Description: A key requirement for high efficiency and the long-term reliability of Fission Power Systems (FPS) is the embedment and metallurgical connection of the heat pipes within the radioactive core material. Creating intimate contact between the heat pipes and the core material with a high thermal conductivity joint enables FPSs to operate at their optimum performance. This proposed Phase II Sequential Effort will advance NASA’s Moon to Mars objectives by facilitating the rapid infusion of this consolidation and joining technology into NASA’s FPSs, particularly for manned lunar missions by improving and optimizing the exchange of thermal energy at the heat pipe to the core interface. This Sequential effort is timely for infusion into upcoming designs for lunar missions; and that success then will be leveraged for Mars missions. Peregrine Falcon Corporation (Peregrine) utilizing our proprietary technology in Liquid Interface Diffusion (LID) bonding will create a solid state joint between the Heat Pipe Wall material and the uranium core material of FPSs. LID bonding relies upon pressure and time at elevated temperatures to depress the melt point of an intermediate material to create incipient melting to initiate metallurgical joining. In this development, force is used to consolidate the heat pipe/core assembly to drive out any gaps and/or voids within the contained assembly and just as important develops pressure across the heat pipe to core interface. Temperatures, durations and pressures have been selected and verified in Phase I and II to create a solid state joint resulting in a high thermal conductivity connection at the heat pipe to core interface. This allows FPSs to operate at their peak performance.

Benefits: The development and characterization of embedment of heat pipes into cores for Fission Power Systems (FPS) will “enable” thermal transfer throughout all FPS versions to optimize performance and reliability. This technology also will allow heat exchanger tubes to be embedded into nuclear thermal power systems. Missions include: Fission Power Systems (10 kWe) for manned lunar missions. Fission Power Systems (≥10 kWe) for manned Mars missions. Fission Power Systems for deep space probes. Nuclear Thermal Propulsion (NTP)

Other projects benefiting from this development will be: Project Pele, a micro reactor project intended for commercial and government applications Project DRACO a DARPA program to develop Nuclear Thermal Propulsion Other small high-performance reactor projects for remote power applications The LID Bond technology developed under this SBIR can be used to embed many other materials within a matrix