Adiabatic Heat of Hydration Calorimetric Measurements for Reference Saltstone Waste (open access)

Adiabatic Heat of Hydration Calorimetric Measurements for Reference Saltstone Waste

The production of nuclear materials for weapons, medical, and space applications from the mid-1950's through the late-1980's at the Savannah River Site (SRS) generated approximately 35 million gallons of liquid high-level radioactive waste, which is currently being processed into vitrified glass for long-term storage. Upstream of the vitrification process, the waste is separated into three components: high activity insoluble sludge, high activity insoluble salt, and very low activity soluble salts. The soluble salt represents 90% of the 35 million gallons of overall waste and is processed at the SRS Saltstone Facility, where it mixed with cement, blast furnace slag, and flyash, creating a grout-like mixture. The resulting grout is pumped into aboveground storage vaults, where it hydrates into concrete monoliths, called saltstone, thus immobilizing the low-level radioactive salt waste. As the saltstone hydrates, it generates heat that slowly diffuses out of the poured material. To ensure acceptable grout properties for disposal and immobilization of the salt waste, the grout temperature must not exceed 95 C during hydration. Adiabatic calorimetric measurements of the heat generated for a representative sample of saltstone were made to determine the time-dependent heat source term. These measurements subsequently were utilized as input to a numerical conjugate …
Date: January 12, 2006
Creator: Bollinger, James
Object Type: Article
System: The UNT Digital Library
Angular dependence of dissociative electron attachment topolyatomic molecules: application to the 2B1 metastable state of the H2Oand H2S anions (open access)

Angular dependence of dissociative electron attachment topolyatomic molecules: application to the 2B1 metastable state of the H2Oand H2S anions

The angular dependence of dissociative electron attachment (DEA) to polyatomic targets is formulated in the local complex potential model, under the assumption that the axial recoil approximation describes the dissociation dynamics. An additional approximation, which is found to be valid in the case of H2O but not in the case of H2S, makes it possible to describe the angular dependence of DEA solely from an analysis of the fixed-nuclei entrance amplitude, without carrying out nuclear dynamics calculations. For H2S, the final-vibrational-state-specific angular dependence of DEA is obtained by incorporating the variation of the angular dependence of the entrance amplitude with nuclear geometry into the nuclear dynamics. Scattering calculations using the complex Kohn method and, for H2S, full quantum calculations of the nuclear dynamics using the Multi-Configuration Time-Dependent Hartree method, are performed.
Date: January 12, 2006
Creator: Haxton, Daniel J.; McCurdy, C. William & Rescigno, Thomas N.
Object Type: Article
System: The UNT Digital Library
Antibody elbow angles are influenced by their light chain class (open access)

Antibody elbow angles are influenced by their light chain class

We have examined the elbow angles for 365 different Fab fragments, and observe that Fabs with lambda light chains have adopted a wider range of elbow angles than their kappa-chain counterparts, and that the lambda light chain Fabs are frequently found with very large (>195{sup o}) elbow angles. This apparent hyperflexibility of lambda-chain Fabs may be due to an insertion in their switch region, which is one residue longer than in kappa chains, with glycine occurring most frequently at the insertion position. A new, web-based computer program that was used to calculate the Fab elbow angles is also described.
Date: January 12, 2006
Creator: Stanfield, R; Zemla, A; Wilson, I & Rupp, B
Object Type: Article
System: The UNT Digital Library
Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents (open access)

