1,322 Matching Results

Search Results

BWR drywell behavior under steam blowdown.

Description: Historically, thermal hydraulics analyses on Large Break Loss of Coolant Accidents (LOCA) have been focused on the transients within the reactor or steam generator. Few have studied the effects of steam blowdown on the containment building. This paper discusses some theoretical issues as well as presenting numerical and experimental results of the blowdown tests performed at the Purdue University Multi-Dimensional Integrated Test Assembly (PUMA).
Date: May 8, 1998
Creator: NguyenLe, Q.
Partner: UNT Libraries Government Documents Department

Audit of subsidized ancillary services at the Nevada Test site

Description: The Department and its contractors have participated in at least six reviews since 1991 encompassing aspects of subsidies at the test site. Several of these reviews resulted in reports recommending reductions to the housing, food, and bus services. A strategic planning report completed in November 1994, for example, recommended closing certain food service facilities, increasing housing rates to fair market value, and studying a bus depot system. Other reports echoed the same themes. The Department should be credited for recognizing that actions should be taken to reduce subsidy costs. Moreover, the Acting Manager, Nevada Operations office, has been proactive in reducing the busing subsidy by decreasing the number of buses and bus routes. The Acting Manager has also been fully supportive of the effort to further reduce subsidies. We appreciate these efforts.
Date: September 8, 1995
Partner: UNT Libraries Government Documents Department

Numerical relativity in a distributed environment.

Description: We have found that the hardware and software infrastructure exists to simulate general relativity problems in a distributed computational environment, at some cost in performance. We examine two different issues for running the Cactus code in such a distributed environment The first issue is running a Cactus simulation on multiple parallel computer systems. Our objective is to perform larger simulations than are currently possible on a single parallel computer. We distribute Cactus simulations across multiple supercomputers using the mechanisms provided by the Globus toolkit. In particular, we use Globus mechanisms for authentication, access to remote computer systems, file transfer, and communication. The Cactus code uses MPI for communication and makes use of an MPI implementation layered atop Globus communication mechanisms. These communication mechanisms allow a MPI application to be executed on distributed resources. We find that without performing any code optimizations, our simulations ran 48% to 100% slower when using an Origin at the National Center for Supercomputing Applications (NCSA) and an Onyx2 at Argonne National Laboratory (ANL). We also ran simulations between Cray T3Es in Germany and a T3E at the San Diego Supercomputing Center (SDSC). Running between the T3Es in Germany resulted in an increase in execution time of 79% to 133%, and running between a German T3E and a T3E at the San Diego Supercomputing Center resulted in an execution time increase of 114% to 186%. We are very encouraged that we are able to run simulations on parallel computers that are geographically distributed, and we have identified several areas to investigate to improve the performance of Cactus simulations in this environment. The second issue we examine here is remote visualization and steering of the Cactus code. Cactus is a modular framework and we have implemented a module for this task. This module performs isosurfacing operations on ...
Date: February 8, 1999
Creator: Benger, W.; Foster, I.; Novotny, J.; Seidel, E.; Shalf, J.; Smith, W. et al.
Partner: UNT Libraries Government Documents Department

