Biosphere Process Model Report (open access)

Biosphere Process Model Report

To evaluate the postclosure performance of a potential monitored geologic repository at Yucca Mountain, a Total System Performance Assessment (TSPA) will be conducted. Nine Process Model Reports (PMRs), including this document, are being developed to summarize the technical basis for each of the process models supporting the TSPA model. These reports cover the following areas: (1) Integrated Site Model; (2) Unsaturated Zone Flow and Transport; (3) Near Field Environment; (4) Engineered Barrier System Degradation, Flow, and Transport; (5) Waste Package Degradation; (6) Waste Form Degradation; (7) Saturated Zone Flow and Transport; (8) Biosphere; and (9) Disruptive Events. Analysis/Model Reports (AMRs) contain the more detailed technical information used to support TSPA and the PMRs. The AMRs consists of data, analyses, models, software, and supporting documentation that will be used to defend the applicability of each process model for evaluating the postclosure performance of the potential Yucca Mountain repository system. This documentation will ensure the traceability of information from its source through its ultimate use in the TSPA-Site Recommendation (SR) and in the National Environmental Policy Act (NEPA) analysis processes. The objective of the Biosphere PMR is to summarize (1) the development of the biosphere model, and (2) the Biosphere Dose Conversion …
Date: May 25, 2000
Creator: Schmitt, J.
Object Type: Report
System: The UNT Digital Library
Critical Characteristics of Radiation Detection System Components to be Dedicated for use in Safety Class and Safety Significant System (open access)

Critical Characteristics of Radiation Detection System Components to be Dedicated for use in Safety Class and Safety Significant System

This document identifies critical characteristics of components to be dedicated for use in Safety Class (SC) or Safety Significant (SS) Systems, Structures, or Components (SSCs). This document identifies the requirements for the components of the common radiation area monitor alarm in the WESF pool cell. These are procured as Commercial Grade Items (CGI), with the qualification testing and formal dedication to be performed at the Waste Encapsulation Storage Facility (WESF), in safety class, safety significant systems. System modifications are to be performed in accordance with the instructions provided on ECN 658230. Components for this change are commercially available and interchangeable with the existing alarm configuration This document focuses on the operational requirements for alarm, declaration of the safety classification, identification of critical characteristics, and interpretation of requirements for procurement. Critical characteristics are identified herein and must be verified, followed by formal dedication, prior to the components being used in safety related applications.
Date: May 25, 2000
Creator: DAVIS, S.J.
Object Type: Report
System: The UNT Digital Library
Travel grant program for the IX International Congresses of Mycology and Bacteriology -- Final report (open access)

Travel grant program for the IX International Congresses of Mycology and Bacteriology -- Final report

In 1999, the American Society for Microbiology (ASM) and the National Academy of Sciences' U.S. National Committee for the International Union of Microbiological Sciences (IUMS) jointly organized a competitive travel grant program to support the participation of U.S. scientists in the 9th International Congresses of the Bacteriological and Applied Microbiology, Mycology and Virology Divisions of the IUMS in Sydney, Australia, August 16-20, 1999. Funding was solicited for the program, and the ASM Minority and International Activities department administered the $40,000 raised. Travel grants in the amount of $2,000 were offered to U.S. investigators (citizens, including federal employees, and permanent residents working in the United States) in the early stages of their careers who planned to attend and present their research at the Congress. Teams of established and new investigators who applied jointly were eligible to received a combined $3,000 award. IUMS developed a questionnaire th at each applicant were required to complete and return, which asked each award recipient about their experience at the Congresses. Questionnaire results are included.
Date: May 25, 2000
Creator: Granigan, Marion
Object Type: Report
System: The UNT Digital Library
FY96-98 Summary Report Mercury: Next Generation Laser for High Energy Density Physics SI-014 (open access)

FY96-98 Summary Report Mercury: Next Generation Laser for High Energy Density Physics SI-014

