Extraction behaviour of actinides and lanthanides in TALSPEAK, TRUEX and NPEX processes of UREX+

Abstract

Actinides / Lanthanides / TALSPEAK / NPEX / Separation / Pu / NpSummary. Bench-scale studies to determine the extraction behavior of Pu, Np, Am and lanthanides with the organophosphorus extractants TBP, CMPO and HDEHP have been carried out. Based on the results obtained using actual spent nuclear fuel solutions, enhancements to the NPEX, TRUEX and TAL-SPEAK processes have been successful. In NPEX, > 99.94% of both Np and Pu were separated from the fission products. In TRUEX, essentially complete recovery of the actinides (An) and the lanthanides (Ln) was achieved. In TALSPEAK, the complete separation of Pu, Np and Am from the lanthanides was demonstrated several times under various process conditions. The recovery of transuranics (TRU), including Am and Cm, is nearly 100% (below detection limit in the Ln stream), while the total recovery of Ln in the product stream exceeded 99.97%.

Do Aqueous Ternary Complexes Influence the TALSPEAK Process?

“…which has the conditional equilibrium constant K 111 ¼ ½MðDTPAÞðLacÞ 3À ½MðDTPAÞ 2À À1 ½Lac À À1 (4) it is useful to know how much a given value of K 111 would affect the distribution ratio and what a reasonable value for K 111 might be. Using the thermodynamic model of Nilsson and Nash [6] with an added term for M(DTPA)(Lac) 3-formation, one can calculate the expected effect of these ternary complexes on the distribution ratio for various values of K 111 .…”

“…Although pilot-scale demonstrations of the TALSPEAK process with spent fuel have shown that it is capable of achieving excellent decontamination of An 3+ from Ln 3+ , [3,4] the chemistry underlying the separations in this very complex system is only beginning to be understood. [5,6] To date, only the role of DTPA in this process is well-defined.…”

Requirements for a Dynamic Solvent Extraction Module to Support Development of Advanced Technologies for the Recycle of Used Nuclear Fuel

“…Notable exceptions include systems where reaction kinetics and/or mass transfer are slow relative to residence time, such as systems with redox reactions or complexation reactions in centrifugal contactors. 22 7. Plant-level solvent extraction models should be built from mathematically reduced models of the underlying continuum level.…”

“…In some instances kinetic models could be favored over equilibrium models for a given component. 22 11. An energy balance should be included in order to predict temperature profiles throughout the process.…”

Chromatographic separation of Am and Cm

“…Their separation and quantification is required in many nuclear applications ranging from validating neutronic code calculations and nuclear fuel burn-up [1][2][3], to the processing of nuclear wastes [4][5][6][7][8], to environmental analysis [9][10][11][12][13][14][15]. Isotopic fingerprinting of these elements is often very useful in such applications, but, their separation from each other is challenging due to their nearly identical solution chemistries.…”