Nuclear power, we’ve learned the hard way, can be dangerous and is always off-the-charts expensive. And if that doesn’t disqualify it as part of the solution to our energy woes, there are the problems of waste and nuclear weapons security.

Or maybe not. Last fall, for the first time in recent memory, nuclear energy was on the agenda of very serious people trying to stop climate change. Meeting at the UN conference in Glasgow, many stakeholders who are wrestling with the climate challenge acknowledged that nuclear power could play a substantial role in averting looming disaster.

In part, this reflects the near-desperation of policymakers facing potent interestgroup resistance — not to mention public wariness — to a rapid transition to other renewable fuels. But it is also due to the emergence of advanced reactor technologies that promise far safer and cheaper nuclear power. Let me bring you up to date.

The State of Play

Despite decades of government incentives along with massive private investment in conservation and renewable energy, the world remains stubbornly dependent on fossil fuels for more than 80 percent of its primary energy. And after a pause created by the Covidinduced recession, the bad news is not going away: greenhouse gas emissions are back on track to continue setting record highs.

The UN’s COP (Conference of Parties) meetings generally focus media attention on the state of play in climate change, with experts and policymakers reasserting the urgency of the moment and trying to build consensus for more determined action. COP 26, the Glasgow meetings, certainly met expectations in those ways. But the rekindled interest in nuclear energy was a bit of a surprise.

It probably shouldn’t have been. Few climate activists talk about it much, but nuclear energy remains one of the leading global sources of carbon-free energy. In the United States, it produces 20 percent of electricity — more than wind and solar combined. Worldwide, the figure is a still-substantial 10 percent, making it the second largest carbon-free source on the planet after hydropower. But thanks to Chernobyl, the public image of nuclear power seemed fatally damaged. Then the disaster at Fukushima in Japan — a country known for its technological prowess and attention to public safety — led to hardened opposition to nuclear power in rich countries.

Construction has continued in fits and starts in France, the UK and the United States (in Georgia). But public skepticism and the ballooning costs of conventional reactors have led to a near dead end in the West. Only Russia and China are pursuing broad expansion plans, in large part because they seek to dominate global nuclear energy markets going forward.

So what’s changed? The emergence of reactor designs that represent a fundamental departure from the commercial technology that emerged after World War II. They promise smaller, cheaper, safer reactors, whose capacity to stay online 24/7 could complement inconstantly available renewable energy in decarbonizing the electricity sector — and also provide space heating, serve as a power source for manufacturing “green hydrogen” fuel, or even power expeditions to Mars. Dozens of designs are in the early stages, and with the go-ahead from regulators and investors, commercial versions could be operational in the 2030s and 2040s. Demonstration projects could be online within the decade.

One goal, of course, is to diversify the clean energy portfolio. But it’s worth noting, too, that advanced technology is also being touted as a response to China and Russia, which plainly seek geopolitical advantage as well as profit from leading the world back to nuclear. (More about that later.)

Why Nuclear?

The primary value proposition for nuclear reactors is, of course, reducing carbon emissions. To be sure, carbon is emitted in the production of all the concrete and steel that goes into reactors. But with no air emissions during operation, the lifecycle greenhouse gas output from nuclear reactors is among the lowest of any energy source.

Moreover, nuclear power has other, not insignificant, advantages. For one thing, it reduces other sorts of air pollution that come from burning fossil fuels. One major study by NASA concluded that nuclear energy has already saved millions of lives worldwide — and could save millions more in the 21st century as it facilitates reductions in fossil fuel use in power production, transportation and space heating. Indeed, one of the ironies of the public’s fear of nuclear energy in the wake of Chernobyl and Fukushima is that the damage to health from these accidents is a drop in the bucket compared to the relentless ongoing damage done by local air pollution from fossil-fuel consumption.

Could public opinion have been turned around post-Fukushima if advocates had used these facts to press their case on safety and health? Maybe. But it is hard to imagine anything persuading investors to risk tens of billions of dollars more to build technologyas- usual plants facing high risks of cost overruns, delays and cancellation.

In the United States, the hoped-for nuclear renaissance of the 2000s petered out into only four reactor projects at two sites. Two of these reactors (in South Carolina) were abandoned after the bankruptcy of Westinghouse, the maker of the reactors. Two more in Georgia, now being built by Bechtel, are six years behind schedule and are expected to cost double the original budget. What’s more, though existing nuclear plants are relatively cheap to run after they are built, competition with natural gas plants and the rising maintenance costs of aging nukes has led to the retirement of almost 10 percent of existing U.S. reactors in the past decade.