The scope of the Mercury Laser project encompasses the research, development, and engineering required to build a new generation of diode-pumped solid-state lasers for Inertial Confinement Fusion (ICF). The Mercury Laser will be the first integrated demonstration of laser diodes, crystals, and gas cooling within a scalable laser architecture. This report is intended to summarize the progress accomplished during the first three years of the project. Due to the technological challenges associated with production of 900 nm diode-bars, heatsinks, and high optical-quality Yb:S-FAP crystals, the initial focus of the project was primarily centered on the R&D in these three areas. During the third year of the project, the R&D continued in parallel with the development of computer codes, partial activation of the laser, component testing, and code validation where appropriate.
Date: May 25, 2000
Creator: Bayramian, A.; Beach, R.; Bibeau, C.; Chanteloup, J.-C.; Ebbers, C.; Emanuel, M. et al.
Object Type: Report
System: The UNT Digital Library
Saturation of impurity-rich phases in a cerium-substituted pyrochlore-rich titanate ceramic: part 1 experimental results (open access)

Saturation of impurity-rich phases in a cerium-substituted pyrochlore-rich titanate ceramic: part 1 experimental results

The saturation of impurity-rich accessory phases in a Ce-analog baseline ceramic formulation for the immobilization of excess plutonium has been tested by synthesizing an impurity-rich baseline compositions at 1300 C, 1350 C, and 1400 C in air. Impurity oxides are added at the 10 wt% level. The resulting phases assemblages are typically rich in pyrochlore, Hf-zirconolite (hafnolite), brannerite and rutile, but in many instances also contain an accessory mineral enriched in the impurity oxide. The concentration of that oxide in coexisting pyrochlore sets the saturation limit for solid solution of the component in question. In most cases, the accessory phase does not contain significant amounts of Ce, Gd or U. Exceptions are the stabilization of a Ca-lanthanide phosphate and a phosphate glass when P{sub 2}O{sub 5} is added to the formulation. P{sub 2}O{sub 5} addition is also very effective in reducing the modal amount of pyrochlore in the form relative to brannerite. Addition of the sodium-aluminosilicate, NaAlSiO{sub 4}, also results in the formation of a grain boundary melt at run conditions, but the fate of this phase on cooling is not well determined. At temperatures above 1300 C, addition of 10 wt% Fe{sub 2}O{sub 3} also leads to melting. Substitution …
Date: May 25, 2000
Creator: Ryerson, F. J.; Ebbinghaus, B.; Kirkorian, O. & VanKonynenburg, R.
Object Type: Report
System: The UNT Digital Library
Pyrochlore-rich titanate ceramics for the immobilization of plutonium: redox effects on phase equilibria in cerium- and thorium- substituted analogs (open access)

Pyrochlore-rich titanate ceramics for the immobilization of plutonium: redox effects on phase equilibria in cerium- and thorium- substituted analogs

Three compositions representing plutonium-free analogs of a proposed Ca-Ti-Gd-Hf-U-PU oxide ceramic for the immobilization of plutonium were equilibrated at 1 atm, 1350 C over a range of oxygen fugacities between air and that equivalent to the iron-wuestite buffer. The cerium analog replaces Pu on a mole-per-mole basic with Ce; the thorium analog replaces Pu with Th. A third material has 10 wt% Al{sub 2}O{sub 3} added to the cerium analog to encourage the formation of a Hf-analog of, CaHfTi{sub 2}O{sub 7}, zirconolite, which is referred to as hafnolite. The predominant phase produced in each formulation under all conditions is pyrochlore, A{sub 2}T{sub 2}O{sub 7}, where the T site is filled by Ti, and Ca, the lanthanides, Hf, U and Pu are accommodated on the A-site. Other lanthanide and uranium-bearing phases encountered include brannerite (UTi{sub 2}O{sub 6}), hafnolite (CaHfTi{sub 2}O{sub 7}), perovskite (CaTiO{sub 3}) and a calcium-lanthanide aluminotitanate with nominal stoichiometry (Ca,Ln)Ti{sub 2}Al{sub 9}O{sub 19}, where Ln is a lanthanide. The phase compositions show progressive shifts with decreasing oxygen fugacity. All of the phases observed have previously been identified in titanate-based high-level radioactive waste ceramics and demonstrate the flexibility of these ceramics to variations in processing parameters. The main variation is …
Date: May 25, 2000
Creator: Ryerson, F. J. & Ebbinghaus, B.
Object Type: Report
System: The UNT Digital Library
Interactions between Liquid-Wall Vapor and Edge Plasmas (open access)

