Ruthenium in Fuel Reprocessing by Fluoride Volatility Process, (II)

Ruthenium Species Appearing in Fluorination Step as Identified by Thermochromatography and IR Measurements

Abstract

The following three reactions were studied by thermochromatography in relation to the reprocessing of oxide fuels : (a) fluorination of RuF₃ by F₂, (b) fluorination of RuO₂ by F₂, (c) fluorination of RuO₂ mixed with an excess of an oxide UO₂ or Y₂O₃. The reaction products were as follows. The RuF₃-F₂ reaction yields RuF₅. Fluorination of RuO₂ by F₂ results in the production of a mixture of RuF₄-RuF₅-RuOF₄. (RuF₅ may be produced by fluorination of RuF₄ resulting from decomposition of RuOF₄ in the apparatus for thermochromatography). When dried at 150°C prior to fluorination the products of RuO₂-F₂ reaction in the presence of an excess UO₂ on Y₂O₃ are much more volatile than those obtained in the absence of these oxides. More than 60% is a mixture of RuF₅ and RuO, with a smaller amount of RuOF₄, RuF₄ and RuF₅. When the RuO₂-Y₂O₃ or UO₂ are dried at 800°C prior to fluorination, RuO₄ and RuF₆ are also produced, but the yields is about 1020%. Results from I. R. measurements are interpreted the same way.