The Tritium Systems Test Assembly (TSTA) has been operating for 4 years with tritium inventories of up to a million Ci and a cumulative (circulated) throughput of over 10 billion Ci to date. During the operational life of the facility 40,000 Ci of HTO waste have been intercepted by the tritium waste treatment system. Stack releases for the 4-year period have totaled < 40 Ci, and exposure to operating personnel has been < 3 mREM/person/yr. This excellect record is due in large part to high priorities placed on tritium-safe design concepts, but real-time computer diagnostics have been equally important in enabling us to anticipate and prevent potential releases of tritium.This work is supported by the US Department of Energy, Office of Fusion Energy.