Characterization and conditioning of SSPX plasma facing surfaces (open access)

Characterization and conditioning of SSPX plasma facing surfaces

The Sustained Spheromak Physics Experiment (SSPX) will examine the confinement properties of spheromak plasmas sustained by DC helicity injection. Understanding the plasma-surface interactions is an important component of the experimental program since the spheromak plasma is in close contact with a stabilizing wall (flux conserver) and is maintained by a high-current discharge in the coaxial injector region. Peak electron temperatures in the range of 400 eV are expected, so the copper plasma facing surfaces in SSPX have been coated with tungsten to minimize sputtering and plasma contamination. Here the authors report on the characterization and conditioning of these surfaces used for the initial studies of spheromak formation in SSPX. The high-pressure plasma-sprayed tungsten facing the SSPX plasma was characterized in-situ using beta-backscattering and ex-situ using laboratory measurements on similarly prepared samples. Measurements indicate that water can be desorbed effectively through baking while hydrocarbon/oxide removal using glow discharge and shot conditioning is slow due to the coating's high porosity.
Date: May 22, 2000
Creator: Buchenauer, D.; Mills, B. E.; Wood, R.; Woodruff, S.; Hill, D. N.; Hooper, E. B. et al.
Object Type: Article
System: The UNT Digital Library
D0 Piping Components (open access)

D0 Piping Components

None
Date: May 22, 2000
Creator: Dixon, K. & Rucinski, R.
Object Type: Report
System: The UNT Digital Library
Data Quality Objectives Process for Designation of K Basins Debris (open access)

Data Quality Objectives Process for Designation of K Basins Debris

The U.S. Department of Energy has developed a schedule and approach for the removal of spent fuels, sludge, and debris from the K East (KE) and K West (KW) Basins, located in the 100 Area at the Hanford Site. The project that is the subject of this data quality objective (DQO) process is focused on the removal of debris from the K Basins and onsite disposal of the debris at the Environmental Restoration Disposal Facility (ERDF). This material previously has been dispositioned at the Hanford Low-Level Burial Grounds (LLBGs) or Central Waste Complex (CWC). The goal of this DQO process and the resulting Sampling and Analysis Plan (SAP) is to provide the strategy for characterizing and designating the K-Basin debris to determine if it meets the Environmental Restoration Disposal Facility Waste Acceptance Criteria (WAC), Revision 3 (BHI 1998). A critical part of the DQO process is to agree on regulatory and WAC interpretation, to support preparation of the DQO workbook and SAP.
Date: May 22, 2000
Creator: WESTCOTT, J.L.
Object Type: Report
System: The UNT Digital Library
Depot Maintenance: Air Force Waiver to 10 U.S.C. 2466 (open access)

Depot Maintenance: Air Force Waiver to 10 U.S.C. 2466

Correspondence issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the Air Force's 50-percent ceiling waiver for depot maintenance, focusing on the: (1) extent to which the Air Force's justification for the waiver was due to its planned use of temporary contracts to support transitioning workloads; and (2) potential for the ceiling to be exceeded in fiscal years 2000 and 2001."
Date: May 22, 2000
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Direct releases to the surface and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant: Cuttings, cavings and spallings (open access)

Direct releases to the surface and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant: Cuttings, cavings and spallings

The following topics related to the treatment of cuttings, cavings and spallings releases to the surface environment in the 1996 performance assessment for the Waste Isolation Pilot Plant (WIPP) are presented: (1) mathematical description of models. (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty, and (4) uncertainty and sensitivity analysis results for CCDFs. The presented results indicate that direct releases due to cuttings, cavings and spallings do not constitute a serious threat to the effectiveness of the WIPP as a disposal facility for transuranic waste. Even when the effects of uncertain analysis inputs are taken into account, the CCDFs for cuttings, cavings and spallings releases fall substantially to the left of the boundary line specified in the US Environmental Protection Agency standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194).
Date: May 22, 2000
Creator: Berglund, J. W.; Garner, J. W.; Helton, Jon Craig; Johnson, J. D.; Smith, L. N. & Anderson, R. P.
Object Type: Article
System: The UNT Digital Library
Disordered vortex phases in YBa{sub 2}Cu{sub 3}O{sub x} (open access)

