An integrated analysis of a NERVA based Nuclear Thermal Propulsion system

This paper presents results and conclusions derived from an integrated analysis of a NERVA based Nuclear Thermal Propulsion (NTP) system. The NTP system is sized to generate a thrust of 70,000 N (15,000 lb(f),), and have a specific impulse (I-sp) of 860 s. This implies a reactor that operates at 350 MWth and has a mixed mean propellant outlet temperature of 2760 K. The integrated analysis will require that self-consistent neutronic/thermalhydraulic/stress analyses be carried out. The major code packages used in this analysis are MCNP, RELAP, and ANSYS. Results from this analysis indicate that nuclear data will have to be re-generated to cover the wide temperature range, zone loading will be necessary to avoid entering the liquidus region for the fuel, and the effectiveness of the ZrC insulator will have implications for bi-modal applications. These results suggest a path forward in the development of a viable NTP system based on a NERVA reactor should initially concentrate on fuel and structural materials and associated coating development. A series of safety related criticality determinations were carried out addressing water immersion following a launch incident.