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Initial preliminary development phases of two distinct SP-100 control drive assembly bearing test programs were successfully completed at elevated temperature in vacuum. The first was for the reflector drive line spherical self-aligning bearings. Each bearing consisted of a carbon-graphite ball mounted on an aluminum oxide-coated Ta-10%W shaft, captured by an aluminum oxide-coated Ta-10%W socket. One set of these bearings was exposed to temperatures up to 1180K (1665°F) at 1.33x10-6 Pa (1x10-8 torr) and subjected to 38000 cycles of motion. Friction coefficients were found to be between 0.11 and 0.25 over the full range of operation. Overall performance of the bearings was excellent, with only slight wear observed. The second test program was for the safety rod slider bearing. Zirconium carbide coated Nb-1%Zr bearing pads were stroked inside a molybdenum tube at temperatures up to 1422K (2100°F) at ∼1.33x10-6 Pa with a normal load of 1.02 Kg between each sliding surface.

The SP-100 reactor will operate at temperatures up to 1500K in high vacuum. Development of bearing coatings is necessary to avoid self welding and/or galling of moving components. No experience base exists for these conditions-the early SNAP (Space Nuclear Auxiliary Power) program requirements were over 400K lower with shorter lifetime requirements. To address the SP-100 needs, a tribology development program has been established at GE to investigate candidate coating materials. Materials were selected based on their high thermodynamic stability, high melting point, compatibility with the substrate, and coefficients of thermal expansion similar to niobium-1% zirconium - the candidate structural material for SP-100. An additional requirement was that the deposition processes should be commercially available to coat large components.

As part of the SP-100 Space Reactor Power System Program being undertaken for the U. S. Department of Energy, GE is developing a thermoelectric (T/E) power converter which utilizes reactor delivered heat and transforms it into usable electric power by purely static means. This converter is based to GE's product line of successful thermoelectric space power systems. The SP-100 power converter embodies the next generation improvement over the type of T/E converter successfully flown on the six U. S. space missions. That is, conduction coupling of T/E cell to both the heat source and the heat rejection elements. The current technology utilizes radiation coupling in these areas. The conduction coupling technique offers significant improvements in system specific power since it avoids the losses associated with parasitic ΔT's across the radiation gap between the heat source and the hot junction of the thermoelectric (T/E) cell.

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.

Previous studies had demonstrated the economic and technical feasibility of producing high-quality forgings for aircraft turbine engine parts from hot-isostatically pressed (HIP) Rene 95 powder billets. The present program was aimed at developing a production practice for making HIP + forged turbine discs. The major goal was improved product fabricability and reliability with minimum cost. The program was conducted using argon atomized Rene 95 powder. Experimental studies were conducted to evaluate the effect of powder characteristics, HIP parameters, preform design, and forging conditions on forgeability, microstructure, and mechanical properties. The results of these studies were incorporated into a pilot production run in which 10 disc forgings were made and evaluated. The selected process involved the consolidation of -60 mesh powder to full density by hot-isostatic pressing at a temperature above the γ' solvus temperature.

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.

Long term multimanned space missions present numerous complex problems in devising a suitable life support system. Among these problems is the management of the waste Products generated during the mission. A promising approach appears to be the wet oxidation process wherein the organic waste materials are decomposed at high pressures (50 atm or higher) and intermediate temperatures (100 - 300 C). This technique is promising because: effluent may be used as a nutrient media, and thermodynamically it is exothermic. Problems associated with the adoption of this approach to waste management are amenable to experimental investigation and resolution.