Disordered vortex phases in YBa{sub 2}Cu{sub 3}O{sub x}

The disordered vortex phases induced by line and point pinning in YBa{sub 2}Cu{sub 3}O{sub x} are explored. At high defect densities there is a single disordered solid separated from the liquid phase by a melting line. At low defect densities the topology of the phase diagram changes dramatically, with a vortex lattice phase adjoining disordered phases at high or low field. Critical points at the termination of first order melting separate the lattice and disordered phases. The line defect disordered phases follow the expected Bose glass behavior, while the point defect disordered phases do not exhibit the expected vortex glass behavior.
Date: May 22, 2000
Creator: Crabtree, G. W.; Kwok, W. K.; Olsson, R. J.; Karapetrov, G.; Paulius, L. M.; Petrean, A. et al.
Object Type: Article
System: The UNT Digital Library
DSE hadron phenomenology. (open access)

DSE hadron phenomenology.

A perspective on the contemporary application of Dyson-Schwinger equations, focusing on some recent phenomenological applications: a description and unification of light-meson observable using a one-parameter model of the effective quark-quark interaction, and studies of leptonic and nonleptonic nucleon form factors. The theory and phenomenological application of Dyson-Schwinger equations (DSEs) have seen something of a renaissance. For example, they have been applied simultaneously to phenomena as apparently unconnected as low-energy {pi}{pi} scattering, B {r_arrow} D{sup *} decays and the equation of state for a quark gluon plasma, and there are renewed attempts to understand the origin of the infrared enhancement necessary in the kernel of the quark DSE (QCD gap equation) to generate dynamical chiral symmetry breaking (DCSB). Also significant is the appreciation that in this approach current algebra's anomalies remain a feature of the global aspects of DCSB.
Date: May 22, 2000
Creator: Hecht, M. B.; Roberts, C. D. & Schmidt, S. M.
Object Type: Article
System: The UNT Digital Library
Electronic Government: Federal Initiatives Are Evolving Rapidly But They Face Significant Challenges (open access)

Electronic Government: Federal Initiatives Are Evolving Rapidly But They Face Significant Challenges

Testimony issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO discussed the evolving electronic government (e-government) environment, focusing on: (1) the statutory and policy framework; (2) key efforts to implement electronic government programs; and (3) the major challenges confronting both government and the private sector in making the transition to online business and service environments."
Date: May 22, 2000
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Explosive Destruction System for Recovered Chemical Munitions Phase II (open access)

Explosive Destruction System for Recovered Chemical Munitions Phase II

None
Date: May 22, 2000
Creator: Haroldsen, Brent & DiBerardo, Raymond
Object Type: Article
System: The UNT Digital Library
Extensions of the direct-semidirect model for calculating the high energy component of fast-nucleon induced gamma spectra (open access)

Extensions of the direct-semidirect model for calculating the high energy component of fast-nucleon induced gamma spectra

This section reviews extensions and variations of the direct-semidirect (DSD) model for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. We describe recent results on the extension of the DSD model to unbound final states, including comparison with proton and neutron capture data. The importance of including convective-current magnetic radiation to explain proton capture angular distributions in the 30 MeV region is shown. We conclude with a brief discussion of a model closely related to the DSD, the pure-resonance model.
Date: May 22, 2000
Creator: Dietrich, F S
Object Type: Report
System: The UNT Digital Library
Future Kaon Programs at BNL, FNAL. (open access)

Future Kaon Programs at BNL, FNAL.

None
Date: May 22, 2000
Creator: Kettell, S. H.
Object Type: Article
System: The UNT Digital Library
Lobbying Activity in Support of China Permanent Normal Trade Relations (open access)

Lobbying Activity in Support of China Permanent Normal Trade Relations

Other written product issued by the General Accounting Office with an abstract that begins "GAO commented on whether the efforts of the White House China Trade Relations Working Group and selected agencies violated the anti-lobbying provisions of 18 U.S.C. 1913. GAO noted that it identified one violation, which involved an electronic mail (e-mail) authorized by an agency representative assigned to the Working Group. While this appeared to constitute a violation of the applicable anti-lobbying appropriation provision, it involved a minimal expenditure of appropriated funds. GAO has discussed this e-mail with the White House Counsel's Office."
Date: May 22, 2000
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Managing Performance Analysis with Dynamic Statistical Projection Pursuit (open access)

