Low-enriched cermet-based fuel options for a nuclear thermal propulsion engine

Highlights: • Nuclear thermal propulsion (NTP) is efficient for Mars missions and beyond. • NTP can produce high thrust and high specific impulse. • Previous historical programs focused on highly enriched uranium (HEU). • LEU tungsten cermet fuel engine is proposed here. • Neutronic and T/H studies are conducted to identify the trade-offs. • The result is an engine design capable of meeting NASA's requirements. - Abstract: Nuclear thermal propulsion is the high thrust, high specific impulse rocket engine technology of choice for future missions to Mars and beyond. Previous engines designed and built under NASA's Rover program made use of highly enriched uranium, a significant barrier to development today due to the political climate. This paper focuses on developing a nuclear thermal rocket engine based on a low enriched uranium (LEU) tungsten cermet fuel. Generally, this design is based on the Pewee reactor built by NASA under the Rover program. However, multiple modifications are introduced to optimize the proposed LEU engine to produce the maximum efficiency while meeting NASA's ground rules as defined in the latest Mars reference missions. This paper presents numerous neutronic and thermal-hydraulic tradeoff studies to approach a near-optimum design. The result is an engine design capable of meeting, and in many cases surpassing, NASA's requirements of a 25 klb_f thrust engine with a thrust-to-weight ratio greater than 3.5 and a specific impulse greater than 900 s.