Office of Scientific and Technical Information
SciTec Connect (Office of Scientific and Technical Information - OSTI, U.S. Department of Energy)Not a member yet
500 research outputs found
Sort by
Micromechanisms of Twin Nucleation in TiAl: Effects of Neutron Irradiation
No full textThe so-called radiation-induced ductility (RID) reported in neutron-irradiated 47at%Al alloys is attributed to the formation of effective twin embryos in the presence of interstitial-type Frank loops in {gamma}-TiAl and the subsequent nucleation and growth of microtwins during post-irradiation tensile deformation. The stability of large faulted Frank loops is explained in terms of the repulsive interaction between Shockley and Frank partials. Interaction of only six ordinary slip dislocations with a Frank loop can facilitate a pole mechanism for twin formation to work. The relative ease of heterogeneous twin nucleation is the reason for the RID and the lack of changes in yield strength and work hardening
Investigation of Combined S02/N0x Removal by Ceria Sorbents
No full textSimultaneous removal of S02 and NOx using a regenerable solid sorbent will constitute an important improvement over the use of separate processes for the removal of these two pollutants from stack gases and possibly eliminate several shortcomings of the individual S02 and NOx removal operations. Recent studies at PHC considered cerium oxide as an alternate adsorbent to CuO. The present study aims to determine the effects of ammonia on the sulfation of the sorbent and to obtain a rate expression for the regeneration of alumina-supported CeOz sorbents. In the past quarter the effect of fly-ash, ammonia, and water on the sulfation of the sorbent was investigated. The analysis of the economics of a commercial scale ceria process has been sub-contracted to TECOGEN. This work has been completed and the report has been received
Thermal-Hydraulic Bases for the Safety Limits and Limiting Safety System Settings for HFIR Operation at 100 MW and 468 psig Primary Pressure, Using Specially Selected Fuel Elements
No full textThis report summarizes thermal hydraulic analyses performed to support HFIR operation at 100 MW and 468 psig pressure using specially selected fuel elements. The analyses were performed with the HFIR steady state heat transfer code, originally developed during HFIR design. This report addresses the increased core heat removal capability which can be achieved in fuel elements having coolant channel thicknesses that exceed the minimum requirements of the HFIR fuel fabrication specifications. Specific requirements for the minimum value of effective uniform as-built coolant channel thickness are established for fuel elements to be used at 100 MW. The burnout correlation currently used in the steady-state heat transfer code was also compared with more recent experimental results for stability of high-velocity flow in narrow heated channels, and the burnout correlation was found to be conservative with respect to flow stability at typical HFIR hot channel exit conditions at full power
Advanced Emissions Control Development Program
No full textThe objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W)
Structural Evolution of Carbon During Oxidation
No full textThe examination of the structural evolution of carbon during oxidation has proven to be of scientific interest. Early modeling work of fluidized bed combustion showed that most of the reactions of interest occurs iOn the micropores, and this work has concentrated on these pores. This work has concentrated on evolution of macroporosity and rnicroporosity of carbons during kinetic controlled oxidation using SAXS, C02 and TEM analysis. Simple studies of fluidized bed combustion of coal chars has shown that many of the events considered fragmentation events previously may in fact be "hidden" or nonaccessible porosity. This makes the study of the microporous combustion characteristics of carbon even more important. The generation of a combustion resistant grid, coupled with measurements of the SAXS and C02 surface areas, fractal analysis and TEM studies has confined that soot particles shrink during their oxidation, as previously suspected. However, this shrinkage results in an overall change in structure. This structure becomes, on a radial basis, much more ordered near the edges, while the center itself becomes transparent to the TEM beam, implying a total lack of structure in this region. Although complex, this carbon structure is probably burning as to keep the density of the soot particles nearly the same. The TEM techniques developed for examination of soots has also been applied to Spherocarb. The Spherocarb during oxidation also increases its ordering,. This ordering, by present theories, would imply that the reactivity would go. However, the reactivity goes up, implying that structure of carbon is secondary in importance to catalytic effects
Privatization Financing Alternatives: Blending Private Capital and Public Resources for a Successful Project
No full textThe U.S. Department of Energy (DOE) launched the Contract Reform Initiative in 1994 in order to improve the effectiveness and effkiency of managing major projects and programs. The intent of this initiative is to help DOE harness both technical and market forces to reduce the overall cost of accomplishing DOE's program goals. The new approach transfers greater risk to private contractors in order to develop incentives that align contractor performance with DOE's objectives. In some cases, this goal can be achieved through public-private partnerships wherein the govermhent and the contractor share risks associated with a project in a way that optimizes its economics. Generally, this requires that project risks are allocated to the party best equipped to manage and/or underwrite them. While the merits of privatization are well documented, the question of how privatized services should be financed is often debated. Given the cost of private sector equity and debt, it is difficult to ignore the lure of the government's "risk free" cost of capital. However, the source of financing for a project is an integral part of its overall risk allocation, and therefore, participation by the government as a financing source could alter the allocation of risks in the project, diminishing the incentive structure. Since the government's participation in the project's financing often can be a requirement for financial feasibility, the dilemma of structuring a role for the government without undermining the success of the project is a common and difficult challenge faced by policymakers around the world. However, before reverting to a