Changes in quantitative composition of NaCl–KCl–UO2Cl2–ZrCl4 melt during electrolysis

 V.Ye. Krotov, Ye. S. Filatov

ABSTRACT:

The changes in concentrations of ZrCl4 and UCl4 depending on the current density (0.08–0.63 A/cm2), duration of electrolysis (1–24 h), and initial content of ZrCl4 (0–12.3 wt %) in the melt (NaCl–KCl)eq–UO2Cl2–ZrCl4 at the UO2–ZrO2 cathode deposits formation were investigated. Uranium tetrachloride appears in the electrolyte as a result of the exchange reaction between ZrCl4 and UO2, which takes place on the electrode when recovering ions. The quantitative difference between the changes in the mole fraction concentrations of zirconium and uranium tetrachloride’s in the salt phase was found. The difference increased as the electrolysis duration and the initial ZrCl4 content in the electrolyte increased and the current density decreased. The ZrCl4 mole fraction concentrationvaries greater compared with that of UCl4. It is shown that the reason for this difference is the higher volatility of ZrCl4 in the molten salt compared with that of UCl4.

KEYWORDS:

 cathode process, molten salt, electrolysis, change in concentration, ZrCl4, UCl4, lack of balance