Utilizing Strong Tight Intermodal Waste Packaging to Meet Accelerated Cleanup Goals at The Savannah River Site (open access)

Utilizing Strong Tight Intermodal Waste Packaging to Meet Accelerated Cleanup Goals at The Savannah River Site

In support of the accelerated cleanup challenge, personnel at the Savannah River Site have been working diligently to identify and acquire cost-effective waste containers that can be used to package a voluminous amount of low level radioactive waste that needs to be disposed. In so doing, personnel have transformed their paradigm in packaging low level radioactive waste in traditional 45-cubic-foot and 90-cubic-foot containers and utilizing refurbished intermodal containers instead. The transition has increased efficiencies in the processing, packaging, transportation, storage, and disposal of low level radioactive waste, while providing decreased procurement costs. Since large items do not have to be size-reduced to fit into the large containers, additional cost savings are being realized by minimizing void space, labor, time, equipment, and risks if size reduction techniques were performed. Cost savings for fiscal year 2003 exceeded one million dollars. Additional savings are estimated to be between 3 million dollars and 4 million dollars through fiscal year 2006.
Date: January 22, 2004
Creator: Kinney, JosephC.
Object Type: Article
System: The UNT Digital Library
A Hydrologic-geophysical Method for Characterizing Flow and Transport Processes Within The Vadose Zone (open access)

A Hydrologic-geophysical Method for Characterizing Flow and Transport Processes Within The Vadose Zone

The primary purpose of this project was to employ two geophysical imaging techniques, electrical resistivity tomography and cross-borehole ground penetrating radar, to image a controlled infiltration of a saline tracer under unsaturated flow conditions. The geophysical techniques have been correlated to other more traditional hydrologic measurements including neutron moisture measurements and induction conductivity logs. Images that resulted during two successive infiltrations indicate the development of what appear to be preferential pathways through the finer grained materials, although the results could also be produced by cationic capture of free ions in clays. In addition the site as well as the developing solute plume exhibits electrical anisotropy which is likely related to flow properties. However the geologic significance of this phenomenon is still under investigation.
Date: January 22, 2004
Creator: Alumbaugh, David; LaBrecque, Douglas; Brainard, James & Yeh, T.C. (Jim)
Object Type: Report
System: The UNT Digital Library
Report of the Solar and Atmospheric Neutrino Working Group (open access)

Report of the Solar and Atmospheric Neutrino Working Group

The highest priority of the Solar and Atmospheric Neutrino Experiment Working Group is the development of a real-time, precision experiment that measures the pp solar neutrino flux. A measurement of the pp solar neutrino flux, in comparison with the existing precision measurements of the high energy {sup 8}B neutrino flux, will demonstrate the transition between vacuum and matter-dominated oscillations, thereby quantitatively testing a fundamental prediction of the standard scenario of neutrino flavor transformation. The initial solar neutrino beam is pure {nu}{sub e}, which also permits sensitive tests for sterile neutrinos. The pp experiment will also permit a significantly improved determination of {theta}{sub 12} and, together with other solar neutrino measurements, either a measurement of {theta}{sub 13} or a constraint a factor of two lower than existing bounds. In combination with the essential pre-requisite experiments that will measure the {sup 7}Be solar neutrino flux with a precision of 5%, a measurement of the pp solar neutrino flux will constitute a sensitive test for non-standard energy generation mechanisms within the Sun. The Standard Solar Model predicts that the pp and {sup 7}Be neutrinos together constitute more than 98% of the solar neutrino flux. The comparison of the solar luminosity measured via neutrinos …
Date: October 22, 2004
Creator: Back, H.; Bahcall, J. N.; Bernabeu, J.; Boulay, M. G.; Bowles, T.; Calaprice, F. et al.
Object Type: Report
System: The UNT Digital Library
Development of a Novel Catalyst for NO Decomposition (open access)

