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Kirk J Cantrell - One of the best experts on this subject based on the ideXlab platform.

  • Effects of hydrated lime on radionuclides stabilization of Hanford tank Residual Waste
    Chemosphere, 2017
    Co-Authors: Guohui Wang, Kirk J Cantrell, Michelle M.v. Snyder, Mark E. Bowden, Mark B. Triplett, Edgar C. Buck
    Abstract:

    Abstract Chemical stabilization of tank Residual Waste is part of a Hanford Site tank closure strategy to reduce overall risk levels to human health and the environment. In this study, a set of column leaching experiments using tank C-104 Residual Waste were conducted to evaluate the leachability of uranium (U) and technetium (Tc) where grout and hydrated lime were applied as chemical stabilizing agents. The experiments were designed to simulate future scenarios where meteoric water infiltrates through the vadose zones into the interior of the tank filled with layers of grout or hydrated lime, and then contacts the Residual Waste. Effluent concentrations of U and Tc were monitored and compared among three different packing columns (Waste only, Waste + grout, and Waste + grout + hydrated lime). Geochemical modeling of the effluent compositions was conducted to determine saturation indices of uranium solid phases that could control the solubility of uranium. The results indicate that addition of hydrated lime strongly stabilized the uranium through transforming uranium to a highly insoluble calcium uranate (CaUO4) or similar phase, whereas no significant stabilization effect of grout or hydrated lime was observed on Tc leachability. The result implies that hydrated lime could be a great candidate for stabilizing Hanford tank Residual Wastes where uranium is one of the main concerns.

  • Contaminant Leach Testing of Hanford Tank 241-C-104 Residual Waste
    2015
    Co-Authors: Kirk J Cantrell, Michelle M.v. Snyder, Guohui Wang, Edgar C. Buck
    Abstract:

    Leach testing of Tank C-104 Residual Waste was completed using batch and column experiments. Tank C-104 Residual Waste contains exceptionally high concentrations of uranium (i.e., as high as 115 mg/g or 11.5 wt.%). This study was conducted to provide data to develop contaminant release models for Tank C-104 Residual Waste and Tank C-104 Residual Waste that has been treated with lime to transform uranium in the Waste to a highly insoluble calcium uranate (CaUO4) or similar phase. Three column leaching cases were investigated. In the first case, C-104 Residual Waste was leached with deionized water. In the second case, crushed grout was added to the column so that deionized water contacted the grout prior to contacting the Waste. In the third case, lime was mixed in with the grout. Results of the column experiments demonstrate that addition of lime dramatically reduces the leachability of uranium from Tank C-104 Residual Waste. Initial indications suggest that CaUO4 or a similar highly insoluble calcium rich uranium phase forms as a result of the lime addition. Additional work is needed to definitively identify the uranium phases that occur in the as received Waste and the Waste after the lime treatment.

  • Chemical Stabilization of Hanford Tank Residual Waste
    Journal of Nuclear Materials, 2014
    Co-Authors: Kirk J Cantrell, Edgar C. Buck, Benjamin D. Williams, Mark E. Bowden, Brandy N. Gartman, Wayne W. Lukens, Edward Mausolf
    Abstract:

    Three different chemical treatment methods were tested for their ability to stabilize Residual Waste from Hanford tank C-202 for reducing contaminant release (Tc, Cr, and U in particular). The three treatment methods tested were lime addition [Ca(OH)2], an in situ Ceramicrete Waste form based on chemically bonded phosphate ceramics, and a ferrous iron/goethite treatment. These approaches rely on formation of insoluble forms of the contaminants of concern (lime addition and Ceramicrete) and chemical reduction followed by co-precipitation (ferrous iron/goethite incorporation treatment). The results have demonstrated that release of uranium from tank Residual Wastes can be dramatically reduced after treatment compared to contact with simulated grout porewater without treatment. All three treatments methods reduced the leachable uranium concentrations by well over three orders of magnitude. In the case of uranium and technetium, released concentrations were well below their respective Maximum Contaminant Levels (MCLs) for the Wastes tested. For tank C-202 Residual Waste, chromium release concentrations were above the MCL but were considerably reduced relative to untreated tank Waste. This innovative approach has the potential to revolutionize Hanford’s tank retrieval process, by allowing larger volumes of Residual Waste to be left in tanks while providing an acceptably low level of risk with respect to contaminant release that is protective of the environment and human health. Such an approach could enable DOE to realize significant cost savings through streamlined retrieval and closure operations.

