Americium-241 Radioisotope Heater to Demonstrate Lunar Night Operations

Zeno Power Systems' Survive-the-Night Package will fly on Firefly Aerospace's Blue Ghost lander no earlier than 2028 as part of NASA's Commercial Lunar Payload Services initiative. The payload centers on a radioisotope heater unit powered by americium-241, designed to maintain critical spacecraft systems during the lunar night when surface temperatures plummet to -208°F or lower.

The lunar thermal environment presents one of exploration's most severe engineering challenges. Near the equator, daytime temperatures exceed 250°F, but darkness brings extreme cold. Permanently shadowed polar craters are even colder. The thin lunar atmosphere cannot retain solar energy, creating temperature swings of hundreds of degrees across the 14-Earth-day lunar cycle.

RHUs have historically used plutonium-238 to generate approximately 1 watt of thermal power, but supply constraints have limited availability
Zeno's design uses americium-241 with a novel fuel and shielding system to achieve higher specific power output
The unit generates passive thermal energy through radioactive decay, requiring no solar input or active power systems
Firefly's first Blue Ghost mission in early 2025 achieved the first fully successful commercial Moon landing and measured nighttime temperatures below -275°F

Supply Chain and Future Lunar Operations

Zeno's payload includes a dedicated platform with structural, communications, electrical, command and data handling, and thermal management subsystems. The radioisotope heater will operate during the lunar night following daytime operations powered by solar panels, demonstrating sustained surface capability across the full lunar cycle.

The demonstration addresses identified gaps in NASA's Moon Base Program, which has prioritized radioisotope power systems for extended lunar exploration. Firefly Vice President Ray Allensworth noted that firsthand thermal data from the first Blue Ghost mission informed development of technologies needed for long-duration surface operations supporting both government and commercial lunar activities.

Zeno's RHU maintains instrument functionality during extended darkness without relying on battery reserves or solar generation
The technology enables operations in permanently shadowed regions inaccessible to solar-powered systems
Successful demonstration will validate americium-241 as a plutonium-238 alternative for future deep space missions
The mission supports broader US space policy objectives announced through a National Security Presidential Memorandum targeting over 1,000 annual launches by 2030

Doosan Enerbility wins Natrium reactor component contract

Doosan Enerbility has secured a manufacturing contract to supply the core barrel, guard vessel and internal supports for TerraPower's Natrium reactor. The award follows a manufacturability review contract signed in December 2024 and reflects years of collaborative development between the two companies.

The contract represents a significant step toward commercial deployment of sodium-cooled fast reactor technology. Doosan Enerbility's scope encompasses critical internal components that support reactor operation and safety. The company has completed design maturity work to prepare for full-scale manufacturing orders.

Natrium technology and deployment timeline

The Natrium reactor is a 345 MWe sodium-cooled fast reactor paired with a molten salt-based energy storage system. The storage capability allows temporary output increases to 500 MWe, enabling the plant to respond to daily load variations and integrate with renewable energy sources.

TerraPower began non-nuclear construction of its first Natrium plant in Kemmerer, Wyoming in June 2024, with completion targeted for 2030. The project is being developed through the US Department of Energy's Advanced Reactor Demonstration Program and is positioned as the first commercial-scale advanced nuclear project in the United States.

Broader supply chain and partnerships

TerraPower has assembled a diverse supplier base for Natrium components. Spain's Equipos Nucleares SA will manufacture the reactor head, while Korea's HD Hyundai will produce the reactor vessel and France's Marmen will build the rotating plug.

Recent agreements between TerraPower, HD Hyundai and SK Innovation expand commercialization plans across the United States, South Korea and select international markets. TerraPower has also committed to supplying up to eight Natrium plants to Meta by 2035, signaling growing demand for advanced reactor capacity among large technology companies.

Manufacturing capability development

Doosan Enerbility's CEO Jongdoo Kim emphasized that the contract reflects established trust and collaboration with TerraPower. The company stated that successful execution will strengthen its SMR manufacturing capabilities and expand its role as a global nuclear supplier.

The multi-year partnership combines TerraPower's reactor technology and safety expertise with Doosan Enerbility's advanced manufacturing capabilities. The supplied components are expected to support timely construction and commercial operation of the first Natrium unit.

Canadian regulator approves Bruce Power hot cell for medical isotope processing

The Canadian Nuclear Safety Commission approved operation of a hot cell facility at Bruce Power following completion of construction in July. The facility represents a significant step in the operator's medical isotope production programme, which has expanded substantially over the past four years.

Bruce Power began producing cobalt-60 for medical sterilisation in 1986 and shifted to cancer-treatment applications in 2021. The operator became the first commercial nuclear facility to produce lutetium-177 in 2022 using an Isotope Production System installed in Bruce unit 7.

Facility capabilities and design

The hot cell enables remote handling of irradiated materials while minimising worker radiation exposure. The facility was constructed through collaboration between Bruce Power, Kinectrics and Bird Construction.

The new capability allows Bruce Power to perform Target Carrier Removal, a critical step in lutetium-177 production. This on-site processing reduces transportation requirements, lowers emissions and streamlines the production workflow.

Isotope applications and expansion

Lutetium-177 is a medium-energy beta emitter with a 6.7-day half-life, suitable for targeted cancer therapy and theranostics—an approach combining diagnostic and therapeutic methods using radiopharmaceuticals. The isotope can be produced by irradiating ytterbium-176 targets, which are then processed for distribution to healthcare facilities.

Bruce Power's CANDU reactors are particularly suited to medical isotope production alongside power generation. The operator is installing an additional Isotope Production System in Bruce unit 6 as part of broader expansion efforts.