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.