Inner-shell electron spectroscopy and chemical properties of atoms and small molecules (open access)

Inner-shell electron spectroscopy and chemical properties of atoms and small molecules

The program has been concerned with gas-phase carbon 1s photoelectron spectroscopy of a number of molecules of potential chemical interest. The primary goals have been to determine carbon 1s ionization energies with a view of relating these to other chemical properties such as electronegativity, acidity, basicity, and reactivity, in order to provide a better understanding of these fundamental properties. The role of electron-donating (methyl) and electron-withdrawing (fluoro) substituents on the carbon 1s ionization energies of substituted benzenes has been studied., and these results have been related to measurements of the reactivities of the same molecule as well as to their affinities for protons (basicity). Opportunities for investigation in unplanned areas have arisen, and the program has been modified to take advantage of these. One has been the realization that, under certain circumstances, inner-shell ionization energies may depend on the molecular conformation. Several examples of this phenomenon have been investigated and it has been shown that this technique provides a tool for the measurement of the energy differences between different conformers of the same substance. The other has been the demonstration that photoelectron recoil can lead to the excitation of vibrational modes that are forbidden in the normal view of photoemission …
Date: January 21, 2009
Creator: Thomas, T. Darrah
Object Type: Report
System: The UNT Digital Library
TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS (open access)

TECHNOLOGY NEEDS AND STATUS ON CLOSURE OF DOE RADIOACTIVE WASTE TANK ANCILLARY SYSTEMS

This paper summarizes the current state of art of sampling, characterizing, retrieving, transferring and treating the incidental waste and stabilizing the void space in tank ancillary systems and the needs involved with closure of these systems. The overall effort for closing tank and ancillary systems is very large and is in the initial stages of being addressed in a systematic manner. It was recognized in doing this effort, that gaps in both technology and material application for characterization and removal of residual waste and closure of ancillary systems would be identified. Great efficiencies are to be gained by defining the technology need areas early in the closure process and providing recommendations for technical programs to improve the closure strategies. Therefore, this paper will not only summarize the state of closure of ancillary systems but also provide recommendations to address the technology gaps identified in this assessment.
Date: January 21, 2009
Creator: Burns, H; Sharon Marra, S & Christine Langton, C
Object Type: Article
System: The UNT Digital Library
Measuring Radiation Damage from Heavy Energetic Ions in Aluminum (open access)

Measuring Radiation Damage from Heavy Energetic Ions in Aluminum

An intense beam of 122 MeV/u (9.3 GeV) 76Ge ions was stopped in aluminum samples at the Coupled Cyclotron Facility at NSCL, MSU. Attempts were made at ORNL to measure changes in material properties by measuring changes in electrical resistivity and microhardness, and by transmission electron microscopy characterization, for defect density caused by radiation damage, as a function of depth and integrated ion flux. These measurements are relevant for estimating damage to components at a rare isotope beam facility.
Date: February 21, 2009
Creator: Kostin, M., PI-MSU; Ronningen, R., PI-MSU; Ahle, L., PI-LLNL; Gabriel, T., Scientific Investigation and Development; Mansur, L., PI-ORNL; Leonard, K., ORNL et al.
Object Type: Report
System: The UNT Digital Library
The Mercury Laser Advances Laser Technology for Power Generation (open access)

The Mercury Laser Advances Laser Technology for Power Generation

The National Ignition Facility (NIF) at Lawrence Livermore Laboratory is on target to demonstrate 'breakeven' - creating as much fusion-energy output as laser-energy input. NIF will compress a tiny sphere of hydrogen isotopes with 1.8 MJ of laser light in a 20-ns pulse, packing the isotopes so tightly that they fuse together, producing helium nuclei and releasing energy in the form of energetic particles. The achievement of breakeven will culminate an enormous effort by thousands of scientists and engineers, not only at Livermore but around the world, during the past several decades. But what about the day after NIF achieves breakeven? NIF is a world-class engineering research facility, but if laser fusion is ever to generate power for civilian consumption, the laser will have to deliver pulses nearly 100,000 times faster than NIF - a rate of perhaps 10 shots per second as opposed to NIF's several shots a day. The Mercury laser (named after the Roman messenger god) is intended to lead the way to a 10-shots-per-second, electrically-efficient, driver laser for commercial laser fusion. While the Mercury laser will generate only a small fraction of the peak power of NIF (1/30,000), Mercury operates at higher average power. The design …
Date: January 21, 2009
Creator: Ebbers, C A; Caird, J & Moses, E
Object Type: Article
System: The UNT Digital Library
Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation (open access)

Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation

Recent results of thermodynamic studies on the complexation of actinides (UO{sub 2}{sup 2+}, NpO{sub 2}{sup +} and Pu{sup 4+}) with F{sup -}, SO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}/HPO{sub 4}{sup 2-} at elevated temperatures are reviewed. The data indicate that, for all systems except the 1:1 complexation of Np(V) with HPO{sub 4}{sup 2-}, the complexation of actinides is enhanced by the increase in temperature. The enhancement is primarily due to the increase in the entropy term (T{Delta}S) that exceeds the increase in the enthalpy ({Delta}H) as the temperature is increased. These data bridge the gaps in the chemical thermodynamic database for nuclear waste repository where the temperature could remain significantly higher than 25 C for a long time after the closure of the repository.
Date: December 21, 2009
Creator: Rao, Linfeng; Tian, Guoxin; Xia, Yuanxian; Friese, Judah I.; Zanonato, PierLuigi & Di Bernardo, Plinio
Object Type: Book
System: The UNT Digital Library
Evaluating Statistical Tests forWithin-Network Classifiers of Relational Data (open access)

Evaluating Statistical Tests forWithin-Network Classifiers of Relational Data

None
Date: September 21, 2009
Creator: Neville, J.; Gallagher, B. & Eliassi-Rad, T.
Object Type: Article
System: The UNT Digital Library
Dye Sensitized Tandem Photovoltaic Cells (open access)

Dye Sensitized Tandem Photovoltaic Cells

This work provided a new way to look at photoelectrochemical cells and their performance. Although thought of as low efficiency, a the internal efficiency of a 9% global efficiency dye sensitized solar cell is approximately equal to an 18% efficient silicon cell when each is compared to their useful spectral range. Other work undertaken with this contract also reported the first growth oriented titania and perovskite columns on a transparent conducting oxide. Other work has shown than significant performance enhancement in the performance of dye sensitized solar cells can be obtained through the use of coupling inverse opal photonic crystals to the nanocrystalline dye sensitized solar cell. Lastly, a quick efficient method was developed to bond titanium foils to transparent conducting oxide substrates for anodization.
Date: December 21, 2009
Creator: Barber, Greg D.
Object Type: Report
System: The UNT Digital Library
Waste Isolation Pilot Plant Annual Site Enviromental Report for 2008 (open access)

Waste Isolation Pilot Plant Annual Site Enviromental Report for 2008

The purpose of the Waste Isolation Pilot Plant Annual Site Environmental Report for 2008 (ASER) is to provide information required by U.S. Department of Energy (DOE) Order 231.1A, Environment, Safety, and Health Reporting. Specifically, the ASER presents summary environmental data to characterize site environmental management performance; summarize environmental occurrences and responses reported during the calendar year; confirm compliance with environmental standards and requirements; highlight significant facility programs and efforts; and describe how compliance and environmental improvement is accomplished through the WIPP Environmental Management System (EMS). The DOE Carlsbad Field Office (CBFO) and the management and operating contractor (MOC), Washington TRU Solutions LLC (WTS), maintain and preserve the environmental resources at the Waste Isolation Pilot Plant (WIPP). DOE Order 231.1A; DOE Order 450.1A, Environmental Protection Program; and DOE Order 5400.5, Radiation Protection of the Public and the Environment, require that the affected environment at and near DOE facilities be monitored to ensure the safety and health of the public and workers, and preservation of the environment. This report was prepared in accordance with DOE Order 231.1A, which requires that DOE facilities submit an ASER to the DOE Headquarters Chief Health, Safety, and Security Officer. The WIPP Hazardous Waste Facility Permit (HWFP) …
Date: September 21, 2009
Creator: Services, Washington Regulatory and Enviromnetal
Object Type: Report
System: The UNT Digital Library
317/319 phytoremediation site monitoring report - 2004 growing season. (open access)

317/319 phytoremediation site monitoring report - 2004 growing season.

