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Title: Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277

Abstract

Solid-phase characterization methods have been used in an ongoing study of residual wastes (i.e., waste remaining after final retrieval operations) from the 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. The results of studies completed to date show significant variability in the compositions of those residual wastes and the compositions, morphologies, and crystallinities of the individual phases that make up these wastes. These differences undoubtedly result from the various waste types stored and transferred in and out each tank and the sluicing and retrieval operations used for waste retrieval. Our studies indicate that these residual wastes are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or co-precipitated within oxide phases. Depending on the specific tank, various solids (e.g., gibbsite; boehmite; dawsonite; cancrinite; Fe oxides such as hematite, goethite, and maghemite; rhodochrosite; lindbergite; whewellite; nitratine; and numerous amorphous or poorly crystalline phases) have been identified by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy in residual wastes studied to date. Our studies also show that contact of residual wastes with Ca(OH)2- and CaCO3-saturated aqueous solutions, which were used as surrogates for themore » compositions of pore-fluid leachants derived from young and aged cements respectively, may alter the compositions of solid phases present in the contacted wastes. Fe oxides/hydroxides have been identified in all residual wastes studied to date. They occur in these wastes as discrete particles, particles intergrown within a matrix of other phases, and surface coatings on other particles or particle aggregates. These Fe oxides/hydroxides typically contain trace concentrations of other transition metals, such Cr, Mn, Ni, and/or Pb. Recent analyses of residual waste from 241-C-103 have revealed the presence of Tc-containing Fe oxide/hydroxide particles, which is believed to be the first direct evidence of Tc in solid phases in actual samples of Hanford pre-retrieval tank waste or post-retrieval residual waste. The presence of mineralized coatings, such as Fe oxides/hydroxides or reaction products precipitated from contact with cement pore fluids, on contaminant-containing particles could decrease the rate of dissolution of these particles and thus the release of contaminants until the coatings had dissolved sufficiently to expose the underlying matrix to infiltrating pore fluids. Certain key cross-cutting geochemical processes and solid phase characteristics important to contaminant waste release are becoming evident, now that residual wastes have been studied from several single-shell tanks. As more residual tank wastes are characterized in terms of composition and contaminant release, it is anticipated that common characteristics with respect to the type of waste stored in the tank will become evident. 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

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
965154
Report Number(s):
PNNL-SA-63382
830403000; TRN: US0903586
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: WM2009 Waste Management for the Nuclear Renaissance, March 1-5, 2009, Phoenix, Arizona
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; AQUEOUS SOLUTIONS; CEMENTS; COATINGS; DAWSONITE; DISSOLUTION; ELECTRONS; GIBBSITE; GOETHITE; HEMATITE; OXIDES; STORAGE; SURFACE COATING; TANKS; TRANSITION ELEMENTS; WASTE MANAGEMENT; WASTE RETRIEVAL; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY; Hanford; sludge; saltcake; tank waste; S-112; C-103; C-106; C-202; C-203; x-ray diffraction; scanning electron microscopy

Citation Formats

Krupka, Kenneth M, Cantrell, Kirk J, Schaef, Herbert T, Arey, Bruce W, Heald, Steve M, Deutsch, William J, and Lindberg, Michael J. Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277. United States: N. p., 2009. Web.
Krupka, Kenneth M, Cantrell, Kirk J, Schaef, Herbert T, Arey, Bruce W, Heald, Steve M, Deutsch, William J, & Lindberg, Michael J. Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277. United States.
Krupka, Kenneth M, Cantrell, Kirk J, Schaef, Herbert T, Arey, Bruce W, Heald, Steve M, Deutsch, William J, and Lindberg, Michael J. 2009. "Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277". United States.
@article{osti_965154,
title = {Characterization of Solids in Residual Wastes from Single-Shell Tanks at the Hanford Site, Washington, USA - 9277},
author = {Krupka, Kenneth M and Cantrell, Kirk J and Schaef, Herbert T and Arey, Bruce W and Heald, Steve M and Deutsch, William J and Lindberg, Michael J},
abstractNote = {Solid-phase characterization methods have been used in an ongoing study of residual wastes (i.e., waste remaining after final retrieval operations) from the 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. The results of studies completed to date show significant variability in the compositions of those residual wastes and the compositions, morphologies, and crystallinities of the individual phases that make up these wastes. These differences undoubtedly result from the various waste types stored and transferred in and out each tank and the sluicing and retrieval operations used for waste retrieval. Our studies indicate that these residual wastes are chemically-complex assemblages of crystalline and amorphous solids that contain contaminants as discrete phases and/or co-precipitated within oxide phases. Depending on the specific tank, various solids (e.g., gibbsite; boehmite; dawsonite; cancrinite; Fe oxides such as hematite, goethite, and maghemite; rhodochrosite; lindbergite; whewellite; nitratine; and numerous amorphous or poorly crystalline phases) have been identified by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy in residual wastes studied to date. Our studies also show that contact of residual wastes with Ca(OH)2- and CaCO3-saturated aqueous solutions, which were used as surrogates for the compositions of pore-fluid leachants derived from young and aged cements respectively, may alter the compositions of solid phases present in the contacted wastes. Fe oxides/hydroxides have been identified in all residual wastes studied to date. They occur in these wastes as discrete particles, particles intergrown within a matrix of other phases, and surface coatings on other particles or particle aggregates. These Fe oxides/hydroxides typically contain trace concentrations of other transition metals, such Cr, Mn, Ni, and/or Pb. Recent analyses of residual waste from 241-C-103 have revealed the presence of Tc-containing Fe oxide/hydroxide particles, which is believed to be the first direct evidence of Tc in solid phases in actual samples of Hanford pre-retrieval tank waste or post-retrieval residual waste. The presence of mineralized coatings, such as Fe oxides/hydroxides or reaction products precipitated from contact with cement pore fluids, on contaminant-containing particles could decrease the rate of dissolution of these particles and thus the release of contaminants until the coatings had dissolved sufficiently to expose the underlying matrix to infiltrating pore fluids. Certain key cross-cutting geochemical processes and solid phase characteristics important to contaminant waste release are becoming evident, now that residual wastes have been studied from several single-shell tanks. As more residual tank wastes are characterized in terms of composition and contaminant release, it is anticipated that common characteristics with respect to the type of waste stored in the tank will become evident. 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.},
doi = {},
url = {https://www.osti.gov/biblio/965154}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jun 01 00:00:00 EDT 2009},
month = {Mon Jun 01 00:00:00 EDT 2009}
}

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