrons with extremely high gradients in a three-dimensional vacuum laser focus. The nonlinear Doppler shift induced by relativistic radiation pressure in Compton backscattering is shown to yield complex nonlinear spectra which can be modified by using temporal laser pulse shaping techniques. Colliding laser pulses, where ponderomotive acceleration and Compton backscattering are combined, could also yield extremely short wavelength photons. Finally, one expects strong radiative corrections when the Doppler-upshifted laser wavelength approaches the Compton scale. These are discussed within the context of high-field classical electrodynamics, a new discipline borne out of the aforementioned innovations.

The J-integral fracture methodology was applied to evaluate the stability of postulated flaws in mild steel storage tanks. The material properties and the J-resistance (JR) curve were obtained from the archival A285 Grade B carbon steel test data. The J-integral calculation is based on the center-cracked panel solution of Shih and Hutchinson (1976). A curvature correction was applied to account for the cylindrical shell configuration. A finite element analysis of an arbitrary flaw in the storage tank geometry demonstrated that the approximate solution is adequate.

A preliminary demonstration of free-space electric power transmission has been conducted using non-coherent laser diode arrays as the transmitter and standard silicon photovoltaic cell arrays as the receiver. The transmitter assembly used a high-power-density array of infrared laser diode bars, water cooled via integrated microchannel heat sinks and focused by cylindrical microlenses. The diode array composite beam was refocused by a parabolic mirror over a 10 meter path, and received on a {approximately}15 x 25 cm panel of thinned single crystal high efficiency silicon solar cells. The maximum cell output obtained was several watts, and the cell output was used to drive a small motor. Due to operating constraints and unexpected effects, particularly the high nonuniformity of the output beam, both the distance and total received power in this demonstration were modest. However, the existing transmitter is capable of supplying several hundred watts of light output, with a projected received electric power in excess of 200 watts. The source radiance is approximately 5 x 10{sup 9} W/m{sup 2}-steradian. With the existing 20 cm aperture, useful power transmission over ranges to {approximately}100 meters should be achievable with a DC to DC efficiency of greater than 10%. Non-coherent sources of this type …

The thermally controlled solidification of a binary alloy, nucleated at isolated sites, is described by the evolution of a probability distribution function, whose variables include grain size and distance to nearest neighbor, together with descriptors of shape, orientation, and such material properties as orientation of nonisotropic elastic modulus and coefficient of thermal expansion. The relevant Liouville equation is described and coupled with global equations for energy and solute transport. Applications are discussed for problems concerning nucleation and impingement and the consequences for final size and size distribution. The goal of this analysis is to characterize the grain structure of the solidified casting and to enable the description of its probable response to thermal treatment, machining, and the imposition of mechanical insults.

In this report, we have described the principal stages of a two-step process for the in-situ stabilization of actinide ions in the environment. The combination of cation exchange and mineralization appears likely to provide a long-term solution to environments contaminated with heavy metals. Relying on a naturally occurring sequestering agent has obvious potential advantages from a regulatory standpoint. There are additional aspects of this technology requiring further elucidation, including the demonstration of the effect of these treatment protocols on the geohydrology of soil columns, further examination of the influence of humates and other colloidal species on cation uptake, and microbiological studies of phytate hydrolysis. We have learned during the course of this investigation that phytic acid is potentially available in large quantities. In the US alone, phytic acid is produced at an annual rate of several hundred thousand metric tons as a byproduct of fermentation processes (11). This material presently is not isolated for use. Instead, most of the insoluble phyate (as phytin) is being recycled along with the other solid fermentation residues for animal feed. This material is in fact considered undesirable in animal feed. The details of possible separation processes for phytate from these residues would have to …

Federal application of ISO 14001 and / or the EPA Code of Environmental Management Principles (CEMP) could substantially improve the mitigation and monitoring aspects of the NEPA process. In addition, application of those management systems could also enhance fulfillment of Section 101 goals of NEPA. An ISO 14001 Environmental Management System would provide for a plan to continually address and improve environmental aspects and impacts. The strong feedback and improvement loops in both CEMP and ISO 14001 would help strengthen this weakness of NEPA by providing a mechanism to foster excellent environmental action, not just more dusty paperwork.

Outdoor performance of photovoltaic modules and systems depends on prevailing conditions at the time of measurement. Outdoor test conditions must be relevant to device performance and readily attainable. Flat-plate, nonconcentrator PV device performance is reported with respect to fixed conditions referred to as Standard Reporting Conditions (SRC) of 1 kW/m{sup 2} plane of array total irradiance, 25 C device temperature, and a reference spectral distribution at air mass 1.5 under certain atmospheric conditions. We report a method of analyzing historical meteorological and irradiance data to determine the range of outdoor environmental parameters and solar irradiance components that affect solar collector performance when the SRC 1 kW/m{sup 2} total irradiance value occurs outdoors. We used data from the 30 year U.S. National Solar Radiation Data Base (NSRDB) , restricting irradiance conditions to within +/- 25 W/m{sup 2} of 1 kW/m{sup 2} on a solar tracking flat-plate collector. The distributions of environmental parameter values under these conditions are non-Gaussian and site dependent. Therefore the median, as opposed to the mean, of the observed distributions is chosen to represent appropriate outdoor reporting conditions. We found the average medians for the direct beam component (834 W/m{sup 2}), ambient temperature (24.4 C), total column water …

We examine the operating modes of a two-bladed teetered wind turbine. Because of the gyroscopic asymmetry of its rotor, this turbine's dynamics can be quite distinct from those of a turbine with three or more blades. This asymmetry leads to system equations with periodic coefficients that are solved using the Floquet approach to extract the correct modal parameters. The system equations are derived using a simple analytical model with four degrees of freedom: cacelle yaw, rotor teeter, and flapping associated with each blade. Results confirm that the turbine modes become more dominated by the centrifugal and gyroscopic effects as the rotor speed increases. They gyroscopic effect may also cause dynamic instability. Under certain design conditions, yaw and teeter modal frequencies may coalesce.