Hanford Contaminant Distribution Coefficient Database and Users Guide

Cantrell, Kirk J.; Serne, R. Jeffrey

doi:10.2172/15001324

Cited by 57 publications

(76 citation statements)

References 36 publications

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“…For this reason, its presence in the waste material and mobility in infiltrating water is of interest. Although 129 I is generally considered mobile as a dissolved constituent in water, small partition coefficients (0.2 to 1 mL/g) are typically calculated when its uptake is measured on Hanford sediments (Cantrell et al 2003;Um et al 2004). Therefore, it is imperative to identify an extraction method that will enable quantitative measurement of total iodine in solid samples such as tank waste.…”

Section: I Extraction and Analysismentioning

confidence: 99%

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

Deutsch¹,

Krupka²,

Lindberg³

et al. 2007

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The CH2M HILL Hanford Group, Inc. (CH2M HILL) is producing risk/performance assessments to support the closure of single-shell tanks at the U.S. Department of Energy's Hanford Site. As part of this effort, staff at Pacific Northwest National Laboratory were asked to develop release models for contaminants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. The primary contaminants of concern in the sludge are 99 Tc, 238 U, 129 I, and Cr because of their potential mobility in the environment and the long half-lives of the radionuclides. A key result from this work is that high percentages (>90%) of these primary contaminants are not readily leachable from the residual waste. This minimizes their future release rates to the environment, and is similar to 99 Tc results found in related studies of sludges from tanks AY-102, C-203, and C-204.Developing release models consists of laboratory testing to produce contaminant release data and a conceptual source release model. After development, the release model can be incorporated into a fate and transport model as part of a long-term risk assessment for the closed tank.Initial laboratory tests (Tier 1) were conducted to characterize the sludge and identify water-leachable constituents. Based on the results of Tier 1 tests, additional analyses were performed to augment the characterization of the material and determine the controlling mechanism(s) for release of contaminants. Tier 2 tests consisted of X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) analyses of the solids to identify reactive phases, and selective extractions to quantify the release of contaminants from particular solid phases.The laboratory results of sludge and liquid testing were used to develop source term models that describe the release of contaminants as infiltrating water contacts the solids in the future. These models simulate the geochemical system in the tank sludge and take into account interactions between the solution phase and the contaminant-containing solids. The release models are simplifications of the complex geochemical interactions occurring; however, they adequately represent the release of the primary contaminants of concern from the sludge as measured in the laboratory tests.Because of the highly complex chemical nature of tank C-106 residual sludge, clear and quantitative phase associations of the contaminants of concern with the phases known to exist in the sludge are difficult to specify. Although the various characterization methods employed in this study have revealed a number of important observations and have provided valuable data for constructing a scientifically defensible release model, many questions remain. Because a thorough understanding of all the important phase associations for the contaminants of concern cannot be developed at this time, an empirically based release model has been developed. Although less satisfying from a mechanistic ...

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Section: I Extraction and Analysismentioning

confidence: 99%

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

Deutsch¹,

Krupka²,

Lindberg³

et al. 2007

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show abstract

“…For this reason, its presence in the waste material and mobility in infiltrating water is of interest. Although iodine is generally considered mobile as a dissolved constituent in water, small partition coefficients (0.2 to 1 mL/g) are typically calculated when its uptake is measured on Hanford sediments (Cantrell et al 2003;Um et al 2004). Therefore, it is imperative to identify an extraction method that will enable quantitative measurement of total iodine in solid samples such as tank waste.…”

Section: I Extraction and Analysismentioning

confidence: 99%

Hanford Tanks 241-C-203 and 241-C-204: Residual Waste Contaminant Release Model and Supporting Data

