The metal product from the electrolytic reduction of uranium oxide in LiCl molten salt retains about 10 ~ 20wt% of the residual salts. Salt vacuum distillation is conducted to separate the residual salt from the metal product and well-performed in a glove box in an argon atmosphere. A dimensionless analysis of the characteristics of a salt vacuum distiller needs to be scaled up for a high capacity process. The vacuum distillation apparatus can be of two different sizes (M-type and P-type). M-type equipment is small in size and exhibits a high recovery rate of more than 95%. A comparison of two salt vacuum distillers was conducted with the dimensionless analysis method. Heat and fluid flows are strongly influenced by the structure of the apparatus and phase transition phenomena of vacuum distillation. The several dimensionless parameters were calculated at the nozzle throat located between the evaporator and the receiver and at different operating temperatures. Both salt vacuum distillers had similar trends of dimensionless parameters. However, the distributions of the parameter values varied with the nozzle geometry and size. The results of the dimensionless analysis will aid the scaling up of the salt distillation process.