Interactions between Liquid-Wall Vapor and Edge Plasmas

The use of liquid walls for fusion reactors could help solve problems associated with material erosion from high plasma heat-loads and neutronic activation of structures. A key issue analyzed here is the influx of impurity ions to the core plasma from the vapor of liquid side-walls. Numerical 2D transport simulations are performed for a slab geometry which approximates the edge region of a reactor-size tokamak. Both lithium vapor (from Li or SnLi walls) and fluorine vapor (from Flibe walls) are considered for hydrogen edge-plasmas in the high- and low-recycling regimes. It is found that the minimum influx is from lithium with a low-recycling hydrogen plasma, and the maximum influx occurs for fluorine with a high-recycling hydrogen plasma.
Date: May 25, 2000
Creator: Rognlien, T D & Rensink, M E
Object Type: Article
System: The UNT Digital Library
WHB/WTB SPACE PROGRAM ANALYSIS FOR SITE RECOMMENDATION (open access)

WHB/WTB SPACE PROGRAM ANALYSIS FOR SITE RECOMMENDATION

The purpose of this analysis is to identify and evaluate the functional space and spatial relationship requirements for the two main nuclear buildings, the Waste Handling Building (WHB) and the Waste Treatment Building (WTB), which are part of the Repository Surface Facilities. This analysis is consistent with the Development Plan for ''WHB/WTB Space Program Analysis for Site Recommendation'' (CRWMS M&O 2000r), which concentrates on the primary, primary support, facility support, and miscellaneous building support areas located in the WHB and WTB. The development plan was completed in accordance with AP-2.134, ''Technical Product Development Planning''. The objective and scope of this analysis is to develop a set of spatial parameters (e.g., square footage, room heights, etc.) and layout requirements (e.g., adjacency and access/circulation requirements, etc.) from which preliminary building floor plans are developed and presented as figures. The resulting figures will provide information to support the Site Recommendation and the total system life cycle cost. This analysis uses the Viability Assessment (VA) ''Surface Nuclear Facilities Space Program Analysis'' (SPA) (CRWMS M&O 1997c) as the baseline reference document and further develops the functional requirements based on Project-directed changes, including incorporation of a new design basis waste stream and the applicable elements of …
Date: May 25, 2000
Creator: Lindholm, W. D.
Object Type: Report
System: The UNT Digital Library
Large-scale structure from quantum fluctuations in the early universe (open access)

Large-scale structure from quantum fluctuations in the early universe

A better understanding of the formation of large-scale structure in the Universe is arguably the most pressing question in cosmology. The most compelling and promising theoretical paradigm, Inflation + Cold Dark Matter, holds that the density inhomogeneities that seeded the formation of structure in the Universe originated from quantum fluctuations arising during inflation and that the bulk of the dark matter exists as slowing moving elementary particles (cold dark matter) left over from the earliest, fiery moments. Large redshift surveys (such as the SDSS and 2dF) and high-resolution measurements of CBR anisotropy (to be made by the MAP and Planck Surveyor satellites) have the potential to decisively test Inflation + Cold Dark Matter and to open a window to the very early Universe and fundamental physics.
Date: May 25, 2000
Creator: Turner, Michael
Object Type: Article
System: The UNT Digital Library
Atom trap trace analysis (open access)

Atom trap trace analysis

A new method of ultrasensitive trace-isotope analysis has been developed based upon the technique of laser manipulation of neutral atoms. It has been used to count individual {sup 85}Kr and {sup 81}Kr atoms present in a natural krypton sample with isotopic abundances in the range of 10{sup {minus}11} and 10{sup {minus}13}, respectively. The atom counts are free of contamination from other isotopes, elements,or molecules. The method is applicable to other trace-isotopes that can be efficiently captured with a magneto-optical trap, and has a broad range of potential applications.
Date: May 25, 2000
Creator: Lu, Z. T.; Bailey, K.; Chen, C. Y.; Du, X.; Li, Y. M.; O'Connor, T. P. et al.
Object Type: Article
System: The UNT Digital Library
In situ real-time studies of oxygen incorporation in complex oxide thin films using spectroscopic ellipsometry and ion scattering and recoil spectrometry (open access)

