conduction is caused by the high temperature environment and the voltage gradient across the alumina insulator. The single crystal alumina has been successfully test at 1673, 1573 and 1473 K with a 4000 V/cm voltage gradient for times which are analytically predicted equivalent lifetimes of seven years at the GFS insulator maximum operating temperature of 1273 K. The single crystal alumina insulator is now being fabricated for testing with lithium on one side of the Nb-lZr and the single crystal alumina on the other side. The analyses predicts that the alumina insulator should also survive these system operating conditions without loss of its required performance. These tests are planned to be complete by the end of FY 1989. The first TE cell, labeled pre-development-one (PD-1) has been successfully assembled. Since this was done before all the flight components are developed it is slightly different than the GFS TE cell. The differences are shown in Fig. 25 as well as shown in comparison to the TE unicouple that is flight hardware. The development of sequence for the power conversion subsystem is as follows: (1) design the power converter to meet the system requirements; (2) develop the components for the TE cell; (3) assemble and test the predevelopment cells using the developed components; (4) assemble and test the development cell which use all the developed components and is prototypic of the flight cell; (5) fabricate and test 2x2, 2x4 and 2x6 TE cell arrays; (6) fabricate and test a 3 X 10 TE cell converter, which is one quarter of a TCA; and then (7) fabricate and test one TCA with lithium heating and cooling. When this sequence is completed successfully, the power converter subsystem technology is considered validated and ready for design, fabrication and qualification of a flight PCA. Heat Rejection Subsystem The heat rejection subsystem configuration and components for 1/12 of the 100 kWe GFS is shown in Fig. 26. The development effort for this subsystem has concentrated mainly on production heat pipes. The GFS heat pipe design was completely reviewed and approved for development at the system design review. The development of the heat-pipe wick and the heat pipe has resulted in analytical heat-pipe performance predictions which were verified by fabricating four niobium and four titanium heat pipes. A niobium heat pipe which was fabricated and tested verified the analytically predicted heat pipe performance limits as well as the heat pipe design requirement of 30 w/cm’2 radial heat flux with a single foil wick. Three titanium/potassium heat pipes were fabricated and shipped to Los Alamos National Laboratory for accelerated life testing. The parts for an additional three titanium heat pipes were also shipped to Los Alamos for assembly, filling and testing as part of the life-test matrix. Due to reduction in the FY 89 SP-100 project annual funding, the heat rejection subsystem development has been put on hold until more funds are available to complete this GES subsystem development. Power Conditioning Control and Distribution Subsystem This subsystem design was completed for the system design review and the configuration and components are shown in Fig. 27. The PCC&D subsystem has been designed using proven components to condition, control and distribute electrical power to the mission module and to the space reactor power system for its own control and operations.
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