The SAFE 30 is a simple, robust space fission power system that is comprised of several independent modules. Each module contains 4 fuel tubes bonded to a central heatpipe. Fission energy is conducted from the fuel tubes to the heatpipe, which in turn transfers the energy to a power conversion system. This paper benchmarks a thermal model of the SAFE 30 with actual test data from simulated SAFE 30 module tests. Two “dummy” SAFE 30 modules were fabricated—each consisted of 4 1-inch dia. tubes (simulating the fuel tubes) bonded to a central 1 dia. tube (simulating the heatpipe). In the first module the fuel tubes were simply brazed to the heatpipe along the line of contact (leaving void space in the interstices), and in the second module the tubes and heatpipe were brazed via tri-cusps that completely fill the interstices between the tubes. In these tests, fission energy is simulated by placing resistance heaters within each of the 4 fuel tubes. The tests were conducted in a vacuum chamber in 4 configurations: tri-cusps filled with and without an outer insulation wrap, and no tri-cusps with and without an outer insulation wrap. The baseline SAFE 30 configuration uses the brazed tri-cusps. During the tests, the power applied to the heaters was varied in a stepwise fashion, until a steady-state temperature profile was reached. These temperature levels varied between 773 K and 1073 K. To benchmark the thermal model, the input energy and chamber surface temperature were used as boundary conditions for the model. The analytical results from the nodes at the same location as the test thermocouples were plotted again test data to determinate the accuracy of the analysis. The unknown variables on the analysis are the radiation emissivity of the pipe and chamber and the radiation view factor between the module and the chamber. A correlation was determined using a parametric analysis by varying the surface emissivity and view factor until a good match was reached. This model and the corresponding data will later be used to evaluate the heat transfer characteristics of the SAFE 30 core, and perform various design trade-offs. Finally, the test data is evaluated to determine the effect of the tri-cusp insert on heat transfer. It is found that the tri-cusps cause a significant increase in module heat transfer.


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    Title :

    Safe affordable fission engine (SAFE 30) module conductivity test thermal model correlation


    Contributors:

    Conference:

    Space Technology and Applications International Forum - 2001 ; 2001 ; Albuquerque, New Mexico


    Published in:

    AIP Conference Proceedings ; 552 , 1 ; 849-853


    Publication date :

    2001-02-02


    Size :

    5 pages





    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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