Loading Capacity and Dilute Nitric Acid Rinse of Diglycolamide Resin for the Recovery of Transplutonium and Rare Earth Elements from Mark-18A Targets

Journal Article · Sun Feb 23 00:00:00 EST 2025 · Solvent Extraction and Ion Exchange

DOI:https://doi.org/10.1080/07366299.2025.2459144· OSTI ID:3013324

Mills, Matthew S. ^[1]; Uba, Samuel ^[1]

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1. Savannah River National Laboratory (SRNL), Aiken, SC (United States)

N,N,N′,N′-tetraoctyldiglycolamide (TODGA) as a resin (“DGA resin”) produced by Eichrom Technologies will be used by Savannah River National Laboratory for the indiscriminate extraction of trivalent actinides and rare earth elements with the intent of recovering Cm and Am from dissolved irradiated ²⁴²Pu Mark-18A targets in 7 to 9 M nitric acid. The extracted constituents will be recovered as an oxide by direct thermal decomposition of the loaded resin followed by calcination of the resultant residue. The characteristics of DGA resin with non-radiological feed simulant representative of the anticipated feed in the Mark-18A process, with Sm and Nd as surrogates for Cm and Am, respectively, including breakthrough point and saturation capacity were evaluated in this work. Additionally, this work examined the losses from the loaded resin by rinsing the resin bed with dilute acid to reduce the nitrate concentration in the resin bed prior to thermal decomposition operations to improve the safety posture of the process. A resin loading profile was developed, and the resin was determined to have a trivalent metal saturation capacity of 74 μmol/mL resin under the experimental conditions evaluated. Following a wash of the loaded resin bed with fresh 8 M HNO₃, the trivalent metals retained was reduced to 68 μmol/mL resin, which represents the practical capacity of the resin for the Mark-18A process. Lighter lanthanides breakthrough the resin well before the saturation capacity is reached. Rinsing the saturated resin bed with 0.26 M HNO₃ was found to result in a rapid reduction in retention of rare earth elements by the resin. After 2.8 bed volumes of dilute acid rinse, the mean resin bed free acid concentration was reduced to 0.28 M and 3.1 bed volumes of dilute acid rinse resulted in a reduction of the cumulative rare earth element retention to 52 μmol/mL of resin.

• Research Organization: Savannah River National Laboratory (SRNL), Aiken, SC (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Environment, Health, Safety and Security (AU); USDOE Office of Environmental Management (EM)
• Grant/Contract Number: 89303321CEM000080
• OSTI ID: 3013324
• Report Number(s): SRNL--STI-2024-00498
• Journal Information: Solvent Extraction and Ion Exchange, Journal Name: Solvent Extraction and Ion Exchange Journal Issue: 2 Vol. 43; ISSN 0736-6299; ISSN 1532-2262
• Publisher: Taylor and Francis
• Country of Publication: United States
• Language: English

Related Subjects

Transplutonium separations
rare earth element separations
resin calcination