The fueling system for ITER is designed to provide gas injection to maintain the plasma edge and divertor conditions and solid pellet injection for deep fueling of the reacting plasma. Two pellet injectors are to be provided by the US for fueling using deuterium-tritium pellets with up to 90% tritium content. The pellet fueling rate is specified to be a maximum of 100 Pa-m3/s (50 Pa-m3/s of T2). This is equivalent to 0.23 g/s or ~1.0 cm3/s solid DT to be delivered to the plasma, which is a significant extrapolation from present fusion fueling devices. Screw type extruders are under development to supply this quantity of solid DT for long durations. A repeating gas gun accelerator is planned for the pellet injectors. The screw extruder supplies the DT ice that is cut into pellets and placed in a barrel for acceleration by a low gas throughput propellant gas valve. The injector utilizes a recirculating propellant gas system and a recirculation of the excess extrusion material in order to offload the handling of these gas streams by the tritium plant. Details of the design and results of a prototype twin-screw deuterium extruder experiment will be presented.