Interim glycol flowsheet reduction/oxidation (redox) model for the Defense Waste Processing Facility (DWPF)

Technical Report · Tue Mar 08 00:00:00 EST 2016

DOI:https://doi.org/10.2172/1244066· OSTI ID:1244066

Jantzen, C. M. ^[1]; Williams, M. S. ^[1]; Zamecnik, J. R. ^[1]; Missimer, D. M. ^[1]

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1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

Control of the REDuction/OXidation (REDOX) state of glasses containing high concentrations of transition metals, such as High Level Waste (HLW) glasses, is critical in order to eliminate processing difficulties caused by overly reduced or overly oxidized melts. Operation of a HLW melter at Fe⁺²/ΣFe ratios of between 0.09 and 0.33, a range which is not overly oxidizing or overly reducing, helps retain radionuclides in the melt, i.e. long-lived radioactive ⁹⁹Tc species in the less volatile reduced Tc⁴⁺ state, ¹⁰⁴Ru in the melt as reduced Ru⁺⁴ state as insoluble RuO₂, and hazardous volatile Cr⁶⁺ in the less soluble and less volatile Cr⁺³ state in the glass. The melter REDOX control balances the oxidants and reductants from the feed and from processing additives such as antifoam. Currently, the Defense Waste Processing Facility (DWPF) is running a formic acid-nitric acid (FN) flowsheet where formic acid is the main reductant and nitric acid is the main oxidant. During decomposition formate and formic acid releases H₂ gas which requires close control of the melter vapor space flammability. A switch to a nitric acid-glycolic acid (GN) flowsheet is desired as the glycolic acid flowsheet releases considerably less H₂ gas upon decomposition. This would greatly simplify DWPF processing. Development of an EE term for glycolic acid in the GN flowsheet is documented in this study.

• Research Organization: Savannah River Site (SRS), Aiken, SC (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 1244066
• Report Number(s): SRNL-STI-2015-00702; TRN: US1601033
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
RADIOACTIVE WASTE PROCESSING
FORMIC ACID
GLYCOLIC ACID
TECHNETIUM 99
NITRIC ACID
GLYCOLS
CHROMIUM IONS
HIGH-LEVEL RADIOACTIVE WASTES
HYDROGEN
OXIDATION
REDUCTION
DECOMPOSITION
IRON IONS
RUTHENIUM 104
RUTHENIUM IONS
RUTHENIUM OXIDES
TECHNETIUM IONS
TRANSITION ELEMENTS
CONTROL
GLASS
VOLATILITY
FLAMMABILITY
FORMATES
OPERATION
FLOWSHEETS