Ab initio Monte Carlo investigation of small lithium clusters. (open access)

Ab initio Monte Carlo investigation of small lithium clusters.

Structural and thermal properties of small lithium clusters are studied using ab initio-based Monte Carlo simulations. The ab initio scheme uses a Hartree-Fock/density functional treatment of the electronic structure combined with a jump-walking Monte Carlo sampling of nuclear configurations. Structural forms of Li{sub 8} and Li{sub 9}{sup +} clusters are obtained and their thermal properties analyzed in terms of probability distributions of the cluster potential energy, average potential energy and configurational heat capacity all considered as a function of the cluster temperature. Details of the gradual evolution with temperature of the structural forms sampled are examined. Temperatures characterizing the onset of structural changes and isomer coexistence are identified for both clusters.
Date: June 16, 1999
Creator: Srinivas, S.
Object Type: Article
System: The UNT Digital Library
ADVANCED SORBENT DEVELOPMENT PROGRAM (open access)

ADVANCED SORBENT DEVELOPMENT PROGRAM

The overall objective of this program was to develop regenerable sorbents for use in the temperature range of 343 to 538 C (650 to 1000 F) to remove hydrogen sulfide (H{sub 2}S) from coal-derived fuel gases in a fluidized-bed reactor. The goal was to develop sorbents that are capable of reducing the H{sub 2}S level in the fuel gas to less than 20 ppmv in the specified temperature range and pressures in the range of 1 to 20 atmospheres, with chemical characteristics that permit cyclic regeneration over many cycles without a drastic loss of activity, as well as physical characteristics that are compatible with the fluidized bed application.
Date: June 16, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Advanced thermal barrier coating system development. Technical progress report (open access)

Advanced thermal barrier coating system development. Technical progress report

The objectives of the program are to provide an improved thermal barrier coating (TBC) system with increased temperature capability and improved reliability relative to current state of the art TBC systems. The development of such a coating system is essential to the Advanced Turbine Systems (ATS) engine meeting its objectives. The base program consists of three phases: Phase 1, Program Planning -- Complete; Phase 2, Development; Phase 3, Selected Specimen -- Bench Test. Work is being performed in Phase 2 and 3 of the program.
Date: June 16, 1998
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Alpha Contamination Levels in SMF South Cell and Compartments (open access)

Alpha Contamination Levels in SMF South Cell and Compartments

This document describes the detailed contamination survey performed in the Shielded Materials Facility (SMF) South Cell and the four compartments used during the CsCl activities. Smears were obtained at each operating station in South Cell and analyzed at the 325 Building. The smear results indicate that the highest contamination levels are in Compartment 1 and South Cell proper, with significantly lower contamination levels measured in the other three compartments. Although some of the smears indicated the presence of alpha contamination, it will be shown that the source of the alpha contamination was cross-contamination during processing in the 325 Building hot cells and that the SMF is free of alpha contamination. The alpha-free status of South Cell is consistent with process knowledge of previous South Cell activities.
Date: June 16, 1998
Creator: Durham, J. S.
Object Type: Report
System: The UNT Digital Library
Alternatives for the disposition of PUREX organic solution (open access)

Alternatives for the disposition of PUREX organic solution

This Supporting Document submits options and recommendations for final management of Tank 40 Plutonium-Uranium Extraction (PUREX) Plant organic solution per Tri-Party Agreement Milestorm Number M-80-00-T03. Hanford is deactivating the PUREX Plant for the US DOE. One the key element of this Deactivation is disposition of approximately 81,300 liters (21,500 gallons) of slightly radioactively contaminated organic solution to reduce risk to the environment, reduce cost of long-term storage, and assure regulatory compliance. An announcement in the Commerce Business Daily (CBD) on October 14, 1994 has resulted in the submission of proposals from two facilities capabLe of receiving and thermally destroying the solution. Total decomposition by thermal destruction is the recommended option for the disposition of the PUREX organic solution and WHC is evaluating the proposals from the two facilities.
Date: June 16, 1995
Creator: Nelson, D. W.
Object Type: Report
System: The UNT Digital Library
Aluminized film, seam sealing tests and observations. Final report (open access)

Aluminized film, seam sealing tests and observations. Final report

The purpose of this work was to investigate various seam sealing techniques, reinforcing methods, fitting installations, seam tolerances and geometric configurations pertinent to an aluminized plastic laminate. The program seeks a successful fabricating method for producing low-diffusion, cylindrical, spar liners to contain pressurized GH{sub 2} and GO{sub 2}. The test plan included: (1) seaming techniques on metallized Mylar film; (2) ``double patches`` for end fittings; (3) stainless steel bulkhead fitting assembly with seals; (4) minimum run tolerance on linear shear seam; (5) peel seam vs. inverted seal seam fabrication.
Date: June 16, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
An analysis of plutonium immobilization versus the "spent fuel" standard (open access)

