As part of the Game Changing Development (GCD) Program, Nuclear Thermal Propulsion (NTP) has been identified as a critical technology needed for human missions to Mars due to its high specific impulse (Isp) as compared to traditional chemical propulsion systems. A critical aspect of the program is to develop a robust, stable cermet based nuclear fuel. To reduce cost and potential burdensome security and handling requirements, one of the primary goals of the GCD Program is to use low enriched uranium (LEU) fuel. As a result, uranium nitride (UN) has been selected as the nuclear fuel. However, techniques are needed to produce refractory metal coatings on the UN particles to allow fabrication of the cermet fuel element and to protect the UN from the hydrogen propellant. In addition, the UN particles will be susceptible to oxygen, so the refractory metal coating is also needed to protect the UN particles from oxidation. During this investigation, advanced coating techniques such as autocatalytic molten salt (AMS) plating and physical vapor deposition (PVD) will be evaluated for producing the refractory metal coating. In addition, techniques are needed to produce spherical UN particles for subsequent coating. Therefore, an innovative Plasma Alloy and Spheroidization (PAS) process will be used to produce spherical UN particles. For the Phase I investigation, a UN surrogate will be used. Detailed characterization of the as-received, post-spheroidized, and post-coated particles will be used to aid in the down selection of the most promising coating technique at the conclusion of the Phase I investigation. During Phase II, the spheroidization and coating techniques will be optimized. Coated particles will be produced and this material will be used to produce cermet based fuel elements that will be delivered to NASA for testing in CFEET and NTREES.
The proposed technology supports NASA’s GCD Program and would directly benefit Nuclear Thermal Propulsion (NTP) and Nuclear Electric Propulsion (NEP). Space nuclear power and propulsion are game changing technologies for space exploration. Potential NASA missions include rapid robotic exploration missions throughout the solar system and piloted missions to Mars and other destinations such as near earth asteroids.
Commercial sectors that will benefit from this technology include medical, power generation, electronics, defense, aerospace, chemicals, and corrosion protection. Targeted commercial applications include net-shape fabrication of refractory metals for rocket nozzles, crucibles, heat pipes, propulsion components, sputtering targets, turbines, rocket engines, and nuclear power components.