OPERATION OF A SIMULATED NONSTEADY TOKAMAK FUEL LOOP USING THE TRITIUM SYSTEMS TEST ASSEMBLY

In order to develop a fuel system for a realistic fusion device in nea r future, a number of experimental campaigns of a simulated fusion fue l loop were performed under practical non-steady conditions at the Tri tium Systems Test Assembly (TSTA). Some technical issues specific for non-steady fuel loop were identified and are being investigated furthe r. The overall process loop was operated with non-steady inputs to bet ter interface with pulsed tokamak operation, which requires a rather d ifferent and improved processing capability specific to each subsystem . The cryogenic distillation columns in the isotope separation are mod ified to provide side-stream recycle paths with isotopic equilibration function. This change improved separation characteristics with variou s feed compositions, and reduces the required number of columns for pr ocessing and resulted in a reduced tritium inventory in the isotope se paration system (ISS). Another major technical development on the ISS is addition of a number of feed-back control loops that automatically operate the distillation columns stably under changing feed conditions . The plasma exhaust processing system composed of palladium diffuser, catalytic reactor, electrolysis cell and cold trap was operated mainl y in the batch mode to handle a broader range of input flow rate and c omposition in various configurations to minimize tritium loss and inve ntory. The results demonstrated the overall capability and flexibility of the TSTA loop to serve as a fuel processing system under non-stead y conditions; however, they imply that many technical issues arise in operating a practical fuel processing system. These may not be foresee n in the design stage and can only be determined during integrated tes ts under realistic operating conditions.