Development of electrochemical separations of uranium and re elements from fluoride melts

The pyrochemical electro-separation methods are in the focus of interest for the whole area of Molten-Salt Reactors fuel cycle with main goal to separate actinides and lanthanides. This study is concentrated on development of electrochemical partitioning method of uranium and chosen lanthanides from molten fluoride salt media. The melt used at present is ternary eutectic mixture of potassium, lithium and sodium fluorides (so-called FLINAK - 42.0% KF, 46.5% LiF, and 11.5% NaF (in molar %)) with the melting point at 454 C. The methods for conditioning of the materials before melting are discussed. The experimental set-up for measurement of electrochemical properties is described together with material selection both for construction material for electrolyser and electrodes, as well as the originally developed reference electrode for measurement in molten fluoride salts. The measured data concerning uranium and neodymium are presented and electrochemical behaviour of these elements in molten fluoride salts is discussed. (author)