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Recent Generic Flight System (GFS) updates have necessitated revisions in the initial startup and restart control strategies. The design changes that have had the most impact on the control strategies are the addition of the Auxiliary Cooling and Thaw (ACT) system for preheating the lithium filled components, changes in the reactivity worths of the reflectors and safety-rods such that initial cold criticality is achieved with only a small amount of reflector movement following the withdrawal of the safety-rods, and the removal of the scram function from the reflectors. Revised control and operating strategies have been developed and tested using the SP-100 dynamic simulation model, ARIES-GFS. The change in the total reactivity worths of the reflectors and safety-rods has eliminated the need for the use of fast and slow reflector drive speeds during the initial on-orbit approach to criticality.

The SP-100 Space Reactor Power System is being developed by GE, under contract to the U.S. Department of Energy, to provide electrical power in the range of 10's to 100's of kW. The system represents an enabling technology for a wide variety of earth orbital and interplanetary science missions, nuclear electric propulsion (NEP) stages, and lunar/Mars surface power for the Space Exploration Initiative (SEI). An effective infrastructure of Industry, National Laboratories and Government agencies has made substantial progress since the 1988 System Design Review. Hardware development and testing has progressed to the point of resolving all key technical feasibility issues. The technology and design is now at a state of readiness to support the definition of early flight demonstration missions. Of particular importance is that SP-100 meets the demanding U.S. safety, performance, reliability and life requirements.

The approach that was utilized to start up and requalify manufacture of the thermoelectric unicouple devices for the Cassini RTG (Radioisotope Thermoelectric Generator) program are described in this paper. Key elements involved in this effort were: engineering review of specifications; training of operators; manufacturing product verification runs; and management review of results. Appropriately, issues involved in activating a fabrication process that has been idle for nearly a decade, such as upgrading equipment, adhering to updated environmental, health, and safety requirements, or approving new vendors, are also addressed. The cumulative results of the startup activities have verified that a production line for this type of device can be reopened successfully.

The major technological developments which have made possible the trend towards higher temperatures in modern aircraft gas turbine engines are discussed. The relative importance of manufacturing processes, material developments, cooling techniques, analytical design procedures, rupture and cyclic life considerations, and aerodynamic and mechanical design improvements are discussed along with illustrative examples and technical data. The need for a balanced design approach is stressed, and examples are given where trade-offs can be made. It is noted that the advances in aircraft engines during the last 10 years have been based on the evolution of sound engineering principles, extensive component and engine development, and careful consideration of the operational requirements rather than a tremendous breakthrough or revolutionary concept in any one area.