Design and Evaluation of Ionic Liquids as Novel CO2 Absorbents

Progress from the fourth quarter 2005 activity on the project ''Design and Evaluation of Ionic Liquids as Novel CO{sub 2} Absorbents'' is provided. Major activities in three areas are reported: compound synthesis, property measurement and molecular modeling. Last quarter we reported the first ever experimental measurement of SO{sub 2} solubility in an ionic liquid. We showed that SO{sub 2} was very soluble in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([hmim][Tf{sub 2}N]). This quarter, we have measured SO{sub 2} solubility in two more ionic liquids: 1-hexyl-3-methylpyridinium bis(trifluoromethanesulfonyl)imide ([hmpy][Tf{sub 2}N]) and 1-hexyl-3-methylimidazolium lactate ([hmim][lactate]). As with [hmim][Tf{sub 2}N], we find very high solubility of SO{sub 2} in these ionic liquids, but the lactate compounds shows the highest affinity for SO{sub 2} at low pressure. CO{sub 2} solubility was measured in three new compounds: [boronium][Tf{sub 2}N], 1-hexyl-3-methylimidazolium acesulfumate ([hmim][ace]), and 1-hexyl-3-methylimidazolium saccharinate ([hmim][sac]). We find relatively poor solubility of CO{sub 2} in the latter two compounds, and solubility comparable to [hmim][Tf{sub 2}N] in the boronium compound. We also synthesized four new ionic liquids this quarter and continued refinement of our molecular simulation technique for measuring gas solubility.
Date: January 12, 2006
Creator: Maginn, Edward J.
Object Type: Report
System: The UNT Digital Library
Development of a Manufacturing Process for High-Precision Cu EOS Targets (open access)

Development of a Manufacturing Process for High-Precision Cu EOS Targets

This document describes the development of a manufacturing process and the production of Cu EOS targets. The development of a manufacturing process for these targets required a great deal of research, because the specifications for the targets required a level of precision an order of magnitude beyond Target Fabrication's capabilities at the time. Strict limitations on the dimensions of the components and the interfaces between them required research efforts to develop bonding and deposition processes consistent with a manufacturing plan with a dimensional precision on the order of 0.1 {micro}m. Several months into this effort, the specifications for the targets were relaxed slightly as a result of discussions between the Target Fabrication Group and the physicists. The level of precision required for these targets remained an order of magnitude beyond previous capabilities, but the changes made it possible to manufacture targets to the specifications. The development efforts and manufacturing processes described in this document successfully produced a complete Cu EOS target that satisfied all of the fabrication and metrology specifications.
Date: January 12, 2006
Creator: Bono, M J; Castro, C & Hibbard, R L
Object Type: Report
System: The UNT Digital Library
Emerging Prospects for Repository Success (open access)

Emerging Prospects for Repository Success

Recent events are again raising some old issues and creating new opportunities regarding the future disposition of the used, or spent, fuel from nuclear power plants. Handling these challenges well will not only help set the stage for a robust nuclear energy future, but will reflect the growing linkages among nuclear power, nuclear waste management, international security, and public and political acceptance. The emerging global nuclear regime may make spent fuel management not only more important, but improve chances of success.
Date: January 12, 2006
Creator: Isaacs, T
Object Type: Article
System: The UNT Digital Library
Evaluation of the DRAGON Code for VHTR Design Analysis. (open access)

Evaluation of the DRAGON Code for VHTR Design Analysis.

This letter report summarizes three activities that were undertaken in FY 2005 to gather information on the DRAGON code and to perform limited evaluations of the code performance when used in the analysis of the Very High Temperature Reactor (VHTR) designs. These activities include: (1) Use of the code to model the fuel elements of the helium-cooled and liquid-salt-cooled VHTR designs. Results were compared to those from another deterministic lattice code (WIMS8) and a Monte Carlo code (MCNP). (2) The preliminary assessment of the nuclear data library currently used with the code and libraries that have been provided by the IAEA WIMS-D4 Library Update Project (WLUP). (3) DRAGON workshop held to discuss the code capabilities for modeling the VHTR.
Date: January 12, 2006
Creator: Taiwo, T. A. & Kim, T. K.
Object Type: Report
System: The UNT Digital Library
Final Report for the Arroyo Las Positas Maintenance Impact Study, Lawrence Livermore National Laboratory (open access)

Final Report for the Arroyo Las Positas Maintenance Impact Study, Lawrence Livermore National Laboratory

