Month

Calcite Precipitation and Trace Metal Partitioning in Groundwater and the Vadose Zone: Remediation of Strontium-90 and Other Divalent Metals and Radionuclides in Arid Western Environments (open access)

Calcite Precipitation and Trace Metal Partitioning in Groundwater and the Vadose Zone: Remediation of Strontium-90 and Other Divalent Metals and Radionuclides in Arid Western Environments

Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) weapons complex. Demonstrating in situ immobilization of these contaminants in vadose zones or groundwater plumes is a cost-effective remediation strategy. However, the implementation of in situ remediation requires definition of the mechanism that controls sequestration of the contaminants. One such mechanism for metals and radionuclides is co-precipitation of these elements in authigenic calcite and calcite overgrowths. Calcite, a common mineral in many aquifers and vadose zones in the arid western U.S., can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of solid solutions. The rate at which trace metals are incorporated into calcite is a function of calcite precipitation kinetics, adsorption interactions between the calcite surface and the trace metal in solution, solid solution properties of the trace metal in calcite, and also the surfaces upon which the calcite is precipitating. A fundamental understanding of the coupling of calcite precipitation and trace metal partitioning and how this may occur in aquifers and vadose environments is lacking. The focus of the research proposed here is to investigate the facilitated partitioning of metal and …
Date: July 19, 2000
Creator: Smith, Robert W.; Colwell, F. S.; Ingram, Jani C.; Ferris, F. Grant & Reysenbach, Anna-Louise
Object Type: Report
System: The UNT Digital Library
Release Storage and Disposal Program Product Sampling Support (open access)

Release Storage and Disposal Program Product Sampling Support

This document includes recommended capabilities and/or services to support transport, analysis, and disposition of Immobilized High-Level and Low-Activity Waste samples as requested by the US DOE-Office of River Protection (DOE-ORP) as specified in the Privatization Contract between DOE-ORP and BNFL Inc. In addition, an approved implementation path forward is presented which includes use of existing Hanford Site services to provide the required support capabilities.
Date: July 19, 2000
Creator: CALMUS, R.B.
Object Type: Report
System: The UNT Digital Library
FY 2000 Tanks Focus Area Corrosion Monitoring Technical Committee Meeting Summary Report (open access)

FY 2000 Tanks Focus Area Corrosion Monitoring Technical Committee Meeting Summary Report

The primary purpose of the annual meeting between the corrosion monitoring personnel at the various DOE sites is to facilitate communications and promote technology transfer between the two sites. The close communications and good spirit of teamwork being exhibited between the parties representing the Hanford and Savannah River Sites has helped the Savannah River Site effort avoid many of the problems encountered during the initial development effort at Hanford. Similar benefits can be expected over the next few years as the ORNL program is developed. Expected products of this meeting as defined in Milestone A.4-1 of TTP RL0-9-WT-41 are reports on the status of technical work at the sites, discussions of emerging technical issues, and results of laboratory experiments and field trials. The formal meeting, informal discussions throughout the week, and the presentation materials shown in the attachment to this document fulfill the expectations of this meeting. At the conclusion of the meeting it was agreed that close communications should continue between the concerned parties at ORNL, SRTC and Hanford. Tentative plans were made to hold a similar meeting in approximately one year.
Date: July 19, 2000
Creator: Norman, E. C.
Object Type: Report
System: The UNT Digital Library
Test plan for Simulated Saltcake Retrieval Test (open access)

Test plan for Simulated Saltcake Retrieval Test

This document describes the plan for a bench-scale laboratory test to evaluate physical and chemical parameters associated with dissolution of a simulated saltcake waste. Parameters to be measured during the test include water addition rate, liquid drainage rate, visual observations of flow patterns, physical appearance and volume of dissolving saltcake, chemical composition of drained liquid, and polarized light microscopy analysis of solids.
Date: July 19, 2000
Creator: Herting, D. L.
Object Type: Report
System: The UNT Digital Library
Slant Borehole Demonstration Summary Report (open access)

Slant Borehole Demonstration Summary Report

This report provides a summary of the demonstration project for development of a slant borehole to retrieve soil samples from beneath the SX-108 single-shell tank. It provides a summary of the findings from the demonstration activities and recommendations for tool selection and methods to deploy into the SX Tank Farm. Daily work activities were recorded on Drilling and Sampling Daily Work Record Reports. The work described in this document was performed during March and April 2000.
Date: July 19, 2000
Creator: GARDNER, M.G.
Object Type: Report
System: The UNT Digital Library
Observation on the CTBT and Nonproliferation (open access)

