skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant

Abstract

A solvent extraction system has been developed for separating trivalent actinides from lanthanides. This “Advanced TALSPEAK” system uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to extract the lanthanides into a n-dodecane-based solvent phase, while the actinides are retained in a citrate-buffered aqueous phase by complexation to N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid. Batch distribution measurements indicate that the separation of americium from the light lanthanides decreases as the pH decreases. For example, the separation factor between La and Am increases from 2.5 at pH 2.0 to 19.3 at pH 3.0. However, previous investigations indicated that the extraction rates for the heavier lanthanides decrease with increasing pH. So, a balance between these two competing effects is required. An aqueous phase in which the pH was set at 2.6 was chosen for further process development because this offered optimal separation, with a minimum separation factor of ~8.4, based on the separation between La and Am. Centrifugal contactor single-stage efficiencies were measured to characterize the performance of the system under flow conditions.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1]; ORCiD logo [1];  [1];  [1];  [3];  [4];  [1]; ORCiD logo [1]
  1. Forschungszentrum Jülich GmbH, Institut für Energie – und Klimaforschung – Nukleare Entsorgung und Reaktorsicherheit (IEK-6), Jülich, Germany
  2. Nuclear Science and Engineering Group, Pacific Northwest National Laboratory, Richland, DC, USA
  3. Aqueous Separations and Radiochemistry Department, Idaho National Laboratory, Idaho Falls, ID, USA
  4. Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE), Karlsruhe, Germany
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1406777
Report Number(s):
PNNL-SA-122678
Journal ID: ISSN 0736-6299; AF5805010
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Solvent Extraction and Ion Exchange; Journal Volume: 35; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; actinide extraction; actinide separation; Advanced TALSPEAK; lanthanide separation; HEH[EHP]

Citation Formats

Wilden, Andreas, Lumetta, Gregg J., Sadowski, Fabian, Schmidt, Holger, Schneider, Dimitri, Gerdes, Markus, Law, Jack D., Geist, Andreas, Bosbach, Dirk, and Modolo, Giuseppe. An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant. United States: N. p., 2017. Web. doi:10.1080/07366299.2017.1368945.
Wilden, Andreas, Lumetta, Gregg J., Sadowski, Fabian, Schmidt, Holger, Schneider, Dimitri, Gerdes, Markus, Law, Jack D., Geist, Andreas, Bosbach, Dirk, & Modolo, Giuseppe. An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant. United States. doi:10.1080/07366299.2017.1368945.
Wilden, Andreas, Lumetta, Gregg J., Sadowski, Fabian, Schmidt, Holger, Schneider, Dimitri, Gerdes, Markus, Law, Jack D., Geist, Andreas, Bosbach, Dirk, and Modolo, Giuseppe. 2017. "An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant". United States. doi:10.1080/07366299.2017.1368945.
@article{osti_1406777,
title = {An Advanced TALSPEAK Concept for Separating Minor Actinides. Part 2. Flowsheet Test with Actinide-spiked Simulant},
author = {Wilden, Andreas and Lumetta, Gregg J. and Sadowski, Fabian and Schmidt, Holger and Schneider, Dimitri and Gerdes, Markus and Law, Jack D. and Geist, Andreas and Bosbach, Dirk and Modolo, Giuseppe},
abstractNote = {A solvent extraction system has been developed for separating trivalent actinides from lanthanides. This “Advanced TALSPEAK” system uses 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester to extract the lanthanides into a n-dodecane-based solvent phase, while the actinides are retained in a citrate-buffered aqueous phase by complexation to N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid. Batch distribution measurements indicate that the separation of americium from the light lanthanides decreases as the pH decreases. For example, the separation factor between La and Am increases from 2.5 at pH 2.0 to 19.3 at pH 3.0. However, previous investigations indicated that the extraction rates for the heavier lanthanides decrease with increasing pH. So, a balance between these two competing effects is required. An aqueous phase in which the pH was set at 2.6 was chosen for further process development because this offered optimal separation, with a minimum separation factor of ~8.4, based on the separation between La and Am. Centrifugal contactor single-stage efficiencies were measured to characterize the performance of the system under flow conditions.},
doi = {10.1080/07366299.2017.1368945},
journal = {Solvent Extraction and Ion Exchange},
number = 6,
volume = 35,
place = {United States},
year = 2017,
month = 8
}
  • 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 ofmore » 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.« less
  • Results are reported from a hot test of a TALSPEAK type process for separation of higher actinides (Am, Cm) from lanthanides. Actinides and lanthanides are extracted by 1 M HDEHP and separated by selective strip of the actinides, using a mixture of DTPA and lactic acid (reversed TALSPEAK process). In order to minimize the generation of secondary waste, a procedure using recirculating DTPA-Lactic acid solution has been developed. A separation factor between Am and Eu of 132 was achieved. In regard to separations of Am and Cm from commercial HLLW (high level liquid wastes), the factor corresponds to 1.5% ofmore » the lanthanide group remaining with the actinides. The loss of Am was about 0.2%. 9 figures, 3 tables.« less
  • A method for separating the trivalent actinides and lanthanides is being developed using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) as the extractant. The method is based on the preferential binding of the actinides in the aqueous phase by N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), which serves to keep the actinides in the aqueous phase while the lanthanides are extracted into an organic phase containing HEH[EHP]. The process is very robust, showing little dependence upon the pH or the HEH[EHP], HEDTA, and citrate concentrations over the ranges that might be expected in a nuclear fuel recycling plant. Single-stage runs with a 2-cm centrifugal contactor indicatemore » that modifications to the process chemistry may be needed to increase the extraction rate for Sm, Eu, and Gd. The hydraulic properties of the system are favorable to application in centrifugal contactors.« less
  • The possibility is shown to design in principle the double-purpose liquid fuel electro nuclear facility for useful power generation and minor actinides transmutation in U-Pu fuel cycle conditions. D2O and a melt of fluorine salts are considered as a working media for liquid fuel. Such facility replenished with depicted or natural uranium only makes it possible to generate power of 900 MW (c) for external consumers and serve 20 WWER-1000 reactors for transmutation of MA. The facility could be thought as an alternative to fast reactors since appr. 30% of the total power confined in uranium is utilized in it.
  • One of the most important problems for nuclear engineering is the minor actinide incineration. There are many questions pretraining to incineration such as the influence on main reactor safety and the different methods of recycling. Incinerations were carried out on the fast breeder reactor EFR. Results are discussed.