Adapted by:
Matías S. Zavia
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Alba Mora
WriterAn established tech journalist, I entered the world of consumer tech by chance in 2018. In my writing and translating career, I've also covered a diverse range of topics, including entertainment, travel, science, and the economy.
The U.S. and China are currently in a competition to establish a lunar base. While NASA triumphed in the previous race to the Moon against the Soviet Union, its current standing is less clear. In fact, Chinese scientists recently criticized a key element of NASA’s lunar program: its power source.
NASA’s nuclear fission reactor. NASA is spearheading U.S. efforts to establish a presence on the Moon, working alongside its Artemis Accords partners. Meanwhile, the China National Space Administration (CNSA), along with Russia’s Roscosmos and a select group of allies, is progressing toward the development of the International Lunar Research Station (ILRS). The ILRS is expected to become operational in 2036 and house thousands of scientists.
On the Moon, a night lasts for 14 Earth days, which means space agencies will need more than just solar panels to sustain the facility’s energy supply. For several years, NASA has been developing a small nuclear power plant designed specifically for operation on the Moon’s surface. This compact fission reactor, known as Fission Surface Power (FSP), is capable of generating 40 kW of power.
Issues with NASA’s design. Analysts at the China National Nuclear Corporation (CNNC) examined NASA’s proposal and found areas needing improvement. A study published in the Chinese scientific journal Atomic Energy Science and Technology discusses these shortcomings. The research work focuses on the composition of the nuclear fuel, the cooling system, and the safety mechanisms of the U.S. reactor.
Chinese scientists acknowledge the compact design of the FSP reactor but criticize the choice of fuel. Their study indicates that using cylindrical rods of highly enriched uranium will necessitate thick layers of beryllium as shielding to manage the intense radiation.
Additionally, according to Chinese researchers, this choice could limit the reactor’s operational lifespan to about eight years due to fuel swelling. This phenomenon causes the material to gradually expand in volume as a result of radiation exposure. Scientists also point out that the reactor’s basic control mechanism may be less safe in critical situations.
China’s proposal. In addition to highlighting the shortcomings of the U.S. design, CNNC scientists introduced an improved version of the fission nuclear reactor. They reference both NASA’s design and an early Soviet space reactor known as TOPAZ-II.
The main improvements of the Chinese reactor are:
- Ring-shaped fuel rods: Unlike solid cylinders, these rods are designed as hollow rings. Inside each ring are small uranium dioxide pellets encased in stainless steel. This design allows for better heat dissipation from the nuclear reaction, utilizing both the inner and outer surfaces of the ring for cooling.
- Dual cooling system: The Chinese reactor employs a cooling system based on a liquid metal (NaK-78) that circulates through the inner and outer channels of the ring fuel rods. This setup helps maintain the reactor temperature below 1,110 degrees Fahrenheit, enhancing safety and stability.
- A more efficient neutron moderator: The design uses a material called yttrium hydride (YH1.8) as a moderator, which slows down neutrons to improve the nuclear reaction’s efficiency. Yttrium hydride is more stable than traditional moderators, like zirconium hydride. This reduces the risk of dangerous hydrogen leaks and increases reactor safety and lifespan.
- Less nuclear fuel required: Thanks to its innovative design and the use of yttrium hydride, the Chinese reactor only requires 40 pounds of uranium-235. In contrast, NASA’s FSP reactor requires around 154 pounds, almost four times as much. This weight reduction is crucial for space missions. It lowers costs and makes launching nuclear materials through the Earth’s atmosphere safer.
How will the U.S. respond? The Chinese reactor is up to 75% more efficient than NASA’s and boasts a 10-year operational lifespan, compared to eight years for the U.S. reactor. A reliable nuclear reactor will be essential for supporting long-term inhabited bases. As such, the recent advancement could place China ahead of the U.S. in the pursuit of establishing a sustainable, self-sufficient presence on the Moon.
However, NASA’s design is neither monolithic nor fixed. Just as China has done, the agency should leverage its competitor’s research to enhance its own technology. This dynamic could also extend to companies developing small modular reactors to supply electricity on Earth. In the end, space races drive innovations and advances in technology that eventually benefit other industries.
Image | NASA
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