Measurement of the Standard Potential of the Np(III)/Np(0) Couple in LiCl ‐ KCl Eutectic

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

doi:10.1149/1.2085738

Cited by 17 publications

(6 citation statements)

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“…The shape of the anodic peak is characteristic of the dissolution of an insoluble phase deposited on the electrode during the forward scan ͑stripping peak͒ 18 and the potential value of the cathodic peak is consistent with the reported values in the literature. 8,19 Square-wave voltammetry technique, which is developed later on, confirmed the number of electrons exchanged for this redox system to be equal to three.…”

Section: Resultsmentioning

confidence: 83%

“…Apparent standard potential of the redox system Np͑III͒/Np͑0͒.-The apparent standard potential of the redox couple Np͑III͒/Np͑0͒ has been calculated from the electromotive force ͑emf͒ measurements of the galvanic cell, Np͑0͒/NpCl 42 Krueger et al 8 Roy et al 19 and Shirai et al 7 but differ from Martinot and Duyckaerts' values. 10 Thermodynamic properties.-The standard free-energy change for the NpCl 3 formation in the eutectic LiCl-KCl has been calculated from the apparent standard potential value by means of the relation…”

Section: ͓4͔mentioning

confidence: 99%

“…Different authors have studied the Np͑III͒/Np redox system from NpCl 3 as a starting material. [7][8][9][10] However, our available material is NpO 2 and several methods for neptunium chloride solutions preparation in LiCl-KCl have been investigated. We paid particular attention to get a solution free of oxygenated species; therefore, the removal of stable Np soluble oxychlorides in the melt was a major concern.…”

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Electrochemical Behavior of Np in the Molten LiCl–KCl Eutectic

Córdoba¹,

Laplace

Lacquement

et al. 2007

J. Electrochem. Soc.

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This work presents a study on the electrochemical behavior of neptunium, and in particular of the Np͑III͒/Np͑0͒ redox system, in the molten LiCl-KCl eutectic. Neptunium solutions have been prepared by two different methods: from NpO 2 dissolution into LiCl-KCl by carbochlorination ͑Cl 2͑g͒ + C ͑s͒ ͒ at 550°C and from metal Np oxidation from an Al-Cu-Np alloy by CuCl 2 . These neptunium solutions were investigated by cyclic voltammetry. A mixture of Np͑III͒, Np͑IV͒ species, and Np͑V͒ soluble oxychloride was obtained from NpO 2 dissolution by carbochlorination. In order to remove any oxygenated species from the melt, this solution was contacted with metal Zr, leading in our experimental conditions to a mixture of stable Np͑IV͒ and Np͑III͒ species. The second method used by Np oxidation from an Al-Cu-Np alloy gave a stable Np͑III͒ solution. The study of the reduction reaction Np͑III͒/Np͑0͒ has been performed by different electrochemical techniques. Apparent standard potentials of the Np͑III͒/Np͑0͒ system at different temperatures were determined by chronopotentiometry at zero current technique ͓E Np͑III͒/Np͑0͒ Ј o = −2.68 vs Cl 2͑g͒ ͑1 atm͒/Cl − at 450°C͔. Standard free energy, enthalpy, and entropy of formation, as well as the activity coefficient of Np͑III͒ in LiCl-KCl, were also obtained.

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Section: Resultsmentioning

confidence: 83%

Section: ͓4͔mentioning

confidence: 99%

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Electrochemical Behavior of Np in the Molten LiCl–KCl Eutectic

Córdoba¹,

Laplace

Lacquement

et al. 2007

J. Electrochem. Soc.

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“…The standard deviation is 0.0009 V. The standard potential vs. the Li/Li(I) couple in LiCl-KCl eutectic salt was also shown in last column of Table III, which was computed from the Li-Al electrode potential vs. the Li/Li(I) couple reported elsewhere. 16 The standard potential for the Np/Np(III) couple was previously reported by Roy et al 17,18 They used an Ag/AgCl reference electrode with a Vycor sheath of which AgCl concentration was 0.00487 mole fraction. In the present study, the mole fraction of AgCl was 0.00390 and the sheath was made of Pyrex glass.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamics of Neptunium in LiCl-KCl Eutectic/Liquid Bismuth Systems

Sakamura

Shirai

Iwai

et al. 2000

J. Electrochem. Soc.

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“…This latter process is imperative in improving the current efficiency for electrochemical reduction of the uranium and plutonium oxides generated and is an important fabrication step in controlling the stoichiometry and atomic arrangement of particles for subsequent steps. Heating the used fuel to high temperatures prior to addition to the molten salt removes the salt-soluble fission products such as caesium, iodine, rubidium and technetium, therefore preventing them from accumulating within the reduction process, although it does generate a separate waste stream containing fission products such as 137 Cs and 99 Tc. The electroreduction procedure involves the dissolution of the uranium and plutonium oxide granules or powder typically into a molten chloride system such as LiCl-Li 2 O at 650 1C (Fig.…”

Section: Electrochemical Reduction and Refining Of Nuclear Materials ...mentioning

confidence: 99%