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1,097 Matching Results

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(open access)

Upscaling of Long-Term U9VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models

Environmental systems exhibit a range of complexities which exist at a range of length and mass scales. Within the realm of radionuclide fate and transport, much work has been focused on understanding pore scale processes where complexity can be reduced to a simplified system. In describing larger scale behavior, the results from these simplified systems must be combined to create a theory of the whole. This process can be quite complex, and lead to models which lack transparency. The underlying assumption of this approach is that complex systems will exhibit complex behavior, requiring a complex system of equations to describe behavior. This assumption has never been tested. The goal of the experiments presented is to ask the question: Do increasingly complex systems show increasingly complex behavior? Three experimental tanks at the intermediate scale (Tank 1: 2.4m x 1.2m x 7.6cm, Tank 2: 2.4m x 0.61m x 7.6cm, Tank 3: 2.4m x 0.61m x 0.61m (LxHxW)) have been completed. These tanks were packed with various physical orientations of different particle sizes of a uranium contaminated sediment from a former uranium mill near Naturita, Colorado. Steady state water flow was induced across the tanks using constant head boundaries. Pore water was removed …

Date: January 25, 2009

Creator: Miller, Andy

Object Type: Report

System: The UNT Digital Library

(open access)

Automated Impedance Tomography for Monitoring Permeable Reactive Barrier Health

The objective of this research was the development of an autonomous, automated electrical geophysical monitoring system which allows for near real-time assessment of Permeable Reactive Barrier (PRB) health and aging and which provides this assessment through a web-based interface to site operators, owners and regulatory agencies. Field studies were performed at four existing PRB sites; (1) a uranium tailing site near Monticello, Utah, (2) the DOE complex at Kansas City, Missouri, (3) the Denver Federal Center in Denver, Colorado and (4) the Asarco Smelter site in East Helena, Montana. Preliminary surface data over the PRB sites were collected (in December, 2005). After the initial round of data collection, the plan was modified to include studies inside the barriers in order to better understand barrier aging processes. In September 2006 an autonomous data collection system was designed and installed at the EPA PRB and the electrode setups in the barrier were revised and three new vertical electrode arrays were placed in dedicated boreholes which were in direct contact with the PRB material. Final data were collected at the Kansas City, Denver and Monticello, Utah PRB sites in the fall of 2007. At the Asarco Smelter site in East Helena, Montana, nearly …

Date: July 2, 2009

Creator: LaBrecque, D J & Adkins, P L

Object Type: Report

System: The UNT Digital Library

(open access)

Numerical investigation for the impact of CO2 geologic sequestration on regional groundwater flow

Large-scale storage of carbon dioxide in saline aquifers may cause considerable pressure perturbation and brine migration in deep rock formations, which may have a significant influence on the regional groundwater system. With the help of parallel computing techniques, we conducted a comprehensive, large-scale numerical simulation of CO{sub 2} geologic storage that predicts not only CO{sub 2} migration, but also its impact on regional groundwater flow. As a case study, a hypothetical industrial-scale CO{sub 2} injection in Tokyo Bay, which is surrounded by the most heavily industrialized area in Japan, was considered, and the impact of CO{sub 2} injection on near-surface aquifers was investigated, assuming relatively high seal-layer permeability (higher than 10 microdarcy). A regional hydrogeological model with an area of about 60 km x 70 km around Tokyo Bay was discretized into about 10 million gridblocks. To solve the high-resolution model efficiently, we used a parallelized multiphase flow simulator TOUGH2-MP/ECO2N on a world-class high performance supercomputer in Japan, the Earth Simulator. In this simulation, CO{sub 2} was injected into a storage aquifer at about 1 km depth under Tokyo Bay from 10 wells, at a total rate of 10 million tons/year for 100 years. Through the model, we can examine …

Date: April 15, 2009

Creator: Yamamoto, H.; Zhang, K.; Karasaki, K.; Marui, A.; Uehara, H. & Nishikawa, N.