Structural Modification of Sol-Gel Materials through Retro Diels-Alder Reaction

Description: Hydrolysis and condensation of organically bridged bis-triethoxysilanes, (EtO){sub 3}Si-R-Si(OEt){sub 3}, results in the formation of three dimensional organic/inorganic hybrid networks (Equation 1). Properties of these materials, including porosity, are dependent on the nature of the bridging group, R. Flexible groups (akylene-spacers longer than five carbons in length) polymerize under acidic conditions to give non-porous materials. Rigid groups (such as arylene-, alkynylene-, or alkenylene) form non-porous, microporous, and macroporous gels. In many cases the pore size distributions are quite narrow. One of the motivations for preparing hybrid organic-inorganic materials is to extend the range of properties available with sol-gel systems by incorporating organic groups into the inorganic network. For example, organically modified silica gels arc either prepared by co-polymerizing an organoalkoxysilane with a silica precursor or surface silylating the inorganic gel. This can serve to increase hydrophobicity or to introduce some reactive organic functionality. However, the type and orientation of these organic functionalities is difficult to control. Furthermore, many organoalkoxysilanes can act to inhibitor even prevent gelation, limiting the final density of organic functionalities. We have devised a new route for preparing highly functionalized pores in hybrid materials using bridging groups that are thermally converted into the desired functionalities after the gel has been obtained. In this paper, we present the preparation and characterization of bridged polysilsesquioxanes with Diels-Alder adducts as the bridging groups from the sol-gel polymerization of monomers 2 and 4. The bridging groups are constructed such that the retro Diela-Alder reaction releases the dienes and leaves the dienophiles as integral parts of the network polymers. In the rigid architecture of a xerogel, this loss of organic functionality should liberate sufficient space to modify the overall porosity. Furthermore, the new porosity will be functionalized with the dienophilic olefin bridging group. We also demonstrate that by changing the type of ...
Date: December 8, 1999
Creator: SHALTOUT,RAAFAT M.; LOY,DOUGLAS A.; MCCLAIN,MARK D.; PRABAKAR,SHESHASAYANA; GREAVES,JOHN & SHEA,KENNETH J.
Partner: UNT Libraries Government Documents Department

Structural analysis of ORNL underground gunite waste storage tanks

Description: The North Tank Farm (NTF) and the South Tank Farm (STF) located at ORNL contains 8 underground waste storage tanks which were built around 1943. The tanks were used to collect and store the liquid portion of the radioactive and/or hazardous chemical wastes produced as part of normal facility operations at ORNL, but are no longer part of the active Low Level Liquid Waste system of the Laboratory. The tanks were constructed of gunite. The six STF tanks are 50 ft in diameter, and have a 12 ft sidewall, and an arched dome rising another 6.25 ft. The sidewall are 6 in. thick and have an additional 1.5 in. gunite liner on the inside. There is a thickened ring at the wall-dome juncture. The dome consists of two 5 in. layers of gunite. The two tanks in the NTF are similar, but smaller, having a 25 ft diameter, no inner liner, and a dome thickness of 3.5 in. Both sets of tanks have welded wire mesh and vertical rebars in the walls, welded wire mesh in the domes, and horizontal reinforcing hoop bars pre-tensioned to 35 to 40 ksi stress in the walls and thickened ring. The eight tanks are entirely buried under a 6 ft layer of soil cover. The present condition of the tanks is not accurately known, since access to them is extremely limited. In order to evaluate the structural capability of the tanks, a finite element analysis of each size tank was performed. Both static and seismic loads were considered. Three sludge levels, empty, half-full, and full were evaluated. In the STF analysis, the effects of wall deterioration and group spacing were evaluated. These analyses found that the weakest element in the tanks is the steel resisting the circumferential (or hoop) forces in the dome ring, ...
Date: November 8, 1995
Creator: Fricke, K.E. & Chung, T.C.
Partner: UNT Libraries Government Documents Department

Comparison of the 200 hPa circulation in CSM and CCM3 simulations and NCEP and ERA reanalysis: seasonal cycle and interannual variation

Description: In this paper the monthly mean vorticity and divergence at 200 hPa are compared from four data sources: The NCEP/NCAR reanalyses 1958 through 1994, the ECMWF (ERA) reanalyses, 1979 through 1994, a NCAR CCM3 integration using prescribed SSTs from 1979 through 1993, and the NCAR CSM 300 year integration. The NCEP, ERA and CCM3 all provide data for the period 1979 through1993. The timescales examined are the annual cycle and interannual variations. The annual mean vorticity of the ERA and NCEP match very closely. The annual cycle is likewise close except in the eastern equatorial Pacific and Indian Ocean. Compared to the reanalyses, the models have adequate annual means but suffer in the depiction of the annual cycle in the regions of the jet maxima and in some regions of the Tropics. The CSM appears to inherit errors from the CCM3 and apparently add some new ones. The annual mean divergence shows a much larger difference between the reanalyses. This is most pronounced in the Tropics especially over the African and South American land masses. The models also show large differences, with the CSM being an outlier in the tropical Pacific. For many tropical and extratropical locations even the annual cycle is not well defined between the NCEP and ERA reanalysis. The NCEP, ERA, CCM3 and CSM agree with respect to the variance of the monthly mean vorticity. The variance for low pass filtered data is too large in the ENSO regions for the CCM3, but too small for the CSM. Both models tend to underestimate the low frequency variance in midlatitudes. The ERA has substantially more monthly variance in the divergence than the NCEP data, especially over the tropical South America and Africa and the dateline. Both models have variance more on the order of the ERA, and have ...
Date: October 8, 1998
Creator: Boyle, J.S.
Partner: UNT Libraries Government Documents Department

