Non-stationary separation processes of multicomponent isotope mixtures seem to be efficient in enriching components of small abundance. Using the separation of (SF6)-S-36 from its multicomponent isotopic mixture SF6 as an example, a numerical simulation method is applied to predict a nonstationary separation process occurring in a short gas centrifuge cascade, and also a corresponding experiment is carried out. The concentrations of the components in the SF6 isotope mixture are measured at different times during the separation process. The simulation results are in good agreement with the experimental ones. As an example of application of the simulation method to practice, a cascade is designed to separate the (SF6)-S-36 component to a concentration of over 99% from the isotopic mixture of natural abundance.