Development of High Waste Loading Glasses for Advanced Melter Technologies

Abstract

Executive SummaryWaste streams at the U.S. Department of Energy's (DOE's) Hanford and Savannah River sites contain a varied array of chemical compounds, a number of which can limit the waste loading or cause operating difficulties with melt rate or equipment corrosion. One such stream is the Hanford C-106/AY-102 High Level Waste (HLW) simulant which represents a blend of tanks that will be processed during initial HLW vitrification efforts at Hanford. The non-radioactive surrogate is based on a specific Hanford waste stream but will also provide valuable information to the Savannah River Site (SRS) -given the relatively high concentrations of Fe 2 O 3 , Cr 2 O 3 , and Al 2 O 3 and the cross-cutting assessment of the strontium/transuranic (TRU) precipitation or permanganate-based pretreatment process being considered at both sites.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 (T L ) 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.In general, the glasses developed (with waste loadings of ≥ 60 mass%) were very prone to devitrification (especially upon centerline canister cooling). The Product Consistency Test (PCT) response was primarily driven by the type and extent of crystallization and its ultimate impact on the residual glass matrix. Although the formation of nepheline was the primary suspect for the negative impact on durability in some glasses, its formation had little or no impact in other glasses -indicating that the residual glass matrix for each of these glasses is durable and acceptable.

Data Packet for the Frit 202-A11 Sb3 Glass System a Candidate for the Cold Crucible Induction Melter Demonstration

“…As the WLs transition to 48% and higher, the slight metallic surface haze transitions to a very reflective, metallic coating for the asfabricated, quenched samples. The metallic surface layer has been observed in other high WL DWPF or Hanford type glasses and, based on XRD analyses, was related to the formation of spinels (e.g., magnetite) (Peeler et al 2002). This will be confirmed for the HTLG glasses as noted later in Section 5.3.…”

Nuclear Waste Vitrification in the United States: Recent Developments and Future Options

“…These higher waste loadings are being developed for DWPF and the WTP currently under construction. Some of these higher loaded glasses have been implemented in the DWPF 43 . The main challenges to higher loading in these wastes are summarized in Table II.…”

“…Some of these higher loaded glasses have been implemented in the DWPF. 43 The main challenges to higher loading in these wastes are summarized in Table II.…”

“…However, the sulfur is introduced into the waste by chemical additions (usually in the form of ferrous sulfamate as a selective reductant). One way to avoid these problems is to minimize the addition of sulfur [43][44][45][46][47][48][49] Sodium-rich wastes typically containing over 70 wt% Na 2 O Chemical durability of the resulting glass (resistance of glass to release of radionuclides through reaction with aqueous environment)…”

An Experimental Assessment of the Impact of Sludge Variation on the Frit 202-A11 - Sb3 Glass System

“…More specifically, Method A of the PCT (ASTM C-1285-2002[see ASTM (2002]) was used for these measurements. Durability is the critical product quality metric for DWPF glass studies.…”