Deutsch¹,

Krupka²,

Lindberg³

et al. 2004

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This report describes the development of release models for key contaminants that are present in residual sludge remaining after closure of Hanford Tanks 241-C-203 (C-203) and 241-C-204 (C-204). The release models were developed from data generated by laboratory characterization and testing of samples from these two tanks. Key results from this work are that future releases from the tanks of the primary contaminants of concern ( 99 Tc and 238 U) can be represented by relatively simple solubility relationships between infiltrating water and solid phases containing the contaminants. In addition, it was found that high percentages of 99 Tc in the sludges (20 wt% in C-203 and 75 wt% in C-204) are not readily water leachable, and, in fact, are very recalcitrant. This is similar to 99 Tc results found in related studies of sludges from Tank AY-102 (Lindberg and Deutsch 2003;Krupka et al. 2004). These release models are being developed to support the tank closure risk assessments performed by CH2M HILL Hanford Group, Inc., for the U.S. Department of Energy.The material used for testing consisted of sludge samples collected from the tanks in September 2003. Initial (Tier 1) testing of the sludges consisted of 1) fusion analysis and acid digestion to determine the total composition of the sludges and 2) water leaching to estimate the soluble portion of the solids. Based on the results of these tests, subsequent analyses were conducted (Tier 2). These included X-ray diffraction (XRD) measurements to identify crystalline solids and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis to provide a close-up view of the morphologies of the sludge material and identify the major constituents of individual minerals and amorphous solids. Periodic replenishment and selective extraction tests were also conducted during the Tier 2 tests to further evaluate water leachability and identify solid phases limiting the release of contaminants to solution. The test data were used to develop conceptual contaminant release models based on a series of solubility controls.The 99 Tc release model developed from the laboratory testing of C-203 and C-204 sludges is based on the concentrations and solubilities of technetium-bearing solids in contact with pore water migrating through the sludges. There are two stages of technetium release to solution: The 238 U release model for C-203 and C-204 sludges is based on the concentrations and solubilities of uranium-and sodium-bearing minerals in contact with pore water migrating through the sludges. There are three stages of uranium release to solution:1. Initially, soluble čejkaite [Na 4 (UO 2 )(CO 3 ) 3 ] and a sodium nitrate solid are present in the sludges at concentrations of 0.16 g U/g-sludge and 0.22 g NaNO 3 /g-sludge for C-203 and 0.068 g U/g-sludge and 0.04 g NaNO 3 /g-sludge for C-204. The common ion effect due to Na + limits the solubility of čejkaite to 0.19 g U/L until all the NaNO 3 is dissolved. The solubility of NaNO 3 is constant at 629 g/L.2. After all the ...

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“…In addition the chelates themselves can adsorb. These arguments are supported by K d measurements made in the presence of EDTA and other chelating agents (Cantrell et al 2002;.…”

Section: K D Values As a Function Of Waste Stream Designations And Immentioning

confidence: 74%

“…An important benefit of the linear adsorption approach at Hanford, is that a relatively extensive database of K d values applicable to Hanford sediments is available for the contaminants of most concern over a fairly broad range of conditions (Cantrell et al 2002). These data have been critically reviewed and cataloged and placed in an accessible database that will be periodically updated as new data become available.…”

Section: The Linear Sorption Model Approach and Its Application At Hamentioning

confidence: 99%

“…These data have been critically reviewed and cataloged and placed in an accessible database that will be periodically updated as new data become available. This K d database (Cantrell et al 2002) includes available data on the solution chemistry, sediment mineralogy, physical properties of the sediment and other experimental parameters used in the determination of the K d values.…”

Section: The Linear Sorption Model Approach and Its Application At Hamentioning

confidence: 99%

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Applicability of the Linear Sorption Isotherm Model to Represent Contaminant Transport Processes in Site Wide Performance Assessments

FOGWELL¹,

LAST²

2003

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Hanford Contaminant Distribution Coefficient Database and Users Guide

Cited by 57 publications

References 36 publications

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

Hanford Tank 241-C-106: Residual Waste Contaminant Release Model and Supporting Data

Hanford Tanks 241-C-203 and 241-C-204: Residual Waste Contaminant Release Model and Supporting Data

Applicability of the Linear Sorption Isotherm Model to Represent Contaminant Transport Processes in Site Wide Performance Assessments

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