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Local Effects of Biased Electrodes in the Divertor of NSTX
The goal of this paper is to characterize the effects of small non-axisymmetric divertor plate electrodes on the local scrape-off layer plasma. Four small rectangular electrodes were installed into the outer divertor plates of NSTX. When the electrodes were located near the outer divertor strike point and biased positively, there was an increase in the nearby probe currents and probe potentials and an increase in the LiI light emission at the large major radius end of these electrodes. When an electrode located farther outward from the outer divertor strike point was biased positively, there was sometimes a significant decrease in the LiI light emission at the small major radius end of this electrode, but there were no clear effects on the nearby probes. No non-local effects were observed with the biasing of these electrodes.
Date:
May 7, 2012
Creator:
: S. Zweben, M.D. Campanell, B.C. Lyons, R.J. Maqueda, Y. Raitses, A.L. Roquemore and F. Scotti
Object Type:
Report
System:
The UNT Digital Library
GLASS FORMULATION TESTING TO INCREASE SULFATE INCORPORATION - Final Report VSL-04R4960-1, Rev 0, 2/28/05, Vitreous State Laboratory, The Catholic University of American, Washington, D.C.
About 50 million gallons of high-level mixed waste is currently in storage in underground tanks at The United States Department of Energy's (DOE's) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE's Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed of in an engineered facility on the Hanford site while the IHLW product will be directed to the national deep geological disposal facility for high-level nuclear waste. The ILAW and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. The Office of River Protection is currently examining options to optimize the Low Activity Waste (LAW) facility and the LAW glass waste form. One option under evaluation is to enhance the waste processing rate of the vitrification plant currently under construction. It is likely that the capacity of the LAW vitrification plant can …
Date:
February 7, 2012
Creator:
AA, KRUGER & KS, MATLACK
Object Type:
Report
System:
The UNT Digital Library
SMALL-SCALE MELTER TESTING WITH LAW SIMULANTS TO ASSESS THE IMPACT OF HIGHER TEMPERATURE MELTER OPERATIONS - Final Report, VSL-04R49801-1, Rev. 0, 2/13/03, Vitreous State Laboratory, The Catholic University of America, Washington, D.C.
About 50 million gallons of high-level mixed waste is currently in storage in underground tanks at The United States Department of Energy's (DOE's) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE's Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed of in an engineered facility on the Hanford site while the IHL W product will be directed to the national deep geological disposal facility for high-level nuclear waste. The ILAW and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. The Office of River Protection is currently examining options to optimize the Low Activity Waste (LAW) facility and the LAW glass waste form. One option under evaluation is to enhance the waste processing rate of the vitrification plant currently under construction. It is likely that the capacity of the LAW vitrification plant …
Date:
February 7, 2012
Creator:
AA, KRUGER & KS, MATLACK
Object Type:
Report
System:
The UNT Digital Library
EFFECT OF GLASS-BATCH MAKEUP ON THE MELTING PROCESS
The response of a glass batch to heating is determined by the batch makeup and in turn determines the rate of melting. Batches formulated for a high-alumina nuclear waste to be vitrified in an all-electric melter were heated at a constant temperature-increase rate to determine changes in melting behavior in response to the selection of batch chemicals and silica grain-size as well as the addition of heat-generating reactants. The type of batch materials and the size of silica grains determine how much, if any, primary foam occurs during melting. Small quartz grains, 5 {micro}m in size, caused extensive foaming because their major portion dissolved at temperatures <800 C, contributing to the formation of viscous glass forming melt that trapped evolving batch gases. Primary foam did not occur in batches with larger quartz grains, {+-}75 {micro}m in size, because their major portion dissolved at temperatures >800 C when batch gases no longer evolved. The exothermal reaction of nitrates with sucrose was ignited at a temperature as low as 160 C and caused a temporary jump in temperature of several hundred degrees. Secondary foam, the source of which is oxygen from redox reactions, occurred in all batches of a limited composition variation …
Date:
December 7, 2010
Creator:
AA, KRUGER & P, HRMA
Object Type:
Article
System:
The UNT Digital Library
GLASSES CONTAINING IRON (II III) OXIDES FOR IMMOBILIZATION OF RADIOACTIVE TECHNETIUM
Technetium-99 (Tc-99) has posed serious environmental threats as US Department of Energy's high-level waste. This work reports the vitrification of Re, as surrogate for Tc-99, by iron-borosilicate and iron-phosphate glasses, respectively. Iron-phosphate glasses can dissolve Re as high as {approx} 1.2 wt. %, which can become candidate waste forms for Tc-99 disposal, while borosilicate glasses can retain less than 0.1 wt. % of Re due to high melting temperature and long melting duration. Vitrification of Re as Tc-99's mimic was investigated using iron-borosilicate and iron-phosphate glasses. The retention of Re in borosilicate glasses was less than 0.1 wt. % and more than 99 wt. % of Re were volatilized due to high melting temperature and long melting duration. Because the retention of Re in iron-phosphate glasses is as high as 1.2 wt. % and the volatilization is reduced down to {approx}50 wt. %, iron-phosphate glasses can be one of the glass waste form candidates for Tc (or Re) disposal. The investigations of chemical durability and leaching test of iron-phosphate glasses containing Re are now underway to test the performance of the waste form.