A transmission electron microscopy evaluation of solid-state upset welds in Type 304L stainless steel

Description: Transmission electron microscopy (TEM) was used to characterize the microstructures at and near the weld interface in upset welded Type 304L stainless steel test samples. Two sample configurations were examined in this study; upset welded cylinders prepared using a commercial resistance welder and cylindrical shaped samples welded in a Gleeble 1500 thermomechanical simulation device. The Gleeble samples evaluated were welded at 800 C, 900 C and 1,200 C with a 0.5 cm weld upset. The base microstructure of the samples varied with weld temperature. The lower temperature specimens contained a large free-dislocation density and distinct dislocation cells. The higher temperature specimens contained well-developed subgrains and a much lower free-dislocation density. The microstructure of the upset welded samples most closely resembled the 1,200 C Gleeble sample. No distinct bond line was observed by TEM in any of the specimens, i.e., diffusion and grain growth occurred across all weld interfaces. However, weld interfaces in both specimen configurations were characterized by the presence of 50--300 nm diameter particles spaced between 300 and 1,300 nm apart. Through the use of electron diffraction analysis and X-ray microanalysis two precipitate types were identified in both specimen configurations. A crystalline phase very similar to Mn{sub 1.5}Cr{sub 1.5}O{sub 4} and an amorphous phase enriched mainly in Si and Al were observed. Surface oxides and/or internal impurities may be sources for these precipitates. Future work will include a controlled study designed to determine the origin of the interface precipitates.
Date: September 8, 1995
Creator: Tosten, M.H.
Partner: UNT Libraries Government Documents Department

Development of Novel Activated Carbon-Based Adsorbents for Control of Mercury Emission From Coal-Fired Power Plants

Description: The overall objective of this study is to evaluate pertinent design and operational parameters that would enable successful application of activated carbon adsorption for the reduction of mercury emissions from coal-fired power plants. The study will evaluate the most suitable impregnate such as sulfur, chloride and other chelating agents for its ability to enhance the adsorptive capacity of activated carbon for mercury vapor under various process conditions. The main process variables to be evaluated include temperature, mercury concentration and speciation, relative humidity, oxygen content, and presence of SO2 and NOx in the flue gas. The optimal amount of impregnate for each of these carbons will be determined based on the exhibited performance. Another important parameter which governs the applicability of adsorption technology for the flue gas clean up is the rate at which vapor phase mercury is being removed from the flue gas by activated carbon. Therefore, the second part of this study will evaluate the adsorption kinetics using the impregnated activated carbons listed above. The rate of mercury uptake will also be evaluated under the process conditions that are representative of coal-fired power plants. Concerned with the ability of the adsorbed mercury to migrate back into the environment once saturated adsorbent is removed from the system, the study will also focus on the mercury desorption rate as a function of the type of impregnate, loading conditions, and the time of contact prior to disposal.
Date: September 8, 1997
Creator: Vidic, Radisav D.
Partner: UNT Libraries Government Documents Department

