Methane-Based Nuclear Thermal Propulsion Engine Considerations

A power balance model of a methane-based nuclear thermal propulsion (M-NTP) engine based on the Testing Reference Design (TRD) NTP engine was assembled in Simulink and a methane pyrolysis literature review was conducted to predict M-NTP engine performance. The literature review implied that the expected composition at the chamber will likely contain methane, ethane, acetylene, vinyl acetylene and molecular hydrogen with trace amounts of atomic carbon suggesting that carbon coking will likely not be a concern. The temperatures and pressures prior to entering the reactor fuel elements were well below the onset of methane pyrolysis leading to turbomachinery operation with pure methane. This study concluded that the expected performance of M-NTP engines will be between LCH4+LOx and LH2+LOx chemical rocket engines depending on the resulting species composition. Better estimates will require laboratory testing of methane pyrolysis at expected MNTP temperatures, pressures, and residency times.