Secondary Waste Form Development and Optimization—Cast Stone

Sundaram, S. K.; Parker, Kent E.; Valenta, Michelle M.; Pitman, Stan G.; Chun, Jaehun; Chung, Chul-Woo; Kimura, Marcia L.; Burns, Carolyn A.; Um, Wooyong; Westsik, Joseph H.

doi:10.2172/1027191

Cited by 19 publications

(77 citation statements)

References 59 publications

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“…Several review articles (Mattus and Gilliam 1994;Langton et al 2001;Milestone et al 2006), books (Neville 1996;Taylor 1990), and Section 3.0 in the Cast Stone Phase II report (Sundaram et al 2011) provide more details on cement hydration processes and the underlying chemical and physical processes that give Cast Stone and Saltstone their desired properties. These resources can be read to gain a deeper understanding.…”

Section: Waste Form Descriptionmentioning

confidence: 99%

“…The oxide composition and some of the physical properties for the three major Cast Stone dry ingredients that were used by PNNL to solidify/stabilize secondary liquid waste during the Phase II activities (see Sundaram et al 2011) are shown in Table 2.1. The Portland cement and BFS were obtained from LaFarge North America, Inc. (closest office Pasco, Washington).…”

Section: Cast Stone Ingredientsmentioning

confidence: 99%

“…The projected WTP secondary waste compositions have varied over time as flow sheets and assumptions have changed. More details on the derivation of the WTP secondary waste compositions can be found in the two previous Cast Stone reports (Pierce et al 2010b;Sundaram et al 2011). The compositions of the dissolved species in secondary waste simulants in general are dominated by sodium and hydroxide with significant concentrations of nitrate and oxalate (represents all organic matter) present in many.…”

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

“…The resultant liquid waste loading in the Cast Stone waste forms ranged from 7.8 to 9.5 wt%, a much narrower range than originally planned. More details can be found in Sundaram et al (2011). New Cast Stone formulations with the same S1 simulant have been generated without the addition of extra water and are currently being tested in a task called Waste Acceptance.…”

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

“…More details on the performance of Basin 42 brine Cast Stone waste forms will be discussed in sections to follow. As shown in Table 2.9, this waste stream has very large concentrations of ammonia, which has been observed to volatilize while mixing Cast Stone dry blend with this waste, and Simulant 4 in the secondary waste simulant work performed by PNNL (Sundaram et al 2011). The Basin 42 simulants-Cast Stone formulations that were deemed best after much formulation testing are shown in Table 2.11.…”

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

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Data Package for Secondary Waste Form Down-Selection—Cast Stone

Serne¹,

Westsik²

2011

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Executive SummaryThe objective of the data packages being generated for four potential waste forms for solidification/ stabilization of Hanford liquid secondary waste streams is to identify, evaluate, and summarize the existing information. This Cast Stone data package includes information available in the open literature and from data obtained from testing currently underway at Pacific Northwest National Laboratory (PNNL). As used at Hanford, the term Cast Stone describes a "grout"-based waste form made predominantly with fly ash and blast furnace slag (BFS) with lesser amounts of Portland cement as the starting dry blend. At Savannah River, this waste form is called Saltstone. The blend of grout reagents in Saltstone has been constant (45 weight percent [wt%] Grade 100 slag cement, 45 wt% Class F fly ash, and 10-wt% Type I/II Portland cement) since the Saltstone Disposal Facility began production in the early 1990s. At Hanford, some cementitious variants to Cast Stone have also been investigated, in which either the fly ash or the BFS is absent or replaced with another material. In this data package, these Cast Stone variants are included for completeness in the review. However, almost all the current Cast Stone waste form testing performed at PNNL uses a dry blend consisting of 47-wt% blast furnace slag (Grade 100), 45-wt% fly ash (Class F), and 8-wt% Portland cement (Type I/II). The sources of the three dry blend ingredients used at Hanford and Savannah River differ and may have subtle impacts on the physical and chemical attributes of the subsequent waste forms. The compositions of the secondary waste simulants used for the PNNL Cast Stone studies also differ from the simulants and actual wastes solidified at Savannah River; although both are caustic-, saline-and sodium-dominated solutions. The Hanford secondary waste simulants anion composition contains much less nitrate/nitrite than the waste streams solidified at Savannah River.Available literature on Cast Stone and Saltstone was reviewed with an emphasis on determining how Cast Stone and related grout waste forms performed in relationship to various criteria that will be used to decide whether a specific type of waste form meets acceptance criteria for disposal in the Integrated Disposal Facility (IDF) at Hanford. The draft waste acceptance criteria include the following requirements or targets:• acceptable leachate concentrations (less than the Universal Treatment Standards in 40 CFR 268) for Resource Conservation and Recovery Act (RCRA) metals using the Toxicity Characteristic Leach Procedure (TCLP) leach test• low bleed water criteria (i.e., no bleed water is tolerated after 28 days of curing)• low leachability index (LI) values for sodium (LI>6), technetium-99 (target LI>9) and iodine-129 (target LI>11)• minimum compressive strength of 500 psi (3.45 MPa).Other attributes of the Cast Stone process were compared with additional criteria, such as:• worker and public safety concerns• cost effectiveness versus other candidate waste forms in regard to ...