An analysis of plutonium immobilization versus the "spent fuel" standard

Safe Pu management is an important and urgent task with profound environmental, national, and international security implications. Presidential Policy Directive 13 and analyses by scientific, technical, and international policy organizations brought about a focused effort within the Department of Energy (DOE) to identify and implement long-term disposition paths for surplus Pu. The principal goal is to render surplus Pu as inaccessible and unattractive for reuse in nuclear weapons as Pu in spent reactor fuel. In the Programmatic Environmental Impact Statement and Record of Decision for the Storage and Disposition of Weapons- Usable Fissile Materials (1997), DOE announced pursuit of two disposition technologies: (1) irradiation of Pu as MOX fuel in existing reactors and (2) immobilization of Pu into solid forms containing fission products as a radiation barrier. DOE chose an immobilization approach that includes �use of the can-in-canister option.. . for a portion of the surplus, non-pit Pu material.� In the can-in-canister approach, cans of glass or ceramic forms containing Pu are encapsulated within canisters of HLW glass. In support of the selection process, a technical evaluation of retrievability and recoverability of Pu from glass and ceramic forms by a host nation and by rogue nations or subnational groups was …
Date: June 16, 1998
Creator: Gray, W. L. & McKibben, J. M.
Object Type: Article
System: The UNT Digital Library
Aqueous complexation of trivalent lanthanide and actinide cations by N,N,N'{sub 2},N'-tetrakis(2-pyridylmethyl)ethylenediamine. (open access)

Aqueous complexation of trivalent lanthanide and actinide cations by N,N,N'{sub 2},N'-tetrakis(2-pyridylmethyl)ethylenediamine.

The aqueous complexation reactions of trivalent lanthanide and actinide cations with the hexadentate ligand N,N,N{prime},N{prime}-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), have been characterized using potentiometric and spectroscopic techniques in 0.1 M NaClO{sub 4} At 25 C, the stability constant of Am(TPEN){sup 3+} is two orders of magnitude larger than that of Sm(TPEN){sup 3+}, reflecting the stronger interactions of the trivalent actinide cations with softer ligands as compared to lanthanide cations.
Date: June 16, 1999
Creator: Beitz, J. V.; Ensor, D. D.; Jensen, M. P. & Morss, L. R.
Object Type: Article
System: The UNT Digital Library
Attempt To Commit A Federal Crime: S. 171, A Proposed General Statute (open access)

Attempt To Commit A Federal Crime: S. 171, A Proposed General Statute

There is no general federal statute proscribing criminal attempts; the federal criminal statutes are written in such a manner so as to include only the attempt to commit a specific substantive crime or substantive offense. Therefore, a specific in intent crime would require that the offender specifically intended to devise a scheme intended to commit the crime. The government, on the other hand, must present proof by inferences from the circumstances that the offender possessed the specific intent to commit the crime. This approach to the law has led to a patchwork of attempt statutes- leaving gaps in coverage, and failing to satisfactorily define exactly what constitutes an attempt in all circumstances an attempt in all circumstances. It is also the intent of the legislation to fill the gaps found in the current attempt statutes. This report will be updated if legislative activity warrant.
Date: June 16, 1998
Creator: Wallace, Paul S., Jr.
Object Type: Report
System: The UNT Digital Library
Cast Polycrystalline Photovoltaic Module Manufacturing Technology Improvements; Final Subcontract Report, 8 December 1993-30 April 1998 (open access)

Cast Polycrystalline Photovoltaic Module Manufacturing Technology Improvements; Final Subcontract Report, 8 December 1993-30 April 1998

This report summarizes work performed by Solarex, A Business Unit of Amoco/Enron Solar, under this subcontract. Among the accomplishments during the program are the following: Converting all of the production casting stations to increase ingot size, operating them at equivalent yields and cell efficiencies, and thus doubling the casting capacity at a 20% lower cost than the cost of new equipment. Developing a wire-saw process and transferring the process to production; as a result, more than 80% of wafering is now done using wire saws, at higher yields and lower costs than achieved on the internal diameter saws. Developing an aluminum paste back-surface field (BSF) process to increase cell efficiency by 5%; researchers also designed, procured, and transferred to manufacturing a fully automated printing system to produce the BSF cells. Fabricating 15.2-cm by 15.2-cm polycrystalline silicon solar cells and building modules using these cells. Modifying the module assembly area to increase capacity by a factor of three. Implementing a single-layer Tedlar backsheet that reduced backsheet cost by $0.50/ft2. Selecting, testing, and qualifying a low-cost (< $1.00 per module) electrical termination system. Qualifying the structure and adhesive system for mounting frameless modules and using the system to build several large arrays.
Date: June 16, 1999
Creator: Wohlgemuth, J.
Object Type: Report
System: The UNT Digital Library
Characterization of damage evolution in an AM60 magnesium alloy by computed tomography (open access)

