The effects of operating conditions such as crystal growing rateand initialimpurity concentrationon separation(or concentration) of cesium and strontium fission products in the LiCl waste salt generated from an electrolytic reduction process of spent oxides on lab-scale layer melt crystallization process wereanalyzed. In a layer crystallization process, impurities(CsCl and SrCl2) are concentrated in a small part of the LiClsalt due to the difference in the solubilityin the melt phase and the solid l phase. The crystal growth rate strongly affects the crystal structure, therefore the separation efficiency, but the effect of the initial Cs and Sr concentrationsin LiCl molten salts was nearly negligible within the experimental range.