Speciation, Dissolution, and Redox Reactions of Chromium Relevant to Pretreatment and Separation of High-Level Tank Wastes

Technical Report · Wed Apr 20 04:00:00 EDT 2005

DOI:https://doi.org/10.2172/838914· OSTI ID:838914

Clark, Sue B ^[1]; Rai, Dhanpat; Rao, Linfeng

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1. Washington State University

Chromium, one of the problematic elements in tank sludges, is considered the most important constituent in defining the total volume of high-level radioactive waste (HLW) glass. Current sludge washing processes (e.g. caustic leaching, 3 M NaOH) are not effective in removing Cr. This inefficient removal would result in production of an unacceptably large volume of HLW glass and thus a tremendous increase in the cost of waste disposal. This proposed research seeks to develop fundamental data for chromium (Cr) reactions that are not currently available but are essential for developing effective methodologies for removing Cr form high-level waste (HLW). Our objectives are to study (1) the dissolution of several solid phases (e.g., CrOOH, Cr2O3(c), Cr(OH)3, and Fe and Cr, binary hydroxides, identified to be important from sludge leaching studies) in highly alkaline solutions and in the presence of other electrolytes (e.g., carbonate, phosphate, sulfate, nitrite), and (2) the effect of the nature of Cr solid phases and aqueous species on their redox reactivity with a variety of potential oxidants (e.g., H2o2, persulfate, O2, and ferrate). This information will provide critical support for developing enhanced pretreatment strategies for removing Cr from HLW and will achieve a major cost reduction HLW disposal.

• Research Organization: Washington State University
• Sponsoring Organization: USDOE Office of Science (SC) (US)
• DOE Contract Number: FG07-98ER14930
• OSTI ID: 838914
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIDES
CHROMIUM
COMPLEXATION
DISSOLUTION
ELECTROLYTES
GLASS
HIGH-LEVEL RADIOACTIVE WASTES
HYDROXIDES
LEACHING
OXIDIZERS
PRODUCTION
REDOX REACTIONS
REMOVAL
SLUDGES
TANKS
TEMPERATURE
THERMODYNAMICS
WASHING
WASTE DISPOSAL
WASTES