‘Fast Reactors’ Also Present a Fast Path to Nuclear Weapons

‘Fast Reactors’ Also Present a Fast Path to Nuclear Weapons

New "fast reactors" promise sustainable nuclear energy. They also pose serious proliferation risks because they can make lots of plutonium.


The Energy Department’s choice for the leading reactor design for reviving nuclear power construction in the United States is so at odds with U.S. nonproliferation policy that it opens America to charges of rank hypocrisy. The Biden administration is proposing to use nuclear fuels that we are telling others—most immediately Iran—not to produce. It will make it difficult to gain the restraints the United States seeks to limit nations’ access to bomb-grade uranium and plutonium.

We are talking here about the Department of Energy’s (DOE’s) enthusiastic support of TerraPower’s proposed Natriumfast reactor” demonstration plant and similar fast reactor projects, which DOE has showered with grants and supports with department-funded enrichment, test reactor, and spent nuclear fuel recycling programs. TerraPower and DOE expect to build hundreds of fast reactors for domestic use and export.  


Unlike conventional nuclear plants that exploit fission reactions triggered by slow neutrons, fast reactors maintain nuclear chain reactions with much more energetic fast neutrons. These reactors are billed as advanced technology, but they are an old idea. The first fast reactor designs date back to post-World War II.

Fast reactors’ main advantage is that they can make lots of plutonium, which can be extracted and used as reactor fuel instead of mining and using more uranium. This sounded good, so good to the Nixon administration that it set a goal to shift electric generation to plutonium-fueled fast reactors by the turn of the century. But the project came a cropper when it ran into safety hurdles that escalated costs. And then the increased awareness of the dangers of putting plutonium—one of the two key nuclear explosives—into the world’s commercial channels finally caused President Gerald Ford to announce the United States would not rely on plutonium fuel until the world could cope with it.    

TerraPower is obviously aware of this history and the public relations landmine it creates for its demonstration project. It insists its Natrium reactor will not use plutonium as fuel or require reprocessing to extract it. The company’s website says, “Both the demonstration plant and the first set of commercial plants will run on high-assay low-enriched uranium (HALEU).” HALEU is uranium enriched to just under the official definition of highly enriched uranium, but well above the level of the uranium fuel used in currently operating nuclear power plants.

In enrichment terms, it is within easy arm’s reach of bomb-grade uranium. It is exactly the stuff we demand that Iran not produce, arguing that they don’t need it for power reactor fuel. It’s also what we’ve been discouraging South Korea from getting into (Seoul says it wants to enrich uranium to boost reactor exports and to power a fleet of nuclear submarines).

Note TerraPower only commits to using HALEU for its first, and likely subsidized, commercial plants. Whether using HALEU is the cheapest way of running Natrium is unclear. Foreign customers—if it ever comes to that—will surely want the “benefits” of the plant’s plutonium production and subsequent operation on plutonium fuel extracted by reprocessing. The Energy Department is already hedging its bets on this option by backing research into “new’ reprocessing technologies at its national laboratories.  

All this will be hard to explain to, say, South Korea, which the State Department is trying to keep from launching into reprocessing to prepare for plutonium-fueled fast reactors, which South Korean nuclear enthusiasts are eager to develop. It also will make it difficult to complain about China’s crash fast reactor and reprocessing programs, which our military fears may be used to fuel China’s growing nuclear weapons effort.

Fast reactor boosters are aware of these points and know that they must at least appear to take account of them. An example is Senator Chris Van Hollen’s (D-MD) amendment to the American Nuclear Infrastructure Act of 2020, which purportedly protects the nuclear explosives (plutonium and uranium 233) these reactors use as fuel or produce, and the reprocessing technologies that extract them. While his amendment may sound tough, it offers little more protection than what is already required by the Nuclear Regulatory Commission, and that protection can be waived if the NRC finds the export is not “inimical” to US interests. The practical effect of the amendment would not be greater protection, but a smoothing of the licensing path for dangerous nuclear exports. 

This is worse than hypocrisy. Once nations have easy access to nuclear explosive material, no inspections can prevent them from making bombs. Congress needs to look behind the Energy Department’s beguiling “advanced reactor” label. When it does, it must line out projects that could turn nuclear explosives into a common article of commerce worldwide. The place to start is with “advanced” fast reactors.

Victor Gilinsky serves as program advisor to The Nonproliferation Policy Education Center, is a physicist, and was a commissioner of the U.S. Nuclear Regulatory Commission during the Ford, Carter, and Reagan administrations.

Henry Sokolski is the executive director of the Nonproliferation Policy Education Center in Arlington, Virginia, and author of Underestimated: Our Not So Peaceful Nuclear Future. He served as deputy for nonproliferation policy in the office of the U.S. Secretary of Defense during the George H.W. Bush administration.

Image: Reuters.