Development of a Novel Catalyst for NO Decomposition

Air pollution arising from the emission of nitrogen oxides as a result of combustion taking place in boilers, furnaces and engines, has increasingly been recognized as a problem. New methods to remove NO{sub x} emissions significantly and economically must be developed. The current technology for post-combustion removal of NO is the selective catalytic reduction (SCR) of NO by ammonia or possibly by a hydrocarbon such as methane. The catalytic decomposition of NO to give N{sub 2} will be preferable to the SCR process because it will eliminate the costs and operating problems associated with the use of an external reducing species. The most promising decomposition catalysts are transition metal (especially copper)-exchanged zeolites, perovskites, and noble metals supported on metal oxides such as alumina, silica, and ceria. The main shortcoming of the noble metal reducible oxide (NMRO) catalysts is that they are prone to deactivation by oxygen. It has been reported that catalysts containing tin oxide show oxygen adsorption behavior that may involve hydroxyl groups attached to the tin oxide. This is different than that observed with other noble metal-metal oxide combinations, which have the oxygen adsorbing on the noble metal and subsequently spilling over to the metal oxide. This observation …
Date: October 22, 2004
Creator: Akyurtlu, Ates & Akyurtlu, Jale F.
Object Type: Report
System: The UNT Digital Library
Final Report for Sheet Beam Klystron Program (open access)

Final Report for Sheet Beam Klystron Program

The Phase I program demonstrated feasibility of the RF circuit, periodic permanent magnet focusing and beam transport. Computer simulations indicate that the device should meet the goals of the program with the anticipated power and efficiency. The electron gun is currently under construction in another program, and the collector is a simple design based on existing technology.
Date: September 22, 2004
Creator: Read, Michael; Ives, Lawrence & Phillips, Purobi
Object Type: Report
System: The UNT Digital Library
Secure password-based authenticated key exchange for web services (open access)

Secure password-based authenticated key exchange for web services

This paper discusses an implementation of an authenticated key-exchange method rendered on message primitives defined in the WS-Trust and WS-SecureConversation specifications. This IEEE-specified cryptographic method (AuthA) is proven-secure for password-based authentication and key exchange, while the WS-Trust and WS-Secure Conversation are emerging Web Services Security specifications that extend the WS-Security specification. A prototype of the presented protocol is integrated in the WSRF-compliant Globus Toolkit V4. Further hardening of the implementation is expected to result in a version that will be shipped with future Globus Toolkit releases. This could help to address the current unavailability of decent shared-secret-based authentication options in the Web Services and Grid world. Future work will be to integrate One-Time-Password (OTP) features in the authentication protocol.
Date: November 22, 2004
Creator: Liang, Fang; Meder, Samuel; Chevassut, Olivier & Siebenlist, Frank
Object Type: Article
System: The UNT Digital Library
Search for higgs, leptoquarks, and exotics at Tevatron (open access)

Search for higgs, leptoquarks, and exotics at Tevatron

This paper reviews some of the most recent results from the CDF and D0 experiments on the searches for Standard Model and Non-Standard Model Higgs bosons, and other new phenomena at the Tevatron. Both experiments examine data from proton anti-proton collision at {radical}s = 1.96 TeV, of integrated luminosity {approx} 200 pb{sup -1} (per experiment), to search for Higgs predicted in the Standard Model and beyond Standard Model, supersymmetric particles in the Gauge Mediated Symmetry Breaking scenario, leptoquarks, and excited electrons. No signal was observed, and limits on the signatures and models are derived.
Date: June 22, 2004
Creator: Wang, Song Ming
Object Type: Article
System: The UNT Digital Library
Probability Distribution for Flowing Interval Spacing (open access)

