X-ray Photoelectron Spectroscopic Study of Hot Particles Formed by Emission from Fuel-Containing Masses Incorporating Ruthenium

X-ray photoelectron spectroscopy was applied to the study of the quantitative elemental and ionic compositions of samples of fuel-containing masses (FCMs) generated under laboratory conditions and incorporating Ru, before and after their heating in air at 1500°C for 2 min, and also of hot particles released in the process and kept in air at 700 and 900°C for 13 s. FCM samples heated under argon at 1900°C for 2 min were studied for comparison. The spectra revealed formation on the FCM sample surface of complex oxides UOx with x varying in the range 2 >x ≤ 3. Ruthenium was detected in at least two oxidation states: Ru(IV) and Ru(VI). The relative concentrations of U and Ru in FCM (89 at. % U and 11 at. % Ru) change, respectively, to ∼99 and ∼1 at. % after heating in air and to ∼80 at. % U and ∼20 at. % Ru after heating under argon. After treatment of the sample surface with Ar+ ions, the carbonate groups disappeared, and the concentrations of the U(IV) and U(VI), as well as of Ru(IV) and Ru(VI) ions, changed. The condensed phase of hot particles consists mainly of ruthenium ions (∼80 at. %), with a lower content of uranium (∼20 at. %). Uranyl compounds of the type RuUO2O3 are probably formed on the surface of hot particles. © MAIK Nauka/Interperiodica 2001.