The U.S. nuclear power industry is at an impasse. Since 2012, 11 of the 104 light-water reactors in operation at the time have closed, mainly as a result of aging infrastructure and the inability to compete with natural gas, wind and solar, which are now the cheapest sources of electricity in the United States and most other countries worldwide.  

In the early 2000s, the industry promoted a “renaissance” to try to stem its incipient decline, and in 2005, Congress authorized $18.5 billion in federal loan guarantees for new nuclear reactors. The result? Only two new Westinghouse AP1000 light-water reactors, still under construction in Georgia, which will cost at least $14 billion apiece—double their estimated price tags—and take more than twice as long as estimated to be completed. Another two partially built AP1000 reactors in South Carolina were abandoned in 2017 after a $9-billion investment.

Given the struggle to build these standard-sized, 1,000-megawatt light-water reactors, the industry has turned to two other gambits to secure a bigger market share: small, modular light-water reactors, which, because they lack the advantage of economies of scale, would produce even more expensive electricity than conventional reactors; and non-light-water “advanced” reactors, which are largely based on unproven concepts from more than 50 years ago.

Unlike light-water reactors, these non-light-water designs rely on materials other than water for cooling. Some developers contend that these reactors, still in the concept stage, will solve the problems that have plagued light-water reactors and be ready for prime time by the end of this decade.

The siren song of a cheap, safe and secure nuclear reactor on the horizon has attracted the attention of Biden administration officials and some key members of Congress, who are looking for any and all ways to curb carbon emissions. But will so-called advanced reactors provide a powerful tool to combat climate change? A Union of Concerned Scientists (UCS) analysis of non-light-water reactor concepts in development suggests that outcome may be as likely as Energy Commission Chairman Lewis Strauss’ famous 1954 prediction that electricity generated by nuclear energy would ultimately become “too cheap to meter.” Written by UCS physicist Edwin Lyman, the 140-page report found that these designs are no better—and in some respects significantly worse—than the light-water reactors in operation today.

Lyman took a close look at the claims developers have been making about the three main non-light-water designs: sodium-cooled fast reactors, high-temperature gas-cooled reactors and molten salt–fueled reactors. With little hard evidence, many developers maintain they will be cheaper, safer and more secure than currently operating reactors; will burn uranium fuel more efficiently, produce less radioactive waste, and reduce the risk of nuclear proliferation; and could be commercialized relatively soon. Those claims, however, do not hold up to scrutiny.

One of the sodium-cooled fast reactors, TerraPower’s 345-megawatt Natrium, received considerable media attention earlier this year when company founder Bill Gates touted it during interviews about his new book, How to Avoid a Climate Disaster. In mid-February, Gates told CBS’s 60 Minutes that the Natrium reactor will be safer and cheaper than a conventional light-water reactor and produce less nuclear waste.

According to the UCS report, however, sodium-cooled fast reactors such as Natrium would likely be less uranium-efficient and would not reduce the amount of waste that requires long-term isolation. They also could experience safety problems that are not an issue for light-water reactors. Sodium coolant, for example, can burn when exposed to air or water, and the Natrium’s design could experience uncontrollable power increases that result in rapid core melting.

In June, TerraPower announced that it would build the first Natrium reactor in Wyoming as part of a 50-50 cost-share program with the Department of Energy. The DOE program originally required TerraPower to have the reactor, still in its early design stage, up and running by 2027. The agency recently changed the target date for commercialization to 2028.

From concept to a commercial unit in seven years?

The new Westinghouse AP1000 light-water reactor provides a cautionary tale. It took more than 30 years of research, development and construction before the first one was built in China and began generating power in 2018. According to the UCS report, if federal regulators require the necessary safety demonstrations, it could take at least 20 years—and billions of dollars in additional costs—to commercialize non-light-water reactors, their associated fuel cycle facilities, and other related infrastructure.

The Nuclear Regulatory Commission (NRC) may have to adapt some regulations when licensing reactor technologies that differ significantly in design from the current fleet. Lyman says that should not mean weakening public health and safety standards, finding no justification for the claim that “advanced” reactors will be so much safer and more secure that the NRC can exempt them from fundamental safeguards. On the contrary, because there are so many open questions about these reactors, he says they may need to meet even more stringent requirements.

The report recommends that the DOE suspend its advanced reactor demonstration program until the NRC determines whether it will require full-scale prototype tests before any designs are licensed for commercial deployment, which the report argues are essential. The report also calls on Congress to require the DOE to convene an independent commission to review the technical merits of non-light-water reactors and approve only those projects that have a high likelihood of commercialization and are clearly safer and more secure than the current fleet.

Finally, it recommends that the DOE and Congress consider spending more research and development dollars on improving the safety and security of light-water reactors, rather than on commercializing immature, overhyped non-light-water reactor designs.

“Unfortunately, proponents of these non-light-water reactor designs are hyping them as a climate solution and downplaying their safety risks,” says Lyman. “Given that it should take at least two decades to commercialize any new nuclear reactor technology if done properly, the non-light-water concepts we reviewed do not offer a near-term solution and could only offer a long-term one if their safety and security risks are adequately addressed.” Any federal appropriations for research, development and deployment of these reactor designs, he says, “should be guided by a realistic assessment of the likely societal benefits that would result from investing billions of taxpayer dollars, not based on wishful thinking.”

This is an opinion and analysis article; the views expressed by the author or authors are not necessarily those of Scientific American.

Editor’s Note (9/9/21): This article has been edited after posting to correct the time frame of the 11 light-water reactors that closed in the U.S. and the description of Congress authorizing federal loan guarantees in 2005.