Probability Distribution for Flowing Interval Spacing

Fracture spacing is a key hydrologic parameter in analyses of matrix diffusion. Although the individual fractures that transmit flow in the saturated zone (SZ) cannot be identified directly, it is possible to determine the fractured zones that transmit flow from flow meter survey observations. The fractured zones that transmit flow as identified through borehole flow meter surveys have been defined in this report as flowing intervals. The flowing interval spacing is measured between the midpoints of each flowing interval. The determination of flowing interval spacing is important because the flowing interval spacing parameter is a key hydrologic parameter in SZ transport modeling, which impacts the extent of matrix diffusion in the SZ volcanic matrix. The output of this report is input to the ''Saturated Zone Flow and Transport Model Abstraction'' (BSC 2004 [DIRS 170042]). Specifically, the analysis of data and development of a data distribution reported herein is used to develop the uncertainty distribution for the flowing interval spacing parameter for the SZ transport abstraction model. Figure 1-1 shows the relationship of this report to other model reports that also pertain to flow and transport in the SZ. Figure 1-1 also shows the flow of key information among the SZ …
Date: September 22, 2004
Creator: Kuzio, S.
Object Type: Report
System: The UNT Digital Library
EMSP Project 70070: Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks - Final Report (open access)

EMSP Project 70070: Reactivity of Primary Soil Minerals and Secondary Precipitates Beneath Leaking Hanford Waste Tanks - Final Report

Since the late 1950s, leaks from 67 single-shell tanks at the Hanford Site have released about 1 million curies to the underlying sediments. The radioactive material was contained in water-based solutions generally characterized as having high pH values (basic solutions), high nitrate and nitrite concentrations, and high aluminum concentrations. The solutions were also hot, in some cases at or near boiling, as well as complex and highly variable in composition reflecting solutions obtained from multiple methods of reprocessing spent nuclear fuel. In order to understand the observed and probable distribution of radionuclides in the ground at Hanford, major reactions that likely occurred between the leaked fluids and the sediment minerals were investigated in laboratory experiments simulating environmental conditions. Reactions involving the dissolution of quartz and biotite and the simultaneous formation of new minerals were quantified at controlled pH values and temperature. Result s show that the dissolution of quartz and formation of new zeolite-like minerals could have altered the flow path of ground water and contaminant plumes and provided an uptake mechanism for positively-charged soluble radionuclides, such as cesium. The dissolution of biotite, a layered-iron-aluminum-silicate mineral, provided iron in a reduced form that could have reacted with negatively-charged soluble chromium, …
Date: April 22, 2004
Creator: Nagy, Kathryn L.
Object Type: Report
System: The UNT Digital Library
Melt Rate Assessment of SB/2/3 with Frit 418 - Effects of Waste Loading and Acid Addition (open access)

Melt Rate Assessment of SB/2/3 with Frit 418 - Effects of Waste Loading and Acid Addition

Preparations are being made by the Defense Waste Processing Facility (DWPF) to blend Sludge Batch 2 (SB2) with Sludge Batch 3 (SB3) (blend referred to as SB2/3), and implement a frit change from Frit 320 to Frit 418. A series of dry-fed tests have been performed to investigate the effect of waste loading (WL) on the melt rate of the SB2/3-Frit 418 system. As was observed in the SB2-Frit 320 system, dry-fed melt rate furnace (MRF) tests of the SB2/3-Frit 418 system showed that melt rate decreased as the waste loading increased (WL range of 31-43 per cent tested). In addition, waste throughput of the SB2/3-Frit 418 system reached a peak (at approximately 34 per cent WL) with increased waste loading before steadily decreasing (based on MRF tests). Based on this testing, the Immobilization Technology Section (ITS) recommends that the waste loading starting point for DWPF should be approximately 34 per cent when the processing of the SB2/3 begins with Frit 418. The current target waste loading for DWPF is 34 per cent with SB2-Frit 320, and the results from this testing do not indicate any reasons to reduce this target. Then after a period of steady processing,incrementally higher waste …
Date: July 22, 2004
Creator: LORIER, TROYH.
Object Type: Report
System: The UNT Digital Library
Special Analysis: Radionuclides Screening Analysis for E Area (open access)

