Technical area status report for low-level mixed waste final waste forms. Volume 1

Mayberry, J.L.; DeWitt, L.M.; Darnell, R.

doi:10.2172/10184160

Cited by 10 publications

(8 citation statements)

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“…The DOE surrogate ash waste composition given in Table 1 closely represents one of the DOE ash waste streams. 1 It consists of fly ash, coal bottom ash, vermiculite, and activated carbon as its major constituents and salts of certain metals as hazardous contaminants.…”

Section: Surrogate Waste Preparationmentioning

confidence: 99%

“…1 Having acknowledged this problem, the DOE has funded several projects in its research laboratories in an effort to find an easy, cost-effective, and safe means of disposing this waste. Much of the DOE waste streams containing heavy metals and radionuclides require solidification/stabilization (S/S) before final disposal to reduce the mobility of contaminants into the environment.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Rao

Pagilla

Wagh

2000

Journal of the Air & Waste Management Association

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Bench-scale and full-scale investigations of waste stabilization and volume reduction were conducted using spiked soil and ash wastes containing heavy metals such as Cd, Cr, Pb, Ni, and Hg. The waste streams were stabilized and solidified using chemically bonded phosphate ceramic (CBPC) binder, and then compacted by either uniaxial or harmonic press for volume reduction. The physical properties of the final waste forms were determined by measuring volume reduction, density, porosity, and compressive strength. The leachability of heavy metals in the final waste forms was determined by a toxicity characteristic leaching procedure (TCLP) test and a 90-day immersion test (ANS 16.1). The structural composition and nature of waste forms were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively.CBPC binder and compaction can achieve 80-wt % waste loading and 39-47% reduction in waste volume. Compressive strength of final waste forms ranged from 1500 to 2000 psi. TCLP testing of waste forms showed that all heavy metals except Hg passed the TCLP limits using the phosphate-based binder. When Na 2 S was added to the binder, the waste forms also passed TCLP limits for Hg. Long-term leachability resistance of the final waste forms was achieved for all metals in both soil and ash IMPLICATIONS Hundreds of millions of dollars are spent by businesses and the government for the treatment and disposal of hazardous waste. This project researched a stabilization and solidification method involving CBPCs. This method reduces heavy metal mobility in soil and ash wastes by producing relatively inert waste forms with good structural properties. In addition, it reduces the final volume of the waste, leading to reduction in transportation and landfill disposal costs.wastes, and the leachability index was ~14. XRD patterns of waste forms indicated vermiculite in the ash waste was chemically incorporated into the CBPC matrix. SEM showed that waste forms are layered when compacted by uniaxial press and are homogeneous when compacted by harmonic press. INTRODUCTIONThe U.S. Department of Energy (DOE) has generated large volumes of low-level radioactive, hazardous, and mixed wastes as a result of its energy-and defense-related research over the last 60 years.1 Having acknowledged this problem, the DOE has funded several projects in its research laboratories in an effort to find an easy, cost-effective, and safe means of disposing this waste. Much of the DOE waste streams containing heavy metals and radionuclides require solidification/stabilization (S/S) before final disposal to reduce the mobility of contaminants into the environment. The most common practice at DOE and commercial facilities is to solidify waste using Portland cement.Although cement stabilization processes are inexpensive, readily available, and easy to process, there are limitations. In most commercial cement stabilization processes, contaminant metals are precipitated as insoluble hydroxides, which have minimum solubility between...

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Section: Surrogate Waste Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Rao

Pagilla

Wagh

2000

Journal of the Air & Waste Management Association

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“…Polymer additives are added to the molten sulfur to enhance the mechanical performance of the concrete. Commercially available sulfur "cement," Chement 2000, is formulated with oligomers of cyclopentadiene at 2-596 by weight (Mayberry et al 1993). …”

Section: Process Descriptionmentioning

confidence: 99%

“…Achieving a moisture content below 1% should not be difficult for glass, but doing so will require process control. Mayberry suggests materials to be combined with sulfur should be heated to 200°C to ensure dryness (Mayberry et al 1993). Heating to this temperature would add considerably to the heating requirements for a quenched-cullet forming process.…”

Section: Process Descriptionmentioning

confidence: 99%

Process system evaluation: Consolidated letter reports. Volume 3: Formulation of final products

