Public reporting burden for this collection of information is estimated to average 1 hour per response, including g the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of the collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate This document has been approved for public release; its distribution is UNLIMITED. 12b. DISTRIBUTION CODE13. ABSTRACT In this project, the components of a Stirling space nuclear power system were modeled using MATLAB® and Simulink® under both steady state and transient conditions. Using information provided through NASA's Glenn Research Center, the Department of Energy's Naval Reactors, and literature from previous work in nuclear space power systems, the system architecture was developed. At steady state, the space power system was designed to produce 200 kW(e) and consisted of a NaK cooled fast reactor linked to four Stirling power converters via two NaK heat transfer loops connected by heat exchangers. A third NaK heat transfer loop was used to transport the waste heat of the Stirling converters to radiator panels, which radiate the heat into ambient space. Heat pipes were modeled which linked the secondary heat transfer loop to the Stirling converters and the third heat transfer loop to the radiator panels. An alternator was used to convert the thermal power input of the Stirling converters into electrical power. The model was based on combining the point reactor kinetic equations with transient energy, force, volume, and mass balances for system components outside the reactor. The model was tested with dynamic perturbations that included small reactivity changes in the reactor, Stirling converter failures, effects of planetary albedo, and electrical resistance load changes. At steady state, the model produced the expected temperatures, pressures, flow rates, and heat flows. The dynamic simulations indicated that the overall system would be load following and stable to external perturbations. However, in cases that varied the electrical load resistance, the thermal efficiency of the Stirling converters were significantly affected. NUMBER OF PAGES 134 SUBJECT TERMS:Stirling space nuclear power system ; space power system ; nuclear power ; converters AbstractIn this project, the components of a Stirling space nuclear power system were modeled using MATLAB ® and Simulink ® under both steady state and transient conditions. Using information provided through NASA's Glenn Research Center, the Department of Energy's Naval Reactors, and literature from previous work in nuclear space power systems, the system architecture was developed. At steady state, the space power system was designed to produce 200 kW(e) and consisted of a NaK cooled fast reactor linked to four Stirling power converters via two NaK heat transfer loops connected by heat ...