Special Analysis: Radionuclides Screening Analysis for E Area

It was recently discovered that waste being disposed of onsite contained radionuclides that had not been analyzed by the Performance Assessment (PA). These radionuclides had been eliminated from the PA in an earlier screening evaluation because they were not expected to be contained in SRS-generated waste or that received from offsite generators. This Special Analysis (SA) is being prepared to establish the screening criteria and level of evaluation for all radionuclides potentially significant to a Low Level Waste PA or Composite Analysis (CA). The screening methodology recommended by the National Council on Radiological Protection and Measurements (NCRP) has been used to identify those radionuclides that require detailed analysis to derive disposal limits. Of the approximately 2800 radionuclides, a total of 826 were considered by the NCRP to be potentially significant. Approximately 686 radionuclides were eliminated from this analysis due to their short half-life or other properties. Approximately 40 of the 140 remaining radionuclides have been analyzed in the existing PA and waste acceptance criteria established. This SA develops the screening criteria and establishes trigger values to be used to determine the level of analysis required for those radionuclides not analyzed in PA. The results of the SA identified 20 radionuclides …
Date: July 22, 2004
Creator: COOK, JAMES
Object Type: Report
System: The UNT Digital Library
Drift-Scale Radionuclide Transport (open access)

Drift-Scale Radionuclide Transport

The purpose of this model report is to document the drift scale radionuclide transport model, taking into account the effects of emplacement drifts on flow and transport in the vicinity of the drift, which are not captured in the mountain-scale unsaturated zone (UZ) flow and transport models ''UZ Flow Models and Submodels'' (BSC 2004 [DIRS 169861]), ''Radionuclide Transport Models Under Ambient Conditions'' (BSC 2004 [DIRS 164500]), and ''Particle Tracking Model and Abstraction of Transport Process'' (BSC 2004 [DIRS 170041]). The drift scale radionuclide transport model is intended to be used as an alternative model for comparison with the engineered barrier system (EBS) radionuclide transport model ''EBS Radionuclide Transport Abstraction'' (BSC 2004 [DIRS 169868]). For that purpose, two alternative models have been developed for drift-scale radionuclide transport. One of the alternative models is a dual continuum flow and transport model called the drift shadow model. The effects of variations in the flow field and fracture-matrix interaction in the vicinity of a waste emplacement drift are investigated through sensitivity studies using the drift shadow model (Houseworth et al. 2003 [DIRS 164394]). In this model, the flow is significantly perturbed (reduced) beneath the waste emplacement drifts. However, comparisons of transport in this perturbed …
Date: September 22, 2004
Creator: Houseworth, J.
Object Type: Report
System: The UNT Digital Library
Statistical Tools for Forensic Analysis of Toolmarks (open access)

Statistical Tools for Forensic Analysis of Toolmarks

Recovery and comparison of toolmarks, footprint impressions, and fractured surfaces connected to a crime scene are of great importance in forensic science. The purpose of this project is to provide statistical tools for the validation of the proposition that particular manufacturing processes produce marks on the work-product (or tool) that are substantially different from tool to tool. The approach to validation involves the collection of digital images of toolmarks produced by various tool manufacturing methods on produced work-products and the development of statistical methods for data reduction and analysis of the images. The developed statistical methods provide a means to objectively calculate a ''degree of association'' between matches of similarly produced toolmarks. The basis for statistical method development relies on ''discriminating criteria'' that examiners use to identify features and spatial relationships in their analysis of forensic samples. The developed data reduction algorithms utilize the same rules used by examiners for classification and association of toolmarks.
Date: April 22, 2004
Creator: Baldwin, David; Morris, Max; Bajic, Stan; Zhou, Zhigang & Kreiser, James
Object Type: Report
System: The UNT Digital Library
Dynamic Time Expansion and Compression Using Nonlinear Waveguides (open access)