Speech coding

Description: Speech is the predominant means of communication between human beings and since the invention of the telephone by Alexander Graham Bell in 1876, speech services have remained to be the core service in almost all telecommunication systems. Original analog methods of telephony had the disadvantage of speech signal getting corrupted by noise, cross-talk and distortion Long haul transmissions which use repeaters to compensate for the loss in signal strength on transmission links also increase the associated noise and distortion. On the other hand digital transmission is relatively immune to noise, cross-talk and distortion primarily because of the capability to faithfully regenerate digital signal at each repeater purely based on a binary decision. Hence end-to-end performance of the digital link essentially becomes independent of the length and operating frequency bands of the link Hence from a transmission point of view digital transmission has been the preferred approach due to its higher immunity to noise. The need to carry digital speech became extremely important from a service provision point of view as well. Modem requirements have introduced the need for robust, flexible and secure services that can carry a multitude of signal types (such as voice, data and video) without a fundamental change in infrastructure. Such a requirement could not have been easily met without the advent of digital transmission systems, thereby requiring speech to be coded digitally. The term Speech Coding is often referred to techniques that represent or code speech signals either directly as a waveform or as a set of parameters by analyzing the speech signal. In either case, the codes are transmitted to the distant end where speech is reconstructed or synthesized using the received set of codes. A more generic term that is applicable to these techniques that is often interchangeably used with speech coding is the ...
Date: May 8, 1998
Creator: Ravishankar, C., Hughes Network Systems, Germantown, MD
Partner: UNT Libraries Government Documents Department

Institutional Plan FY 1999-2003

Description: Computational science is becoming an increasingly important component of Pacific Northwest's support to DOE's major missions. The advanced parallel computing systems in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), coupled with new modeling and simulation software, data management tools, and user interfaces, are providing solutions to previously intractable problems. Research focuses on developing software and other tools to address computational challenges in molecular science, environmental management, global climate change, advanced materials and manufacturing processes, molecular biology, and information management. The Graphics and Visualization Laboratory is part of EMSL'S Molecular Science Computing Facility (MSCF). The MSCF contains a 512-processor IBM RISC System/6000 scalable power parallel computer system that provides the advanced computing capability needed to address ''Grand Challenge'' environmental research problems. The MSCF provides an integrated computing environment with links to facilities in the DOE complex, universities, and industry. The image inserts are graphical representations of simulations performed with software developed at the Laboratory.
Date: February 8, 1999
Creator: Hughes, P.J.
Partner: UNT Libraries Government Documents Department

Microbial Population Changes During Bioremediation of an Experimental Oil Spill

Description: A field experiment was conducted in Delaware (USA) to evaluate three crude oil bioremediation techniques. Four treatments were studied: no oil control, oil alone, oil + nutrients, and oil + nutrients + an indigenous inoculum. The microbial populations were monitored by standard MPN techniques, PLFA profile analysis, and 16S rDNA DGGE analysis for species definition. Viable MPN estimates showed high but steadily declining microbial numbers and no significant differences among treatments during the 14-weeks. Regarding the PLFA results, the communities shifted over the 14-week period from being composed primarily of eukaryotes to Gram-negative bacteria. The Gram-negative communities shifted from the exponential to the stationary phase of growth after week 0. All Gram-negative communities showed evidence of environmental stress. The 16S rDNA DGGE profile of all plots revealed eight prominent bands at time zero. The untreated control plots revealed a simple, dynamic dominant population structure throughout the experiment. The original banding pattern disappeared rapidly in all oiled plots, indicating that the dominant species diversity changed and increased substantially over 14 weeks. The nature of this change was altered by nutrient-addition and the addition of the indigenous inoculum.
Date: August 8, 1998
Creator: Chang, Y. J.; Davis, G. A.; Macnaughton, S. J.; Stephen, J. R.; Venosa, A. D. & White, D. C.
Partner: UNT Libraries Government Documents Department

Acceptance test procedure (ATP) for the master equipment list(MEL) database system -- phase I

Description: The Waste Remediation System Facilities Configuration Management Integration group has requested development of a system to help resolve many of the difficulties associated with management of master equipment list information. This project has been identified as Master Equipment List (MEL) database system. Further definition is contained in the system requirements specification (SRS).
Date: January 8, 1997
Creator: Thornton, M.W.
Partner: UNT Libraries Government Documents Department

