NASA talks about building a nuclear reactor in space and what’s next


Earlier this year, the U.S. Department of Energy (DOE) awarded three contracts, each worth approximately $5 million, to three companies for surface energy system design proposals. nuclear fission that can be deployed on the Moon. According to NASA, such technology could be deployed on the Moon by the end of the decade.

Funds granted by DOE contracts are to be used for the development of initial design concepts for a 40 kilowatt fission power system that should be designed to last at least 10 years in the harsh environment of the Moon. Lockheed Martin, Westinghouse and IX were the companies selected for the contract and all three will partner with other companies for the development of the design.

Since nuclear fission systems are relatively small and light, they are ideal for the lunar environment. They can also reliably generate electricity without depending on location, available sunlight and other natural conditions. If such technology is successfully developed and deployed, it could pave the way for long-duration missions to the Moon, Mars and beyond.

Todd Tofil, Fission Surface Power Project Manager at Nasa’s Glenn Research Center, interacted with by email.

The interview has been edited and condensed.

Q. Nuclear reactors on Earth are usually placed in large containment buildings, but the artist’s depiction of a reactor on the Moon does not appear to have such a structure. What is the reason for this?

Tofil: The reactor for the Moon has containment, but it is much smaller than what is needed for a terrestrial reactor. A typical terrestrial nuclear reactor generates 1000 megawatts of power, while the lunar reactor will produce 40 kilowatts, or 0.04 megawatts. Because the lunar reactor contains much less nuclear material, the structure (including containment and shielding) is much smaller than that needed for a typical terrestrial reactor.

Safety is a fundamental principle for all activities carried out by NASA, on Earth and in space, and safety is integrated into every phase of the design, testing, manufacture and operation of space nuclear systems. . The design of the lunar system will provide the same standards of protection and security applied to terrestrial systems.

Q. What are the biggest challenges that need to be overcome before such a reactor can be deployed on the Moon?

Tofil: One of the challenges is that the launch and ascent to the Moon involves strong vibrations and shocks as the rocket stages separate after burning their fuel. A space reactor must have a rugged and robust design for structure, electronics, communications equipment, and power conversion equipment to survive the launch environment. Another challenge for operating on the surface of the Moon is rejecting the power processing heat produced by the reactor. Water or air cooling systems like those used on Earth are not possible on the Moon.

Instead, NASA will need thermal radiators to cool the reactor by rejecting waste heat to space. It’s the same process used to manage heat on the International Space Station. Finally, another challenge is to operate the power plant 250,000 miles from Earth. Autonomous control systems should be developed and tested to ensure safe operation and fault detection. All of these challenges can and will be overcome through detailed design and testing activities.

Q. How much harder would it be to deal with a nuclear meltdown in space, compared to a meltdown on Earth?

Tofil: Such an event is extremely unlikely. Safety analyzes will include all aspects, both normal and abnormal operational phases of the system. NASA places a very high priority on safety, and safety is built into every phase of the design, testing, manufacturing, and operation of space nuclear systems.

This includes multiple layers of protection features within a power system that minimize the risk of failure during operation as well as backup safety controls in the event of a failure. For example, the lunar surface fission power system will have redundant control measures to detect a fault and shut down the reactor long before its operation becomes critical. The control subsystems will have active and passive measures to ensure that the reactor core can be brought back to a subcritical state and that the reactor fuel is operating at stable temperatures at all times.

Q. What effect will fluctuating ambient temperatures on the moon have on the operation of such a reactor?

Tofil: The system’s thermal management design accounts for fluctuating ambient temperatures on the lunar surface. Radiator panels are used to reject waste heat to the space over the entire operating temperature range. The size of the thermal radiator panels will be designed to withstand even the most extreme lunar conditions.

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