Reactors on the Moon, Rules Still on Earth
In late August, NASA asked contractors to prepare a nuclear reactor that could be launched by December 2030 and run without maintenance near the lunar south pole. Russia, in partnership with China, is working on its own reactor, called Selena, for 2036. According to a recent New York Times investigation, the rush has a clear motive: NASA fears that a rival reactor could create a de facto exclusion zone on the Moon.
That fear says a lot about where this race is heading. A reactor is not only a source of power for a future base; it is a way to claim a place. And yet the rules that should govern these machines were written for a very different moment.
What the rules say today
Two instruments deal directly with nuclear power in space. The first is the 1992 UN Principles Relevant to the Use of Nuclear Power Sources in Outer Space, adopted by the General Assembly. They require safety assessments, limit when a reactor can become critical (only once it has reached its operating orbit or trajectory), and call for prompt notification if a malfunction could lead to the return of radioactive material to Earth. The second is the 2009 Safety Framework, prepared jointly by the UN Committee on the Peaceful Uses of Outer Space (COPUOS) and the International Atomic Energy Agency (IAEA), which offers goal-based guidance for states and organizations.
Both are soft law. Neither creates binding obligations, and neither has a body to check whether states comply. The only binding anchor is Article IX of the Outer Space Treaty, which asks states to consult each other before an activity that could cause harmful interference with the activities of others. It is a useful principle, but it was not designed to supervise a nuclear reactor on another celestial body.
Three gaps that matter: Fuel, Opacity and End of Life
NASA says it will use high-assay low-enriched uranium (HALEU), considered safer from a proliferation point of view. But HALEU is in short supply in the United States, which banned Russian uranium imports in 2024, and the Times reports that at least one potential bidder is developing a reactor that uses highly enriched uranium. Russia has not said what fuel it will use; its older space reactors used highly enriched fuel. The 1992 Principles themselves appear to refer to highly enriched uranium 235 as the fuel for space reactors, a text written in a different technological and political context. Today the question is not only technical. Highly enriched uranium raises proliferation concerns that the space regime was never built to address.
In the United States, space reactors are supposed to be reviewed by experts from seven agencies, but that review is internal. On the other side, Rosatom declined to comment, saying its space program is classified. Each bloc is asking the other, and the rest of the international community, to trust its safety assessment without being able to read it. The Safety Framework assumes a level of transparency that the current race does not encourage.
On Earth, decommissioning a reactor is a long and careful process. On the Moon, the Times reports that both NASA and the Russian agencies say they would simply leave the radioactive material behind. The existing instruments say little about what happens to a reactor after its useful life outside Earth, and Article IX’s concern with harmful contamination sits uneasily with that plan.
Why this matters beyond the technology
Without common rules, each reactor becomes a tool of positioning. The country that lands first and sets a safety perimeter around its reactor will shape, in practice, who can operate nearby. Safety zones are justified on technical grounds, but their size and location are decided by the operator. In a race, that is a recipe for suspicion. The precedent of Kosmos 954, the Soviet satellite whose uncontrolled re-entry scattered radioactive debris over northern Canada in 1978, is a reminder that failure has consequences that cross borders.
A realistic next step
A new binding treaty looks unlikely in the current climate. A more achievable goal would be a notification and information-sharing mechanism within COPUOS: before launching a lunar reactor, states would report its fuel type, shielding approach, planned safety perimeter, and end-of-life plan. It would not stop the race, but it would make the race more transparent, and transparency is what the current framework lacks the most.
As one expert quoted by the Times put it, governments have achieved more in space by working together than by competing. The reactors may be ready by 2030 or 2036. The rules should not be left behind.
Sources
Gebrekidan, Selam. “Superpowers Race to Put Nuclear Reactors on the Moon.” The New York Times, October 4, 2026.
United Nations General Assembly. Principles Relevant to the Use of Nuclear Power Sources in Outer Space, A/RES/47/68, December 14, 1992.
UN Committee on the Peaceful Uses of Outer Space (Scientific and Technical Subcommittee) and International Atomic Energy Agency. Safety Framework for Nuclear Power Source Applications in Outer Space, A/AC.105/934, 2009.
Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (Outer Space Treaty), 610 U.N.T.S. 205, 1967, Article IX.
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