Evaporation of CsCl, BaCl₂, and SrCl₂ from the LiCl–Li₂O molten salt of the electrolytic reduction process

Abstract

The metal product from the electrolytic reduction of oxide spent fuel in LiCl–Li₂O molten salt retains about 20 wt% of the residual salts, which contain some salt-soluble fission products such as Cs, Sr, and Ba. To separate the residual salt from the metal product of the electrolytic reduction, the evaporation behaviors of the LiCl and salt-soluble chlorides were investigated using the vacuum distillation equipment. The evaporation rate of the LiCl molten salt was considerably decreased by the addition of BaCl₂, SrCl₂, and Li₂O. For LiCl and CsCl, the complete removal of the salts from the evaporator was accomplished by reducing the pressure to less than 100 mTorr and heating to 900 °C. However, for BaCl₂ and SrCl₂, only about 30 % were vaporized at 900 °C. BaCl₂ and SrCl₂ were not vaporized by their own single component, but could be vaporized through a co-vaporization with LiCl salt. Evaporation efficiencies of 100 % were achieved by heating above 1,000 °C.