In situ real-time studies of oxygen incorporation in complex oxide thin films using spectroscopic ellipsometry and ion scattering and recoil spectrometry

The surface termination of c-axis oriented YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and the oxygen incorporation mechanism has been investigated using a unique combination of spectroscopic ellipsometry (SE) and time of flight ion scattering and recoil spectrometry (ToF-ISARS). The high surface sensitivity of the ToF-ISARS technique combined with the bulk oxygen sensitivity of SE are shown to yield complimentary information. The SE provided the film orientation and quality, while ToF-ISARS supplied surface compositional and structural information and enabled isotopic {sup 18}O tracer studies. It was determined that the O content of the film had little effect on the surface termination of the film, indicating a lack of labile Cu(1) sites at the c-axis oriented YBCO surface. Also, strong evidence for a Ba or BaO terminated structure is shown. The data related to the {sup 18}O tracer studies indicate that O from the reaction ambient incorporates only into the labile Cu(1) sites during both deposition and annealing, while stable O sites were populated with O from the sputtered target, indicating either the need for sputtered atomic O or sputtered YCuO complexes to occupy the stable Cu(2) sites.
Date: May 25, 2000
Creator: Mueller, A. H.; Gao, Y.; Irene, E. A.; Auciello, O.; Krauss, A. R. & Achultz, J. A.
Object Type: Article
System: The UNT Digital Library
In-line ultrasonic monitoring of waste slurry suspended solids (open access)

In-line ultrasonic monitoring of waste slurry suspended solids

During the transport of tank waste, it is very important to quantitatively measure the percent solids concentration (PSC) of the waste, which indicates the flow conditions and the extent of solids settling. At Argonne National Laboratory, an in-line, real-time, a nonintrusive ultrasonic monitoring system has been developed to measure the PSC and flow density of tank waste by measuring sound velocity and attenuation in the flow. This system consists of a pair of longitudinal transducers bonded to waveguides on the opposite sides of the pipe and operating at IMHz simultaneously in pulse-and-echo and pitch-and-catch modes. The PSC measurement is provided by attenuation, while the density measurement is calculated by impedance and sound velocity. A thermocouple is attached to one of the waveguides for automatic temperature correction of the measurements. This system was one of four evaluated for in-line measurement of slurry at Oak Ridge National Laboratory in 1998. The results indicate that the measurements are in good agreement with a Coriolis meter and that the system can be used to monitor PSC up to 40 wt.%. However, the system is greatly affected by entrained air bubbles within the solid flow during Puisair mixing. A different mixing mechanism will solve this …
Date: May 25, 2000
Creator: Chien, H. T.; Sheen, S. H. & Raptis, A. C.
Object Type: Article
System: The UNT Digital Library
Overview of impurity control and wall conditioning in NSTX (open access)

Overview of impurity control and wall conditioning in NSTX

The National Spherical Torus Experiment (NSTX) started plasma operations in February 1999, and promptly achieved high current, inner wall limited, double null, and single null plasma discharges, initial Coaxial Helicity Injection, and High Harmonic Fast Wave results. NSTX is designed to study the physics of Spherical Tori (ST) in a device that can produce non-inductively sustained high-{beta} discharges in the 1 MA regime and to explore approaches toward a small, economical high power density ST reactor core. As expected, discharge reproducibility and performance were strongly affected by wall conditions. In this paper, the authors describe the internal geometry, and initial plasma discharge, impurity control, wall conditioning, erosion, and deposition results.
Date: May 25, 2000
Creator: Kugel, H. W.; Maingi, R.; Bell, M.; Blanchard, W.; Gates, D.; Johnson, D. et al.
Object Type: Article
System: The UNT Digital Library
Preferential recycling/rejection in CFBC/FBC systems using triboelectrostatic separation (open access)

Preferential recycling/rejection in CFBC/FBC systems using triboelectrostatic separation

