Separation of Uranium from Uranium-Aluminium Alloys by Chlorination

Electrochemical separation techniques in molten LiCl-KCl using solid aluminium cathodes are developed in ITU to recover all actinides from spent nuclear fuel. Actinide ions are group-selectively electrochemically reduced on the cathode, forming solid actinide-aluminium (An-Al) alloys. Chlorination by pure chlorine gas in presence of carbon is under development for recovery of actinides from obtained alloys. The proposed route is consisting of three steps: (i) vacuum distillation for removal of salt adhered on the electrode, (ii) chlorination of remaining An-Al alloy by chlorine gas and (iii) sublimation of formed AlCl3 by heating under inert atmosphere. Initially, a thermochemical study of the route was performed using the FactSage software. It indicated that the key issue of the process would be to manage full chlorination of An-Al alloys without any An losses by volatilization. In the present work, systematic studies of the chlorination step are summarized and evaluated. The experimental work was carried out with UAl3 alloy prepared by melting of metals in an arc furnace. According to the theoretical study, chlorination of all actinides should be feasible under conditions enabling chlorination of uranium. The work was focused on determination of optimal temperature and Cl2/UAl3 molar ratio, providing full alloy chlorination without formation of volatile UCl5 and UCl6. The tested temperatures were 150, 160 and 170°C and the Cl2/UAl3 molar ratio varied in a range 18 - 72. In addition, the process was verified using U-Al alloy obtained by electrochemical deposition of uranium onto solid aluminium plate in molten LiCl-KCl. The recommended conditions for the chlorination step are temperature 150°C and minimal possible molar ratio Cl2/UAl3.

SOUCEK Pavel;  MALMBECK Rikard;  MENDES Eric;  NOURRY Christophe;  GLATZ Jean-Paul; 

2009-12-15

French Nuclear Energy Society (SFEN)

JRC56080

https://www.sfen.fr/index.php/plain_site/global_2009,    https://publications.jrc.ec.europa.eu/repository/handle/JRC56080,