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Abstract Residual Waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the Residual Wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich Residual Wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all Residual Waste samples studiedmore » to date. Contaminant release from the Residual Wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on Waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U Residual Wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the Waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less leachable (<10 wt% of the available mass in the Waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.« less

William J Deutsch - One of the best experts on this subject based on the ideXlab platform.

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Abstract Residual Waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the Residual Wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich Residual Wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all Residual Waste samples studiedmore » to date. Contaminant release from the Residual Wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on Waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U Residual Wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the Waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less leachable (<10 wt% of the available mass in the Waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.« less

  • Hanford tank Residual Waste – Contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, R. Jeffrey Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • thermodynamic model for uranium release from hanford site tank Residual Waste
    Environmental Science & Technology, 2011
    Co-Authors: Kirk J Cantrell, William J Deutsch, Michael J Lindberg
    Abstract:

    A thermodynamic model of U solid-phase solubility and paragenesis was developed for Hanford Site tank Residual Waste that will remain in place after tank closure. The model was developed using a combination of Waste composition data, Waste leach test data, and thermodynamic modeling of the leach test data. The testing and analyses were conducted using actual Hanford Site tank Residual Waste. Positive identification of U phases by X-ray diffraction was generally not possible either because solids in the Waste were amorphous or their concentrations were not detectable by XRD for both as-received and leached Residual Waste. Three leachant solutions were used in the studies: deionized water, CaCO3 saturated solution, and Ca(OH)2 saturated solution. Analysis of calculated saturation indices indicate that NaUO2PO4·xH2O and Na2U2O7(am) are present in the Residual Wastes initially. Leaching of the Residual Wastes with deionized water or CaCO3 saturated solution results in preferential dissolution Na2U2O7(am) and ...

  • Contaminant Release from Residual Waste in Single Shell Tanks at the Hanford Site, Washington, USA - 9276
    2009
    Co-Authors: Kirk J Cantrell, Kenneth M Krupka, William J Deutsch, Michael J Lindberg
    Abstract:

    Determinations of elemental and solid-phase compositions, and contaminant release studies have been applied in an ongoing study of Residual tank Wastes (i.e., Waste remaining after final retrieval operations) from five of 149 underground single-shell storage tanks (241-C-103, 241-C-106, 241-C-202, 241-C-203, and 241-S-112) at the U.S. Department of Energy’s Hanford Site in Washington State. This work is being conducted to support performance assessments that will be required to evaluate long-term health and safety risks associated with tank site closure. The results of studies completed to date show significant variability in the compositions, solid phase properties, and contaminant release characteristics from these Residual tank Wastes. This variability is the result of differences in Waste chemistry/composition of Wastes produced from several different spent fuel reprocessing schemes, subsequent Waste reprocessing to remove certain target constituents, tank farm operations that concentrated Wastes and mixed Wastes between tanks, and differences in retrieval processes used to remove the Wastes from the tanks. Release models were developed based upon results of chemical characterization of the bulk Residual Waste, solid-phase characterization (see companion paper 9277 by Krupka et al.), leaching and extraction experiments, and geochemical modeling. In most cases empirical release models were required to describe contaminant release frommore » these Wastes. Release of contaminants from Residual Waste was frequently found to be controlled by the solubility of phases that could not be identified and/or for which thermodynamic data and/or dissolution rates have not been measured. For example, significant fractions of Tc-99, I-129, and Cr appear to be coprecipitated at trace concentrations in metal oxide phases that could not be identified unambiguously. In the case of U release from tank 241-C-103 Residual Waste, geochemical calculations indicated that leachate concentrations of U were likely controlled by the solubility of schoepite (UO3•2H2O). Therefore, a reactive transport model based upon solubility of schoepite and the expected composition and infiltration rates of pore water could be used to simulate future release of U from this Residual tank Waste. In addition to the development of release models, the Residual tank Waste studies completed so far have provided a number of new insights that have changed our understanding of Residual tank Waste. For example, the release of contaminants from different tanks, although governed by the same general chemical principles, can be very different. It has also been found that significant fractions of Tc-99 and other typically highly mobile contaminants are frequently not readily released from tank Residuals and occur in recalcitrant phases that are resistant to aqueous dissolution. As these studies progress, such key cross-cutting geochemical processes and solid phase characteristics important to contaminant release from Residual tank Waste are becoming apparent. This may allow the grouping of tanks into general categories with certain common chemical features and contaminant release characteristics – an important goal because complete characterization of Residual Wastes from all 149 single-shell storage tanks is not practical.« less