Characterization of damage evolution in an AM60 magnesium alloy by computed tomography

Lawrence Livermore National Lab and Sandia National Laboratories, CA are collaborating on the development of new techniques to study damage evolution and growth in material specimens subjected to mechanical loading. These techniques include metallography, radiography, computed tomography (CT) and modeling. The material specimens being studied include cast magnesium and aluminum alloys, and forged stainless steel. The authors concentrate on characterizing monotonically loaded Mg alloy specimens using CT. Several notched tensile specimens were uniaxially loaded to different percentages of the failure load. Specimens were initially characterized by radiography and computed tomography to determine the preloaded state. Subsequent CT scans were performed after the samples were loaded to different percentages of the load failure. The CT volumetric data are being used to measure void size, distribution and orientation in all three dimensions nondestructively to determine the effect of void growth on the mechanical behavior of the materials.
Date: June 16, 1999
Creator: Waters, A.; Green, R.E.; Martz, H.; Dolan, K.; Horstemeyer, M. & Derrill, R.
Object Type: Article
System: The UNT Digital Library
Characterization of phase assemblage and distribution in titanate ceramics with SEM/EDS and x-ray mapping. (open access)

Characterization of phase assemblage and distribution in titanate ceramics with SEM/EDS and x-ray mapping.

Titanate ceramics have been selected for the immobilization of excess plutonium. The baseline ceramic formulation leads to a multi-phase assemblage, which consists of a majority pyrochlore phase plus secondary phases. The phase distribution depends on processing conditions and impurity loading. In this paper, we report on the characterization of the phase assemblage and distribution in titanate ceramics using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), and x-ray dot mapping. Two titanate ceramics were studied a baseline ceramic and a ceramic with impurities. In the baseline ceramic, the secondary phases that were observed include zirconolite, brannerite, and rutile. Additional phases, such as perovskite, an Al-Ti-Ca phase, and a silicate phase, formed in the impurity ceramic. The distribution of these phases was characterized with backscattered electron (BSE) imaging, except for zirconolite. While the zirconolite exhibited weak contrasts in BSE images and could not be easily distinguished from the pyrochlore matrix, its distribution was effectively characterized with x-ray mapping. Quantitative analyses of BSE images and x-ray maps reveal that the impurity ceramic contains less brannerite, rutile, and pores than the baseline ceramic.
Date: June 16, 1999
Creator: Luo, J. S.
Object Type: Article
System: The UNT Digital Library
Cs, Sr, and Ba Sorption on Clays and Fe-Oxides (open access)

Cs, Sr, and Ba Sorption on Clays and Fe-Oxides

Technical guidance for performance assessment (PA) of low-level radioactive waste (LLRW) sites is currently dependent upon experimental retardation factors (K{sub D}'s) to predict radionuclide transport. Accurate predictions of waste transport or retardation will require mechanistic models of radionuclide sorption so as to be applicable to a wide range of soil/groundwater environments. To that end, we have investigated Cs{sup +}, Sr{sup +}, and Ba{sup 2+} sorption on several clay and Fe-oxide minerals. Relative metal binding strengths for montmorillonite clay decrease from Ba{sup 2+} to Sr{sup +}, which is similar to that sorption trend noticed for kaolinite. Molecular dynamics simulations for kaolinite suggest that Cs{sup +} is sorbed at aluminol (010) edge sites as an inner-sphere complex and weakly sorbed as an outer-sphere complex on (001) basal surfaces. Sorption is thought to occur on similar sites for smectite clays, however, the basal plane residual charge and its increased basal plane exposure should have a greater influence on metal sorption. On the other hand, phase transformation kinetics (e.g., ferrihydrite to goethite) is a very important control of metal sorption and resorption for Fe-oxides/hydroxides. These results provide a basis for understanding and predicting metal sorption on complex soil minerals.
Date: June 16, 1999
Creator: Anderson, H. L.; Brady, P. V.; Cygan, R. T.; Gruenhagen, S. E.; Nagy, K. L. & Westrich, H. R.
Object Type: Article
System: The UNT Digital Library
D0 Silicon Upgrade: Transfer Line Branch Considerations for Solenoid & VLPC (open access)