Date:
November 7, 2011
Creator:
AA, KRUGER; J, HEO; K, XU; JK, CHOI; PR, HRMA & W, UM
Object Type:
Article
System:
The UNT Digital Library
EVALUATION OF TEMPORAL VARIATIONS IN HYDRAULIC CAPTURE DUE TO CHANGING FLOW PATTERNS USING MAPPING AND MODELING TECHNIQUES
Robust performance evaluation represents one of the most challenging aspects of groundwater pump-and-treat (P&T) remedy implementation. In most cases, the primary goal of the P&T system is hydraulic containment, and ultimately recovery, of contaminants to protect downgradient receptors. Estimating the extent of hydraulic containment is particularly challenging under changing flow patterns due to variable pumping, boundaries and/or other conditions. We present a systematic approach to estimate hydraulic containment using multiple lines of evidence based on (a) water-level mapping and (b) groundwater modeling. Capture Frequency Maps (CFMs) are developed by particle tracking on water-level maps developed for each available water level data set using universal kriging. In a similar manner, Capture Efficiency Maps (CEMs) are developed by particle tracking on water-levels calculated using a transient groundwater flow model: tracking is undertaken independently for each stress period using a very low effective porosity, depicting the 'instantaneous' fate of each particle each stress period. Although conceptually similar, the two methods differ in their underlying assumptions and their limitations: their use together identifies areas where containment may be reliable (i.e., where the methods are in agreement) and where containment is uncertain (typically, where the methods disagree). A field-scale example is presented to illustrate these …
Date:
April 7, 2011
Creator:
AA, SPILIOTOPOULOS; LC, SWANSON; R, SHANNON & MJ, TONKIN
Object Type:
Article
System:
The UNT Digital Library
Search for Contact Interactions in Dimuon Events From $Pp$ Collisions at $\sqrt{s}=7$ TeV With the ATLAS Detector
None
Date:
June 7, 2013
Creator:
Aad, Georges
Object Type:
Article
System:
The UNT Digital Library
Search for Extra Dimensions Using Diphoton Events in 7 TeV Proton-Proton Collisions with the ATLAS Detector
None
Date:
May 7, 2013
Creator:
Aad, Georges
Object Type:
Article
System:
The UNT Digital Library
Fermi Observations of the Very Hard Gamma-Ray Blazar PG 1553+113
None
Date:
December 7, 2011
Creator:
Abdo, A. A.
Object Type:
Article
System:
The UNT Digital Library
A Method of Optimizing Field Roll-Off and the Peak Field of Hybrid Planar Undulators
None
Date:
October 7, 2013
Creator:
Abliz, M. & Vasserman, I. (Accelerator Systems Division (APS)) Accelerator Systems Division (APS)
Object Type:
Report
System:
The UNT Digital Library
Hard Probes in Heavy Ion Collisions at the LHC: PDFs, Shadowing and $pA$ Collisions
None
Date:
August 7, 2013
Creator:
Accardi, Alberto; Armesto, N.; Botje, M.; Brodsky, S. J.; Cole, B.; Eskola, K. J. et al.