Dynamic Time Expansion and Compression Using Nonlinear Waveguides

Dynamic time expansion or compression of a small amplitude input signal generated with an initial scale is performed using a nonlinear waveguide. A nonlinear waveguide having a variable refractive index is connected to a bias voltage source having a bias signal amplitude that is large relative to the input signal to vary the reflective index and concomitant speed of propagation of the nonlinear waveguide and an electrical circuit for applying the small amplitude signal and the large amplitude bias signal simultaneously to the nonlinear waveguide. The large amplitude bias signal with the input signal alters the speed of propagation of the small-amplitude signal with time in the nonlinear waveguide to expand or contract the initial time scale of the small-amplitude input signal.
Date: June 22, 2004
Creator: Findikoglu, Alp T.; Hahn, Sangkoo F. & Jia, Quanxi
Object Type: Text
System: The UNT Digital Library
A COMPUTATIONAL WORKBENCH ENVIRONMENT FOR VIRTUAL POWER PLANT SIMULATION (open access)

A COMPUTATIONAL WORKBENCH ENVIRONMENT FOR VIRTUAL POWER PLANT SIMULATION

In this report is described the work effort to develop and demonstrate a software framework to support advanced process simulations to evaluate the performance of advanced power systems. Integrated into the framework are a broad range of models, analysis tools, and visualization methods that can be used for the plant evaluation. The framework provides a tightly integrated problem-solving environment, with plug-and-play functionality, and includes a hierarchy of models, ranging from fast running process models to detailed reacting CFD models. The framework places no inherent limitations on the type of physics that can be modeled, numerical techniques, or programming languages used to implement the equipment models, or the type or amount of data that can be exchanged between models. Tools are provided to analyze simulation results at multiple levels of detail, ranging from simple tabular outputs to advanced solution visualization methods. All models and tools communicate in a seamless manner. The framework can be coupled to other software frameworks that provide different modeling capabilities. Three software frameworks were developed during the course of the project. The first framework focused on simulating the performance of the DOE Low Emissions Boiler System Proof of Concept facility, an advanced pulverized-coal combustion-based power plant. The …
Date: December 22, 2004
Creator: Bockelie, Mike; Swensen, Dave; Denison, Martin; Sarofim, Adel & Senior, Connie
Object Type: Report
System: The UNT Digital Library
Princeton Plasma Physics Laboratory Annual Site Environmental Report for Calendar Years 2002 and 2003 (open access)

Princeton Plasma Physics Laboratory Annual Site Environmental Report for Calendar Years 2002 and 2003

This report provides the U.S. Department of Energy (DOE) and the public with information on the level of radioactive and non-radioactive pollutants (if any) that are added to the environment as a result of Princeton Plasma Physics Laboratory's (PPPL) operations. The results of the 2002 and 2003 environmental surveillance and monitoring program for PPPL are presented and discussed. The report also summarizes environmental initiatives, assessments, and programs that were undertaken in 2002 and 2003.
Date: December 22, 2004
Creator: Virginia L. Finley, Editor
Object Type: Report
System: The UNT Digital Library
NOVEL IN-SITU METAL AND MINERAL EXTRACTION TECHNOLOGY (open access)

NOVEL IN-SITU METAL AND MINERAL EXTRACTION TECHNOLOGY

This white paper summarizes the state of art of in-situ leaching of metals and minerals, and describes a new technology concept employing improved fragmentation of ores underground in order to prepare the ore for more efficient in-situ leaching, combined with technology to continuously improve solution flow patterns through the ore during the leaching process. The process parameters and economic benefits of combining the new concept with chemical and biological leaching are described. A summary is provided of the next steps required to demonstrate the technology with the goal of enabling more widespread use of in-situ leaching.
Date: September 22, 2004
Creator: O'Gorman, Glenn; Michaelis, Hans von & Olson, Gregory J.
Object Type: Report
System: The UNT Digital Library
Nonlinear Turbulence Simulations for NSTX H-modes (open access)