Owner Involvement in Construction at a National Laboratory

Description: In a construction project, the contractor and the owner each have a responsibility for ensuring the health and safety of personnel on a project site. The contractor has the responsibility for ensuring that the provisions of OSHA'S safety and health regulations are followed and that the work is conducted in a safe and well thought out manner (Kohn 1996). The owner has a responsibility for disclosing to the contractor those owner-controlled hazards that are present in the work area due to ongoing and past operations (OSHA 1997). With the owner taking an active role in disclosing the potential hazards, the contractor is able to account for, plan, and mitigate potential health and safety issues during the performance phase of the project. At Sandia National Laboratories, this disclosure is made early in the project through the use of processes developed specifically for this purpose.
Date: March 8, 1999
Creator: Lipka, G.
Partner: UNT Libraries Government Documents Department

Performance of keck adaptive optics with sodium laser guide star

Description: The Keck telescope adaptive optics system is designed to optimize performance in he 1 to 3 micron region of observation wavelengths (J, H, and K astronomical bands). The system uses a 249 degree of freedom deformable mirror, so that the interactuator spacing is 56 cm as mapped onto the 10 meter aperture. 56 cm is roughly equal to r0 at 1.4 microns, which implies the wavefront fitting error is 0.52 ({lambda}/2{pi})({ital d}/{ital r}{sub 0}){sup 5/6} = 118 nm rms. This is sufficient to produce a system Strehl of 0.74 at 1.4 microns if all other sources of error are negligible, which would be the case with a bright natural guidestar and very high control bandwidth. Other errors associated with the adaptive optics will however contribute to Strehl degradation, namely, servo bandwidth error due to inability to reject all temporal frequencies of the aberrated wavefront, wavefront measurement error due to finite signal-to-noise ratio in the wavefront sensor, and, in the case of a laser guidestar, the so-called cone effect where rays from the guidestar beacon fail to sample some of the upper atmosphere turbulence. Cone effect is mitigated considerably by the use of the very high altitude sodium laser guidestar (90 km altitude), as opposed to Rayleigh beacons at 20 km. However, considering the Keck telescope`s large aperture, this is still the dominating wavefront error contributor in the current adaptive optics system design.
Date: March 8, 1996
Creator: Gavel, D.T.; Olivier, S. & Brase, J.
Partner: UNT Libraries Government Documents Department

Shake table testing of structural clay tile infilled frames

Description: Two steel frames with structural clay tile infills were tested under simulated seismic loads in both the out-of-plane and in-plane direction. Out-of-plane testing showed that infill panels separate from their bounding frame, and respond at their own natural frequency during a seismic excitation. Due to arching, the panels remain stable. In-plane seismic testing showed similar behavior patterns to previous static testing. The natural frequency was adequately predicted using a piecewise linear equivalent strut analytical method. The structure was then subjected to over one thousand cycles of loading using a sine sweep before failure.
Date: March 8, 1996
Creator: Bennett, R.M.; Fowler, J.J. & Flanagan, R.D.
Partner: UNT Libraries Government Documents Department

OTP for belhaven flammable gas monitor at 241-T-104

Description: This Operational Test Procedure tests the operability of the Safety Class 3 flammable gas monitoring system with equipment shutdown capability. This test includes the flammable gas monitor, heat trace system, pneumatic system, and the interface with existing equipment.
Date: March 8, 1996
Creator: Zuroff, W.F.
Partner: UNT Libraries Government Documents Department

A Continuous Automated Vault Inventory System (CAVIS) for accountability monitoring of stored nuclear materials

Description: Nearly all facilities that store hazardous (radioactive or non-radioactive) materials must comply with prevailing federal, state, and local laws. These laws usually have components that require periodic physical inspections to insure that all materials remain safely and securely stored. The inspections are generally labor intensive, slow, put personnel at risk, and only find anomalies after they have occurred. The system described in this paper was developed for monitoring stored nuclear materials resulting from weapons dismantlement, but its applications extend to any storage facility that meets the above criteria. The traditional special nuclear material (SNM) accountability programs, that are currently used within most of the Department of Energy (DOE) complex, require the physical entry of highly trained personnel into SNM storage vaults. This imposes the need for additional security measures, which typically mandate that extra security personnel be present while SNM inventories are performed. These requirements increase labor costs and put additional personnel at risk to radiation exposure. In some cases, individuals have received radiation exposure equivalent to the annual maximum during just one inventory verification. With increasing overhead costs, the current system is rapidly becoming too expensive to operate, the need for an automated method of inventory verification is evident. The Continuous Automated Vault Inventory System (CAVIS) described in this paper was designed and prototyped as a low cost, highly reliable, and user friendly system that is capable of providing, real-time weight, gamma. and neutron energy confirmation from each item stored in a SNM vault. This paper describes the sensor technologies, the CAVIS prototype system (built at Y- 12 for highly enriched uranium storage), the technical requirements that must be achieved to assure successful implementation, and descriptions of sensor technologies needed for a plutonium facility.
Date: December 8, 1994
Creator: Pickett, C. A.; Barham, M. A.; Gafford, T. A.; Hutchinson, D. P.; Jordan, J. K.; Maxey, L. C. et al.
Partner: UNT Libraries Government Documents Department