In 2000, the Lawrence Livermore National Laboratory's (LLNL) Environmental Protection Department, in coordination with Plant Engineering (PE), began dredging sections of the Arroyo Las Positas (ALP) to alleviate concerns about flooding of sensitive facilities within the mainsite of Lawrence Livermore National Laboratory. In order to reduce potential impacts on the federally threatened California red-legged frog (Rana aurora draytonii), LLNL proposed to dredge sections of the ALP in a ''checkerboard pattern'', resulting in a mosaic of open water habitat and vegetated sections (Figure 1). The Arroyo Las Positas Management Plan (Plan) was coordinated with both state and federal agencies including the U.S. Fish and Wildlife Service (USFWS), California Department of Fish and Game (CDF&G), San Francisco Regional Water Quality Control Board (SFRWQCB), and the Army Corp of Engineers (ACOE). Water Discharge Requirements (WDRs) were issued for this project on December 30, 1999 (Order No. 99-086) by the SFRWQCB. Provision 19 of the WDRs outlined a five-year (2000 through 2004) Maintenance Impact Study (MIS) that LLNL began in coordination with dredging work that was conducted as part of the Arroyo Las Positas Management Plan. Provision 20 of these WDRs requires LLNL to submit a final report of the results of the Maintenance …
Date: January 12, 2006
Creator: van Hattem, M & Paterson, L
Object Type: Report
System: The UNT Digital Library
First Results from IceCube (open access)

First Results from IceCube

IceCube is a 1 km{sup 3} neutrino observatory being built to study neutrino production in active galactic nuclei, gamma-ray bursts, supernova remnants, and a host of other astrophysical sources. High-energy neutrinos may signal the sources of ultra-high energy cosmic rays. IceCube will also study many particle-physics topics: searches for WIMP annihilation in the Earth or the Sun, and for signatures of supersymmetry in neutrino interactions, studies of neutrino properties, including searches for extra dimensions, and searches for exotica such as magnetic monopoles or Q-balls. IceCube will also study the cosmic-ray composition. In January, 2005, 60 digital optical modules (DOMs) were deployed in the South Polar ice at depths ranging from 1450 to 2450 meters, and 8 ice-tanks, each containing 2 DOMs were deployed as part of a surface air-shower array. All 76 DOMs are collecting high-quality data. After discussing the IceCube physics program and hardware, I will present some initial results with the first DOMs.
Date: January 12, 2006
Creator: Klein, Spencer R.
Object Type: Article
System: The UNT Digital Library
A hybrid FEM-BEM unified boundary condition with sub-cycling for electromagnetic radiation (open access)

A hybrid FEM-BEM unified boundary condition with sub-cycling for electromagnetic radiation

Hybrid solutions to time-domain electromagnetic problems offer many advantages when solving open-region scattering or radiation problems. Hybrid formulations use a finite-element or finite-difference discretization for the features of interest, then bound this region with a layer of planar boundary elements. The use of volume discretization allows for intricate features and many changes in material within the structure, while the boundary-elements provide a highly accurate radiating boundary condition. This concept has been implemented previously, using the boundary elements to set the E-field, H-field, or both for an FDTD grid, for example in [1][2][3], or as a mixed boundary condition for the second order wave equation solved by finite elements [4]. Further study has focused on using fast methods, such as the Plane Wave Time Domain method [3][4] to accelerate the BEM calculations. This paper details a hybrid solver using the coupled first-order equations for the E and H fields in the finite-element region. This formulation is explicit, with a restriction on the time step for stability. When this time step is used in conjunction with the boundary elements forming either a inhomogeneous Dirichlet or Neuman boundary condition on the finite-element mesh, late time instabilities occur. To combat this, a Unified Boundary …
Date: January 12, 2006
Creator: Fasenfest, B.; White, D.; Stowell, M.; Rieben, R.; Sharpe, R.; Madsen, N. et al.
Object Type: Article
System: The UNT Digital Library
Materials System for Intermediate Temperature Solid Oxide Fuel Cell (open access)