Object Type:
Article
System:
The UNT Digital Library
International Trade and Finance: Key Policy Issues for the 112th Congress
This report highlights major international trade and finance issues Congress may address this year.
Date:
January 7, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
International Trade and Finance: Key Policy Issues for the 112th Congress
This report examines the trade relations between the United States, the European Union, and China.
Date:
January 7, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Transatlantic Regulatory Cooperation: Background and Analysis
This report discusses commercial ties between the United States and the 27-member European Union. These ties are substantial, growing, and mutually beneficial, but differences in regulatory approaches limit an even more integrated marketplace from developing. This report is intended to serve as an introduction and primer on this complicated, broad, and often highly technical set of issues.
Date:
March 7, 2011
Creator:
Ahearn, Raymond J.
Object Type:
Report
System:
The UNT Digital Library
Electronic Structure of Ligated CdSe Clusters: Dependence on DFT Methodology
Simulations of ligated semiconductor quantum dots (QDs) and their physical properties, such as morphologies, QD-ligand interactions, electronic structures, and optical transitions, are expected to be very sensitive to computational methodology. We utilize Density Functional Theory (DFT) and systematically study how the choice of density functional, atom-localized basis set, and a solvent affects the physical properties of the Cd{sub 33}Se{sub 33} cluster ligated with a trimethyl phosphine oxide ligand. We have found that qualitative performance of all exchange-correlation (XC) functionals is relatively similar in predicting strong QD-ligand binding energy ({approx}1 eV). Additionally, all functionals predict shorter Cd-Se bond lengths on the QD surface than in its core, revealing the nature and degree of QD surface reconstruction. For proper modeling of geometries and QD-ligand interactions, however, augmentation of even a moderately sized basis set with polarization functions (e.g., LANL2DZ* and 6-31G*) is very important. A polar solvent has very significant implications for the ligand binding energy, decreasing it to 0.2-0.5 eV. However, the solvent model has a minor effect on the optoelectronic properties, resulting in persistent blue shifts up to {approx}0.3 eV of the low-energy optical transitions. For obtaining reasonable energy gaps and optical transition energies, hybrid XC functionals augmented by a …
Date:
July 7, 2011
Creator:
Albert, VV; Ivanov, SA; Tretiak, S & Kilina, SV
Object Type:
Article
System:
The UNT Digital Library
A Multifaceted Mathematical Approach for Complex Systems
Applied mathematics has an important role to play in developing the tools needed for the analysis, simulation, and optimization of complex problems. These efforts require the development of the mathematical foundations for scientific discovery, engineering design, and risk analysis based on a sound integrated approach for the understanding of complex systems. However, maximizing the impact of applied mathematics on these challenges requires a novel perspective on approaching the mathematical enterprise. Previous reports that have surveyed the DOE's research needs in applied mathematics have played a key role in defining research directions with the community. Although these reports have had significant impact, accurately assessing current research needs requires an evaluation of today's challenges against the backdrop of recent advances in applied mathematics and computing. To address these needs, the DOE Applied Mathematics Program sponsored a Workshop for Mathematics for the Analysis, Simulation and Optimization of Complex Systems on September 13-14, 2011. The workshop had approximately 50 participants from both the national labs and academia. The goal of the workshop was to identify new research areas in applied mathematics that will complement and enhance the existing DOE ASCR Applied Mathematics Program efforts that are needed to address problems associated with complex systems. …
Date:
March 7, 2012
Creator:
Alexander, F.; Anitescu, M.; Bell, J.; Brown, D.; Ferris, M.; Luskin, M. et al.
