An optimal model to schedule fuel regeneration is developed for the Tokamak Cryopumps and Cryogenic Viscous Compressors (CVCs) of the fuel cycle of ITER. The objective is to minimize the tritium inventory inside the Isotope Separation Systems (ISS) while supplying the tokamak's required amount of fuel considering fueling stages: ramp-up, flat-top, and ramp-down for each tokamak operation mode (Inductive, Hybrid, and NonInductive). Case studies of CVC regeneration times are presented to illustrate how CVC regeneration affects the ISS tritium working inventory. Results showed that nine iterations of CVC regeneration are enough to maintain ISS working tritium inventory management during Non-Inductive tokamak operation mode. The developed model uses mixed integer linear programming of the state-task network.