Circulating Fluidized Bed Combustion (CFBC) and Fluidized Bed Combustion (FBC) with recirculation are widely used technologies in the US for power generation. They have the advantage of fuel flexibility, and low NO{sub x} and SO{sub x} emissions. Typically, as partially combusted fuel is circulated in the system, only a split stream of this circulating stream is rejected, with remainder recycled to the combustor. As a consequence, there is unburned carbon and partially used, valuable, calcium hydroxide in the reject stream. If these useful materials in the reject stream can be recovered and sent back to the combustor, the efficiency of the system will be increased significantly and the equivalent emissions will be lower. This project studies an innovative concept to incorporate triboelectric separation into CFBC/FBC systems in order to preferentially split its recycle/reject streams based on material compositions of the particles. The objective is to answer whether useful constituents, like carbon, calcium carbonate and calcium hydroxide or oxide, can be selectively separated from combustion ash at elevated temperatures. Laboratory experimental studies are performed at temperatures from 25 C to 210 C, the data from which are presented in the form of recovery curves. These curves present quality-versus-quantity information useful for …
Date: May 25, 2000
Creator: Ban, Heng & Stencel, J.M.
Object Type: Report
System: The UNT Digital Library
Electroweak symmetry breaking by extra dimensions (open access)

Electroweak symmetry breaking by extra dimensions

Electroweak symmetry breaking may be naturally induced by the observed quark and gauge fields in extra dimensions without a fundamental Higgs field. The authors show that a composite Higgs doublet can arise as a bound state of (t,b){sub L} and a linear combination of the Kaluza-Klein states of t{sub R}, due to QCD in extra dimensions. The top quark mass depends on the number of active t{sub R} Kaluza-Klein modes, and is consistent with the experimental value.
Date: May 25, 2000
Creator: Cheng, Hsin-Chia & Hill, Bogdan A. Dobrescu and Christopher T.
Object Type: Article
System: The UNT Digital Library
Suppression of erosion in the DIII-D divertor with detached plasmas (open access)

Suppression of erosion in the DIII-D divertor with detached plasmas

The ability to withstand disruptions makes carbon-based materials attractive for use as plasma-facing components in divertors. However, such materials suffer high erosion rates during attached plasma operation which, in high power long pulse machines, would give short component lifetimes and high tritium inventories. The authors present results from recent experiments in DIII-D, in which the Divertor Materials Evaluation System (DiMES) was used to examine erosion and deposition during short exposures to well defined plasma conditions. These studies show that during operation with detached plasmas, produced by gas injection, net erosion is suppressed everywhere in the divertor. Net deposition of carbon with deuterium was observed at the inner and outer strikepoints and in the private-flux region between strikepoints. For these low temperature plasmas (T{sub e} < 2eV), physical sputtering is eliminated. These results show that with detached plasmas, the location of carbon net erosion and the carbon impurity source, probably lies outside the divertor. Physical or chemical sputtering by charge-exchange neutrals or ions in the main plasma chamber is a probable source of carbon under these plasma conditions.
Date: May 25, 2000
Creator: Wampler, William R.; Bastasz, Robert J.; Whyte, D. G.; Wong, C. P. C. & West, W. P.
Object Type: Article
System: The UNT Digital Library
Electroweak measurements from hadron machines (open access)

Electroweak measurements from hadron machines

The discovery of the W and Z gauge bosons at the Sp{bar p}S in 1983 marked the beginning of direct electroweak measurements at a hadron machine. These measurements vindicated the tree level predictions of the Standard Model. The new generation of hadron collider machines now have data of such precision that the electroweak measurements are probing the quantum corrections to the Standard Model. The importance of these quantum corrections was recognized in the award of the 1999 Nobel Price. These corrections are being tested by a wide variety of measurements ranging from atomic parity violation in cesium to precision measurements at the Z pole and above in e{sup +}e{sup {minus}} collisions. In this article, the latest experimental electroweak data from hadron machines is reviewed. The author has taken a broad definition of a hadron machine to include the results from NuTeV ({nu}N collisions) and HERA (ep collisions) as well as the results of the Tevatron (p{bar p} collisions). This is not an exhaustive survey of all results, but a summary of the new results of the past year and in particular those results which have an influence on the indirect determination of the Higgs mass. This article will cover the …
Date: May 25, 2000
Creator: Lancaster, Mark
Object Type: Article
System: The UNT Digital Library
High-temperature batteries for geothermal and oil/gas borehole applications (open access)