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Section: Waste Form Descriptionmentioning

confidence: 99%

Section: Cast Stone Ingredientsmentioning

confidence: 99%

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

Section: Range Of Wastes/compositions Testedmentioning

confidence: 99%

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Data Package for Secondary Waste Form Down-Selection—Cast Stone

Serne¹,

Westsik²

2011

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Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Jin

Kim

Tucker

et al. 2015

Journal of Non-Crystalline Solids

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a b s t r a c tVolatile loss of radioactive technetium-99 ( 99 Tc) to off-gas is a major challenge when vitrifying low-activity waste (LAW) at the U.S. Department of Energy's Hanford Site in Washington State. We investigated the partitioning and incorporation of rhenium (Re) (a nonradioactive surrogate for 99 Tc) into the glass melt during crucible melting of two simulated LAW feeds that have exhibited a large difference in 99m Tc/Re retention in glass from small-scale melter tests. Each feed was prepared from a simulated liquid LAW and additives (boric acid, silica sand, etc.). The as-mixed slurry feeds were dried at 105°C and heated to 600-1100°C at 5 K/min. The dried feeds and heat-treated samples were leached with deionized water for 10 min at room temperature followed by 24-h leaching at 80°C. Chemical compositions of the resulting solutions and insoluble solids were analyzed. Volume expansion measurements and X-ray diffraction (XRD) analyses were performed on dried feeds and heat-treated samples to characterize the progress of feed-to-glass conversion reactions. We found that incorporation of Re into the glass melt was virtually completed during the major feed-to-glass conversion reactions that occurred at ≤700°C. The results of our study suggest that the different compositions of the salt phases formed during early stages of melting at ≤700°C are responsible for the large difference in Re incorporation into the glass melt in these two feeds.

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Reductive capacity measurement of waste forms for secondary radioactive wastes

Yang

Serne

et al. 2015

Journal of Nuclear Materials

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The reductive capacities of dry ingredients and final solid waste forms were measured using both the Cr(VI) and Ce(IV) methods and the results were compared. Blast furnace slag (BFS), sodium sulfide, SnF , and SnCl 2 used as dry ingredients to make various waste forms showed significantly higher reductive capacities compared to other ingredients regardless of which method was used. Although the BFS exhibits appreciable reductive capacity, it requires greater amounts of time to fully react. In almost all cases, the Ce(IV) method yielded larger reductive capacity values than those from the Cr(VI) method and can be used as an upper bound for the reductive capacity of the dry ingredients and waste forms, because the Ce(IV) method subjects the solids to a strong acid (low pH) condition that dissolves much more of the solids. Because the Cr(VI) method relies on a neutral pH condition, the Cr(VI) method can be used to estimate primarily the waste form surface-related and readily dissolvable reductive capacity. However, the Cr(VI) method does not measure the total reductive capacity of the waste form, the long-term reductive capacity afforded by very slowly dissolving solids, or the reductive capacity present in the interior pores and internal locations of the solids.

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Secondary Waste Form Development and Optimization—Cast Stone

Cited by 19 publications

References 59 publications

Data Package for Secondary Waste Form Down-Selection—Cast Stone

Data Package for Secondary Waste Form Down-Selection—Cast Stone

Reactions during melting of low-activity waste glasses and their effects on the retention of rhenium as a surrogate for technetium-99

Reductive capacity measurement of waste forms for secondary radioactive wastes

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