Object Type: Article

System: The UNT Digital Library

(open access)

Electrochemical arsenic remediation for rural Bangladesh

Arsenic in drinking water is a major public health problem threatening the lives of over 140 million people worldwide. In Bangladesh alone, up to 57 million people drink arsenic-laden water from shallow wells. ElectroChemical Arsenic Remediation(ECAR) overcomes many of the obstacles that plague current technologies and can be used affordably and on a small-scale, allowing for rapid dissemination into Bangladesh to address this arsenic crisis. In this work, ECAR was shown to effectively reduce 550 - 580 mu g=L arsenic (including both As[III]and As[V]in a 1:1 ratio) to below the WHO recommended maximum limit of 10 mu g=L in synthetic Bangladesh groundwater containing relevant concentrations of competitive ions such as phosphate, silicate, and bicarbonate. Arsenic removal capacity was found to be approximately constant within certain ranges of current density, but was found to change substantially between ranges. In order of decreasing arsenic removal capacity, the pattern was: 0.02 mA=cm2> 0.07 mA=cm2> 0.30 - 1.1 mA=cm2> 5.0 - 100 mA=cm2. Current processing time was found to effect arsenic removal capacity independent of either charge density or current density. Electrode polarization studies showed no passivation of the electrode in the tested range (up to current density 10 mA=cm2) and ruled out oxygen …

Date: January 1, 2009

Creator: Addy, Susan Amrose

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Pretreatment Engineering Platform Phase 1 Final Test Report

Pacific Northwest National Laboratory (PNNL) was tasked by Bechtel National Inc. (BNI) on the River Protection Project, Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to conduct testing to demonstrate the performance of the WTP Pretreatment Facility (PTF) leaching and ultrafiltration processes at an engineering-scale. In addition to the demonstration, the testing was to address specific technical issues identified in Issue Response Plan for Implementation of External Flowsheet Review Team (EFRT) Recommendations - M12, Undemonstrated Leaching Processes.( ) Testing was conducted in a 1/4.5-scale mock-up of the PTF ultrafiltration system, the Pretreatment Engineering Platform (PEP). Parallel laboratory testing was conducted in various PNNL laboratories to allow direct comparison of process performance at an engineering-scale and a laboratory-scale. This report presents and discusses the results of those tests.

Date: December 23, 2009

Creator: Kurath, Dean E.; Hanson, Brady D.; Minette, Michael J.; Baldwin, David L.; Rapko, Brian M.; Mahoney, Lenna A. et al.

Object Type: Report

System: The UNT Digital Library

(open access)

in situ Calcite Precipitation for Contaminant Immobilization

in situ Calcite Precipitation for Contaminant Immobilization Yoshiko Fujita (Yoshiko.fujita@inl.gov) (Idaho National Laboratory, Idaho Falls, Idaho, USA) Robert W. Smith (University of Idaho-Idaho Falls, Idaho Falls, Idaho, USA) Subsurface radionuclide and trace metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE’s greatest challenges for long-term stewardship. One promising stabilization mechanism for divalent trace ions, such as the short-lived radionuclide strontium-90, is co-precipitation in calcite. Calcite, a common mineral in the arid western U.S., can form solid solutions with trace metals. The rate of trace metal incorporation is susceptible to manipulation using either abiotic or biotic means. We have previously demonstrated that increasing the calcite precipitation rate by stimulating the activity of urea hydrolyzing microorganisms can result in significantly enhanced Sr uptake. Urea hydrolysis causes the acceleration of calcium carbonate precipitation (and trace metal co-precipitation) by increasing pH and alkalinity, and also by liberating the reactive cations from the aquifer matrix via exchange reactions involving the ammonium ion derived from urea: H2NCONH2 + 3H2O ? 2NH4+ + HCO3- + OH- urea hydrolysis >X:2Ca + 2NH4+ ? 2>X:NH4 + Ca2+ ion exchange Ca2+ + HCO3- + OH- ? CaCO3(s) + H2O calcite precipitation where >X: is a …

Date: August 1, 2009

Creator: Fujita, Yoshiko & Smith, Robert W.

Object Type: Article

System: The UNT Digital Library

(open access)

Radionuclide Partitioning in an Underground Nuclear Test Cavity

In 2004, a borehole was drilled into the 1983 Chancellor underground nuclear test cavity to investigate the distribution of radionuclides within the cavity. Sidewall core samples were collected from a range of depths within the re-entry hole and two sidetrack holes. Upon completion of drilling, casing was installed and a submersible pump was used to collect groundwater samples. Test debris and groundwater samples were analyzed for a variety of radionuclides including the fission products {sup 99}Tc, {sup 125}Sb, {sup 129}I, {sup 137}Cs, and {sup 155}Eu, the activation products {sup 60}Co, {sup 152}Eu, and {sup 154}Eu, and the actinides U, Pu, and Am. In addition, the physical and bulk chemical properties of the test debris were characterized using Scanning Electron Microscopy (SEM) and Electron Microprobe measurements. Analytical results were used to evaluate the partitioning of radionuclides between the melt glass, rubble, and groundwater phases in the Chancellor test cavity. Three comparative approaches were used to calculate partitioning values, though each method could not be applied to every nuclide. These approaches are based on: (1) the average Area 19 inventory from Bowen et al. (2001); (2) melt glass, rubble, and groundwater mass estimates from Zhao et al. (2008); and (3) fission product …

Date: January 9, 2009

Creator: Rose, T. P.; Hu, Q.; Zhao, P.; Conrado, C. L.; Dickerson, R.; Eaton, G. F. et al.