A study of over-production and enhanced secretion of enzymes. Quarterly report 2

Description: This project is concerned with the over-production of ligno-cellulolytic enzymes which are relevant to the paper-pulp industry and agricultural community. Since ligno-cellulosics are components of wood, the project involves the forest, a renewable energy resource. Attention is focused on the following: over-production of polyphenol oxidase; establishment of the route of polyphenol oxidase secretion; regulation of polyphenol oxidase secretion; purification of extracellular oxidase.
Date: April 8, 1993
Creator: Dashek, W.V.
Partner: UNT Libraries Government Documents Department

Analysis for Eccentric Multi Canister Overpack (MCO) Drops at the Canister Storage Building (CSB) (CSB-S-0073)

Description: Multi-Canister Overpacks (MCOs) containing spent nuclear fuel (SNF) will be routinely handled at the Canister Storage Building (CSB) during fuel movement operations in the SNF Project. This analysis was performed to investigate the potential for damage from an eccentric accidental drop onto the standard storage tube, overpack tube, service station, or sample/weld station. Appendix D was added to the FDNW document to include the peer Review Comment Record & transmittal record.
Date: October 8, 1999
Creator: TU, K.C.
Partner: UNT Libraries Government Documents Department

Molten salt destruction of energetic material wastes as an alternative to open burning

Description: The Lawrence Livermore National Laboratory in conjunction with the Energetic Materials Center (a partnership of Lawrence Livermore and Sandia National Laboratories), is developing methods for the safe and environmentally sound destruction of explosives and propellants as a part of the Laboratory`s ancillary demilitarization mission. As a result of the end of the Cold War and the shift in emphasis to a smaller stockpile, many munitions, both conventional and nuclear, are scheduled for retirement and rapid dismantlement and demilitarization. major components of these munitions are the explosives and propellants, or energetic materials. The Department of Energy has thousands of pounds of energetic materials which result from dismantlement operations at the Pantex Plant. The Department of Defense has several hundred million pounds of energetic materials in its demilitarization inventory, with millions more added each year.
Date: September 8, 1994
Creator: Upadhye, R.S.; Brummond, W.A.; Pruneda, C.O. & Watkins, B.E.
Partner: UNT Libraries Government Documents Department

Quarterly Report for High NA Optics Development: Q3-1999 International Sematech Project LITH 112

Description: This quarterly report provides a status update for each of the milestones for the International Sematech project on the development of high-NA optics for a small-field EUVL exposure tool. The optical design has been completed, which employs two aspheric mirrors yielding diffraction-limited imaging within a 600 {micro}m x 200 {micro}m field with a numerical aperture of 0.3 and a 5x reduction. Preliminary aerial image calculations show good resolution of 30nm features with partially coherent illumination. Contracts have been awarded for the fabrication and multilayer coating of the mirror elements and a detailed specification package has been generated for one of the mirror substrates (M1). Metrology instrumentation is being assembled and fabrication has been initiated on M1. Key progress includes the design and fabrication of kinematic mounting fixtures that enable the vendor to perform interferometry in a geometry compatible with PO Box fixturing. The first substrate is proceeding according to schedule, with delivery expected in December 1999.
Date: October 8, 1999
Creator: Taylor, J.S.
Partner: UNT Libraries Government Documents Department