Summary of Results for Expanded Macrobatch 3 Variability Study

Herman, C.C.

doi:10.2172/799667

Cited by 19 publications

(17 citation statements)

References 4 publications

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“…In this report, predictability is based on the 95% two-sided confidence interval for an individual PCT response as generated by the Thermodynamic Hydration Energy Reaction Model (THERMO™) ∆G P model . This definition is consistent with that used in recent variability studies (e.g., Harbour et al 2000;Herman et al 2001). A comparison is made of the actual leaching performance as determined by the PCT and the prediction limits for an individual glass generated by the THERMO™ model.…”

Section: Applicability Of ∆G P To Projected Sb3 Compositional Regionsupporting

confidence: 60%

“…This technique has been utilized in previous DWPF variability studies (Peeler 1996a;Peeler 1996b;Edwards and Brown 1998;Harbour et al 2000;and Herman et al 2001) with technical justification given the oxidizing nature of the DWPF flowsheet (e.g., excessive nitric acid). In fact, Brown, Postles, and Edwards (2002) indicate that the majority of elements considered in PCCS possess only a single corresponding oxide as indicated by Schreiber and Hockman (1987) -with one exception copper.…”

Section: Effect Of Redox On Pct Responsementioning

confidence: 99%

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Sludge Batch 3 Phase 1 Variability Study

Peeler¹

2003

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Executive SummaryThe objective of this task was to assess the applicability of the current Product Composition Control System (PCCS) durability model (∆G P ) to the anticipated compositional region of interest to Sludge Batch 3 (SB3). The assessment of applicability was accomplished via a compositional variation study in which the durability response of various glasses was experimentally determined and compared to model predictions. Typically, variability studies are compositionally focused on a specific frit coupled with a known sludge composition over a waste loading range of interest. In the present study, various candidate frits were used with different sludge compositional views representing possible washing scenarios. Operating windows were defined for various glass systems using Defense Waste Processing Facility (DWPF) measurement acceptability criteria that formed the basis for the targeted glass compositions.The experimental results demonstrated applicability (or conservatism) of the ∆G P model for each of the 42 SB3 test matrix glasses when fabricated under oxidizing conditions. The Product Consistency Test (PCT) response for all glasses (both quenched and centerline cansiter cooled) were also acceptable being at least an order of magnitude more durable than the 16.695 g/L value for normalized boron release as reported for the Environmental Assessment (EA) glass.In this phase of the variability study, only a limited assessment of the impact of reduction / oxidation (redox) on the PCT response was experimentally determined. Once again, the limited results indicated that the PCT responses from glasses that bound the acceptable redox range for DWPF were very acceptable with respect to the EA glass. In terms of predictability, the ∆G P model was either predictable or conservative. However, model predictions suggest that the impact of redox on processability (i.e., the predicted ∆G P value in relation to the acceptance criterion value) could have a detrimental effect on the projected operating windows. The projected negative impact would be most severe for glass systems whose upper waste loading is (or is nearly) PCT limited as redox transitions from the oxidized to the reduced state.Immobilization Technology Section

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Section: Applicability Of ∆G P To Projected Sb3 Compositional Regionsupporting

confidence: 60%

Section: Effect Of Redox On Pct Responsementioning

confidence: 99%

Sludge Batch 3 Phase 1 Variability Study

Peeler¹

2003

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“…Therefore, durability testing must be performed to confirm that any crystallization that might occur during canister cooling or during GCM formation has minimal impact. [66,67,68,69] Since the geological repository is most interested in the maximum radionuclide release, the most important elements to be analyzed for in a durability test are the leachate species that represent the maximum dissolution of the glassy waste form. For example, elements that are not sequestered in precipitates that participate in surface alteration reactions, and are also not solubility limited are good indicators of waste form durability.…”

Section: Basic Constructs (1) Modeling a Single Source Termmentioning

confidence: 99%

Durable Glass for Thousands of Years

Jantzen

Brown

Pickett

2010

Int J of Appl Glass Sci

179

156

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The durability of natural glasses on geological time scales and ancient glasses for thousands of years is well documented. The necessity to predict the durability of high level nuclear waste (HLW) glasses on extended time scales has led to various thermodynamic and kinetic approaches. Advances in the measurement of medium range order (MRO) in glasses has led to the understanding that the molecular structure of a glass, and thus the glass composition, controls the glass durability by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. During the early stages of glass dissolution, a "gel" layer resembling a membrane forms through which ions exchange between the glass and the leachant. The hydrated gel layer exhibits acid/base properties which are manifested as the pH dependence of the thickness and nature of the gel layer. The gel layer ages into clay or zeolite minerals by Ostwald ripening. Zeolite mineral assemblages (higher pH and Al 3+ rich glasses) may cause the dissolution rate to increase which is undesirable for long-term performance of glass in the environment. Thermodynamic and structural approaches to the prediction of glass durability are compared versus Ostwald ripening.

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“…Savannah River Technology Center forming chemicals) to obtain glass properties for various blends of the simulant and frit together 7 . The second step is to perform process testing using nonradioactive sludge slurry simulants 4 .…”

Section: Introductionmentioning

confidence: 99%

Confirmation Run of the DWPF SRAT Cycle Using the Sludge-Only Flowsheet with Tank 40 Radioactive Sludge and Frit 200 in the Shielded Cells Facility

Fellinger¹

2002

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Summary of Results for Expanded Macrobatch 3 Variability Study

Cited by 19 publications

References 4 publications

Sludge Batch 3 Phase 1 Variability Study

Sludge Batch 3 Phase 1 Variability Study

Durable Glass for Thousands of Years

Confirmation Run of the DWPF SRAT Cycle Using the Sludge-Only Flowsheet with Tank 40 Radioactive Sludge and Frit 200 in the Shielded Cells Facility

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