Nonlinear Turbulence Simulations for NSTX H-modes

Present evidence points to remarkably resilient electron temperature profiles in high-density H-mode plasmas on the National Spherical Torus Experiment (NSTX), suggesting that the underlying electron thermal transport mechanisms respond in a highly nonlinear fashion to changes in the gradients. This paper uses measured plasma profiles as input to linear gyrokinetic analysis to identify candidate micro-instabilities that may be responsible for the electron thermal transport. The criteria for useful nonlinear micro-stability analyses are discussed along with necessary approximations and computational issues.
Date: June 22, 2004
Creator: Redi, M. H.; Kaye, S.; Dorland, W.; Bell, R.; Bourdelle, C.; Ethier, S. et al.
Object Type: Report
System: The UNT Digital Library
The coming revolution in particle physics: Report of the Fermilab Long Range Planning Committee (open access)

The coming revolution in particle physics: Report of the Fermilab Long Range Planning Committee

In early 2003, the Fermilab Director formed a committee (Appendix A) to examine options for the long-range future of Fermilab. Specifically, the committee was asked to respond to a charge (Appendix B), which laid out the assumptions, which were to underlie our discussions. The committee met a few times during the spring of 2003 and formulated a plan of action. It identified a number of issues that deserved attention, and a subcommittee was formed to focus on each. We agreed that in addressing these key issues, a broader participation was appropriate. The manner in which that was achieved varied from subcommittee to subcommittee to group. In some cases the expanded membership participated in all the discussions, in others, particular presentations were solicited and heard. Some subgroups met regularly over several months, others convened only for a small number of discussions. We have attempted to list participants in Appendix C. General presentations indicating the purpose of the work were given, for example at the Fermilab Users Annual Meeting. Towards the end of the summer some sense of direction developed and a series of open meetings was organized by the different subgroups. These meetings of two and more hour's duration gave the …
Date: June 22, 2004
Creator: al., Jeff Appel et
Object Type: Report
System: The UNT Digital Library
High strength and heat resistant chromium steels for sodium-cooled fast reactors. (open access)

High strength and heat resistant chromium steels for sodium-cooled fast reactors.

This report provides the results of a preliminary phase of a project supporting the Advanced Nuclear Fuel Cycle Technology Initiative at ANL. The project targets the Generation IV nuclear energy systems, particularly the area of reducing the cost of sodium-cooled fast-reactors by utilizing innovative materials. The main goal of the project is to provide the nuclear heat exchanger designers a simplified means to quantify the cost advantages of the recently developed high strength and heat resistant ferritic steels with 9 to 13% chromium content. The emphasis in the preliminary phase is on two steels that show distinctive advantages and have been proposed as candidate materials for heat exchangers and also for reactor vessels and near-core components of Gen IV reactors. These steels are the 12Cr-2W (HCM12A) and 9Cr-1MoVNb (modified 9Cr-1Mo). When these steels are in tube form, they are referred to in ASTM Standards as T122 and T91, respectively. A simple thermal-hydraulics analytical model of a counter-flow, shell-and-tube, once-through type superheated steam generator is developed to determine the required tube length and tube wall temperature profile. The single-tube model calculations are then extended to cover the following design criteria: (i) ratio of the tube stress due to water/steam pressure to …
Date: December 22, 2004
Creator: Kamal, S.; Grandy, C.; Farmer, M. & Brunsvold, A.
Object Type: Report
System: The UNT Digital Library
Site Environmental Report for 2003, Volume 2 (open access)

