Refractory Metal Coated Uranium Nitride Fuel for Nuclear Thermal Propulsion

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.nbsp; A critical aspect of the program is to develop a robust, stable cermet based nuclear fuel.nbsp; 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.nbsp; As a result, uranium nitride (UN) has been selected as the nuclear fuel.nbsp; 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.nbsp; 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.nbsp; 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.nbsp; In addition, techniques are needed to produce spherical UN particles for subsequent coating.nbsp; Therefore, an innovative Plasma Alloy and Spheroidization (PAS) process will be used to produce spherical UN particles.nbsp; For the Phase I investigation, a UN surrogate will be used.nbsp; 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.nbsp; During Phase II, the spheroidization and coating techniques will be optimized.nbsp; 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.nbsp;