Standard Potentials of Lanthanide and Actinide Trichlorides in Molten Eutectic LiCl-KCl Electrolyte

Roy, J. J.; Grantham, L.F.; McCoy, L.R.; Krueger, C.; Storvick, T. S.; Inoue, Toshihiro; Miyashiro, Hajime; Takahashi, Naoto

doi:10.4028/www.scientific.net/msf.73-75.547

Cited by 9 publications

(16 citation statements)

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“…It is also observed from the table that there is an increase of c with the temperature; that is, Sm(III) ions are less solvated by molten chloride as the temperature increases. Similar behaviour has been observed for other cations [7,[23][24][25].…”

Section: Samarium Activity Coefficient Determinationsupporting

confidence: 81%

An electrochemical study of samarium ions in the molten eutectic LiCl+KCl

Córdoba

Caravaca

2004

Journal of Electroanalytical Chemistry

108

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Section: Samarium Activity Coefficient Determinationsupporting

confidence: 81%

An electrochemical study of samarium ions in the molten eutectic LiCl+KCl

Córdoba

Caravaca

2004

Journal of Electroanalytical Chemistry

108

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“…6 The previously reported rare earth data did not show the same degree of consistency with theory (i.e., calculated ion valence, standard potential temperature dependence) as for the reported actinide results.…”

supporting

confidence: 48%

“…6 Data for Am are summarized in Table XII. The standard potential for Am 2ϩ at 450ЊC obtained here is within 10 mV of the value reported in earlier work.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic Properties for Rare Earths and Americium in Pyropartitioning Process Solvents

Fusselman¹,

Roy²,

Grimmett³

et al. 1999

J. Electrochem. Soc.

127

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A pyrochemical process is being developed to recover the longlived alpha-decaying radioactive nuclides from PUREX (plutonium uranium extraction), high-level wastes generated by the reprocessing of spent nuclear fuel. 1 These aqueous wastes contain fission products (noble metals, rare earths, transition metals, rubidium, strontium, cesium, barium, cadmium, tin, selenium) and actinides, the former being predominately short-lived, the latter containing many long-lived radionuclides. Removal of these alpha-decaying actinides from the residues reduces the long-term radiotoxicity and simplifies waste management. 2,3 Molten LiCl-KCl eutectic salt, cadmium and bismuth are used as solvents in the TRUMP-S (transuranic management by pyropartitioning separation) process. Process goals are to remove 99% of the actinides (U, Np, Pu, Am, and Cm) from chlorinated PUREX residues and to recover a product that is greater than 90% actinides by weight. The process separates the waste 4 into four fractions: actinides, rare earths, metals more noble than actinides, and metals more active than the rare earths. Separation of actinides and rare earths as a group from noble and active metals is accomplished by reductive extraction from the chlorinated high-level waste (HLW) residues into liquid Cd. The actinides are separated from the rare earths by electrorefining and countercurrent reductive extraction into liquid bismuth. A full set of consistent thermodynamic property measurements for the actinides and rare earths in the process solvents is required to predict actinide/rare earth separation. Data for the major trivalent actinides were reported previously. 5 Thermodynamic data obtained from measurements for the trivalent rare earths and americium are reported in this paper.Electrochemical potentials were measured and used to calculate the standard Gibbs free energy of formation of the metal chlorides in LiCl-KCl eutectic. Potential measurements at the LiCl-KCl/Cd and LiCl-KCl/Bi interfaces were made to calculate the activity coefficients for Am in the liquid Cd and Bi phases. These thermodynamic properties provide a basis for predicting composition in the salt and metal phases and of the separation products from electrorefining and extraction processes.Equilibrium potential measurements in LiCl-KCl eutectic have been reported previously for the actinides 5 and rare earths. 6 The previously reported rare earth data did not show the same degree of consistency with theory (i.e., calculated ion valence, standard potential temperature dependence) as for the reported actinide results.New data for the rare earths and Am are reported here. Improvements to the electrochemical cell design and experimental procedures were implemented for the experiments reported. For the rare earth chlorides, rare earth metal was deposited onto a Ta cathode to ensure a reliable electrical contact to the rare earth metal in equilibrium with the salt. A thoroughly characterized AgCl-LiCl-KCl salt was used in the reference electrodes. Relatively large amounts of Am a...

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“…The apparent standard Gibbs energy of formation DG Ã GdCl 3 is calculated according to [ 38], j, Lanteleme et al [39], Å, Fusselman et al [14], h Roy et al [17] and r Yang and Hudson [41]. The plot of the DG Ã GdCl 3 as a function of the temperature shows a linear dependence.…”

Section: Thermodynamic Propertiesmentioning

confidence: 99%

“…For this purpose, it is important to know accurately the electrochemical and thermodynamic properties of actinides and rare earths elements in each phase. Electrochemical data for actinides [9][10][11][12][13][14] and lanthanides [15][16][17][18] obtained using different electrochemical techniques in LiCl-KCl are available, and from these data thermodynamic quantities were derived (enthalpy and entropy of formation, activity coefficients). However, in some cases some discrepancies were observed.…”

Section: Introductionmentioning

confidence: 99%