In 1999, Argonne National Laboratory (ANL) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooting at various predetermined depths. The plants were installed using various methods including Applied Natural Science's TreeWell{reg_sign} system. The goal of the installation was to protect downgradient surface and groundwater by hydraulic control of the contaminated plume by intercepting the contaminated groundwater with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or transpiring the residual volatile organic compounds (VOCs), and removing tritium from the subsoil and groundwater. This report presents the results of the monitoring activities conducted by Argonne's Energy Systems Division (ES) in the growing season of 2004. Monitoring of the planted trees began soon after the trees were installed in 1999 and has been conducted every summer since then. As the trees grew and consolidated their growth into the contaminated soil and groundwater, their exposure to the contaminants was progressively shown through tissue sampling. Since the inception of the project, significant progress was made in the refinement and testing of the analytical method (for which no official method is available), the determination …
Date: February 21, 2009
Creator: Negri, M. C.; Gopalakrishnan, G.; Bogner, J. & Systems, Energy
Object Type: Report
System: The UNT Digital Library
DEVELOPMENT OF PROCESS CONTROL EQUATIONS TO SUPPORT DETOXIFICATION OF COPPER USING NATURAL HUMATE AMENDMENTS (open access)

DEVELOPMENT OF PROCESS CONTROL EQUATIONS TO SUPPORT DETOXIFICATION OF COPPER USING NATURAL HUMATE AMENDMENTS

Recent scientific research and changes in regulatory policies have led to reductions in the allowable discharges of several contaminant metals, including copper, into surface water. Low target concentrations and variable outfall conditions challenge the efficacy of traditional treatment technologies such as ion exchange. In reviewing various treatment options, scientists and engineers at the Savannah River Site (SRS) developed a treatment strategy focusing on toxicity reduction (rather than the removal of the copper) and demonstrated that the method is viable and promising for mitigating copper toxicity. The resulting outfall chemistry protects the ecosystem in the receiving stream in a manner that is equal to, or better than, technologies that remove copper to the emerging regulatory levels. Further, the proposed toxicity reduction strategy results in collateral beneficial changes in outfall water chemistry such that the outfall more closely matches the chemistry of natural streams for key parameters such as the dissolved organic carbon (DOC). The detoxification process is based on the EPA BLM. Specifically, modeling indicates that copper toxicity can be mitigated by modest additions of natural organic carbon and that the amount of amendment needed can be determined based on pH and stream flow. The organic carbon amendments proposed for the …
Date: August 21, 2009
Creator: Looney, B.; Millings, M.; Halverson, N. & Nichols, R.
Object Type: Report
System: The UNT Digital Library
Research and development for electropolishing of Nb for ILC accelerator cavities (open access)

Research and development for electropolishing of Nb for ILC accelerator cavities

The objectives of this project are to 1, Expand the scientific and technological understanding of the effect of post-treatment (electropolish, buffered chemical polish, low-temperature baking) on the surface of niobium; 2, Relate the knowledge to the performance of niobium superconducting radiofrequency accelerator cavities; and, 3, Thereby design and demonstrate an electropolish process that can be applied to complete cavities.
Date: September 21, 2009
Creator: Kelley, Michael J.
Object Type: Report
System: The UNT Digital Library
Nonlocal Transport in the Reversed Field Pinch (open access)

Nonlocal Transport in the Reversed Field Pinch

Several heuristic models for nonlocal transport in plasmas have been developed, but they have had a limited possibility of detailed comparision with experimental data. Nonlocal aspects introduced by the existence of a known spectrum of relatively stable saturated tearing modes in a low current reversed field pinch offers a unique possibility for such a study. A numerical modelling of the magnetic structure and associated particle transport is carried out for the reversed-field pinch experiment at the Consorzio RFX, Padova, Italy. A reproduction of the tearing mode spectrum with a guiding center code1 reliably reproduces the observed soft X-ray tomography. Following particle trajectories in the stochastic magnetic field shows the transport across the unperturbed flux surfaces to be due to a spectrum of Levy flights, with the details of the spectrum position dependent. The resulting transport is subdiffusive, and cannot be described by Rechester-Rosenbluth diffusion, which depends on a random phase approximation. If one attempts to fit the local transport phenomenologically, the subdiffusion can be fit with a combination of diffusion and inward pinch2. It is found that whereas passing particles explore the stochastic field and hence participate in Levy flights, the trapped particles experience normal neoclassical diffusion. A two fluid …
Date: September 21, 2009
Creator: G. Spizzo, R. B. White, S. Cappello, and L. Marrelli
Object Type: Report
System: The UNT Digital Library
Lessons Learned in Risk Management on NCSX (open access)