Managing Performance Analysis with Dynamic Statistical Projection Pursuit

Computer systems and applications are growing more complex. Consequently, performance analysis has become more difficult due to the complex, transient interrelationships among runtime components. To diagnose these types of performance issues, developers must use detailed instrumentation to capture a large number of performance metrics. Unfortunately, this instrumentation may actually influence the performance analysis, leading the developer to an ambiguous conclusion. In this paper, we introduce a technique for focusing a performance analysis on interesting performance metrics. This technique, called dynamic statistical projection pursuit, identifies interesting performance metrics that the monitoring system should capture across some number of processors. By reducing the number of performance metrics, projection pursuit can limit the impact of instrumentation on the performance of the target system and can reduce the volume of performance data.
Date: May 22, 2000
Creator: Vetter, J.S. & Reed, D.A.
Object Type: Article
System: The UNT Digital Library
MEASUREMENT OF B(K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}}) (open access)

MEASUREMENT OF B(K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}})

The experimental measurement of K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}} is reviewed. New results from experiment E787 at BNL are presented: with data from 1995-97 the branching ratio has been measured to be B(K{sup +} {yields} {pi}{sup +} {nu}{bar {nu}}) = (1.5{sub {minus}1.2}{sup +3.4}) x 10{sup {minus}10}. The future prospects for additional data in this mode are examined.
Date: May 22, 2000
Creator: KETTELL,S.H.
Object Type: Article
System: The UNT Digital Library
Mechanical Testing Development for Reservoir Forgings (open access)

Mechanical Testing Development for Reservoir Forgings

The goal of this project was to determine the machining techniques and testing capabilities required for mechanical property evaluation of commercially procured reservoir forgings. Due to the small size of these specific forgings, specialized methods are required to adequately machine and test these sub-miniature samples in accordance with the requirements of ASTM-E8 and ASTM-E9. At the time of project initiation, no capability existed at Federal Manufacturing & Technologies (FM&T) to verify the physical properties of these reservoirs as required on the drawing specifications. The project determined the sample definitions, machining processes, and testing procedures to verify the physical properties of the reservoir forgings; specifically, tensile strength, yield strength, reduction of area, and elongation. In addition, a compression test method was also developed to minimize sample preparation time and provide a more easily machined test sample while maintaining the physical validation of the forging.
Date: May 22, 2000
Creator: Wenski, E. G.
Object Type: Report
System: The UNT Digital Library
Microstructures of laser deposited 304L austenitic stainless steel (open access)

Microstructures of laser deposited 304L austenitic stainless steel

Laser deposits fabricated from two different compositions of 304L stainless steel powder were characterized to determine the nature of the solidification and solid state transformations. One of the goals of this work was to determine to what extent novel microstructure consisting of single-phase austenite could be achieved with the thermal conditions of the LENS [Laser Engineered Net Shape] process. Although ferrite-free deposits were not obtained, structures with very low ferrite content were achieved. It appeared that, with slight changes in alloy composition, this goal could be met via two different solidification and transformation mechanisms.
Date: May 22, 2000
Creator: Brooks, John A.; Headley, Thomas J. & Robino, Charles V.
Object Type: Article
System: The UNT Digital Library
NEUTRON TOTAL CROSS SECTIONS OF 235U FROM TRANSMISSION MEASUREMENTS IN THE ENERGY RANGE 2 keV to 300 keV AND STATISTICAL MODEL ANALYSIS OF THE DATA (open access)

NEUTRON TOTAL CROSS SECTIONS OF 235U FROM TRANSMISSION MEASUREMENTS IN THE ENERGY RANGE 2 keV to 300 keV AND STATISTICAL MODEL ANALYSIS OF THE DATA

