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Title: Advances in Geochemical Testing of Key Contaminants in Residual Hanford Tank Waste

Abstract

This report describes the advances that have been made over the past two years in testing and characterizing waste material in Hanford tanks.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
878278
Report Number(s):
PNNL-15372
11694; 830403000; TRN: US0602272
DOE Contract Number:
AC05-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; HANFORD RESERVATION; STORAGE FACILITIES; RADIOACTIVE WASTES; CHEMICAL ANALYSIS; TECHNOLOGY ASSESSMENT; Environmental Molecular Sciences Laboratory

Citation Formats

Deutsch, William J., Krupka, Kenneth M., Cantrell, Kirk J., Brown, Christopher F., Lindberg, Michael J., Schaef, Herbert T., Heald, Steve M., Arey, Bruce W., and Kukkadapu, Ravi K. Advances in Geochemical Testing of Key Contaminants in Residual Hanford Tank Waste. United States: N. p., 2005. Web. doi:10.2172/878278.
Deutsch, William J., Krupka, Kenneth M., Cantrell, Kirk J., Brown, Christopher F., Lindberg, Michael J., Schaef, Herbert T., Heald, Steve M., Arey, Bruce W., & Kukkadapu, Ravi K. Advances in Geochemical Testing of Key Contaminants in Residual Hanford Tank Waste. United States. doi:10.2172/878278.
Deutsch, William J., Krupka, Kenneth M., Cantrell, Kirk J., Brown, Christopher F., Lindberg, Michael J., Schaef, Herbert T., Heald, Steve M., Arey, Bruce W., and Kukkadapu, Ravi K. Fri . "Advances in Geochemical Testing of Key Contaminants in Residual Hanford Tank Waste". United States. doi:10.2172/878278. https://www.osti.gov/servlets/purl/878278.
@article{osti_878278,
title = {Advances in Geochemical Testing of Key Contaminants in Residual Hanford Tank Waste},
author = {Deutsch, William J. and Krupka, Kenneth M. and Cantrell, Kirk J. and Brown, Christopher F. and Lindberg, Michael J. and Schaef, Herbert T. and Heald, Steve M. and Arey, Bruce W. and Kukkadapu, Ravi K.},
abstractNote = {This report describes the advances that have been made over the past two years in testing and characterizing waste material in Hanford tanks.},
doi = {10.2172/878278},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Nov 04 00:00:00 EST 2005},
month = {Fri Nov 04 00:00:00 EST 2005}
}

Technical Report:

