An Assessment of the Impacts of Adding Am/Cm and Pu/Gd Waste Streams to Sludge Batch 3 on DWPF H2 Generation Rates and Glass Properties

The Defense Waste Processing Facility (DWPF) is currently processing Sludge Batch 2 (SB2) and plans to initiate processing of SB3 in the spring of 2004. In addition, the Savannah River High Level Waste Division proposes to transfer existing excess Pu and Am/Cm materials through the Liquid Radioactive Waste Handling Facility directly to the Extended Sludge Process Facility. Current blending strategies have both the Pu and Am/Cm materials being vitrified within SB3 in the DWPF

Melt Rate Improvements for DWPF MB3: Frit Development and Model Assessment

The objective of this research was to enhance the basic understanding of the role of glass batch chemistry (more specifically via control of frit composition) on the overall melting process for Macrobatch 3 (MB3). The overall strategy for the frit development activities was to explore frit compositional regions which challenged ''acceptable'' predicted property behavior

Applying laboratory methods for durability assessment of vitrified material to archaeological samples

Laboratory testing used to assess the long-term chemical durability of nuclear waste forms may not be applicable to disposal because the accelerated conditions may not represent disposal conditions. To address this, we examine the corrosion of vitrified archeological materials excavated from the near surface of a ~1500-year old Iron Age Swedish hillfort, Broborg, as an analog for the disposal of vitrified nuclear waste. We compare characterized site samples with corrosion characteristics generated by standard laboratory durability test methods including the product consistency test (PCT), the vapor hydration test (VHT), and the EPA Method 1313 test. Results show that the surficial layer of the Broborg samples resulting from VHT displays some similarities to the morphology of the surficial layer formed over longer timescales in the environment. This work provides improved understanding of long-term glass corrosion behavior in terms of the thickness, morphology, and chemistry of the surficial features that are formed

Melt Rate Improvement for DWPF MB3: Foaming Theory and Mitigation Techniques

The objective of this research is to enhance the basic understanding of the role of glass chemistry, including the chemical kinetics of pre-melting, solid state reactions, batch melting, and the reaction pathways in glass and/or acid addition strategy changes on the overall melting process for the Defense Waste Processing Facility (DWPF) Macrobatch 3 (MB3)

Hanford SPA Glasses: Fabrication, Characterization, and Chemical Analysis

The U.S. Department of Energy is formulating plans to vitrify the 204,400 m3 of radioactive waste contained in the 177 waste storage tanks at the Hanford Site in Washington State. Interim Hanford high-level waste glass TL models for use in the site flowsheet software are currently being updated (Vienna et al. [2001]). An integral part of this approach involves fabrication and testing of specific properties for glasses that adequately cover the compositional region of interest. As a result, Pacific Northwest National Laboratory (PNNL) developed a 45-glass test matrix (referred to as the SPA glass test matrix or SPA glasses) for which liquidus temperature (TL) will be measured. The Savannah River Technology Center (SRTC) is supporting PNNL efforts by (1) fabricating the SPA glasses and (2) analyzing their chemical composition

Development of High Waste Loading Glasses for Advanced Melter Technologies

The vitrification programs at Hanford and Savannah River may benefit from higher temperature glass formulations that are processable in advanced melters (e.g., induction-heated, cold-crucible melter (ICCM)) or by changing the current liquidus temperature (TL) limit for Joule heated ceramic melters (JHCM). The focus of this report was on the glass formulation activities in support of the ICCM and JHCM demonstrations with C-106/AY-102 simulant. The intent was to provide preliminary (non-optimized) glass formulations for a specific waste stream that met processing requirements, DOE product quality specifications, and programmatic objectives for the two melter types

Results of an inter-laboratory study of glass formulation for the immobilization of excess plutonium

The primary focus of the current study is to determine allowable loadings of feed streams containing different ratios of plutonium, uranium, and minor components into the LaBS glass and to evaluate thermal stability with respect to the DWPF pour

Sludge Batch 2/3 Case No. 6 and Case No. 7 Washing and Blending Strategies: A Model-Based Assessment for Projected Operating Windows

This report summarizes the assessments of four derivatives of the potential SB2/SB3 baseline and alternative washing scenarios that were provided by Program Development and Integration. For each of the four derivatives, two options were provided based on the timing in which SB3 would be blended with SB2. The first option assumes an additional 110 canisters will be produced with SB2 prior to blending SB3. The second option is based on the assumption that an additional 250 canisters will be produced with SB2 prior to SB3 blending. These two cases were assessed for the four different derivatives of the washing strategies resulting in 8 different or individual cases

Reduction of Constraints: Applicability of the Homogeneity Constraint for Macrobatch 3

The Product Composition Control System (PCCS) is used to determine the acceptability of each batch of Defense Waste Processing Facility (DWPF) melter feed in the Slurry Mix Evaporator (SME). This control system imposes several constraints on the composition of the contents of the SME to define acceptability. These constraints relate process or product properties to composition via prediction models. A SME batch is deemed acceptable if its sample composition measurements lead to acceptable property predictions after accounting for modeling, measurement and analytic uncertainties. The baseline document guiding the use of these data and models is ''SME Acceptability Determination for DWPF Process Control (U)'' by Brown and Postles [1996]. A minimum of three PCCS constraints support the prediction of the glass durability from a given SME batch. The Savannah River Technology Center (SRTC) is reviewing all of the PCCS constraints associated with durability. The purpose of this review is to revisit these constraints in light of the additional knowledge gained since the beginning of radioactive operations at DWPF and to identify any supplemental studies needed to amplify this knowledge so that redundant or overly conservative constraints can be eliminated or replaced by more appropriate constraints

Development of the Am/Cm Batch Vitrification Process

A batch vitrification process, which utilizes an oxalate precipitate and frit (or cullet), is being developed at the Savannah River Technology Center (SRTC) to immobilize an Am-Cm solution. Prior to being accepted as the baseline flowsheet, numerous laboratory-scale tests were conducted to demonstrate its feasibility and to characterize the general melt behavior of the oxalate/frit system. The effects of frit particle size and oxalate precipitation temperature were the initial focus of these studies. Two technical issues were identified during these initial tests that warranted further study: a volume or bed expansion was observed at approximately 1140 degrees C and ''excessive'' bubble formation between 1220 - 1250 degrees C. Although high temperature bubble formation does not pose a serious process concern (i.e., longer residence times and/or higher process temperatures minimize bubble retention), the volume expansion is undesirable during processing. The volume expansion may limit the amount of glass that can be produced in a single batch. That is, the batch height may have to be controlled so that the material is contained within the Pt-Rh vessel at all times. Both the volume expansion and high temperature bubble formation have been linked to the thermal reduction of CeO{sub 2}. As part of the oxalate feed, Ce is reduced (3 plus state). Upon thermal decomposition of the oxalate under oxidizing conditions, Ce will oxidize (3 plus (r) 4 plus state) which provides the opportunity for thermal reduction at higher temperatures liberating O2. Tests using a ''Ce-free'' oxalate have been performed in which no indication of either the volume expansion or high temperature bubble formation were observed. Complementary studies focused on redox and off-gas related issues provided a fundamental understanding of the melting behavior of the oxalate/frit system and lead to the successful development of the batch vitrification process