Investigation of the impacts of gamma radiolysis on an advanced TALSPEAK separation

Journal Article · Mon Sep 28 00:00:00 EDT 2015 · Separation Science and Technology

DOI:https://doi.org/10.1080/01496395.2015.1085419· OSTI ID:1294594

Zarzana, Christopher A. ^[1]; Peterman, Dean R. ^[1]; Groenewold, Gary S. ^[1]; Olson, Lonnie G. ^[1]; McDowell, Rocklan G. ^[1]; Bauer, William F. ^[1]; Morgan, Sabrina J. ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

Here, the advanced TALSPEAK process is a selective solvent extraction that utilizes 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) to separate lanthanide elements from trivalent actinides, which are held back in the aqueous phase by N-hydroxylethyl-N,N’,N’-ethylenediamine triacetic acid (HEDTA) buffered by citric acid. Gamma irradiation of an experiment containing Eu(III) and Am(III) as representative lanthanide and actinide elements resulted in higher distribution ratios of both and separation factors which decreased in an exponential fashion with increasing dose. Analysis of the reagents showed that the HEDTA concentration also decreased in an exponential fashion, strongly suggesting that degradation was correlated with loss of separation selectivity. In contrast, the concentration of citrate was unaffected, and while the concentration of HEH[EHP] did decrease, its dose-dependent kinetic profile indicated that it was not limiting partitioning. A second set of experiments were conducted using a citrate concentration that was 7.5 X higher, with the expectation that citrate would protect the HEDTA by scavenging radiolytically formed OH radicals. HEDTA degradation was significantly mitigated at higher gamma doses, but the Eu-Am separation was worse than in the low citrate experiments, presumably because at the high citrate concentrations, the Eu-citrate complexes formed in abundances competitive with the Am complexes, and are more effectively held back in the aqueous phase.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE)
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1294594
• Report Number(s): INL/CON-14-32597
• Journal Information: Separation Science and Technology, Vol. 50, Issue 18; Conference: Eighteenth Symposium on Separation Science and Technology for Energy Applications; ISSN 0149-6395
• Publisher: Taylor & Francis
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
advanced TALSPEAK
separation
actinide
lanthanide