EXPECTED IMPACT OF HANFORD PROCESSING ORGANICS OF PLUTONIUM DURING TANK WASTE SLUDGE RETRIEVAL
This document evaluates the potential for extracting plutonium from Hanford waste tanks into residual organic solvents and how this process may have an impact on criticality specifications during the retrieval of wastes. The two controlling factors for concentrating plutonium are the solubility of the plutonium in the wastes and the extraction efficiency of the potential organic extractants that may be found in these wastes. Residual Hanford tank sludges contain plutonium in solid forms that are expected to be primarily insoluble Pu(IV) hydroxides. Evaluation of thermodynamic Pourbaix diagrams, documentation on solubility studies of various components in waste tank matrices, and actual analysis of plutonium in tank supernates all indicate that the solubility of Pu in the alkaline waste is on the order of 10{sup -6} M. Based on an upper limit plutonium solubility of 10{sup -5} M in high pH and a conservative distribution coefficient for organic extractants of <0.01 (the E{sub a}{sup 0} for plutonium in 30% TBP at 0.07 M HNO{sub 3}), the estimated concentration for plutonium in the organic phase would be <1 x 10{sup -7} M. This is well below the process control criteria. A significant increase in plutonium solubility or the E{sub a}{sup o} would have to occur to raise this concentration to the 0.01 M concern level for organics. Measured tank chemical component values, expected operating conditions, and the characteristics of the expected chemistry and extraction mechanisms indicate that concentration of plutonium from Hanford tank residual sludges to associated process organic extractants is significantly below levels of concern.
- Research Organization:
- CH2M Hill Hanford Group, Inc., Richland, WA (United States)
- Sponsoring Organization:
- ENVIRONMENTAL MANAGEMENT (US)
- DOE Contract Number:
- AC27-99RL14047
- OSTI ID:
- 823762
- Report Number(s):
- RPP-20041, Rev.0; DE-AC27-99RL14047; TRN: US0401812
- Resource Relation:
- Other Information: PBD: 18 Mar 2004
- Country of Publication:
- United States
- Language:
- English
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