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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. Initial work to produce release models was conducted on residual tank sludge using pure water as the leaching agent. The results were reported in an earlier report. The decision has now been mademore » to close the tanks after waste retrieval with a cementitious grout to minimize infiltration and maintain the physical integrity of the tanks. This report describes testing of the residual waste with a leaching solution that simulates the composition of water passing through the grout and contacting the residual waste at the bottom of the tank.« less
  • This Test Plan describes the testing and chemical analyses release rate studies on tank residual samples collected following the retrieval of waste from the tank. This work will provide the data required to develop a contaminant release model for the tank residuals from both sludge and salt cake single-shell tanks. The data are intended for use in the long-term performance assessment and conceptual model development.
  • 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, crushedmore » 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.« less
  • Lockheed Martin Hanford Company (LMHC) is designing and assessing the performance of disposal facilities to receive radioactive wastes that are stored in single- and double-shell tanks at the Hanford Site. The preferred method of disposing of the portion that is classified as low-activity waste is to vitrify the liquid/slurry and place the solid product in near-surface, shallow-land burial facilities. The LMHC project to assess the performance of these disposal facilities is the Hanford Immobilized Low-Activity Tank Waste (ILAW) Performance Assessment (PA) activity. The goal of this project is to provide a reasonable expectation that the disposal of the waste ismore » protective of the general public, groundwater resources, air resources, surface-water resources, and inadvertent intruders. Achieving this goal will require prediction of contaminant migration from the facilities. This migration is expected to occur primarily via the movement of water through the facilities, and the consequent transport of dissolved contaminants in the porewater of the vadose zone. Pacific Northwest National Laboratory assists LMHC in their performance assessment activities. One of the PNNL tasks is to provide estimates of the geochemical properties of the materials comprising the disposal facility, the disturbed region around the facility, and the physically undisturbed sediments below the facility (including the vadose zone sediments and the aquifer sediments in the upper unconfined aquifer). The geochemical properties are expressed as parameters that quantify the adsorption of contaminants and the solubility constraints that might apply for those contaminants that may exceed solubility constraints. The common parameters used to quantify adsorption and solubility are the distribution coefficient (K{sub d}) and the thermodynamic solubility product (K{sub sp}), respectively. In this data package, the authors approximate the solubility of contaminants using a more simplified construct, called the solution concentration limit, a constant value. In future geochemical data packages, they will determine whether a more rigorous measure of solubility is necessary or warranted based on the dose predictions emanating from the ILAW 2001 PA and reviewers' comments. The K{sub d}s and solution concentration limits for each contaminant are direct inputs to subsurface flow and transport codes used to predict the performance of the ILAW system. In addition to the best-estimate K{sub d}s, a reasonable conservative value and a range are provided. They assume that K{sub d} values are log normally distributed over the cited ranges. Currently, they do not give estimates for the range in solubility limits or their uncertainty. However, they supply different values for both the K{sub d}s and solution concentration limits for different spatial zones in the ILAW system and supply time-varying K{sub d}s for the concrete zone, should the final repository design include concrete vaults or cement amendments to buffer the system pH.« less
  • Lockheed Martin Hanford Company (LMHC) is designing and assessing the performance of disposal facilities to receive radioactive wastes that are stored in single- and double-shell tanks at the Hanford Site. The preferred method of disposing of the portion that is classified as low-activity waste is to vitrify the liquid/slurry and place the solid product in near-surface, shallow-land burial facilities. The LMHC project to assess the performance of these disposal facilities is the Hanford Immobilized Low-Activity Tank Waste (ILAW) Performance Assessment (PA) activity. The goal of this project is to provide a reasonable expectation that the disposal of the waste ismore » protective of the general public, groundwater resources, air resources, surface-water resources, and inadvertent intruders. Achieving this goal will require prediction of contaminant migration from the facilities. This migration is expected to occur primarily via the movement of water through the facilities, and the consequent transport of dissolved contaminants in the porewater of the vadose zone. Pacific Northwest National Laboratory (PNNL) assists LMHC in their performance assessment activities. One of the PNNL tasks is to provide estimates of the geochemical properties of the materials comprising the disposal facility, the disturbed region around the facility, and the physically undisturbed sediments below the facility (including the vadose zone sediments and the aquifer sediments in the upper unconfined aquifer). The geochemical properties are expressed as parameters that quantify the adsorption of contaminants and the solubility constraints that might apply for those contaminants that may exceed solubility constraints. The common parameters used to quantify adsorption and solubility are the distribution coefficient (K{sub d}) and the thermodynamic solubility product (K{sub sp}), respectively. In this data package, we approximate the solubility of contaminants using a more simplified construct, called the solution concentration limit, a constant value. In future geochemical data packages, we will determine whether a more rigorous measure of solubility is necessary or warranted based on the dose predictions emanating from the ILAW 2001 PA and reviewers' comments. The K{sub d}s and solution concentration limits for each contaminant are direct inputs to subsurface flow and transport codes used to predict the performance of the ILAW system. In addition to the best-estimate K{sub d}s, a reasonable conservative value and a range are provided. We assume that K{sub d} values are log normally distributed over the cited ranges. Currently, we do not give estimates for the range in solubility limits or their uncertainty. However, we supply different values for both the K{sub d}s and solution concentration limits for different spatial zones in the ILAW system and supply time-varying K{sub d}s for the concrete zone, should the final repository design include concrete vaults or cement amendments to buffer the system pH. If warranted, more technically rigorous information on uncertainty in the geochemical parameter values and estimates of the changes in parameter values over time will be supplied in future data packages.« less