Lessons Learned in Risk Management on NCSX

The National Compact Stellarator Experiment (NCSX) was designed to test physics principles of an innovative stellarator design developed by the Princeton Plasma Physics Laboratory and Oak Ridge National Laboratory. Construction of some of the major components and sub-assemblies was completed, but the estimated cost and schedule for completing the project grew as the technical requirements and risks became better understood, leading to its cancellation in 2008. The project's risks stemmed from its technical challenges, primarily the complex component geometries and tight tolerances that were required. The initial baseline, established in 2004, was supported by a risk management plan and risk-based contingencies, both of which proved to be inadequate. Technical successes were achieved in the construction of challenging components and subassemblies, but cost and schedule growth was experienced. As part of an effort to improve project performance, a new risk management program was devised and implemented in 2007-08. It led to a better understanding of project risks, a sounder basis for contingency estimates, and improved management tools. Although the risks ultimately were unacceptable to the sponsor, valuable lessons in risk management were learned through the experiences with the NCSX project.
Date: July 21, 2009
Creator: G.H. Neilson, C.O. Gruber, J.H. Harris, D.J. Rej, R.T. Simmons, and R.L. Strykowsky
Object Type: Article
System: The UNT Digital Library
Versatile P(acman) BAC Libraries for Transgenesis Studies in Drosophila melanogaster (open access)

Versatile P(acman) BAC Libraries for Transgenesis Studies in Drosophila melanogaster

We constructed Drosophila melanogaster BAC libraries with 21-kb and 83-kb inserts in the P(acman) system. Clones representing 12-fold coverage and encompassing more than 95percent of annotated genes were mapped onto the reference genome. These clones can be integrated into predetermined attP sites in the genome using Phi C31 integrase to rescue mutations. They can be modified through recombineering, for example to incorporate protein tags and assess expression patterns.
Date: April 21, 2009
Creator: Venken, Koen J.T.; Carlson, Joseph W.; Schulze, Karen L.; Pan, Hongling; He, Yuchun; Spokony, Rebecca et al.
Object Type: Article
System: The UNT Digital Library
FINAL TECHNICAL REPORT: Request for support of the 11th Workshop on the Physics of Dusty Plasmas (open access)

FINAL TECHNICAL REPORT: Request for support of the 11th Workshop on the Physics of Dusty Plasmas

This grant supported the publication of student papers that were presented at the 11th Workshop on the Physics of Dusty Plasmas. Papers were published in a Special Issue of the IEEE Transactions on Plasma Science, Vol. 32, Issue 2 in April, 2007.
Date: May 21, 2009
Creator: Thomas, Edward
Object Type: Report
System: The UNT Digital Library

Data Collection & Analysis for ARRA Fuel Cell Projects

The data analysis objectives are: (1) Independent assessment of technology, focused on fuel cell system and hydrogen infrastructure:performance, operation, and safety; (2) Leverage data processing and analysis capabilities from the fuel cell vehicle Learning Demonstration project and DoD Forklift Demo; (3) Establish a baseline of real-world fuel cell operation and maintenance data and identify technical/market barriers; (4) Support market growth of fuel cell technologies by reporting on technology features relevant to the business case; and (5) Report on technology to fuel cell and hydrogen communities and stakeholders.
Date: August 21, 2009
Creator: Kurtz, J.; Ramsden, T.; Wipke, K. & Sprik, S.
Object Type: Presentation
System: The UNT Digital Library
7th International Workshop on Microbeam Probes of Cellular Radiation Response (open access)

7th International Workshop on Microbeam Probes of Cellular Radiation Response

The extended abstracts that follow present a summary of the Proceedings of the 7th International Workshop: Microbeam Probes of Cellular Radiation Response, held at Columbia University’s Kellogg Center in New York City on March 15–17, 2006. These International Workshops on Microbeam Probes of Cellular Radiation Response have been held regularly since 1993 (1–5). Since the first workshop, there has been a rapid growth (see Fig. 1) in the number of centers developing microbeams for radiobiological research, and worldwide there are currently about 30 microbeams in operation or under development. Single-cell/single-particle microbeam systems can deliver beams of different ionizing radiations with a spatial resolution of a few micrometers down to a few tenths of a micrometer. Microbeams can be used to addressquestions relating to the effects of low doses of radiation (a single radiation track traversing a cell or group of cells), to probe subcellular targets (e.g. nucleus or cytoplasm), and to address questions regarding the propagation of information about DNA damage (for example, the radiation-induced bystander effect). Much of the recent research using microbeams has been to study low-dose effects and ‘‘non-targeted’’ responses such as bystander effects, genomic instability and adaptive responses. This Workshop provided a forum to assess the …
Date: July 21, 2009
Creator: Brenner, David J.
Object Type: Report
System: The UNT Digital Library
A Voltage Controlled Oscillator for a Phase-Locked Loop Frequency Synthesizer in a Silicon-on-Sapphire Process (open access)