The average {sup 235}U neutron total cross sections were obtained in the energy range 2 keV to 330 keV from high-resolution transmission measurements of a 0.033 atom/b sample. The experimental data were corrected for the contribution of isotope impurities and for resonance self-shielding effects in the sample. The results are in very good agreement with the experimental data of Poenitz et al. in the energy range 40 keV to 330 keV and are the only available accurate experimental data in the energy range 2 keV to 40 keV. ENDF/B-VI evaluated data are 1.7% larger. The SAMMY/FITACS code was used for a statistical model analysis of the total cross section, selected fission cross sections and {alpha} data in the energy range 2 keV to 200 keV. SAMMY/FITACS is an extended version of SAMMY which allows consistent analysis of the experimental data in the resolved and unresolved resonance region. The Reich-Moore resonance parameters were obtained from a SAMMY Bayesian fits of high resolution experimental neutron transmission and partial cross section data below 2.25 keV, and the corresponding average parameters and covariance data were used in the present work as input for the statistical model analysis of the high energy range of the …
Date: May 22, 2000
Creator: Derrien, H.
Object Type: Report
System: The UNT Digital Library
Park Service: Agency Is Not Meeting Its Structural Fire Safety Responsibilities (open access)

Park Service: Agency Is Not Meeting Its Structural Fire Safety Responsibilities

A letter report issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO reviewed the National Park Service's (NPS) structural fire safety efforts, focusing on: (1) whether national parks are effectively addressing their structural fire safety responsibilities and if not, what are the main reasons; and (2) what improvements, if any, are under way to address identified problems."
Date: May 22, 2000
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Photoconductive properties of GaAs{sub 1{minus}x}N{sub x} double heterostructures as a function of excitation wavelength (open access)

Photoconductive properties of GaAs{sub 1{minus}x}N{sub x} double heterostructures as a function of excitation wavelength

The ternary semiconductor GaAs{sub 1{minus}x}N{sub x} with 0 < x < 0.3 can be grown epitaxially on GaAs and has a very large bowing coefficient. The alloy bandgap can be reduced to about 1.0 eV with about a 3% nitrogen addition. In this work, the authors measured the internal spectral response and recombination lifetime of a number of alloys using the ultra-high frequency photoconductive decay (UHFPCD) method. The data shows that the photoconductive excitation spectra of the GaAs{sub 0.97}N{sub 0.03} alloy shows a gradual increase in response through the absorption edge near E{sub g}. This contrasts with most direct bandgap semiconductors that show a steep onset of photoresponse at E{sub g}. The recombination lifetimes frequently are much longer than expected from radiative recombination and often exceeded 1.0{mu}s. The data were analyzed in terms of a band model that includes large potential fluctuations in the conduction band due to the random distribution of nitrogen atoms in the alloy.
Date: May 22, 2000
Creator: Ahrenkiel, R. K.; Mascarenhas, A.; Johnston, S. W.; Zhang, Y.; Friedman, D. J. & Vernon, S. M.
Object Type: Article
System: The UNT Digital Library
Radionuclide and colloid transport in the Culebra Dolomite and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant (open access)

Radionuclide and colloid transport in the Culebra Dolomite and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

The following topics related to radionuclide and colloid transport in the Culebra Dolomite in the 1996 performance assessment for the Waste Isolation Pilot Plant (WIPP) are presented: (1) mathematical description of models, (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, and (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty. The presented results indicate that radionuclide and colloid transport in the Culebra Dolomite does not constitute a serious threat to the effectiveness of the WIPP as a disposal facility for transuranic waste. Even when the effects of uncertain analysis inputs are taken into account, no radionuclide transport to the boundary with the accessible environment was observed; thus the associated CCDFs for comparison with the boundary line specified in the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194) are degenerate in the sense of having a probability of zero of exceeding a release of zero.
Date: May 22, 2000
Creator: Ramsey, James L.; Blaine, R.; Garner, J. W.; Helton, Jon Craig; Johnson, J. D.; Smith, L. N. et al.
Object Type: Article
System: The UNT Digital Library
Radionuclide transport in the vicinity of the repository and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant (open access)

Radionuclide transport in the vicinity of the repository and associated complementary cumulative distribution functions in the 1996 performance assessment for the Waste Isolation Pilot Plant

