Process chemistry for the pretreatment of Hanford tank wastes

Conference · Sat Aug 01 04:00:00 EDT 1992

OSTI ID:10110951

Lumetta, G J; Swanson, J L ^[1]; Barker, S A ^[2]

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1. Pacific Northwest Lab., Richland, WA (United States)
2. Westinghouse Hanford Co., Richland, WA (United States)

Current guidelines for disposing radioactive wastes stored in underground tanks at the US Department of Energy`s Hanford Site call for the vitrification of high-level waste in borosilicate glass and disposal of the glass canisters in a deep geologic repository. Low-level waste is to be cast in grout and disposed of on site in shallow burial vaults. Because of the high cost of vitrification and geologic disposal, methods are currently being developed to minimize the volume of high-level waste requiring disposal. Two approaches are being considered for pretreating radioactive tank sludges: (1) leaching of selected components from the sludge and (2) acid dissolution of the sludge followed by separation of key radionuclides. The leaching approach offers the advantage of simplicity, but the acid dissolution/radionuclide extraction approach has the potential to produce the least number of glass canisters. Four critical components (Cr, P, S, and Al) were leached from an actual Hanford tank waste-Plutonium Finishing Plant sludge. The Al, P, and S were removed from the sludge by digestion of the sludge with 0.1 M NaOH at 100{degrees}C. The Cr was leached by treating the sludge with alkaline KMnO{sub 4} at 100{degrees}C. Removing these four components from the sludge will dramatically lower the number of glass canisters required to dispose of this waste. The transuranic extraction (TRUEX) solvent extraction process has been demonstrated at a bench scale using an actual Hanford tank waste. The process, which involves extraction of the transuranic elements with octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), separated 99.9% of the transuranic elements from the bulk components of the waste. Several problems associated with the TRUEX processing of this waste have been addressed and solved.

• Research Organization: Pacific Northwest Lab., Richland, WA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 10110951
• Report Number(s): PNL-SA--20608; CONF-920815--28; ON: DE94004591
• Country of Publication: United States
• Language: English

Related Subjects

052002
054000
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BOROSILICATE GLASS
DISSOLUTION
HANFORD RESERVATION
HEALTH AND SAFETY
HIGH-LEVEL RADIOACTIVE WASTES
LEACHING
MINIMIZATION
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE STORAGE
SLUDGES
SOLVENT EXTRACTION
TANKS
TRUEX PROCESS
UNDERGROUND STORAGE
VITRIFICATION
WASTE DISPOSAL AND STORAGE