D0 Silicon Upgrade: Transfer Line Branch Considerations for Solenoid & VLPC

The transfer line for the solenoid currently has a dead branch on it. Issues regarding the solenoid transfer line also apply to the VLPC transfer line. Issues that need to be addressed are: (1) What is the heat load on the branch? (2) Would it be a good idea to run the LN2 radiation shield on the branch? (3) What are the thermal acoustic oscillation parameters of a dead headed branch? A simple remedy, although not analyzed was to install a jumper with a flow restriction at the end of the helium piping to allow a small flow to pass from supply to return. Thus eliminating a stagnant gas volume in which pressure pulses would develop. (4) Do we need to have a vapor trap to keep liquid from sloshing back and forth from the cold end to the warm end? (5) Comment: The tee that passes the 2-phase return into the nested LHe supply/return pipe should be pointed up so that the volume of transfer line acts sort of like a phase separator full of liquid. It is very difficult to predict the behavior of the dead ended branch. Therefore the conservative thing to do is to keep the …
Date: June 16, 1995
Creator: Rucinski, Russ
Object Type: Report
System: The UNT Digital Library
Defense Budget: Alternative Measures of Costs of Military Commitments Abroad (open access)

Defense Budget: Alternative Measures of Costs of Military Commitments Abroad

This report contains he measures of costs of military commitments abroad and an analysis of the strengths and weaknesses of each overseas costs.
Date: June 16, 1995
Creator: Daggett, Stephen
Object Type: Report
System: The UNT Digital Library
Definition of total bootstrap current in tokamaks (open access)

Definition of total bootstrap current in tokamaks

Alternative definitions of the total bootstrap current are compared. An analogous comparison is given for the ohmic and auxiliary currents. It is argued that different definitions than those usually employed lead to simpler analyses of tokamak operating scenarios.
Date: June 16, 1995
Creator: Ross, D.W.
Object Type: Report
System: The UNT Digital Library
Department of Defense: Improving the DOD Payment Process, Using Recovery Auditing and Changing the Prompt Payment Act (open access)

Department of Defense: Improving the DOD Payment Process, Using Recovery Auditing and Changing the Prompt Payment Act

Testimony issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO discussed the Department of Defense's (DOD) payment problems and how recovery auditing is being used to identify and recover overpayments."
Date: June 16, 1999
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Development of a common software interface (open access)

Development of a common software interface

The variety of applications, databases, and information technologies makes it difficult to locate and retrieve information or applications that are otherwise openly available. The promise of the World Wide Web was that it was a paradigm for organizing and distributing information. Under this project, we looked at how we could more tightly couple the Web with the UNIX operating system for exchanging information, connecting programs and data, and facilitating collaboration between people in a more natural way. Ease of secure access and the ability to have electronic dialogues on specific questions will become increasingly important as the pressure Increases for scientists and analysts to rapidly access diverse information to make informed judgments and initiate new lines of Investigation.
Date: June 16, 1997
Creator: Davis, B. & Parrett, J.
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF AN ON-LINE, REAL-TIME ALPHA RADIATION MEASURING INSTRUMENT FOR LIQUID STREAMS (open access)

DEVELOPMENT OF AN ON-LINE, REAL-TIME ALPHA RADIATION MEASURING INSTRUMENT FOR LIQUID STREAMS

Thermo Power Corporation has proven the technical viability of an on-line, real-time alpha radionuclide instrument for aqueous sample analysis through laboratory and initial field tests of the instrument. The instrument has been shown to be isotonically sensitive to extremely low (ten parts per trillion, or femto Curies per liter) levels of a broad range of radioisotopes. Performance enhancement and other scaling data obtained during the course of this investigation have shown that on-line, real-time operation is possible, with a sub 30-minute response time analyzing 20 ppb (30 pCi/1) natural uranium. Now that these initial field tests in Oak Ridge, Tennessee have been successfully completed, Thermo Power plans to conduct comprehensive field tests of the instrument. The purpose of these endurance tests will be to determine the endurance characteristics of the Thermo Alpha Monitor for Water when it is used by non-Thermo Power personnel in a series of one or more extended field tests. Such endurance testing is the vital next step towards the commercialization of the Alpha Monitor. Subsequently, it will be possible to provide the DOE with an instrument that has the capability of obtaining rapid feedback about the concentrations of alpha-emitting isotope contamination in effluent water streams (Subsurface …
Date: June 16, 1999
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Edge reclamation in position-sensitive photomultiplier tubes (open access)