traditional procurement approach where the government enters into a cost-plus risk profile, the government should exhaust all options that keep the private entity at risk for important aspects of the project. Government participation in a project can include a broad range of options and can be applied with precision to bridge a gap in the project's financial structure. As a general rule, the method and magnitude of this participation should depend on the unique requirements of the project and should serve to enhance the ability to raise private financing and lower overall project cost to the government. In order to properly evaluate the available options, it is important first to define the government's objectives in the project. The government then needs to analyze and determine the risk allocation structure, including the appropriate mix of private and government financing, which maximizes the project's efficiency and still allows the project to proceed in a way that meets the government's objectives for privatization
A Preliminary Survey of Terrestrial Plant Communities in the Sierra de los Valles
No full textTo more fully understand the species compositions and environmental relationships of high-elevation terrestrial plant communities in the Los Alamos region, 30 plots in randomly selected, upland locations were sampled for vegetation, topographic, and soils characteristics. The locations of these plots were constrained to be above 2,134 m (7,000 ft) above mean sea level. The field results were summarized, analyzed, and incorporated into a previously developed classification of vegetation and land cover types. The revised and updated discussions of the environmental relationships at these sites and their associated species compositions are included in this report. A key to the major land cover types in the Los Alamos region was also revised in accordance with the new information and included herein its entirety
Characterization of Transport and Solidification in the Metal Recycling Processes
No full textThe characterization of the transport and solidification of metal in the melting and casting processes is significant for the optimization of the radioactively contaminated metal recycling and refining processes. . In this research project, the transport process in the melting and solidification of metal was numerically predicted, and the microstructure and radionuclide distribution have been characterized by scanning electron microscope/electron diffractive X-ray (SEWEDX) analysis using cesium chloride (CSC1) as the radionuclide surrogate. In the melting and solidification process, a resistance furnace whose heating and cooling rates are program- controlled in the helium atmosphere was used. The characterization procedures included weighing, melting and solidification, weighing after solidification, sample preparation, and SEM/EDX analysis. This analytical methodology can be used to characterize metal recycling and refining products in order to evaluate the performance of the recycling process. The data obtained provide much valuable information that is necessary for the enhancement of radioactive contaminated metal decontamination and recycling technologies. The numerical method for the prediction of the melting and solidification process can be implemented in the control and monitoring system-of the melting and casting process in radioactive contaminated metal recycling. The use of radionuclide surrogates instead of real radionuclides enables the research to be performed without causing harmfid effects on people or the community. This characterization process has been conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University since October 1995. Tests have been conducted on aluminum (Al) and copper (Cu) using cesium chloride (CSCI) as a radionuclide surrogate, and information regarding the radionuclide transfer and distribution in melting and solidification process has been obtained. The numerical simulation of the solidification of molten metal has been very successful for aluminium; however, a stability problem in the simulation of iron/steel solidification poses a challenge. Thus, additional development is needed to simulate the radionuclide transfer and distribution behaviors in the melting and casting processes. This project was initially based on a two-year plan. However, due to technical and financial difficulties, the project ended in FY96. The work which has been accomplished in the first year includes the characterization of radionuclide transfer and distribution in the melting-solidification process and the numerical simulation of metal solidification. The Argon-arc melting method was tested for the melting of copper and steel materials. Five tests were performed to characterize the transfer and distribution of radionuclides in the aluminiurn and copper melting/solidification process using CSC1 as radionuclide surrogates. The numerical simulation of molten aluminium and steel solidification process was performed. Different boundary conditions were applied in the simulations
Petroleum Supply Monthly, September 1998, with data for July 1998
No full textThe Petroleum Supply Monthly (PSM) is one of a family of four publications produced by the Petroleum Division within the Energy Information Administration (EIA) reflecting different levels of data timeliness and completeness. The other publications are the Weekly Petroleum Status Report WPSR), the Winter Fuels Report, and the Petroleum Supply Annual (PSA). Data presented in the PSM describe the suppiy and disposition of petroleum products in the United States and major U.S. geographic regions. The data series describe production, imports and exports, inter-Petroleum Administration for Defense (PAD) District movements, and inventories by the primary suppliers of petroleum products in the United States (50 States and the District of Columbia). The reporting universe includes those petroleum sectors in primary supply. Included are: petroleum refiners, motor gasoline blenders, operators of natural gas processing plants and fractionators, inter-PAD transporters, importers, and major inventory holders of petroleum products and crude oil. When aggregated, the data reported by these sectors approximately represent the consumption of petroleum products in the United States. Data presented in the PSM are divided into two sections: Summary Statistics and Detailed Statistic
Midland Core Repository
No full textThe facility continues to be organized and data continue to be entered into the same database that contains the Austin facility's information. This is expected to continue throughout FY98. The roof has new been repaired