Site Environmental Report for 2003, Volume 2

Volume II of the ''Site Environmental Report for 2003'' is provided by Ernest Orlando Lawrence Berkeley National Laboratory as a supplemental appendix to Volume I, which contains the body of the report. Volume II contains the environmental monitoring and sampling data used to generate summary results of routine and nonroutine activities at the Laboratory (except for groundwater sampling data, which may be found in the reports referred to in Chapter 6). Volume I summarizes the results from analyses of the data. For completeness, results from sample collections beginning or ending in calendar year (CY) 2003 are included in this volume but samples representing CY 2002 data are not used in summary results reported in Volume I. (For example, although Ambient Air samples collected on January 6, 2003, are presented in Volume II, they represent December 2002 data and are not included in Tables 4-6 and 4-7 in Volume I.) When appropriate, sampling results are reported in both conventional and International System of Units (SI). For some results, the rounding procedure used in data reporting may result in apparent differences between the numbers reported in SI and conventional units. For example, stack air results reported as < 1.1 Bq/m{sup 3} are …
Date: June 22, 2004
Creator: Pauer, Ron
Object Type: Report
System: The UNT Digital Library
Conceptual Model and Numerical Approaches for Unsaturated Zone Flow and Transport (open access)

Conceptual Model and Numerical Approaches for Unsaturated Zone Flow and Transport

None
Date: September 22, 2004
Creator: Liu, H.H.
Object Type: Report
System: The UNT Digital Library
SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE (open access)

SEEPAGE MODEL FOR PA INCLUDING DRIFT COLLAPSE

The purpose of this report is to document the predictions and analyses performed using the seepage model for performance assessment (SMPA) for both the Topopah Spring middle nonlithophysal (Tptpmn) and lower lithophysal (Tptpll) lithostratigraphic units at Yucca Mountain, Nevada. Look-up tables of seepage flow rates into a drift (and their uncertainty) are generated by performing numerical simulations with the seepage model for many combinations of the three most important seepage-relevant parameters: the fracture permeability, the capillary-strength parameter 1/a, and the percolation flux. The percolation flux values chosen take into account flow focusing effects, which are evaluated based on a flow-focusing model. Moreover, multiple realizations of the underlying stochastic permeability field are conducted. Selected sensitivity studies are performed, including the effects of an alternative drift geometry representing a partially collapsed drift from an independent drift-degradation analysis (BSC 2004 [DIRS 166107]). The intended purpose of the seepage model is to provide results of drift-scale seepage rates under a series of parameters and scenarios in support of the Total System Performance Assessment for License Application (TSPA-LA). The SMPA is intended for the evaluation of drift-scale seepage rates under the full range of parameter values for three parameters found to be key (fracture permeability, …
Date: September 22, 2004
Creator: Tsang, C.
Object Type: Report
System: The UNT Digital Library
Colloid Formation at Waste Plume Fronts (open access)

Colloid Formation at Waste Plume Fronts

Highly saline and caustic tank waste solutions containing radionuclides and toxic metals have leaked into sediments at U. S. Department of Energy (DOE) facilities such as the Hanford Site (Washington State). Colloid transport is frequently invoked to explain migration of radionuclides and metals in the subsurface. To understand colloid formation during interactions between highly reactive fluids and sediments and its impact on contaminant transport, we simulated tank waste solution (TWS) leakage processes in laboratory columns at ambient and elevated (70 C) temperatures. We found that maximum formation of mobile colloids occurred at the plume fronts (hundreds to thousands times higher than within the plume bodies or during later leaching). Concentrations of suspended solids were as high as 3 mass%, and their particle-sizes ranged from tens of nm to a few {micro}m. Colloid chemical composition and mineralogy depended on temperature. During infiltration of the leaked high Na{sup +} waste solution, rapid and completed Na{sup +} replacement of exchangeable Ca{sup 2+} and Mg{sup 2+} from the sediment caused accumulation of these divalent cations at the moving plume front. Precipitation of supersaturated Ca{sup 2+}/Mg{sup 2+}-bearing minerals caused dramatic pH reduction at the plume front. In turn, the reduced pH caused precipitation of other …
Date: May 22, 2004
Creator: Wan, Jiamin; Tokunaga, Tetsu K.; Saiz, Eduardo; Larsen, Joern T.; Zheng, Zuoping & Couture, Rex A.
Object Type: Article
System: The UNT Digital Library