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Title: An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 1. Process Optimization and Flowsheet Development

Journal Article · · Solvent Extraction and Ion Exchange
ORCiD logo [1];  [1]; ORCiD logo [2];  [1];  [1];  [1];  [1];  [3]; ORCiD logo [2]
  1. Pacific Northwest National Laboratory, Nuclear Science and Engineering Group, Richland, WA, USA
  2. Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung – Nukleare Entsorgung und Reaktorsicherheit (IEK-6), Jülich, Germany
  3. Idaho National Laboratory, Aqueous Separations and Radiochemistry Department, Idaho Falls, ID, USA
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A system is being developed to separate trivalent actinides from lanthanide fission product elements that uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to extract the lanthanide ions into an organic phase, while the actinide ions are held in the citrate-buffered aqueous phase by complexation to N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA). Earlier investigations of this system using a 2-cm centrifugal contactor revealed that the relatively slow extraction of Sm3+, Eu3+, and Gd3+ resulted in low separation factors from Am3+. In the work reported here, adjustments to the aqueous phase chemistry were made to improve the extraction rates. The results suggest that increasing the concentration of the citric acid buffer from 0.2 to 0.6 mol/L, and lowering the pH from 3.1 to 2.6, significantly improved lanthanide extraction rates resulting in an actinide/lanthanide separation system suitable for deployment in centrifugal contactors. Experiments performed to evaluate whether the lanthanide extraction rates can be improved by replacing aqueous HEDTA with nitrilotriacetic acid (NTA) exhibited promising results. However, NTA exhibited an unsatisfactorily high distribution value for Am3+ under the extraction conditions examined.

Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
1406725
Report Number(s):
PNNL-SA-122677; AF5805010
Journal Information:
Solvent Extraction and Ion Exchange, Vol. 35, Issue 6; ISSN 0736-6299
Publisher:
Taylor and Francis
Country of Publication:
United States
Language:
English

References (34)

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Related Subjects

actinide extraction
actinide separation
HEH[EHP]
TALSPEAK