Object Type:
Report
System:
The UNT Digital Library
THE IMPACT OF KINETICS ON NEPHELINE FORMATION IN NUCLEAR WASTE GLASSES
Sixteen glass compositions were selected to study the potential impacts of the kinetics of nepheline formation in high-level nuclear waste (HLW) glass. The chosen compositions encompassed a relatively large nepheline discriminator (ND) range, 0.40-0.66, and included a relatively broad range, and amount of, constituents including high aluminum and high boron concentrations. All glasses were fabricated in the laboratory and subsequently exposed to six different cooling treatments. The cooling treatments consisted of three 'stepped' profiles and their corresponding 'smooth' profiles. Included in the cooling treatment was the Defense Waste Processing Facility (DWPF) canister centerline cooling (CCC) profile in addition to a 'faster' and a 'slower' total cooling line. After quenching and heat treating, x-ray diffraction confirmed the type and amount of any resultant crystallization. The target compositions were shown to be consistent with the measured compositions. Two quenched glasses and several treated glasses exhibited minor amounts of spinel and spinel-like phases. Nepheline was not observed in any of the quenched glasses but was observed in many of the treated glasses. The amount of nepheline ranged from approximately 2wt% to 30wt% for samples cooled over shorter times and longer times respectively. Differences were observed in the amount of nepheline crystallization after smooth …
Date:
March 7, 2011
Creator:
Amoroso, J.
Object Type:
Report
System:
The UNT Digital Library
ADDITIVE TESTING FOR IMPROVED SULFUR RETENTION: PRELIMINARY REPORT
The Savannah River National Laboratory is collaborating with Alfred University to evaluate the potential for additives in borosilicate glass to improve sulfur retention. This preliminary report provides further background on the incorporation of sulfur in glass and outlines the experiments that are being performed by the collaborators. A simulated waste glass composition has been selected for the experimental studies. The first phase of experimental work will evaluate the impacts of BaO, PbO, and V{sub 2}O{sub 5} at concentrations of 1.0, 2.0, and 5.0 wt % on sulfate retention in simulated high level waste borosilicate glass. The second phase of experimental work will evaluate the effects of time at the melt temperature on sulfur retention. The resulting samples will be characterized to determine the amount of sulfur remaining as well as to identify the formation of any crystalline phases. The results will be used to guide the future selection of frits and glass forming chemicals in vitrifying Department of Energy wastes containing high sulfur concentrations.
Date:
September 7, 2011
Creator:
Amoroso, J. & Fox, K.
Object Type:
Report
System:
The UNT Digital Library
Compact Linear Accelerator Sources for Gamma-ray Generation
None
Date:
June 7, 2011
Creator:
Anderson, S. G.; Barty, C. P.; Beer, G.; Cross, R. R.; Ebbers, C. A.; Gibson, D. J. et al.
Object Type:
Article
System:
The UNT Digital Library
Single Shot Longitudinal Profile Monitors using Coherent Smith-Purcell Radiation
None
Date:
October 7, 2013
Creator:
Andrews, H. L.; Taheri, F. Bakkali; Barros, J.; Bartolini, R.; Cassinari, L.; Clarke, C. et al.
Object Type:
Article
System:
The UNT Digital Library
Angelina & Neches River Authority Annual Financial Report: 2011
Annual financial report of the Angelina & Neches River Authority containing independently-audited financial information for fiscal year 2011, including statements of assets, expenses, revenues, and cash flows, with supplementary notes and information.
Date:
December 7, 2011
Creator:
Angelina & Neches River Authority (Tex.)
Object Type:
Report
System:
The Portal to Texas History
The European Union: Questions and Answers
This report serves as a primer on the EU. Despite the UK's vote to leave the EU, the UK remains a full member of the bloc until it completes withdrawal negotiations and officially exits the EU (expected to occur in March 2019). As such, this report largely addresses the EU and its institutions as they currently exist. It also briefly describes U.S.-EU political and economic relations that may be of interest in the 115th Congress.
Date:
September 7, 2018
Creator:
Archick, Kristin
Object Type:
Report
System:
The UNT Digital Library
Northern Ireland's Snap Assembly Elections: Outcome and Implications
This report discusses the snap elections for Northern Ireland's Assembly, its regional legislature.
Date:
March 7, 2017
Creator:
Archick, Kristin
Object Type:
Report
System:
The UNT Digital Library
U.S.-EU Cooperation on Ukraine and Russia
This report examines the U.S. and EU reactions to the crisis in Ukraine, focusing on the EU's hesitation to issue severe sanctions on par with the U.S. prior to the crash of Malaysia Airlines Flight MH17. The report discusses the EU's new, wider-ranging sanctions in the wake of MH17 and its implications on U.S.-EU relations.
Date:
August 7, 2014
Creator:
Archick, Kristin & Mix, Derek E.
Object Type:
Report
System:
The UNT Digital Library