Glass Formulation Development For The Vitrification Of Oak Ridge Tank Waste

Radioactive waste from four different Oak Ridge tank farms will be immobilized. The sludges in these tanks contain transuranic radionuclides and RCRA metals at levels which will make the final waste from both TRU and mixed. The final waste form in the immobilization of these sludges may be glass because of its ability to accept a wide variety of components into its network structure. The results of these tests indicate that sufficient waste loadings can be obtained in the glass to significantly reduce the waste volume. This paper will present the results of the glass formulation efforts.

As part of joint project between the Oak Ridge National Laboratory (ORNL) and the Savannah River Technology Center (SRTC), radioactive waste from four different ORNL tank farms will be immobilized. This work, which is funded by the DOE Office of Science and Technology, is designed to create a direct comparison between grouting and vitrification technologies. SRTC efforts have been focused on developing and testing glass formulations for the vitrification of the tank wastes. The radioactive waste is from four different ORNL tank farms: Melton Valley Storage Tanks (MVST), Bethel Valley Evaporator Service Tanks (BVEST), Gunite and Associated Tanks (GAAT), and Old Hydrafracture Tanks (OHF). The sludges in these tanks contain transuranic radionuclides at levels which will make the final waste form (at reasonable waste loadings) TRU. Glass is an acceptable waste form because of its ability to accept a wide variety of components into its network structure. This is important since the waste varies significantly from tank to tank and from tank farm to tank farm. Therefore, glass formulation efforts have centered on developing a formulation that is robust enough to handle large fluctuations in waste composition. Crucible studies have been performed with simulated GAAT, MVST and BVEST sludges. The results of these tests indicate that high waste loadings can be obtained in the glass to significantly reduce the waste volume. This paper will present the results of the glass formulation efforts.

This report describes the results of a glass feasibility study on vitrification of Oak Ridge National Laboratory (ORNL) Gunite waste into an Iron Phosphate glass. This glass feasibility study is part of a larger ORNL Gunite and Associated Tanks Treatability program (TTPSR1-6-WT-31). The treatability program explores different immobilization techniques of placing Gunite waste into a glass or grout form for long term storage. ORNL Gunite tanks contain waste that originated from years of various ORNL Research and Development programs. The available analyses of the Gunite Waste Tanks indicate, uranium and/or thorium as the dominant chemical constituent (50% +) and Cs137 the primary radionuclide. This information was utilized in determining a preliminary iron phosphate glass formulation. Chemical and physical properties: processing temperature, waste loading capability, chemical durability, density and redox were determined.

The Office of Science and Technology of the DOE has funded a joint project between the Oak Ridge National Laboratory (ORNL) and the Savannah River Technology Center (SRTC) to evaluate vitrification and grouting for the immobilization of sludge from ORNL tank farms. The radioactive waste is from the Gunite and Associated Tanks (GAAT), the Melton Valley Storage Tanks (MVST), the Bethel Valley Evaporator Service Tanks (BVEST), and the Old Hydrofractgure Tanks (OHF). Glass formulation development for sludge from these tanks is discussed in an accompanying article for this conference (Andrews and Workman). The sludges contain transuranic radionuclides at levels which will make the glass waste form (at reasonable waste loadings) TRU. Therefore, one of the objectives for this project was to ensure that the vitrified waste form could be disposed of at the Waste Isolation Pilot Plant (WIPP). In order to accomplish this, the waste form must meet the WIPP Waste Acceptance Criteria (WAC). An alternate pathway is to send the glass waste forms for disposal at the Nevada Test Site (NTS). A sludge waste loading in the feed of 6 wt percent will lead to a waste form which is non-TRU and could potentially be disposed of at NTS. The waste forms would then have to meet the requirements of the NTS WAC. This paper presents SRTC's efforts at demonstrating that the glass waste form produced as a result of vitrification of ORNL sludge will meet all the criteria of the WIPP WAC or NTS WAC.

The Office of Environmental Management's (EM) technical reports bibliography is an annual publication that contains information on scientific and technical reports sponsored by the Office of Environmental Management added to the Energy Science and Technology Database from July 1, 1994 through June 30, 1995. This information is divided into the following categories: Focus Areas, Cross-Cutting Programs, and Support Programs. In addition, a category for general information is included. EM's Office of Science and Technology sponsors this bibliography.

Preliminary glass development was carried out on four surrogate wastes. The surrogate wastes evaluated were ash and sludge from Oak Ridge National Laboratory, sludge from Rocky Flats, and sludge from Los Alamos National Laboratory. The work involved numerous melting trails followed by visual homogeneity examination and short-duration leach testing on glass specimens. Melter testing on selected compositions was performed with a laboratory-scale joule-heated furnace. With proper formulations and melter operating parameters, these mixed wastes appear to be readily adaptable to available vitrification technology.