Materials System for Intermediate Temperature Solid Oxide Fuel Cell

The objective of this work was to obtain a stable materials system for intermediate temperature solid oxide fuel cell (SOFC) capable of operating between 600-800 C with a power density greater than 0.2 W/cm{sup 2}. The solid electrolyte chosen for this system was La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3}, (LSGM). To select the right electrode materials from a group of possible candidate materials, AC complex impedance spectroscopy studies were conducted between 600-800 C on symmetrical cells that employed the LSGM electrolyte. Based on the results of the investigation, LSGM electrolyte supported SOFCs were fabricated with La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3}-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3} (LSCF-LSGM) composite cathode and Nickel-Ce{sub 0.6}La{sub 0.4}O{sub 3} (Ni-LDC) composite anode having a barrier layer of Ce{sub 0.6}La{sub 0.4}O{sub 3} (LDC) between the LSGM electrolyte and the Ni-LDC anode. Electrical performance and stability of these cells were determined and the electrode polarization behavior as a function of cell current was modeled between 600-800 C. The electrical performance of the anode-supported SOFC was simulated assuming an electrode polarization behavior identical to the LSGM-electrolyte-supported SOFC. The simulated electrical performance indicated that the selected material system would provide a stable cell capable of operating between 600-800 C …
Date: January 12, 2006
Creator: Pal, Uday B. & Gopalan, Srikanth
Object Type: Report
System: The UNT Digital Library
Methodology for Modeling 2-D Groundwater Motion in a Geographic Information System (GIS) (open access)

Methodology for Modeling 2-D Groundwater Motion in a Geographic Information System (GIS)

None
Date: January 12, 2006
Creator: Bollinger, James S. & Reed, John K.
Object Type: Article
System: The UNT Digital Library
Observations on a Montana Water Quality Proposal. (open access)

Observations on a Montana Water Quality Proposal.

In May 2005, a group of petitioners led by the Northern Plains Resource Council (NPRC) submitted a petition to revise water quality requirements to the Montana Board of Environmental Review (BER). Under Montana law, the BER had to consider the petition and either reject it or propose it as a new regulation. In September 2005, the BER announced proposed changes to the Montana water quality regulations. The proposal, which included almost the exact language found in the petition, was directed toward discharges of water from coal bed natural gas (CBNG) production. The key elements of the proposal included: (1) No discharges of CBNG water are allowed to Montana surface waters unless operators can demonstrate that injection to aquifers with the potential for later recovery of the water is not feasible. (2) When operators can demonstrate the injection is not feasible, the CBNG water to be discharged must meet very strict technology-based limits for multiple parameters. (3) The Montana water quality standards for the sodium adsorption ratio (SAR) and electrical conductivity (EC) would be evaluated using the 7Q10 flow (lowest 7-consecutive-day flow in a 10-year period) rather than a monthly flow that is currently used. (4) SAR and EC would be …
Date: January 12, 2006
Creator: Veil, J. A. & Puder, M. G.
Object Type: Report
System: The UNT Digital Library
Performance of low-rank QR approximation of the finite element Biot-Savart law (open access)

Performance of low-rank QR approximation of the finite element Biot-Savart law

We are concerned with the computation of magnetic fields from known electric currents in the finite element setting. In finite element eddy current simulations it is necessary to prescribe the magnetic field (or potential, depending upon the formulation) on the conductor boundary. In situations where the magnetic field is due to a distributed current density, the Biot-Savart law can be used, eliminating the need to mesh the nonconducting regions. Computation of the Biot-Savart law can be significantly accelerated using a low-rank QR approximation. We review the low-rank QR method and report performance on selected problems.
Date: January 12, 2006
Creator: White, D. A. & Fasenfest, B. J.
Object Type: Article
System: The UNT Digital Library
Savannah River Site Operating Experience with TRU Waste Retrieval (open access)

Savannah River Site Operating Experience with TRU Waste Retrieval

None
Date: January 12, 2006
Creator: Stone, K. A. & Milner, T. N.
Object Type: Article
System: The UNT Digital Library
Tritium Transport in South Atlantic Coastal Waters (open access)

Tritium Transport in South Atlantic Coastal Waters

None
Date: January 12, 2006
Creator: Garrett, Alfred J.; Bollinger, James S.; Koffman, Larry D. & Hayes, David W.
Object Type: Article
System: The UNT Digital Library
Wideband Multichannel Time-Reversal Processing for Acoustic Communications in a Tunnel-like Structure (open access)

Wideband Multichannel Time-Reversal Processing for Acoustic Communications in a Tunnel-like Structure

