A dynamic simulation has been developed for the ITER fuel cycle including vacuum pumping, fuel processing, fueling, pellet injection, tritium breeding blanket detritiation, fuel purification and isotope separation. The dynamic simulation model is used for calculating the unsteady-state flow of materials through the various fuel processing systems. Since many of the systems have substantial hold-up times, and the ITER reactor burn and dwell cycle is periodic, a steady state model cannot provide a complete picture of system behavior. The dynamic model allows assessment of flowrates and minimum and maximum inventories under a wide range of dynamic conditions. This information is necessary for proper specification of system design requirements.