The electrochemical reduction of spent nuclear fuel in LiCl–Li
2O molten salt for the conditioning of spent nuclear fuel requires the separation of the residual salts from a reduced metal product after the reduction process. Considering the behavior of spent nuclear fuel during the electrochemical reduction process, a surrogate material matrix was constructed and inactive tests on a salt separation were carried out to produce the data required for active tests. Fresh uranium metal prepared from the electrochemical reduction of U
3O
8 powder was used as the surrogates of the spent nuclear fuel components which might be metallized by the electrochemical reduction process. LiCl, Li
2O, Y
2O
3 and SrCl
2 were selected as the components of the residual salts. Interactions between the salts and their influence on the separation of the residual salts were analyzed by differential scanning calorimetry (DSC) and thermogravimetry (TG). Eutectic melting of LiCl–Li
2O and LiCl–SrCl
2 led to a melting point which was lower than that of the LiCl molten salt was observed. Residual salts were separated by a vaporization method. Co-vaporization of LiCl–Li
2O and LiCl–SrCl
2 was achieved below the temperatures which could make the uranium metal oxidation by Li
2O possible. The salt vaporization rates at 950°C were measured as follows: LiCl–8 wt% Li
2O > LiCl > LiCl–8 wt% SrCl
2 > SrCl
2.
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