Observation on the CTBT and Nonproliferation

The CTBT sits in a broad national security context. The stated purpose of the treaty is to ban nuclear testing and thereby slow nuclear proliferation. However, it also heightens issues of concern for U.S. national security related to stockpile stewardship, worldwide monitoring, and the status of other countries' nuclear weapons programs. These issues were recognized during the negotiation of the CTBT and articulated, in August 1995, as the set of safeguards under which the U.S. would be willing to sign a CTBT. Safeguards A, B, C, and F address maintenance of the U.S. nuclear stockpile, Safeguard D addresses improved monitoring capabilities, and Safeguard E addresses the need to be knowledgeable about foreign nuclear programs.
Date: July 19, 2000
Creator: Shotts, W. J.
Object Type: Article
System: The UNT Digital Library
Overview of the Flammability of Gases Generated in Hanford Waste Tanks (open access)

Overview of the Flammability of Gases Generated in Hanford Waste Tanks

This report presents an overview of what is known about the flammability of the gases generated and retained in Hanford waste tanks in terms of the gas composition, flammability and detonability limits of the gas constituents, and availability of ignition sources. The intrinsic flammability (or non-flammability) of waste gas mixtures is one major determinant of whether a flammable region develops in the tank headspace; other factors are the rate, surface area, and volume of the release and the tank ventilation rate, which are not covered in this report.
Date: July 19, 2000
Creator: Mahoney, Lenna A.; Huckaby, James L.; Bryan, Samuel A. & Johnson, Gerald D.
Object Type: Report
System: The UNT Digital Library
T-Phase Observations from the May 1999 Ascension Island Experiment (open access)

T-Phase Observations from the May 1999 Ascension Island Experiment

The Comprehensive Nuclear-Test-Ban Treaty (CTBT) specifies that an International Monitoring System (IMS) will be used to detect and locate disturbances that could be related to nuclear testing. In order to monitor disturbances in and near the world's oceans, the IMS will rely on a network of 11 hydroacoustic stations. This hydroacoustic network will be composed of 6 hydrophone stations and 5 T-phase seismic stations. The hydrophone stations will record pressure variations in the ocean. The T-phase stations will record the seismic waves in the solid earth that are excited when an hydroacoustic wave strikes an island or continental margin. The coupling of hydroacoustic-to-seismic energy for the purpose of CTBT monitoring is currently an active area of research. We report observations of hydroacoustic waves and their conversion to seismic waves (T-waves) at the volcanic edifice of Ascension Island. Earthquakes to the south of Ascension Island were recorded by International Monitoring System hydrophones and temporary seismic stations deployed on Ascension Island by LLNL. The hydrophone recordings are rich in high frequency (10-40 Hz) energy. However, the converted seismic waves (T-waves) are dominated by much lower frequencies (2-8 Hz). The T-waves demonstrate amplitude and travel time variations on the Island. We performed two-dimensional …
Date: July 19, 2000
Creator: Rodgers, A & Harben, P
Object Type: Article
System: The UNT Digital Library
Pinch Me - I'm Fusing! (open access)

Pinch Me - I'm Fusing!

The process of combining nuclei (the protons and neutrons inside an atomic nucleus) together with a release of kinetic energy is called fusion. This process powers the Sun, it contributes to the world stockpile of weapons of mass destruction and may one day generate safe, clean electrical power. Understanding the intricacies of fusion power, promised for 50 years, ,is sometimes difficult because there are a number of ways of doing it. There is hot fusion, cold fusion and con-fusion. Hot fusion is what powers suns through the conversion of mass energy to kinetic energy. Cold fusion generates con-fusion and nobody really knows what it is. Honestly - this is true. There does seem to be something going on here; I just don't know what. Apparently some experimenters get energy out of a process many call cold fission but no one seems to know what it is, or how to do it reliably. It is not getting much attention from the mainline physics community. Even so, no one is generating electrical power for you and me with either method. In this article 1 will point out some basic features of the mainstream approaches taken to hot fusion power, as well as …
Date: July 19, 2000
Creator: DERZON,MARK S.
Object Type: Article
System: The UNT Digital Library
DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES (open access)