The development of multichannel time-reversal (T/R) processing techniques continues to progress rapidly especially when the need to communicate in a highly reverberative environment becomes critical. The underlying T/R concept is based on time-reversing the Green's function characterizing the uncertain communications channel investigating the deleterious dispersion and multipath effects. In this paper, attention is focused on two major objectives: (1) wideband communications leading to a time reference modulation technique; and (2) multichannel acoustic communications in a tunnel (or cave or pipe) with many obstructions, multipath returns, severe background noise, disturbances, long propagation paths ({approx}180) with disruptions (bends). For this extremely hostile environment, it is shown that multichannel T/R receivers can easily be extended to the wideband designs while demonstrating their performance in both the ''canonical'' stairwell of our previous work as well as a tunnel-like structure. Acoustic information signals are transmitted with an 8-element host or base station array to two client receivers with a significant loss in signal levels due to the propagation environment. In this paper, the results of the new wideband T/R processor and modulation scheme are discussed to demonstrate the overall performance for both high (24-bit) and low (1-bit) bit level analog-to-digital (A/D) converter designs. These results …
Date: January 12, 2006
Creator: Candy, J. V.; Chambers, D. H.; Robbins, C. L.; Guidry, B. L.; Poggio, A. J.; Dowla, F. et al.
Object Type: Article
System: The UNT Digital Library
CO2 Sequestration and Recycle by Photosynthesis (open access)

CO2 Sequestration and Recycle by Photosynthesis

Hydrocarbon oxygenate synthesis from photocatalytic reactions of CO{sub 2} and H{sub 2}O over various catalysts is a very attractive process. However, the formation rate of the hydrocarbons and oxygenates is significantly lower than conventional catalysis. One possible reason for the low rate of product formation is the presence of oxidation sites which reoxidize the products back to CO{sub 2} and H{sub 2}O. For further improvement of catalytic activity for the reduction process, it is essential to understand the oxidation reaction process. We have studied photocatalytic oxidation of methylene blue and found the oxidation rate is significantly higher than the reduction rate.
Date: February 12, 2006
Creator: Chuang, Steven S.C.
Object Type: Report
System: The UNT Digital Library
CO2 Sequestration and Recycle by Photosynthesis (open access)

CO2 Sequestration and Recycle by Photosynthesis

Hydrocarbon synthesis from photocatalytic reactions of CO{sub 2} and H{sub 2}O over various catalysts has been studied by UV-visible light. The quantum efficiencies suggest that Pd/TiO{sub 2} sol gel exhibits the highest activity for hydrocarbon synthesis from photocatalytic reactions. The in situ IR could successfully monitor the adsorbed hydrocarbon species. The UV-visible, IR spectroscopy and XRD techniques were used to characterize the catalysts to obtain the information of properties of the process and catalyst before/after reaction. The UV-visible spectroscopy provides the information about the surface band gap energy of each catalyst. In situ UV-visible studies reveals that TiO{sub 2}-supported catalysts require the higher energy (i.e. shorter wavelength) to pass through the water-thin film deposited on the surface to activate the photocatalytic reaction. XRD data show there is changes in the crystal structure of TiO{sub 2} sol gel from photon energy during photo reaction. The information from this study can lead to a better understanding of the nature of the catalysts and photoreaction processes, which might provide the information to develop better catalysts and reaction process for the hydrocarbon synthesis from photocatalytic reactions of CO{sub 2} and H{sub 2}O.
Date: February 12, 2006
Creator: Chuang, Steven S.C.
Object Type: Report
System: The UNT Digital Library
Correction of Distributed Optical Aberrations (open access)

Correction of Distributed Optical Aberrations

The objective of this project was to demonstrate the use of multiple distributed deformable mirrors (DMs) to improve the performance of optical systems with distributed aberrations. This concept is expected to provide dramatic improvement in the optical performance of systems in applications where the aberrations are distributed along the optical path or within the instrument itself. Our approach used multiple actuated DMs distributed to match the aberration distribution. The project developed the algorithms necessary to determine the required corrections and simulate the performance of these multiple DM systems.
Date: February 12, 2006
Creator: Baker, K.; Olivier, S.; Carrano, C. & Phillion, D.
Object Type: Report
System: The UNT Digital Library
Dynamic simulation tools for the analysis and optimization of novel collection, filtration and sample preparation systems (open access)

Dynamic simulation tools for the analysis and optimization of novel collection, filtration and sample preparation systems

