Application of bromine trifluoride for pre-concentration and determination of rare-earth elements in fuel uranium dioxide

摘要

Radioactive indicator's (~(152)Eu) method was used to study the behavior of rare-earth element (REE) micro-impurities at fluorination of fuel UO2 with bromine trifluoride. The proposed process is very simple and carried out under a blanket layer of Freon-113 in the glassy carbon (vitreous) crucibles. It was shown that uranium matrix completely removes from reaction sphere in the form of UF6 and REE contaminations quantitatively remain in crucible owing to practical non-volatility of their fluorides. High purity of fuel UO2 causes small amount of the non-volatile rest (0.3-2 wt.% from initial weight) that considerably facilitates a problem of confident diagnostics of the strictly limited REE content in this material. Removal of uranium and concentration of REE from analyzed test samples via fluorination is several hundred times more rapid scheme of pre-sampling to atomic emission spectral determination of REE micro-quantities in UO2 than traditionally used extraction and ion-exchange ways of the preliminary concentration of contaminations and removal of uranium.