DEVELOPMENT OF HIGH ACTIVITY, COAL-DERIVED, PROMOTED CATALYTIC SYSTEMS FOR NOx REDUCTION AT LOW TEMPERATURES

This project is directed at an investigation of catalytic NO{sub x} reduction mechanisms on coal-derived, activated carbon supports at low temperatures. Promoted carbon systems offer some potentially significant advantages for heterogeneous NO{sub x} reduction. These include: low cost; high activity at low temperatures, which minimizes carbon loss; oxygen resistance; and a support material which can be engineered with respect to porosity, transport and catalyst dispersion characteristics. During the reporting period, the following has been accomplished: (1) A packed bed reactor/gas flow system has been tested and applied to performing NO-carbon reactivity studies. This system employs a Kin-Tek gas calibration/mixing system for varying NO and CO concentrations in the feed gas to the packed bed, a NO{sub x} chemiluminescence analyzer (ThermoElectron, Model 10), and a quadrupole mass spectrometer (Ametek). This system is used for both steady-state reactivity studies, as well as mechanistic studies on the effects of NO and CO in the gas phase on intermediate oxygen surface complex populations on the carbon substrates. (2) Reactivity studies of the NO-carbon system have been performed as a function of temperature and NO concentration. It was found that apparent activation energy in the ''high temperature'' regime of 180 {+-} 10 kJ/mol agrees well …
Date: July 19, 2000
Creator: Calo, Joseph M.
Object Type: Report
System: The UNT Digital Library
What Makes a Beam Shaping Problem Difficult? (open access)

What Makes a Beam Shaping Problem Difficult?

The authors have discussed the three factors that they believe are the most important in determining the difficulty of a beam shaping problem: scaling, smoothness, and coherence. The arguments have been almost completely based on considering how these factors influence beam shaping lenses that were designed using geometrical optics. However, they believe that these factors control the difficulty of beam shaping problems even if one does not base ones design strategy on geometrical optics. For example, they have shown that a lens designed using geometrical optics will not work well unless {beta} is large. However, they have also shown that if {beta} is small the uncertainty principle shows that it is impossible to do a good job of beam shaping no matter how one designs ones lens.
Date: July 19, 2000
Creator: Romero, Louis & Dickey, Fred M.
Object Type: Article
System: The UNT Digital Library
Continuous Wave Operation of 1.3{sub micro}m Vertical Cavity InGaAsN Quantum Well Lasers (open access)

Continuous Wave Operation of 1.3{sub micro}m Vertical Cavity InGaAsN Quantum Well Lasers

None
Date: July 19, 2000
Creator: Fischer, Arthur J.; Klem, John F.; Choquette, Kent D.; Spahn, Olga B.; Allerman, Andrew A.; Fritz, Ian J. et al.
Object Type: Article
System: The UNT Digital Library
Radial Moment Calculations of Coupled Electron-Photon Beams (open access)

Radial Moment Calculations of Coupled Electron-Photon Beams

The authors consider the steady-state transport of normally incident pencil beams of radiation in slabs of material. A method has been developed for determining the exact radial moments of 3-D beams of radiation as a function of depth into the slab, by solving systems of 1-D transport equations. They implement these radial moment equations in the ONEBFP discrete ordinates code and simulate energy-dependent, coupled electron-photon beams using CEPXS-generated cross sections. Modified P{sub N} synthetic acceleration is employed to speed up the iterative convergence of the 1-D charged particle calculations. For high-energy photon beams, a hybrid Monte Carlo/discrete ordinates method is examined. They demonstrate the efficiency of the calculations and make comparisons with 3-D Monte Carlo calculations. Thus, by solving 1-D transport equations, they obtain realistic multidimensional information concerning the broadening of electron-photon beams. This information is relevant to fields such as industrial radiography, medical imaging, radiation oncology, particle accelerators, and lasers.
Date: July 19, 2000
Creator: Franke, Brian C. & Larsen, Edward W.
Object Type: Article
System: The UNT Digital Library
Unconstrained and Constrained Minimization, Linear Scaling, and the Grassmann Manifold: Theory and Applications (open access)

Unconstrained and Constrained Minimization, Linear Scaling, and the Grassmann Manifold: Theory and Applications