What has changed from even a decade earlier is the softening of opposition to anything promising to slow climate change, combined with cautious optimism that new reactor technology will fundamentally improve the economics and safety profile of nuclear power. With support from Congress, U.S. developers and utilities have announced six demonstration projects and have plans for as many as 12 by 2030. More than 30 demonstration projects are planned globally, with the first ones already online in Russia and China.

If the gamble pays off, it could pay off big. For emerging-market countries, advanced reactors could offer scalable, low-carbon energy to meet the needs of rapid economic growth. Indeed, the countries seemingly most inclined to take the financial risk, including the oil-rich United Arab Emirates along with Turkey, Egypt and Bangladesh, are new to the nuclear ranks. Even some countries well behind them on the development timeline — notably in sub-Saharan Africa — are now weighing the nuclear option for the first time, in part due to the smaller sizes of new reactor designs, which better fit their small-butgrowing energy grids.

There’s another factor at work, too: the mixed blessing of reemerging geopolitical competition between Russia, China and the United States. The U.S. once dominated the global nuclear energy industry. But with sales long stalled due to high costs, it is now dwarfed by Russia and is set to be further eclipsed by China. The U.S.’s potential equalizers are its lab- and university-based R&D prowess, its efficient capital markets and its flexible environment for business startups. Similarly, other developed countries including Canada and South Korea are pursuing nuclear innovation largely because they don’t want to be shut out of export opportunities.

The path to advanced reactors playing a broad role in the energy transition is bound to be fraught with challenges and speed bumps. Nuclear energy will have to compete with the established, politically connected natural gas industry while also integrating with renewable sectors both technically and economically. Meanwhile, a hoary regulatory system adapted to oversee earlier generations of reactors must be modernized for the U.S. industry to compete with other nuclear-capable countries in the global market.

Evolution From the Light-water Dinosaurs

Commercial fission reactors today — fusion reactors may be coming, but that is a very different story — are “light-water” behemoths. They use fuel rods composed of uranium pellets, with ordinary water (as opposed to “heavy water,” which contains a different isotopic form of hydrogen) as both a coolant and a heat transfer medium. These reactors must be very large to operate efficiently. Thus most existing commercial reactors produce more than a billion watts at full power — enough to keep the lights on in whole cities.

The new reactor designs coming down the pike do share some characteristics of large light-water reactors. They “burn” — well really, fission — uranium to produce heat, which is converted to electricity. But the angels are in the details. And in reviewing new designs in depth, a technology primer attempting the common touch from the Nuclear Innovation Alliance described advanced reactors “as different from one another as gouda and gorgonzola, as Beethoven from Bon Jovi.”

Small modular light-water reactors (SMRs for short) are smaller cousins to existing gigawatt- sized facilities. They are much reduced in output — in the 50-to-300-megawatt range — giving them the potential output of, say, a large windfarm or a medium-size natural gas plant. The idea is to shrink familiar, proven technology, allowing vendors to use existing supply chains to build reactors offsite in factories.

NuScale Power received the first Nuclear Regulatory Commission design approval for an SMR in 2020. The company recently announced plans to go public at an almost $2 billion valuation and is currently pursuing a demonstration project with a consortium of small Utah utilities that is scheduled for completion by 2030. Similar vendors include traditional nuclear industry leaders GE Hitachi and U.S.-based Holtec, along with Russia’s Rosatom, which can boast of the first operational SMR.

But other advanced designs use alternative fuel forms or coolants that promise key advantages over light-water designs, several of which are worth a closer look.

High-temperature gas reactors replace water with inert gases, like helium, to cool the fission reactor and to transfer heat. Fuel forms vary but one favored option is called tri-structural isotropic particle fuel (TRISO). Uranium and other materials are encapsulated in a kernel around the size of poppy seed and then combined into larger spheres the size of tennis balls. Their big selling point: TRISO can withstand extremely high temperatures and accident conditions without releasing radioactive materials.

Among other developers, the company Xenergy is pursuing a TRISO-fueled design for a planned reactor demonstration project in eastern Washington State. Funded in part by the federal government, the reactor is planned to become operational by 2028 and will likely be sited near the existing Columbia Generating Station nuclear power plant in Richland, Washington.

In molten salt reactors, uranium is dissolved in super-hot molten salt (or a mix of chemical salts) that serves as the heat-transfer mechanism. Since they operate at much higher temperatures than light-water reactors, they are more efficient at transferring energy. But since the salts remain liquid at lower atmospheric pressures than water, containment of the core is easier and major accidents are less likely.