Object Type: Report

System: The UNT Digital Library

(open access)

Pulse Jet Mixing Tests With Noncohesive Solids

This report summarizes results from pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid conducted during FY 2007 and 2008 to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant (WTP). Tests were conducted at three geometric scales using noncohesive simulants. The test data were used to independently develop mixing models that can be used to predict full-scale WTP vessel performance and to rate current WTP mixing system designs against two specific performance requirements. One requirement is to ensure that all solids have been disturbed during the mixing action, which is important to release gas from the solids. The second requirement is to maintain a suspended solids concentration below 20 weight percent at the pump inlet. The models predict the height to which solids will be lifted by the PJM action, and the minimum velocity needed to ensure all solids have been lifted from the floor. From the cloud height estimate we can calculate the concentration of solids at the pump inlet. The velocity needed to lift the solids is slightly more demanding than "disturbing" the solids, and is used as a surrogate for this metric. We applied the models to assess WTP …

Date: May 11, 2009

Creator: Meyer, Perry A.; Bamberger, Judith A.; Enderlin, Carl W.; Fort, James A.; Wells, Beric E.; Sundaram, S. K. et al.

Object Type: Report

System: The UNT Digital Library

(open access)

Slipstream, Volume 49, Number 2, February 2009

Monthly magazine published by the Maverick Region of the Porsche Club of America containing stories related to the organization or of interest to the group's members including news, upcoming and past events, other feature articles, and classified advertisements.

Date: February 2009

Creator: Porsche Club of America. Maverick Region.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Archer County Advocate (Holliday, Tex.), Vol. 7, No. 12, Ed. 1 Thursday, March 19, 2009

Weekly newspaper from Holliday, Texas that includes local, state, and national news along with advertising.

Date: March 19, 2009

Creator: Lewinski, Steve

Object Type: Newspaper

System: The Portal to Texas History

(open access)

The Albany News (Albany, Tex.), Vol. 134, No. 27, Ed. 1 Thursday, November 26, 2009

Weekly newspaper from Albany, Texas that includes local, county, and state news along with extensive advertising.

Date: November 26, 2009

Creator: Lucas, Melinda L.

Object Type: Newspaper

System: The Portal to Texas History

(open access)

Slipstream, Volume 47, Number 10, October 2009

Date: October 2009

Creator: Porsche Club of America. Maverick Region.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Texas Highways, Volume 56, Number 5, May 2009

Monthly travel magazine discussing locations and events in Texas to encourage travel within the state.

Date: May 2009

Creator: Texas. Department of Transportation.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Slipstream, Volume 49, Number 3, March 2009

Date: March 2009

Creator: Porsche Club of America. Maverick Region.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Journal of the Effective Schools Project, Volume 16, 2009

The Journal of the Effective Schools Project covers topics related to the member schools involved in the program. The Journal includes articles from several educators and education specialists.

Date: 2009

Creator: Tarleton State University. Effective Schools Project.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Slipstream, Volume 47, Number 9, September 2009

Date: September 2009

Creator: Porsche Club of America. Maverick Region.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

Sweetwater Reporter (Sweetwater, Tex.), Vol. 112, No. 11, Ed. 1 Wednesday, November 25, 2009

Daily newspaper from Sweetwater, Texas that includes local, state, and national news along with advertising.

Date: November 25, 2009

Creator: Rodriguez, Tatiana

Object Type: Newspaper

System: The Portal to Texas History

(open access)

Slipstream, Volume 47, Number 11, November 2009

Date: November 2009

Creator: Porsche Club of America. Maverick Region.

Object Type: Journal/Magazine/Newsletter

System: The Portal to Texas History

(open access)

De Leon Free Press (De Leon, Tex.), Vol. 118, No. 40, Ed. 1 Thursday, April 9, 2009

Weekly newspaper from De Leon, Texas that includes local, state, and national news along with advertising.

Date: April 9, 2009

Creator: Kestner, Laura

Object Type: Newspaper

System: The Portal to Texas History

(open access)

[2009 Directory of Texas Daily Newspapers]

The 2009 Director of the Texas Daily Newspapers, published by the Texas Daily Newspaper Association. The text document details the origins of the Texas Daily Newspaper and gives in lenght details on the officers, directors, staff and services that TDNA provides.

Date: 2009

Creator: Texas Daily Newspaper Association

Object Type: Book

System: The UNT Digital Library