Interaction between UN and CdCl2 in molten LiCl-KCl eutectic. I. Experiment at 773 K

The interaction between UN and CdCl2 in the LiCl-KCl molten eutectic was studied at 773 K.The reaction was controlled by sampling the melt, as well as by analysis of the resulting precipitate. The process was shown to proceed according to several parallel reactions. The summary reaction was determined to have two stages: a fast one and a slow one. The 19–53% UN → UCl3 conversion was obtained for the molar ratio of CdCl2/UN = 1.22–14.9. The rest of UN converts into the precipitate of complex composition (UNCl + U2N3 + U4N7 + UN2). The increase in the CdCl2/UN molar ratio from 1.22 to 14.9 resulted in the decrease in duration of the first “fast” stage of the process from 18 h to 1 h. Keywords: Spent nuclear fuel, Nitride nuclear fuel, Chlorination, Pyrochemistry, UN, UNCl, Molten salts