A simple and effective separation of UO2 and Ln2O3 assisted by NH4Cl in LiCl–KCl eutectic

For UO 2 -based spent fuel , it is usually electrochemically reduced and then refined in molten salt with respect to the so-called pyrochemical reprocessing approach. In this work, we report a new method with the assistance of NH 4 Cl to directly achieve convenient separation of UO 2 over La 2 O 3 in Ar atmosphere which does not require an electrochemical process . According to the results from both powder and pellet samples, the separation is achieved by dissolving La 2 O 3 into the LiCl–KCl molten salt with NH 4 Cl, whilst UO 2 cannot be dissolved and remains in solid form. It was found that the dissolution kinetics of La 2 O 3 in the powder sample was fast and its removal efficiency in the mixture of La 2 O 3 and UO 2 was high, but a specific amount of UO 2 was also dissolved, which lead to a low recovery efficiency of UO 2 . In contrast, when the pellet samples after sintering at 1473 K were used, the recovery efficiency of UO 2 can be increased. Nevertheless, the dissolution kinetics of La 2 O 3 was correspondingly reduced, and more NH 4 Cl was required to complete the dissolution reaction . By improving and optimizing the experimental conditions, the UO 2 recovery efficiency of 92.0% can be achieved, while the removal efficiency of La 2 O 3 was 94.4%. More importantly, this novel separation method may be also useful for the separation of UO 2 over mixed lanthanide oxides.