A Voltage Controlled Oscillator for a Phase-Locked Loop Frequency Synthesizer in a Silicon-on-Sapphire Process

Engineers from a government-owned engineering and manufacturing facility were contracted by government-owned research laboratory to design and build an S-band telemetry transmitter using Radio Frequency Integrated Circuit (RFIC) technology packaged in a Low-Temperature Co-fired Ceramic (LTCC) Multi-Chip Module. The integrated circuit technology chosen for the Phase-Locked Loop Frequency Synthesizer portion of the telemetry transmitter was a 0.25 um CMOS process that utilizes a sapphire substrate and is fabricated by Peregrine Semiconductor corporation. This thesis work details the design of the Voltage Controlled Oscillator (VCO) portion of the PLL frequency synthesizer and constitutes an fully integrated VCO core circuit and a high-isolation buffer amplifier. The high-isolation buffer amplifier was designed to provide 16 dB of gain for 2200-3495 MHz as well as 60 dB of isolation for the oscillator core to provide immunity to frequency pulling due to RF load mismatch. Actual measurements of the amplifier gain and isolation showed the gain was approximately 5 dB lower than the simulated gain when all bond-wire and test substrate parasitics were taken into account. The isolation measurements were shown to be 28 dB at the high end of the frequency band but the measurement was more than likely compromised due to the aforementioned …
Date: May 21, 2009
Creator: Garrison, Sean
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties (open access)

Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.
Date: August 21, 2009
Creator: Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D. et al.
Object Type: Article
System: The UNT Digital Library
EVALUATION OF TGA AS A QUALITY ASSURANCE TOOL FOR SURFACEMODIFIED ZIRCOLOY-4 (open access)

EVALUATION OF TGA AS A QUALITY ASSURANCE TOOL FOR SURFACEMODIFIED ZIRCOLOY-4

Thermogravimetric analysis (TGA) and coupled Mass Spectroscopy (MS) were evaluated to determine their suitability as a quality assurance tool for surface modified nickel plated zircaloy-4 liner tubes. Samples with 0, 0.1, 0.2, 0.3, and 0.4 mils of heat treated nickel plate were tested at 330, 370, and 400 C. Not all of the samples exhibited the expected typical parabolic shaped oxidation curve. The measured weight change was consistent for the as received and 0.2 mil and the 0.4 mil surface modified samples. None of the samples were tested under aggressive enough conditions to consume the surface modified materials during the test duration. Use of the Mass Spectrometer in conjunction with the TGA did not produce valuable data and was only used for the 400 C test series; however, the TGA was valuable. The 0.1 and 0.3 mil surface modified Zr-4 samples exhibited thru surface modified layer cracks which could account for the variation in oxidation behavior. TGA tests for periods up to six hours appear viable as a method to ascertain oxidation behavior for consistent results. Additional testing of samples with known variations in surface modified layer thickness and quality is recommended as part of the QA acceptance testing.
Date: September 21, 2009
Creator: Korinko, P. & Imrich, K.
Object Type: Report
System: The UNT Digital Library
Neutron Detector Gamma Insensitivity Criteria (open access)

Neutron Detector Gamma Insensitivity Criteria

The shortage of 3He has triggered the search for an effective alternative neutron detection technology for radiation portal monitor applications. Any new detection technology must satisfy two basic criteria: 1) it must meet the neutron detection efficiency requirement, and 2) it must be insensitive to gamma ray interference at a prescribed level, while still meeting the neutron detection requirement. It is the purpose of this document to define this latter criterion.
Date: October 21, 2009
Creator: Kouzes, Richard T.; Ely, James H.; Lintereur, Azaree T. & Stephens, Daniel L.
Object Type: Report
System: The UNT Digital Library
Recent Fast Wave Coupling and Heating Studies on NSTX, with Possible Implications for ITER (open access)

Recent Fast Wave Coupling and Heating Studies on NSTX, with Possible Implications for ITER

