Laboratory stabilization/solidification of surrogate and actual mixed-waste sludge in glass and grout

A vitrification process was developed and successfully implemented by the US Department of Energy's (DOE) Savannah River Site (SRS) and at the West Valley Nuclear Services (WVNS) to convert high-level liquid nuclear wastes (HLLW) to a solid borosilicate glass for safe long term geologic disposal. Over the last decade, SRS has successfully completed two additional vitrification projects to safely dispose of mixed low level wastes (MLLW) (radioactive and hazardous) at the SRS and at the Oak Ridge Reservation (ORR). The SRS, in conjunction with other laboratories, has also demonstrated that vitrification can be used to dispose of a wide variety of MLLW and low-level wastes (LLW) at the SRS, at ORR, at the Los Alamos National Laboratory (LANL), at Rocky Flats (RF), at the Fernald Environmental Management Project (FEMP), and at the Hanford Waste Vitrification Project (HWVP). The SRS, in conjunction with the Electric Power Research Institute and the National Atomic Energy Commission of Argentina (CNEA), have demonstrated that vitrification can also be used to safely dispose of ion-exchange (IEX) resins and sludges from commercial nuclear reactors. In addition, the SRS has successfully demonstrated that numerous wastes declared hazardous by the US Environmental Protection Agency (EPA) can be vitrified, e.g. mining industry wastes, contaminated harbor sludges, asbestos containing material (ACM), Pb-paint on army tanks and bridges. Once these EPA hazardous wastes are vitrified, the waste glass is rendered non-hazardous allowing these materials to be recycled as glassphalt (glass impregnated asphalt for roads and runways), roofing shingles, glasscrete (glass used as aggregate in concrete), or other uses. Glass is also being used as a medium to transport SRS americium (Am) and curium (Cm) to the Oak Ridge Reservation (ORR) for recycle in the ORR medical source program and use in smoke detectors at an estimated value of $1.5 billion to the general public.

https://digital.library.unt.edu/ark:/67531/metadc709331/m2/1/high_res_d/753906.pdf

Savannah River Site waste vitrification projects initiated throughout the United States: Disposal and recycle options

Technologies are being developed by the US Department of Energy`s (DOE) Savannah River Site (SRS) in conjunction with the Electric Power Research Institute (EPRI) and the commercial sector to convert low-level radioactive ion exchange (IEX) resin wastes from the nuclear utilities to solid stabilized waste forms for permanent disposal. One of the alternative waste stabilization technologies is vitrification of the resin into glass. Wastes can be vitrified at elevated temperatures by thermal treatment. One alternative thermal treatment is conventional Joule heated melting. Vitrification of wastes into glass is an attractive option because it atomistically bonds both hazardous and radioactive species in the glass structure, and volume reduces the wastes by 70-80%. The large volume reductions allow for large associated savings in disposal and/or long term storage costs.

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Vitrification of ion-exchange (IEX) resins: Advantages and technical challenges

This report includes strategies for treating the incidental waste left in the emptied tanks as non-retrievable heels and methods and materials for physically stabilizing the void space in the tanks to prevent future subsidence.

/pdf/state-of-the-art-report-on-high-level-waste-tank-closure-kmr4g2q9kb.pdf

State of the Art Report on High-Level Waste Tank Closure

A model is presented based upon calculated bridging oxygens which allows the prediction of the region of acceptable glass compositions for a lime-soda-silica glass-forming system containing mixed waste. The model can be used to guide glass formulation studies (e.g., treatability studies) or assess the applicability of vitrification to candidate waste streams.

/pdf/waste-vitrification-prediction-of-acceptable-compositions-in-2kskux310r.pdf

Waste vitrification: prediction of acceptable compositions in a lime-soda-silica glass-forming system

Treatability studies have been conducted at the laboratory-scale to evaluate vitrification of waste water sludges at the Oak Ridge Reservation (ORR). These studies are being conducted jointly by Westinghouse Savannah River Technology Center (SRTC) and Oak Ridge National Laboratory (ORNL). These studies include testing with surrogate waste formulations at both the laboratory-scale and pilot-scale, and testing with actual waste at the laboratory-scale, pilot-scale, and field-scale. ORR was chosen as the host site for the field-scale demonstration. The Y-12 West End Treatment Facility (WETF) waste water treatment sludges, which are RCRA F-listed wastes, were chosen as the candidate waste stream for the first field-scale demonstration. The laboratory-scale ``proof-of-principle`` demonstrations reported in this study and the pilot-scale studies planned for FY95 on the WETF sludge will provide needed operating parameters for the planned field-scale demonstration. These laboratory-scale ``proof-of-principle`` and pilot-scale studies also provide needed data for the evaluation of the feasibility of vitrification as a stabilization option for a variety of wastes which do not currently meet RCRA/LDR (Resource Conservation and Recovery Act/Land Disposal Restrictions) requirements for storage/disposal and/or those for which treatment capacity does not presently exist.

Vitrification treatability studies of actual waste water treatment sludges

The Federal Facility Compliance Agreement (FFCA) establishes an aggressive schedule for conducting studies and treatment method development under the treatability exclusion of RCRA for those mixed wastes for which treatment methods and capabilities have yet to be defined. One of these wastes is a radioactive cooling tower sludge. This paper presents some results of a treatability study of the stabilization of this cooling tower sludge in cementitious waste forms. The sample of the cooling tower sludge obtained for this study was found to be not characteristically hazardous in regard to arsenic, barium, chromium, lead, and selenium, despite the waste codes associated with this waste. However, the scope of this study included spiking three RCRA metals to two orders of magnitude above the initial concentration to test the limits of cementitious stabilization. Chromium and arsenic were spiked at concentrations of 200, 2,000, and 20,000 mg/kg, and selenium was spiked at 100, 1,000, and 10,000 mg/kg (concentrations based on the metal in the sludge solids). Portland cement, Class F fly ash, and slag were selected as stabilizing agents in the present study. Perlite, a fine, porous volcanic rock commonly used as a filter aid, was used as a water-sorptive agent in this study in order to control bleed water for high water contents. The highly porous perlite dust absorbs large amounts of water by capillary action and does not present the handling and processing problems exhibited by clays used for bleed water control.

/pdf/cementitious-stabilization-of-chromium-arsenic-and-selenium-3c2o1kx8hw.pdf

R. D. Spence

Papers

Vitrification treatability studies of actual waste water treatment sludges

Cementitious stabilization of chromium, arsenic, and selenium in a cooling tower sludge