NASA is nearing completion of the initial phase of its fission surface dynamics project, which is focused on developing a conceptual design for a small-scale power-generating nuclear fission reactor that could be used in future lunar demonstrations and inform future Martian designs.
NASA awarded three $5 million contracts in 2022 for each commercial partner to develop an initial design, including a reactor; its power conversion, heat dissipation, power management and distribution systems; estimated costs; and a development program that could pave the way for a sustained human presence on the lunar surface for at least a decade.
A nuclear power source needs to be demonstrated on the moon to prove that it is a safe, clean, reliable option," said Trudy Cortez, director of the Technology Demonstration Mission Program at the Space Technology Mission Directorate at NASA's headquarters in Washington.
From a technical point of view, the moon's night is challenging, so having an energy source like this nuclear reactor that operates independently of the sun is a favorable option for long-term exploration and scientific work on the moon. ”
While solar power systems have limitations on the Moon, nuclear reactors can be placed in permanently shaded areas (where there may be water ice) or continuously generate electricity at night on the Moon (14 and a half Earth days long).
NASA's design requirements for this initial reactor are open and flexible to maintain the ability of commercial partners to bring creative approaches to the technical review.
There are a variety of methods; They are very unique to each other," said Lindsey Carldon, program manager for fissile surface dynamics at NASA's Cleveland Glen Research Center. "We deliberately didn't ask them too much because we wanted them to think outside the box. ”
However, NASA does stipulate that the reactor should be kept under 6 tons in weight and capable of producing 40 kilowatts (kW), ensuring that there is enough power for demonstration purposes and providing additional power to run lunar habitats, rovers, backup grids, or scientific experiments. In the United States, an average of 40 kW can provide electricity to 33 homes.
NASA has also set a goal that the reactor should be able to operate for ten years without human intervention, which is key to its success. Safety, especially in terms of radiation dose and shielding, is another key driver of the design.
In addition to the set requirements, the partners envisioned how to start and control the reactor remotely. They identified potential faults and considered different types of fuels and configurations. Having ground-based nuclear companies work with companies with expertise in space can generate a wide range of ideas.
NASA plans to extend three contracts for the first phase to gather more information before the second phase, when the industry will be invited to design the final reactor for demonstration on the moon. Carlton said this additional knowledge will help the agency develop the requirements for the second phase.
We got a lot of information from the three partners," Carlton said. "We have to take some time to process all of this and see what it makes sense to move into Phase 2 and take the best out of Phase 1 to determine the requirements for designing a low-risk system. ”
The second phase is scheduled for a public tender in 2025.
After the second stage, the target date for delivering the reactor to the launch pad is the early 2030s. On the moon, the reactor will complete a one-year demonstration, followed by nine years of operation. If all goes well, the reactor design may be updated for use on Mars.
In addition to preparing for Phase II, NASA recently awarded contracts to Rolls-Royce North American Technologies, Brayton Energy and General Electric for Layton power converters.
The heat energy produced by nuclear fission must be converted into electricity before it can be used. The Brayton converter solves this problem by taking advantage of the difference in heat to rotate the turbine inside the converter. However, current Brayton converters waste a lot of heat, so NASA has asked companies to improve the efficiency of these engines.
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