The goal of the high harmonic fast wave (HHFW) research on NSTX is to maximize the coupling of RF power to the core of the plasma by minimizing the coupling of RF power to edge loss processes. HHFW core plasma heating efficiency in helium and deuterium L-mode discharges is found to improve markedly on NSTX when the density 2 cm in front of the antenna is reduced below that for the onset of perpendicular wave propagation (nonset ∝ B*k|| 2/ω). In NSTX, the observed RF power losses in the plasma edge are driven in the vicinity of the antenna as opposed to resulting from multi-pass edge damping. PDI surface losses through ion-electron collisions are estimated to be significant. Recent spectroscopic measurements suggest that additional PDI losses could be caused by the loss of energetic edge ions on direct loss orbits and perhaps result in the observed clamping of the edge rotation. Initial deuterium H-mode heating studies reveal that core heating is degraded at lower kφ (- 8 m-1 relative to 13 m-1) as for the Lmode case at elevated edge density. Fast visible camera images clearly indicate that a major edge loss process is occurring from the plasma scrape off …
Date: July 21, 2009
Creator: J.C. Hosea, R.E. Bell, E. Feibush, R.W. Harvey, E.F. Jaeger, B.P LeBlanc, R. Maingi, C.K. Phillips, L. Roquemore, P.M. Ryan, G. Taylor, K. Tritz, E.J. Valeo, J. Wilgen, J.R. Wilson, and the NSTX Team
Object Type: Article
System: The UNT Digital Library
Conceptual Engineering Method for Attenuating He Ion Interactions on First Wall Components in the Fusion Test Facility (FTF) Employing a Low-Pressure Noble Gas (open access)

Conceptual Engineering Method for Attenuating He Ion Interactions on First Wall Components in the Fusion Test Facility (FTF) Employing a Low-Pressure Noble Gas

It has been shown that post detonation energetic helium ions can drastically reduce the useful life of the (dry) first wall of an IFE reactor due to the accumulation of implanted helium. For the purpose of attenuating energetic helium ions from interacting with first wall components in the Fusion Test Facility (FTF) target chamber, several concepts have been advanced. These include magnetic intervention (MI), deployment of a dynamically moving first wall, use of a sacrificial shroud, designing the target chamber large enough to mitigate the damage caused by He ions on the target chamber wall, and the use of a low pressure noble gas resident in the target chamber during pulse power operations. It is proposed that employing a low-pressure (~ 1 torr equivalent) noble gas in the target chamber will thermalize energetic helium ions prior to interaction with the wall. The principle benefit of this concept is the simplicity of the design and the utilization of (modified) existing technologies for pumping and processing the noble ambient gas. Although the gas load in the system would be increased over other proposed methods, the use of a "gas shield" may provide a cost effective method of greatly extending the first wall …
Date: September 21, 2009
Creator: C.A.Gentile, W.R.Blanchard, T.Kozub, C.Priniski, I.Zatz, S.Obenschain
Object Type: Article
System: The UNT Digital Library
THE IMPACT OF DISSOLVED SALTS ON PASTES CONTAINING FLY ASH, CEMENT AND SLAG (open access)

THE IMPACT OF DISSOLVED SALTS ON PASTES CONTAINING FLY ASH, CEMENT AND SLAG

The degree of hydration of a mixture of cementitious materials (Class F fly ash, blast furnace slag and portland cement) in highly concentrated alkaline salt solutions is enhanced by the addition of aluminate to the salt solution. This increase in the degree of hydration, as monitored with isothermal calorimetry, leads to higher values of dynamic Young's modulus and compressive strength and lower values of total porosity. This enhancement in performance properties of these cementitious waste forms by increased hydration is beneficial to the retention of the radionuclides that are also present in the salt solution. The aluminate ions in the solution act first to retard the set time of the mix but then enhance the hydration reactions following the induction period. In fact, the aluminate ions increase the degree of hydration by {approx}35% over the degree of hydration for the same mix with a lower aluminate concentration. An increase in the blast furnace slag concentration and a decrease in the water to cementitious materials ratio produced mixes with higher values of Young's modulus and lower values of total porosity. Therefore, these operational factors can be fine tuned to enhance performance properties of cementitious waste form. Empirical models for Young modulus, …
Date: September 21, 2009
Creator: Harbour, J.; Edwards, T. & Williams, V.
Object Type: Article
System: The UNT Digital Library