Jeffrey R Serne - One of the best experts on this subject based on the ideXlab platform.

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Abstract Residual Waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the Residual Wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich Residual Wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all Residual Waste samples studiedmore » to date. Contaminant release from the Residual Wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on Waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U Residual Wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the Waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less leachable (<10 wt% of the available mass in the Waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.« less

Kenneth M Krupka - One of the best experts on this subject based on the ideXlab platform.

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Abstract Residual Waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the Residual Wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich Residual Wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all Residual Waste samples studiedmore » to date. Contaminant release from the Residual Wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on Waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U Residual Wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the Waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less leachable (<10 wt% of the available mass in the Waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.« less

  • Hanford tank Residual Waste – Contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, R. Jeffrey Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • Contaminant Release from Residual Waste in Single Shell Tanks at the Hanford Site, Washington, USA - 9276
    2009
    Co-Authors: Kirk J Cantrell, Kenneth M Krupka, William J Deutsch, Michael J Lindberg
    Abstract:

    Determinations of elemental and solid-phase compositions, and contaminant release studies have been applied in an ongoing study of Residual tank Wastes (i.e., Waste remaining after final retrieval operations) from five of 149 underground single-shell storage tanks (241-C-103, 241-C-106, 241-C-202, 241-C-203, and 241-S-112) at the U.S. Department of Energy’s Hanford Site in Washington State. This work is being conducted to support performance assessments that will be required to evaluate long-term health and safety risks associated with tank site closure. The results of studies completed to date show significant variability in the compositions, solid phase properties, and contaminant release characteristics from these Residual tank Wastes. This variability is the result of differences in Waste chemistry/composition of Wastes produced from several different spent fuel reprocessing schemes, subsequent Waste reprocessing to remove certain target constituents, tank farm operations that concentrated Wastes and mixed Wastes between tanks, and differences in retrieval processes used to remove the Wastes from the tanks. Release models were developed based upon results of chemical characterization of the bulk Residual Waste, solid-phase characterization (see companion paper 9277 by Krupka et al.), leaching and extraction experiments, and geochemical modeling. In most cases empirical release models were required to describe contaminant release frommore » these Wastes. Release of contaminants from Residual Waste was frequently found to be controlled by the solubility of phases that could not be identified and/or for which thermodynamic data and/or dissolution rates have not been measured. For example, significant fractions of Tc-99, I-129, and Cr appear to be coprecipitated at trace concentrations in metal oxide phases that could not be identified unambiguously. In the case of U release from tank 241-C-103 Residual Waste, geochemical calculations indicated that leachate concentrations of U were likely controlled by the solubility of schoepite (UO3•2H2O). Therefore, a reactive transport model based upon solubility of schoepite and the expected composition and infiltration rates of pore water could be used to simulate future release of U from this Residual tank Waste. In addition to the development of release models, the Residual tank Waste studies completed so far have provided a number of new insights that have changed our understanding of Residual tank Waste. For example, the release of contaminants from different tanks, although governed by the same general chemical principles, can be very different. It has also been found that significant fractions of Tc-99 and other typically highly mobile contaminants are frequently not readily released from tank Residuals and occur in recalcitrant phases that are resistant to aqueous dissolution. As these studies progress, such key cross-cutting geochemical processes and solid phase characteristics important to contaminant release from Residual tank Waste are becoming apparent. This may allow the grouping of tanks into general categories with certain common chemical features and contaminant release characteristics – an important goal because complete characterization of Residual Wastes from all 149 single-shell storage tanks is not practical.« less

