Chinese experience in the removal of actinides from highly active waste by trialkylphosphine-oxide extraction
- Tsinghua Univ., Beijing (China). Inst. of Nuclear Energy Technology
Mixed trialkylphosphine oxide (TRPO) (alkyl is C[sub 6]-C[sub 8]) was chosen as the extractant for the removal of uranium, neptunium, plutonium, and americium from highly active waste (HAW) in China. Composition and properties of the extractant and process chemistry are based on 30 vol% TRPO-kerosene as solvent. Hexa- and tetravalent actinides are highly extractable in 30 vol% TRPO extraction from acidic HAW, and trivalent americium (curium) can be extracted effectively from HAW with a nitric acid concentration of [approximately]1 mol/[ell]. Actinides extracted can be stripped successively by 5.5 mol/[ell] HNO[sub 3], 0.6 mol/[ell] H[sub 2]C[sub 2]O[sub 4], and 5% Na[sub 2]CO[sub 3] into americium + rare earth, neptunium + plutonium, and uranium fractions, respectively. The loading capacity of TRPO solvent is higher than that of bifunctional organophosphorus extractants, and the radiolytic stability of TRPO is higher than that of tributyl phosphate (TBP) and bis(2-ethyl hexyl)phosphoric acid. The extraction and stripping rate of TRPO is high enough to be compatible with the centrifugal contactors. Optimized process parameters of multistage countercurrent extraction and stripping and results of experimental verification are established. In both a batch experiment with simulated nuclear power plant (NPP) spent-fuel Purex HAW and a continuous experiment with real NPP spent-fuel Purex HAW, 99.9% recovery of actinides was achieved. The modification of the solvent system with TBP to fit the conditions in the chemical pretreatment of defense HAW is considered.
- OSTI ID:
- 6688061
- Journal Information:
- Nuclear Technology; (United States), Vol. 108:3; ISSN 0029-5450
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ACTINIDES
MATERIALS RECOVERY
SOLVENT EXTRACTION
HIGH-LEVEL RADIOACTIVE WASTES
RADIOACTIVE WASTE PROCESSING
ELEMENTS
EXTRACTION
MANAGEMENT
MATERIALS
METALS
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE MANAGEMENT
RADIOACTIVE WASTES
SEPARATION PROCESSES
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
052001* - Nuclear Fuels- Waste Processing