An unconstrained minimization algorithm for electronic structure calculations using density functional for systems with a gap is developed to solve for nonorthogonal Wannier-like orbitals in the spirit of E. B. Stechel, A. R. Williams, and P. J. Feibelman, Phys. Rev. B 49, 10,008 (1994). The search for the occupied sub-space is a Grassmann conjugate gradient algorithm generalized from the algorithm of A. Edelman, T.A. Arias, and S. T. Smith, SIAM J. on Matrix Anal. Appl. 20, 303 (1998). The gradient takes into account the nonorthogonality of a local atom-centered basis, gaussian in their implementation. With a localization constraint on the Wannier-like orbitals, well-constructed sparse matrix multiplies lead to O(N) scaling of the computationally intensive parts of the algorithm. Using silicon carbide as a test system, the accuracy, convergence, and implementation of this algorithm as a quantitative alternative to diagonalization are investigated. Results up to 1,458 atoms on a single processor are presented.
Date: July 19, 2000
Creator: Raczkowski, David; Fong, C. Y.; Schultz, Peter A.; Lippert, Ross A. & Stechel, E. B.
Object Type: Article
System: The UNT Digital Library
Gas generation and bubble formation model for crystalline silicotitanate ion exchange columns (open access)

Gas generation and bubble formation model for crystalline silicotitanate ion exchange columns

The authors developed a transient model to describe the process of gas generation due to radiolysis and bubble formation in crystalline silicotitanate (CST) ion exchange (IX) columns using the Aspen Custom Modeler (ACM) software package. The model calculates gas concentrations and onset of bubble formation for large CST IX columns. The calculations include cesium loading as a function of time, gas generation as a function of cesium loading, and bubble formation as a function of gas solubility. This report summarizes the model development and predictions.
Date: July 19, 2000
Creator: Hang, T.
Object Type: Report
System: The UNT Digital Library
Neutron Algorithm Verification Testing (open access)

Neutron Algorithm Verification Testing

Active well coincidence counter assays have been performed on uranium metal highly enriched in {sup 235}U. The data obtained in the present program, together with highly enriched uranium (HEU) metal data obtained in other programs, have been analyzed using two approaches, the standard approach and an alternative approach developed at BNL. Analysis of the data with the standard approach revealed that the form of the relationship between the measured reals and the {sup 235}U mass varied, being sometimes linear and sometimes a second-order polynomial. In contrast, application of the BNL algorithm, which takes into consideration the totals, consistently yielded linear relationships between the totals-corrected reals and the {sup 235}U mass. The constants in these linear relationships varied with geometric configuration and level of enrichment. This indicates that, when the BNL algorithm is used, calibration curves can be established with fewer data points and with more certainty than if a standard algorithm is used. However, this potential advantage has only been established for assays of HEU metal. In addition, the method is sensitive to the stability of natural background in the measurement facility.
Date: July 19, 2000
Creator: Cowgill, Melvyn & Mosby, William
Object Type: Article
System: The UNT Digital Library
Tank farm organic PISA study final report (open access)

Tank farm organic PISA study final report

Concentration, Storage and Transfer Engineering (CSTE) requested that the Savannah River Technology Center (SRTC) investigate the behavior of tri-n-butyl phosphate (TPB) and its degradation products (dibutyl phosphate (DBP), monobutyl phosphate (MBP), and butanol) under simulated waste conditions. SRTC also reviewed the impact of other organic materials that are present in small quantities in the high level waste system. The purpose of this work was to determine the TBP decomposition rate (n-butanol production rate) as a function of temperature, salt solution type, and catalyst.
Date: July 19, 2000
Creator: Swingle, R.F. II
Object Type: Report
System: The UNT Digital Library
A process to recover fibers from polymer matrix composites. (open access)

A process to recover fibers from polymer matrix composites.

None
Date: July 19, 2000
Creator: Jody, B. J.; Daniels, E. J. & Pomykala, J. A., Jr.
Object Type: Article
System: The UNT Digital Library
Overview of ''Red Oil'' Frequency Analyses for F-Canyon (open access)

Overview of ''Red Oil'' Frequency Analyses for F-Canyon

A very small potential exists in the Savannah River Site (SRS) separations operations for an uncontrolled reaction between tri-n-butyl phosphate (TBP) and nitric acid that could result in unacceptable damage to separations facilities and a significant release of radioactive materials. The recent ''red oil'' (TBP and nitric acid) accident in Tomsk, Russia, resulted in considerable damage and radioactive release. Explosions have also occurred at SRS during the early years of operations. While the SRS separations facilities have operated without incident for many years, it is prudent to revisit the SRS defense-in-depth approach to preventing such an accident and to upgrade preventive procedures and hardware as appropriate.
Date: July 19, 2000
Creator: Lux, C.R.
Object Type: Report
System: The UNT Digital Library