Journal of Nuclear Fuel Cycle and Waste Technology

When considering the long-term safety assessment of spent-nuclear fuel management, americium is one of the most radio-toxic actinides. Although spectroscopic methods are widely used for the study of actinide chemistry, application of those methods to americium chemistry has been limited. Herein, we purified 241Am to obtain a highly pure stock solution required for spectroscopic studies. Quantitative and qualitative analyses of purified 241Am were carried out using liquid scintillation counting, and gamma and alpha radiation spectrometry. Highly sensitive absorption spectrometry coupled with a liquid waveguide capillary cell and time-resolved laser fluorescence spectroscopy were employed for the study of Am(Ⅲ) hydrolysis and oxalate (Ox) complexation. Am3+ ions under acidic conditions exhibit maximum absorbance at 503 nm, with a molar absorption coefficient of 424 ± 8 cm-1·M-1. Am(OH)3(s) colloidal particles formed under near neutral pH conditions were identified by monitoring the absorbance at around 506-507 nm. The formation of Am(Ox)3 3- was detected by red-shifts of the absorption and luminescence spectra of 4 and 5 nm, respectively. In addition, considerable enhancements of the luminescence intensities were observed. The luminescence lifetime of Am(Ox)3 3- increased from 23 to 56 ns, which indicates that approximately six water molecules are replaced by carboxylate ligands in the inner-sphere of the Am(Ⅲ). These results suggest that Am(Ox)3 3- is formed through the bidentate coordination of the oxalate ligands.

Keywords

아메리슘,방사분석,UV-Vis 흡수 분광학,시간분해 레이저 형광 분광학,화학종 규명