The following topics related to radionuclide transport in the vicinity of the repository in the 1996 performance assessment for the Waste Isolation Pilot Plant are presented (1) mathematical description of models, (2) uncertainty and sensitivity analysis results arising from subjective (i.e., epistemic) uncertainty for individual releases, (3) construction of complementary cumulative distribution functions (CCDFs) arising from stochastic (i.e., aleatory) uncertainty, and (4) uncertainty and sensitivity analysis results for CCDFs. The presented results indicate that no releases to the accessible environment take place due to radionuclide movement through the anhydrite marker beds, through the Dewey Lake Red Beds or directly to the surface, and also that the releases to the Culebra Dolomite are small. Even when the effects of uncertain analysis inputs are taken into account, the CCDFs for release to the Culebra Dolomite fall to the left of the boundary line specified in the US Environmental Protection Agency's standard for the geologic disposal of radioactive waste (40 CFR 191, 40 CFR 194).
Date: May 22, 2000
Creator: Stockman, Christine T.; Garner, J. W.; Helton, Jon Craig; Johnson, Jay Dean; Shinta, A. & Smith, L. N.
Object Type: Article
System: The UNT Digital Library
Recent developments in high-efficiency PV cells (open access)

Recent developments in high-efficiency PV cells

Enormous progress has been made in recent years on a number of photovoltaic (PV) materials and devices in terms of conversion efficiencies. Ultrahigh-efficiency (>30{percent}) PV cells have been fabricated from gallium arsenide (GaAs) and its ternary alloys such as gallium indium phosphide (GaInP{sub 2}). The high-efficiency GaAs-based solar cells are being produced on a commercial scale, particularly for space applications. Efficiencies in the range of 18{percent} to 24{percent} have been achieved in traditional silicon-based devices fabricated from both multicrystalline and single-crystal materials. Major advances in efficiency have also been made on various thin-film solar cells based on amorphous silicon (aSi:H), copper gallium indium diselenide (CIGS), and cadmium telluride materials. This paper gives a brief overview of the recent progress in PV cell efficiencies based on these materials and devices.
Date: May 22, 2000
Creator: Deb, S.
Object Type: Article
System: The UNT Digital Library
Regulatory basis for the Waste Isolation Pilot Plant performance assessment (open access)

Regulatory basis for the Waste Isolation Pilot Plant performance assessment

The Waste Isolation Pilot Plant (WIPP) is the first operational repository designed for the safe disposal of transuranic (TRU) radioactive waste from the defense programs of the US Department of Energy (DOE). The US Environmental Protection Agency (EPA) is responsible for certifications and regulation of the WIPP facility for the radioactive components of the waste. The EPA has promulgated general radioactive waste disposal standards at 40 CFR Part 191. and WIPP-specific criteria to implement and interpret the generic disposal standards at 40 CFR Part 194. In October 1996. the DOE submitted its Compliance Certification Application (CCA) to the EPA to demonstrate compliance with the disposal standards at Subparts B and C of 40 CFR Part 191. This paper summarizes the development of the overall legal framework for radioactive waste disposal at the WIPP, the parallel development of the WIPP performance assessment (PA), and how the EPA disposal standards and implementing criteria formed the basis for the CCA WIPP PA. The CCA resulted in a certification in May 1998 by the EPA of the WIPP'S compliance with the EPA's disposal standard, thus enabling the WIPP to begin radioactive waste disposal.
Date: May 22, 2000
Creator: Howard, Bryan A.; Crawford, M. B.; Galson, D. A. & Marietta, Melvin G.
Object Type: Article
System: The UNT Digital Library
Review and perspectives on spallings release models in the 1996 performance assessment for the Waste Isolation Pilot Plant (open access)

Review and perspectives on spallings release models in the 1996 performance assessment for the Waste Isolation Pilot Plant

The Waste Isolation Pilot Plant was licensed for disposal of transuranic wastes generated by the US Department of Energy. The facility consists of a repository mined in a bedded salt formation, approximately 650 m below the surface. Regulations promulgated by the US Environmental Protection Agency require that performance assessment calculations for the repository include the possibility that an exploratory drilling operation could penetrate the waste disposal areas at some time in the future. Release of contaminated solids could reach the surface during a drilling intrusion. One of the mechanisms for release, known as spallings, can occur if gas pressures in the repository exceed the hydrostatic pressure of a column of drilling mud. Calculation of solids releases for spallings depends critically on the conceptual models for the waste, for the spallings process, and assumptions regarding driller parameters and practices. The paper presents a review of the evolution of these models during regulatory review of the Compliance Certification Application for the repository. A summary and perspectives on the implementation of conservative assumptions in model development are also provided.
Date: May 22, 2000
Creator: Knowles, M. K; Hansen, F. D.; Thompson, T. W.; Schatz, J. F. & Gross, M.
Object Type: Article
System: The UNT Digital Library