The company TerraPower, backed by Bill Gates, is leading development of the molten salt Natrium design. A sodium-cooled reactor, Natrium features an integrated molten salt energy storage system to complement variable renewable energy production. TerraPower has also won a major government contract to build a demonstration project that will replace a coal plant in Wyoming owned by Berkshire Hathaway’s PacifiCorp by 2028.

Beyond reactor types, nuclear innovators are also looking at even more dramatic changes in the size of the reactors. Most notable are a class called microreactors, in the 1-to-50-megawatt range, equivalent in output to small wind or solar plants. A radical departure from nuclear energy of the past, microreactors would facilitate the use of nuclear energy as a decentralized energy source.

Given short construction timeframes, microreactors are likely to be the first of the advanced designs to market. Among other market leaders, Oklo is licensing the Aurora reactor in Idaho, Ultra Safe Nuclear Corporation is developing a project for the University of Illinois and multiple vendors are competing to supply microreactors to the Department of Defense. Kairos Power is also licensing a micro-scale test reactor as part of a phased program to build a larger-scale reactor within a decade.

Why Advanced Reactors Are Better

Like existing reactors, advanced reactors are all carbon-free (in operation), do not emit hazardous air pollutants and can be expected to generate power 24/7.

Safety is, of course, a necessary (if not sufficient) part of the package. Conventional reactors have, in fact, managed to sustain good health and safety profiles over the decades. Even including Three Mile Island, as far as we know, no member of the American public has been harmed by radiation from the commercial nuclear industry. However, scale creates complexity, and the need for utterly reliable secondary sources of electricity to pump coolant through a large light-water reactor create potential vulnerabilities — like the once-in-a-millennia tsunami that hit Fukushima and knocked out the plant’s auxiliary diesel generators.

The equation for calculating industrial risk is relatively simple: the risk of something happening times the consequences if it does happen. Advanced reactors minimize both risk and consequence

New designs do not rely upon “active safety” systems — typically electrically powered pumps along with highly skilled personnel to manage events during the crisis. Instead, they lean on “inherent safety,” designed from the get-go to avoid risks of accidents, minimize the need for operator intervention and reduce the impact of accidents if they do occur.

In many cases, basic physics provides solutions that reduce the risk of an accident. Microreactors are often so small that they can rely on heat conduction to the surrounding ground to cool the reactor sufficiently to prevent leaks of radioactive material if coolant isn’t circulating. Other reactors, using fuels such as TRISO or molten salt, operate at low pressures, making breeches of containment unlikely. NuScale’s light-water reactor reduces the need for pumped coolant by designing the reactor to bleed off excess heat into a gigantic swimming pool.

If an accident does occur, advanced reactors are less likely to create health disasters because they operate at low pressures and contain smaller quantities of radiological materials. A microreactor can be one-thousandth the scale of a conventional reactor, meaning even a severe accident would have the risk profile of an industrial accident rather than a Chernobyl- or Fukushima-scale event.

Just as new designs improve safety performance by reducing complexity, they also improve economic prospects by making reactors cheaper and quicker to build. Historically, large light-water reactors cost billions (or tens of billions) of dollars with much of the bill attributable to decade-long construction timeframes and the need for humungous core containment systems. Cost overruns and project cancellations were endemic.

Advanced reactor developers are pursuing multiple strategies to be cost-competitive with renewables. Smaller, simpler designs should open sales to small cities, large industrial plants and even remote towns for the first time. Smaller projects would also mean shorter construction timeframes — and less interest to pay before the plant begins to generate electricity and revenue. Today’s reactors are bespoke behemoths, purpose-built to fit individual sites and circumstances. By centralizing production in factories, vendors hope to achieve manufacturing economies of scale never before available to the industry.

Perhaps more than anything else, nuclear innovators are pursuing a strategy perfected by renewable energy developers: technological learning — or, in econ-speak, learning by doing. When project timelines are short, developers can run through many generations of a project in relatively short order. Each generation provides opportunities to learn from the shortcomings of the last.

The primary goal, of course, is to make nuclear comparable with renewables in terms of safety and the cost of electricity. But they may offer something different, too — the opportunity to decarbonize more than just electricity production.

Non-power sectors are very hard to decarbonize, especially with renewables. But heat from SMRs could be used directly for industrial processes. Russia’s first SMR is already producing heat for homes in the Russian Arctic.

Advanced reactors should also be well suited to produce hydrogen gas through electrolysis for use in transportation — both land and sea — and in other applications. What’s more, the technology could even power the ongoing commercialization of outer space.

