Regulatory-Compliant Tritium Mini-RHU: A Scalable Alternative for Next Gen. Space Power

City Labs proposes a Tritium Mini-Radioisotope Heater Unit (Mini-RHU) utilizing advanced tritium metal hydride technology to provide scalable, long-duration thermal energy for dynamic power conversion systems. The Tritium Mini-RHU is a compact, cost-effective alternative to traditional Pu-238-based Radioisotope Power Systems (RPS), offering thermal power ranging from milliwatts to hundreds of watts and beyond. Leveraging City Labs' expertise in tritium betavoltaics and metal hydride storage, the Mini-RHU uses titanium tritide as a heat source. Tritium’s advantages include minimal shielding requirements, long half-life, commercial availability, and low regulatory overhead. Following NSPM-20 guidelines, tritium RHUs will provide a streamlined regulatory framework for space launches. City Labs' state-of-the-art facility, capable of safely handling and loading tritium, positions the company to support future missions. The Mini-RHU’s modular design enables scalable power generation and meets NASA’s needs for high-efficiency, autonomous power systems in harsh space environments. Unlike Pu-238, tritium is readily available, significantly reducing both costs and regulatory complexities. City Labs’ facility is capable of managing tritium under high pressures and temperatures. Furthermore, City Labs is actively pursuing FAA payload approval for a 2026 launch of betavoltaic devices containing up to 20 kCi of tritium, reinforcing its commitment to safely integrating tritium-based technologies in space missions. This project’s intended deliverable, the 1,000 Ci Mini-RHU can be bundled to provide scalable power while reducing regulatory barriers, streamline mission planning, and provide a cost-effective, reliable power solution for lunar and deep-space exploration. It directly supports NASA's goals for long-duration lunar operations and high-power energy generation, advancing the integration of tritium-based RHUs into NASA’s RPS program.