High-temperature batteries for geothermal and oil/gas borehole applications

A literature survey and technical evaluation was carried out of past and present battery technologies with the goal of identifying appropriate candidates for use in geothermal borehole and, to a lesser extent, oil/gas boreholes. The various constraints that are posed by such an environment are discussed. The promise as well as the limitations of various candidate technologies are presented. Data for limited testing of a number of candidate systems are presented and the areas for additional future work are detailed. The use of low-temperature molten salts shows the most promise for such applications and includes those that are liquid at room temperature. The greatest challenges are to develop an appropriate electrochemical couple that is kinetically stable with the most promising electrolytes--both organic as well as inorganic--over the wide operating window that spans both borehole environments.
Date: May 25, 2000
Creator: GUIDOTTI,RONALD A.
Object Type: Article
System: The UNT Digital Library
New Phenomena I: Searches for new physics at CDF and D0 (open access)

New Phenomena I: Searches for new physics at CDF and D0

This paper summarizes results of recent searches for new phenomena with the CDF and D0 detectors at the Fermilab Tevatron. All results shown correspond to analysis from the past Run I data corresponding to a total integrated luminosity of {approximately} 100 pb{sup {minus}1} per experiment. In particular, the authors show new results from stop quark searches, neutral supersymmetric Higgs boson searches, a reinterpretation of the CDF second and third generation leptoquark searches in terms of leptoquark resonant production through technicolor interactions and, finally, they report a new D0 search for large extra space dimensions from high mass Drell-Yan dielectron and diphoton events.
Date: May 25, 2000
Creator: Valls, Juan A.
Object Type: Article
System: The UNT Digital Library
Investigations of chemical vapor deposition of GaN using synchrotron radiation (open access)

Investigations of chemical vapor deposition of GaN using synchrotron radiation

The authors apply synchrotron x-ray analysis techniques to probe the surface structure of GaN films during synthesis by metal-organic chemical vapor deposition (MOCVD). Their approach is to observe the evolution of surface structure and morphology in real time using grazing incidence x-ray scattering (GIXS). This technique combines the ability of x-rays to penetrate the chemical vapor deposition environment for in situ measurements, with the sensitivity of GIXS to atomic scale structure. In this paper they present examples from some of their studies of growth modes and surface evolution as a function of process conditions that illustrate the capabilities of synchrotron x-ray analysis during MOCVD growth. They focus on studies of the homoepitaxial growth mode, island coarsening dynamics, and effects of impurities.
Date: May 25, 2000
Creator: Thompson, C.; Stephenson, G. B.; Eastman, J. A.; Munkholm, A.; Auciello, O.; Murty, M. V. R. et al.
Object Type: Article
System: The UNT Digital Library
Thermal-sprayed, thin-film pyrite cathodes for thermal batteries -- Discharge-rate and temperature studies in single cells (open access)

Thermal-sprayed, thin-film pyrite cathodes for thermal batteries -- Discharge-rate and temperature studies in single cells

Using an optimized thermal-spray process, coherent, dense deposits of pyrite (FeS{sub 2}) with good adhesion were formed on 304 stainless steel substrates (current collectors). After leaching with CS{sub 2} to remove residual free sulfur, these served as cathodes in Li(Si)/FeS{sub 2} thermal cells. The cells were tested over a temperature range of 450 C to 550 C under baseline loads of 125 and 250 mA/cm{sup 2}, to simulate conditions found in a thermal battery. Cells built with such cathodes outperformed standard cells made with pressed-powder parts. They showed lower interracial resistance and polarization throughout discharge, with higher capacities per mass of pyrite. Post-treatment of the cathodes with Li{sub 2}O coatings at levels of >7% by weight of the pyrite was found to eliminate the voltage transient normally observed for these materials. Results equivalent to those of standard lithiated catholytes were obtained in this manner. The use of plasma-sprayed cathodes allows the use of much thinner cells for thermal batteries since only enough material needs to be deposited as the capacity requirements of a given application demand.
Date: May 25, 2000
Creator: GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; DAI,JINXIANG; XIAO,T. DANNY & REISNER,DAVID
Object Type: Article
System: The UNT Digital Library
Surveillance of Site A and Plot M - Report for 1999. (open access)

Surveillance of Site A and Plot M - Report for 1999.