Note, too, that next-generation designs offer advantages for drought-prone regions. Molten salt reactors and microreactors do not need access to water from rivers or the sea to operate. Even SMRs, like those designed by NuScale, could be adapted to dry-cooling technologies.

Would You Believe: Bipartisanship?

In the last five years, support for innovation in nuclear power has been a rare spot of bipartisanship in energy policy. In 2018, Congress passed the Nuclear Energy Innovation Capabilities Act, which established key programs for the Department of Energy to pursue, including a National Reactor Innovation Center and a national Versatile Test Reactor to support basic nuclear science.

In 2019, President Trump also signed the Nuclear Energy Innovation and Modernization Act, which sought to restructure nuclear regulation with next-gen technologies in mind. And just before the White House changed hands, Congress passed the Energy Act of 2020 that among many other things, authorized funding for the Advanced Reactor Demonstration Program, which is funding the X-energy and TerraPower demonstration projects as well as eight other new designs. The act also authorized an advanced fuels program to support development of high-assay low enriched uranium (HALEU) — the more concentrated source of uranium-235, which is needed for most advanced reactor designs.

Why this sustained bipartisan interest in nuclear innovation? An interesting intersection of causes carries both Democrats and Republicans.

Start with climate change. Although the Republican Party is still home to climate deniers, the pragmatists in the party who don’t want to be caught with their heads in the sand as Miami and Houston float away are adopting a de facto climate change policy that they call “energy innovation.” The idea is to have it both ways — to stimulate innovation in carbon- sparing technologies without taxing fossil fuels or suppressing their use with regulation. Subsidies for advanced reactor development along with regulatory streamlining fit the bill nicely.

On the Democratic side, climate has moved from an issue of interest to a major pillar of party politics. The role of nuclear energy was hotly debated during the 2020 Democratic presidential primaries, with candidates on both sides of the issue. But after the party rallied around Biden, whose instincts were to triangulate, nuclear energy became part of the party’s stated climate strategy. The progressive wing of the party is still skeptical but understands that packaging nuclear energy with other green initiatives is good politics.

The reemergence of great power competition with Russia and China is also creating some common ground for the two parties. Nuclear reactors are long-term infrastructure, and a deal to build a reactor establishes the foundation for a relationship that lasts decades. Thus, Russia and China are seeking to use foreign nuclear deals to leverage global influence. And neither U.S. political party wants to be tarred as the party that let them get a leg up.

Nuclear power is also being touted for new military applications — and, again, neither party wishes to be seen as behind in supporting a strong defense. To promote energy resilience at military facilities, the Department of Defense is planning to build a prototype microreactor for an Air Force base in Alaska. It is also working on Project Pele, a transportable microreactor that could power military operations far from modern infrastructure. Cold warriors in the U.S., China and Russia are also mulling other potential military applications, including powering high-energy weapons like lasers and railguns, or providing propulsion for military spacecraft. Russia is already testing a nuclear-powered cruise missile.

While Washington is supporting nuclear innovation, it’s the states where the proverbial rubber meets the road. And some are now rethinking policy with the goal of encouraging advanced reactor projects within their borders as economic development initiatives. In the last five years, many have passed clean energy or decarbonization standards that would allow utilities to get partway home with nuclear power. In 2021, Montana removed restrictions on constructing new nuclear power plants, and West Virginia followed suit in 2022, hoping to find an energy future beyond coal.

Historically, the concurrent development of nuclear weapons with nuclear energy during the Cold War left a legacy of harm from mining and weapons waste that badly stained the industry’s reputation. But if done right, advanced reactors could be a successful bridge between energy transition and environmental justice communities. That’s a big “if,” of course. While permanent, safe storage of nuclear waste is a formidable political problem, a fair reading of the evidence suggests it is a manageable technical one. The big question is whether, as a society, we can get from here to there.

Tortuous Road to Commercialization

When it comes to bringing energy technologies to the marketplace, there are two “valleys of death” in which an idea can stall and succumb. First, a promising idea has to navigate R&D to reach the prototype stage, where it is possible to test the technical validity of a concept (but not its economic viability). Then, a technically feasible idea must prove it can be competitive at commercial scale — which often requires a huge investment. Today, the leading advanced nuclear designs are just now crossing the first valley.

But with only a handful of exceptions, even the most basic claims about safety and viability have yet to be demonstrated. And in light of the nuclear industry’s long history of “this time is different” promises, it wouldn’t take much of a stumble to push the initiative to the side of the road. Early bipartisan political support is essential to giving the sector its best shot. But it will be up to industry to prove that advanced reactor technology can bring nuclear back into the fast lane.

A whole lot, alas, is riding on it.