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The work reported here was funded by Washington River Protection Solutions (WRPS). Dave Swanberg with WRPS led the effort and provided both programmatic guidance and technical input to the project team. These screening tests were very laboratory intensive. At Pacific Northwest National Laboratory (PNNL), Ben Williams was instrumental in preparing the Cast Stone specimens and conducting the leach tests. Don Rinehart prepared the simulants. Keith Geiszler, Steve Baum, Igor Kutnyakov, Christian Iovin, and Dennesse Smith analyzed the many samples. Stan Pitman, Mike Dahl, and Karl Mattlin conducted the compressive strength measurements. At Savannah River National Laboratory (SRNL), Vickie Williams was the cornerstone of the preparation and measurement of the Cast Stone fresh properties, Kim Wyszynski and Vickie Williams prepared the simulants, and David Best, Whitney Riley, and Beverly Wall performed the analyses. John Harris with LaFarge graciously provided the dry blend ingredients sourced from the northwest.

Washington River Protection Solutions is considering the design and construction of a Solidification Treatment Unit (STU) for the Effluent Treatment Facility (ETF) at the Hanford Site. The ETF is a Resource Conservation and Recovery Act-permitted, multi-waste, treatment and storage unit that can accept dangerous, low-level, and mixed wastewaters for treatment. The STU needs to be operational by 2018 to receive secondary liquid wastes generated during operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The STU will provide the additional capacity needed for ETF to process the increased volume of secondary wastes expected to be produced by the WTP. Pacific Northwest National Laboratory is conducting a secondary waste form screening program to support the evaluation and selection of waste forms to stabilize and solidify the liquid secondary waste stream from the WTP. The following monolith waste forms are being evaluated for immobilizing the secondary wastes: 1) Cast Stone; 2) DuraLith alkali aluminosilicate geopolymer; 3) Ceramicrete phosphate-bonded ceramic; and 4) THOR ® fluidized bed steam reforming waste product encapsulated in geopolymer. This report documents work to further develop and characterize the Cast Stone waste form. Other reports will cover the development and characterization of the other three waste forms. Follow-on activities will address the mechanisms of radionuclide retention to support disposal-system performance assessments, and regulatory and waste acceptance testing to demonstrate the waste forms will meet requirements for disposal at the Hanford Integrated Disposal Facility. Cast Stone (also called-Containerized Cast Stone‖) is a cementitious waste form that is essentially a mixture of Class F fly ash, Grade 100 or 120 blast furnace slag, and Type I/II Portland cement. CH2M Hill Hanford Group Inc. developed this waste form to solidify numerous waste streams, including secondary waste generated at the Hanford Site. The Cast Stone cementitious waste form is the current baseline for solidifying the liquid secondary wastes from the WTP. Pierce et al. (2010) demonstrated that the Cast Stone is a viable waste form for immobilizing WTP secondary wastes. This statement is based on the leachability of technetium-99 (99 Tc) as determined using draft U.S. Environmental Protection Agency (EPA) test methods examining contaminant diffusivity (Method 1315) and the impacts of solution pH (Method 1313) and liquid-to-solids ratio (Method 1316). 1 The Cast Stone testing reported here focused on optimizing waste loading and evaluating the robustness of the waste form to waste stream variability. Because of the extensive work on the Cast Stone formulation and the similar Saltstone formulation used at the Savannah River Site for low-level tank waste immobilization, testing conducted as part of this current test plan relied on those previous testing studies and did not aim to optimize the dry-blend material components or mix ratios beyond what has already been accomplished.

Executive SummaryWashington River Protection Solutions (WRPS) is responsible for the design and construction of upgrades to the Effluent Treatment Facility (ETF) at Hanford necessary to support the 2018 operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP). Upgrades to ETF will include a Solidification Treatment Unit (STU). The ETF is a Resource Conservation and Recovery Act (RCRA)-permitted multi-waste treatment and storage unit that can accept dangerous, low-level, and mixed wastewaters for treatment. Addition of the STU to ETF will provide the additional capacity needed for ETF to process the increased volume of secondary wastes expected to be produced by WTP. Although the current baseline calls for solidification of the ETF evaporator concentrate in a cement-based waste form, an evaluation is being conducted to identify and characterize other candidate stabilization technologies that are mature enough and have the potential of successfully treating the WTP's secondary liquid waste stream.Pacific Northwest National Laboratory (PNNL) is initiating a waste form testing program to support the evaluation and selection of waste forms for stabilization and solidification of the liquid secondary waste stream from the WTP. A literature survey was conducted to identify candidate waste forms. The candidate stabilization technologies selected include Cast Stone, Duralith alkali-alumino-silicate geopolymer (Geopolymer), fluidized-bed steam reformer (FBSR) granular product encapsulated in a geopolymer matrix, and a Ceramicrete phosphate bonded ceramic. These wastes forms have been shown to meet waste disposal acceptance criteria, including compressive strength and universal treatment standards for RCRA metals (as measured by the Toxicity Characteristic Leaching Procedure [TCLP]) to be acceptable for land disposal. Previous testing reported in the literature indicated there were some formulation issues that needed to be addressed for the Geopolymer and Ceramicrete waste forms, and information is needed on all four waste forms with respect to their ability to minimize the release of technetium. Technetium is a radionuclide predicted to be in the secondary liquid wastes in small quantities, and a recent risk assessment analyses for the Integrated Disposal Facility (IDF) showed technetium has the largest contribution to the estimated IDF disposal impacts to groundwater.To support a final waste form down selection, PNNL is conducting screening tests on the candidate waste forms to provide a basis for comparison and to resolve the formulation and data needs identified in the literature review. This report documents the screening test results on the Cast Stone cementitious waste form and the Geopolymer waste form. Screening tests on the Ceramicrete phosphate bonded ceramic and the encapsulated FBSR material will be conducted and documented as those materials become available. Later, more comprehensive and longer term performance testing will be conducted, following the guidance provided by the secondary wa...