The results of the environmental surveillance program conducted at Site A/Plot M in the Palos Forest Preserve area for Calendar Year 1999 are presented. Based on the results of the 1976-1978 radiological characterization of the site, a determination was made that a surveillance program be established. The characterization study determined that very low levels of hydrogen-3 (as tritiated water) had migrated from the burial ground and were present in two nearby hand-pumped picnic wells. The current surveillance program consists of sample collection and analysis of surface and subsurface water. The results of the analyses are used to (1) monitor the migration pathway of water from the burial ground (Plot M) to the handpumped picnic wells, (2) establish if buried radionuclides other than hydrogen-3 have migrated, and (3) generally characterize the radiological environment of the area. Hydrogen-3 in the Red Gate Woods picnic wells was still detected this year, but the average and maximum concentrations were significantly less than found earlier. Tritiated water continues to be detected in a number of wells, boreholes, dolomite holes, and a surface stream. For many years it was the only radionuclide found to have migrated in measurable quantities. Analyses since 1984 have indicated the presence …
Date: May 25, 2000
Creator: Golchert, N. W.
Object Type: Report
System: The UNT Digital Library
Preferential recycling/rejection in CFBC/FBC systems using triboelectrostatic separation (open access)

Preferential recycling/rejection in CFBC/FBC systems using triboelectrostatic separation

Circulating Fluidized Bed Combustion (CFBC) and Fluidized Bed Combustion (FBC) with recirculation are widely used technologies in the US for power generation. They have the advantage of fuel flexibility, and low NO{sub x} and SO{sub x} emissions. Typically, as partially combusted fuel is circulated in the system, only a split stream of this circulating stream is rejected, with remainder recycled to the combustor. As a consequence, there is unburned carbon and partially used, valuable, calcium hydroxide in the reject stream. If these useful materials in the reject stream can be recovered and sent back to the combustor, the efficiency of the system will be increased significantly and the equivalent emissions will be lower. This project studies an innovative concept to incorporate triboelectric separation into CFBC/FBC systems in order to preferentially split its recycle/reject streams based on material compositions of the particles. The objective is to answer whether useful constituents, like carbon, calcium carbonate and calcium hydroxide or oxide, can be selectively separated from combustion ash at elevated temperatures. Laboratory experimental studies are performed at temperatures from 25 C to 210 C, the data from which are presented in the form of recovery curves. These curves present quality-versus-quantity information useful for …
Date: May 25, 2000
Creator: Ban, Heng & Stencel, J.M.
Object Type: Report
System: The UNT Digital Library
Superheavy dark Matter (open access)

Superheavy dark Matter

If there exists fields of mass of the order of 10{sup 13} GeV and large field inflation occurs, their interaction with classical gravitation will generate enough particles to give the universe critical density today regardless of their nongravitational coupling. In the standard dark matter scenarios, WIMPs are usually considered to have once been in local thermodynamic equilibrium (LTE), and their present abundance is determined by their self-annihilation cross section. In that case, unitarity and the lower bound on the age of the universe constrains the mass of the relic to be less than 500 TeV. On the other hand, if the DM particles never attained LTE in the past, self-annihilation cross section does not determine their abundance. For example, axions, which may never have been in LTE, can have their abundance determined by the dynamics of the phase transition associated with the breaking of U(1){sub PQ}. These nonthermal relics (ones that never obtained LTE) are typically light. However, there are mechanisms that can produce superheavy (many orders of magnitude greater than the weak scale) nonthermal relics. Some of this is reviewed in reference 2. Although not known at the time when this talk was given, it is now known that …
Date: May 25, 2000
Creator: Chung, Daniel
Object Type: Article
System: The UNT Digital Library