Edge reclamation in position-sensitive photomultiplier tubes

We have investigated the performance of a position-sensitive, gamma-ray detector based on a CsI(Na) scintillator coupled to a Hamamatsu R3292 Position-Sensitive Photomultiplier Tube (PSPMT). The R3292 has an active area 10.0 cm in diameter (quoted). Utilization of the full active area of the photocathode is a goal that has been previously unrealized due to edge effects. Initial measurements with a 0.75 cm thick CsI(Na) crystal indicate that the performance (position resolution linearity) starts to degrade as one reaches a radius of only 3.5 cm, reducing the active area by 60%. Measuring the anode wires we have found that this fall off is not solely due to crystal edge effects, but rather is inherent to the tube crystal system. In this paper we describe the results of our measurements and how good performance can be maintained across a full 10cm of the tube face through the use of a few additional electronics channels.
Date: June 16, 1999
Creator: Nakae, L. F. & Ziock, K. P.
Object Type: Article
System: The UNT Digital Library
Emerging patterns in cross-sector partnerships national lab partnerships: what works and what doesn`t (open access)

Emerging patterns in cross-sector partnerships national lab partnerships: what works and what doesn`t

All elements of the research triad in this country - universities, federal laboratories, and industrial labs - have spent a good part of the last decade in a very changeable and changing environment. In the area of partnerships with industry there have been a lot of experiments, such as the Advanced Technology Program (ATP), the Technology Reinvestment Program (TRP), and the Department of Energy`s (DOE) analog, the Technology Transfer Initiative (TM). We now have, at least in principle, gained enough experience with cross-sector partnerships to make some observations on what works and what doesn`t. My judgments are preliminary and driven by the idiosyncrasies of my own lab. I think the general themes at Livermore are reflected in other DOE national security labs and, at least to some extent, in other federal labs. Although we share some features in common with universities and industrial labs, I think the nature of our funding sources, and the way in which we are affected by global political factors such as the Cold War, pose a somewhat special set of circumstances for our institutions.
Date: June 16, 1997
Creator: Tarter, C.B.
Object Type: Article
System: The UNT Digital Library
Ensuring cost effectiveness in the TAP process (open access)

Ensuring cost effectiveness in the TAP process

The Training Accredition Program (TAP) at the Waste Isolation Division (WID) is discussed by the general manager. Cost effectiveness in the TAP process is made possible by saving through sharing which refers to the exchange and co-development of information and technology among Westinghouse Government owned-contractor operators and with other organizations. In 1990 a comprehensive management and supervisor training (MAST) program plan was devised and a MAST certification program of 31 self-paced written moduler was developed. This program has proven to be inexpensive to develop and implement when compared to classroom training. In addition, total quality is used as a tool to continuously improve work process. Continuous improvement requires continued evaluation of work process, such as TAP analysis and development in summary to make training at DOE facilities the most cost-effective training anywhere, we need to share, challenge conventional wisdom, and seek to continuously improve.
Date: June 16, 1992
Creator: Trego, A. L.
Object Type: Article
System: The UNT Digital Library
Errata to RISKIND - a computer program for calculating radiological consequences and health risks from transportation of spent nuclear fuel. (open access)

Errata to RISKIND - a computer program for calculating radiological consequences and health risks from transportation of spent nuclear fuel.

None
Date: June 16, 1999
Creator: Biwer, B. M.; Chen, S. Y.; LePoire, D. J. & Yuan, Y. C.
Object Type: Report
System: The UNT Digital Library
An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations (open access)

An Evaluation of Neutron Energy Spectrum Effects in Iron Based on Molecular Dynamics Displacement Cascade Simulations

The results of molecular dynamics (MD) displacement cascade simulations in bcc iron have been used to obtain effective cross sections for two measures of primary damage production: (1) the number of surviving point defects expressed as a fraction of the displacements calculated using the standard secondary displacement model of Norgett, Robinson, and Torrens (NRT), and (2) the fraction of the surviving interstitials contained in clusters that formed during the cascade event. Primary knockon atom spectra for iron obtained from the SPECTER code have been used to weight these MD-based damage production cross sections in order to obtain spectrally-averaged values for several locations in commercial fission reactors and materials test reactors. An evaluation of these results indicates that neutron energy spectrum differences between the various enviromnents do not lead to significant differences between the average primary damage formation parameters. In particular, the defect production cross sections obtained for PWR and BWR neutron spectra were not significantly different. The variation of the defect production cross sections as a function of depth into the reactor pressure vessel wall is used as a sample application of the cross sections. A slight difference between the attenuation behavior of the PWR and BWR was noted; this …
Date: June 16, 1998
Creator: Stoller, R. E. & Greenwood, L. R.
Object Type: Article
System: The UNT Digital Library