[en] Several key NSSS auxiliary systems are needed to support the reactor and main heat transport systems. These auxiliary systems include fuel handling and storage, reactor auxiliary cooling, sodium purification, and cover gas processing and control. Work has been performed on each of these systems, either to develop appropriate system conceptual designs or to investigate problem areas and identify solutions. For the fuel handling and storage system, the reactor auxiliary cooling system (RACS), and the primary sodium purification system overall system designs have been generated. Conceptual and/or preliminary designs of major components have been generated. For the cover gas system, two key aspects have been studied. The cover gas pressure control performance requirements have been defined and a suitable control system identified. In addition gas leakage through the component-to-deck seals has been analyzed. Recommended seal types and configurations have been established