Josephson¹,

Chapman²,

Albertsen³

1996

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SummaryGlass discharged from the low-level waste (LLW) melter may be processed into a variety of different forms for storage and disposal. The purpose of the study reported here is to identify and evaluate processing options for forming the glass. The glass forms selected included: Cullet -glass is water quenchedFl& -glass is cooled over dry rollers Cullet in sulfur -water-quenched cullet is dried and encapsulated in sulfur polymer cementMarbles -glass is processed into 2.5cmdia. (1-in.dia.) marbles Pressed shapes -glass "gobs" are pressed into a rectangular block Plute -glass is floated over a molten metal and cooling is controlled to prevent cracking Monolith -molten glass is poured into a large container where it cools.Each form was then qualitatively evaluated and given relative rankings in the areas of Performance -waste form environmental performance Capacity -ability to achieve required production capacity Retrievubility -ability to retrieve following disposal Operability/mintenance -ability to operate and maintain the equipment in a radioactive process Volume cost -efficiency of disposal volume use Equipment cost -cost of equipment and plant space Quulity ussurunce -ability to control the process to produce quality glass and recycle poor quality glass, if required.Generally, larger forms received better qualitative scores than smaller forms. Cullet and flake have very high surface areas, which results in low environmental performance scores. Adding sulfur cement to the cullet improves the performance but complicates the operation and maintenance of the process.iii Marbles have less surface area than cullet or flake, but their production process is more difficult to operate and maintain, Because marbles are spherical, their packing efficiency in the storage/disposal container is reduced. Larger forms such as pressed shapes and plate glass have greatly reduced surface area, but require equipment that is difficult to operate and maintain in a radioactive environment. In addition, the cost for the initial equipment and plant space is higher.The preferred form for the LLW glass is the large casting or "monolith." Casting monoliths is a simple process that produces high marks in nearly all of the evaluation criteria. The surface area is relatively small (even after cracking during cooling), the relative cost for equipment and plant space is low, a high production capacity is possible, and the equipment is relatively easy to maintain. In addition, selection of the monolith form minimizes constraints on the melter operation and glass formulation. The weakest point for the monolith form was the difficulty involved in recycling any out-ofspecification glass back to the melter for reprocessing. However, large castings are the standard form for high-level glass production. Process control methods have been used at high-level waste (HLW) vitrification plants in Britain and France to mitigate the difficulties of recycling out-of-specification glass. Thus, this apparent wealcness has been addressed successfully.The sel...

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“…Upon cooling, cracks can develop in the glass (NRC, 1996). Cracking of glass is a well recognized phenomenon, and increases in the geometric surface area due to cracking by a factor of five (Mayberry et al, 1993) and 20 have been suggested. In the model used here, a factor of 20 was assumed for the 60-cm canister glass form and no increase for the 1-cm pellets.…”

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confidence: 99%

Evaluation of the capabilities of the Hanford Reservation and Envirocare of Utah for disposal of potentially problematic mixed low-level waste streams

Waters¹,

Pohl²,

Cheng³

et al. 1998

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The U.S. Department of Energy's (DOE) Mixed Waste Focus Area is developing a program to address and resolve issues associated with final waste form performance in treating and disposing of DOE's mixed low-level waste (MLLW) inventory. A key issue for the program is identifying MLLW streams that may be problematic for disposal. Previous reports have quantified and qualified the capabilities of fifteen DOE sites for MLLW disposal and provided volume and radionuclide concentration estimates for treated MLLW based on the DOE inventory. Scoping-level analyses indicated that 101 waste streams identified in this report (approximately 6250 m3 of the estimated total treated MLLW) had radionuclide concentrations that may make their disposal problematic. The radionuclide concentrations of these waste streams were compared with the waste acceptance criteria (WAC) for a DOE disposal facility at Hanford and for Envirocare's commercial disposal facility for MLLW in Utah. Of the treated MLLW volume identified as potentially problematic, about 100 m3 exceeds the WAC for disposal at Hanford, and about 4500 m3 exceeds the WAC for disposal at Envirocare. Approximately 7% of DOE's total MLLW inventory has not been sufficiently characterized to identify a treatment process for the waste and was not included in the analysis. In addition, of the total treated MLLW volume, about 30% was associated with waste streams that did not have radionuclide concentration data and could not be included in the determination of potentially problematic waste streams. 3. This page intentionally left blank 4 Executive SummaryIn March 1996, the U. S. Depgrtment of Energy's (DOE) Office of Science and Technology (EM-50) asked the DOE Mixed Waste Focus Area to develop and lead a program that would address and resolve issues associated with final waste form performance in treating and disposing of the DOE mixed low-level waste (MLLW) inventory. This program, named the Waste Form Initiative, has the primary goal of ensuring that the MLLW treatment technologies being developed, currently used, or planned for use by DOE will produce final waste forms that will satis@ the waste acceptance criteria (WAC) of the existing andor planned MLLW disposal facilities. A key issue for the program and the subject of this report is identifying MLLW streams that may be problematic for disposal. The selected treatment processes and waste forms for these waste streams will be reexamined to determine areas for improvement in terms of acceptance for disposal.The Federal Facilities Compliance Act (FFCAct) Disposal Workgroup has conducted previous work on disposal issues. The DOE established the group in 1993 to work with the States in identifying, from among the sites currently storing or expected to generate MLLW, those that might be suitable for MLLW disposal. The disposal capabilities of the fifteen sites selected through this process were quantified and qualified in the scoping-level performance evaluation (PE) project completed in early 1996. An additional scoping...

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Technical area status report for low-level mixed waste final waste forms. Volume 1

Cited by 10 publications

References 0 publications

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Stabilization and Solidification of Metal-Laden Wastes by Compaction and Magnesium Phosphate-Based Binder

Process system evaluation: Consolidated letter reports. Volume 3: Formulation of final products

Evaluation of the capabilities of the Hanford Reservation and Envirocare of Utah for disposal of potentially problematic mixed low-level waste streams

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