The formation and composition of secondary precipitate in course of spent fuel dissolution

• Published in: Journal of nuclear science and technology Vol. 58; no. 3; pp. 315 - 321
• Main Authors: Fang, Liu, Tai-Hong, Yan, Bin, Li, Song-Tao, Xiao, Yi-Qun, Xiao, Guo-an, Ye
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis 04.03.2021; Taylor & Francis Ltd
• Subjects: Dissolution; insoluble residue; Nitric acid; platinum group metals; Residues; Ruthenium; secondary precipitates; Zirconium
• ISSN: 0022-3131; 1881-1248
• DOI: 10.1080/00223131.2020.1825234

The dissolution behaviors of spent fuel were studied and the secondary precipitate was obtained and characterized. The experimental results showed that the spent fuel sliced to 20-30 mm in length was completely dissolved within 5 hours in 6.5 M nitric acid at about 90°C and the precipitating of Ru happened in the course of dissolution, and the secondary precipitate formed in the following 24 hours aging time after the solution has been filtered. The amount of the secondary precipitate was about 0.222 g/kgU-0.292 g/kgU. The results of component analyses showed that the main components of the residue are Ru, Mo, Rh, Tc, Zr, etc., the main non-metallic element was oxygen. The mass content of U and Pu in the insoluble residue may be negligible. The micro-graphs of the secondary precipitate residue were observed by SEM.