The focus of research effort described here is to develop novel simulation tools to address design and optimization needs in the general class of problems that involve species and fluid (liquid and gas phases) transport through sieving media. This was primarily motivated by the heightened attention on Chem/Bio early detection systems, which among other needs, have a need for high efficiency filtration, collection and sample preparation systems. Hence, the said goal was to develop the computational analysis tools necessary to optimize these critical operations. This new capability is designed to characterize system efficiencies based on the details of the microstructure and environmental effects. To accomplish this, new lattice Boltzmann simulation capabilities where developed to include detailed microstructure descriptions, the relevant surface forces that mediate species capture and release, and temperature effects for both liquid and gas phase systems. While developing the capability, actual demonstration and model systems (and subsystems) of national and programmatic interest were targeted to demonstrate the capability. As a result, where possible, experimental verification of the computational capability was performed either directly using Digital Particle Image Velocimetry or published results.
Date: February 12, 2006
Creator: Clague, D; Weisgraber, T; Rockway, J & McBride, K
Object Type: Report
System: The UNT Digital Library
Environmental Solutions FY05: PNNL Contributions to Fluor Hanford (open access)

Environmental Solutions FY05: PNNL Contributions to Fluor Hanford

This report describes Pacific Northwest National Laboratory's scientific and technical contributions to Fluor Hanford in FY05. This includes work on the spent nuclear fuel basins as well as cribs and trenches.
Date: February 12, 2006
Creator: Scott, Paul A. & Manke, Kristin L.
Object Type: Report
System: The UNT Digital Library
The Liquefaction of Hydrogen and Helium Using Small Coolers (open access)

The Liquefaction of Hydrogen and Helium Using Small Coolers

This report discusses the history of the liquefaction of hydrogen and helium using small coolers. This history dates form the 1960's when two stage GM coolers capable of reaching 7 K were used to liquefy helium and hydrogen by suing an added compressor and J-T circuit. Liquefaction using the added circuit failed to become mainstream because the J-T valve and heat exchanger clogged because of impurities in the gas being liquefied. Liquefaction using a GM cooler without an added J-T circuit proved to be difficult because the first stage was not used to pre-cool the gas coming to the second stage of the cooler. Once the gas being liquefied was pre-cooled using the cooler first stage, improvements in the liquefaction rates were noted. The advent of low temperature pulse tube cooler (down to 2.5 K) permitted one to achieve dramatic improvement is the liquefactions rates for helium. Similar but less dramatic improvements are expected for hydrogen as well. Using the PT-415 cooler, one can expect liquefaction rates of 15 to 20 liters per day for helium or hydrogen provided the heat leak into the cooler and the storage vessel is low. A hydrogen liquefier for MICE is presented at the …
Date: February 12, 2006
Creator: Green, Michael A.
Object Type: Report
System: The UNT Digital Library
Benefits of IEEE-754 features in modern symmetric tridiagonaleigensolvers (open access)

Benefits of IEEE-754 features in modern symmetric tridiagonaleigensolvers

Bisection is one of the most common methods used to compute the eigenvalues of symmetric tridiagonal matrices. Bisection relies on the Sturm count: For a given shift a, the number of negative pivots in the factorization T - {sigma}I = LDL{sup T} equals the number of eigenvalues of T that are smaller than a. In IEEE-754 arithmetic, the value oo permits the computation to continue past a zero pivot, producing a correct Sturm count when T is unreduced. Demmel and Li showed that using oo rather than testing for zero pivots within the loop could significantly improve performance on certain architectures. When eigenvalues are to be computed to high relative accuracy, it is often preferable to work with LDL{sup T} factorizations instead of the original tridiagonal T. One important example is the MRRR algorithm. When bisection is applied to the factored matrix, the Sturm count is computed from LDL{sup T} which makes differential stationary and progressive qds algorithms the methods of choice. While it seems trivial to replace T by LDL{sup T}, in reality these algorithms are more complicated: In IEEE-754 arithmetic, a zero pivot produces an overflow followed by an invalid exception (NaN, or 'Not a Number') that renders …
Date: March 12, 2006
Creator: Marques, Osni; Riedy, Jason E. & Vomel, Christof
Object Type: Article
System: The UNT Digital Library