  • Hanford Tank 241-S-112 Residual Waste Composition and Leach Test Data
    2008
    Co-Authors: Kirk J Cantrell, Kenneth M Krupka, Michael J Lindberg, Bruce W. Arey, Keith N. Geiszler, Herbert T. Schaef
    Abstract:

    This report presents the results of laboratory characterization and testing of two samples (designated 20406 and 20407) of Residual Waste collected from tank S-112 after final Waste retrieval. These studies were completed to characterize the Residual Waste and assess the leachability of contami¬nants from the solids. This is the first report from this PNNL project to describe the composition and leach test data for Residual Waste from a salt cake tank. All previous PNNL reports (Cantrell et al. 2008; Deutsch et al. 2006, 2007a, 2007b, 2007c) describing contaminant release models, and characterization and testing results for Residual Waste in single-shell tanks were based on samples from sludge tanks.

Michael L Lindberg - One of the best experts on this subject based on the ideXlab platform.

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Abstract Residual Waste is expected to be left in 177 underground storage tanks after closure at the US Department of Energy’s Hanford Site in Washington State, USA. In the long term, the Residual Wastes may represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt.%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt.%, respectively. Aluminum concentrations are high (8.2–29.1 wt.%) in some tanks (C-103, C-106, and S-112) and relatively low (

  • hanford tank Residual Waste contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, Jeffrey R Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (<1.5 wt%) in other tanks (C-202 and C-203). Gibbsite is a common mineral in tanks with high Al concentrations, while non-crystalline U-Na-C-O-P±H phases are common in the U-rich Residual Wastes from tanks C-202 and C-203. Iron oxides/hydroxides have been identified in all Residual Waste samples studiedmore » to date. Contaminant release from the Residual Wastes was studied by conducting batch leach tests using distilled deionized water, a Ca(OH)2-saturated solution, or a CaCO3-saturated water. Uranium release concentrations are highly dependent on Waste and leachant compositions with dissolved U concentrations one or two orders of magnitude higher in the tests with high U Residual Wastes, and also higher when leached with the CaCO3-saturated solution than with the Ca(OH)2-saturated solution. Technetium leachability is not as strongly dependent on the concentration of Tc in the Waste, and it appears to be slightly more leachable by the Ca(OH)2-saturated solution than by the CaCO3-saturated solution. In general, Tc is much less leachable (<10 wt% of the available mass in the Waste) than previously predicted. This may be due to the coprecipitation of trace concentrations of Tc in relatively insoluble phases such as Fe oxide/hydroxide solids.« less

  • Hanford tank Residual Waste – Contaminant source terms and release models
    Applied Geochemistry, 2011
    Co-Authors: William J Deutsch, Kenneth M Krupka, Michael L Lindberg, Kirk J Cantrell, R. Jeffrey Serne
    Abstract:

    Residual Waste is expected to be left in 177 underground storage tanks after closure at the U.S. Department of Energy’s Hanford Site in Washington State (USA). In the long term, the Residual Wastes represent a potential source of contamination to the subsurface environment. Residual materials that cannot be completely removed during the tank closure process are being studied to identify and characterize the solid phases and estimate the release of contaminants from these solids to water that might enter the closed tanks in the future. As of the end of 2009, Residual Waste from five tanks has been evaluated. Residual Wastes from adjacent tanks C-202 and C-203 have high U concentrations of 24 and 59 wt%, respectively, while Residual Wastes from nearby tanks C-103 and C-106 have low U concentrations of 0.4 and 0.03 wt%, respectively. Aluminum concentrations are high (8.2 to 29.1 wt%) in some tanks (C-103, C-106, and S-112) and relatively low (