SUMMARY

Nuclear thermal propulsion offers high thrust and specific impulse engine capabilities for future manned missions to Mars and beyond. Legacy nuclear engine designs experimented with highly enriched uranium for engine maneuvers. Extensive research is performed to analyze the behavior of low enriched uranium reactors for engine application to meet the current regulation limits associated with uranium fuel systems. Most of these analyses are focused on sophisticated steady-state calculations to determine key engine performance parameters. Often time these computational frameworks decouple various engine components in the calculation phase, resulting in uncertainties. The challenges and limiting factors associated with transient operations in low enriched uranium reactors, such as engine startups and shutdowns, are also not well understood. The objective of this thesis is to present a computational transient framework that examines a system-wide low enriched uranium nuclear thermal engine. The framework leverages the use of a steady-state code to converge on pumping requirements and conserve enthalpy prior to the start of a transient. A separate script in the framework can generate operational maps that show the feasibility of control based on nozzle chamber conditions for a given user-inputted engine design. The results examine sensitivity studies to show the feasibility of an engine startup through the perturbation of various key factors.