Can small modular reactors at chemical plants save nuclear energy?

The US Nuclear Regulatory Commission (NRC) made history early this year when it gave its first approval to a new type of nuclear power plant: the small modular reactor (SMR).

Conventional nuclear power plants are huge, producing 1–3 GW of electricity, enough to power a medium city. The SMR approved by the NRC, NuScale Power’s Voygr, would produce 50 MW of electricity. The reactors are about the size of grain silos, and NuScale is marketing them in packs of 4, 6, and 12.

Voygr is one of several SMR designs that are attracting attention and investment as potential sources of reliable, steady power with minimal associated greenhouse gas emissions.

Nuclear power has plenty of critics and, especially in the US and Europe, a history of massive construction projects that come in way over budget. Proponents of SMRs say the technology lends itself to more modest, reproducible projects that can deliver low-carbon energy at a reasonable price. If the technology’s backers are right, the US and other countries will be one step closer to meeting ambitious goals for reducing carbon dioxide emissions.

Go green by going nuclear

Supplying electricity to the power grid is likely the biggest market for new nuclear installations. But industrial companies like Dow, the largest US chemical maker, also see emerging nuclear technology as a perfect fit for their manufacturing plants, both to replace aging fossil-powered heat sources and to power the production of hydrogen and other clean fuels. The size of SMRs, generally 300 MW or smaller, is a good match for the energy needs of heavy industry, and their road through regulation and construction may be smoother than that of their grid-scale counterparts.

Dow plans to repower its massive complex in Seadrift, Texas, with a set of four SMRs from the nuclear technology firm X-Energy. The Seadrift plant makes polyethylene, ethylene oxide, ethylene glycol, ethanolamines, and glycol ethers for many end markets. Each reactor has an output that is adjustable between 80 MW of electricity and 200 MW of heat.

Kreshka Young, Dow’s North America business director for energy and climate, says the SMR quartet will be the sole power source for the Seadrift plant, where it will replace a boiler fueled by natural gas. The boiler system, which Young says emits 440,000 metric tons of CO₂ per year, is scheduled for retirement in the early 2030s.

The nuclear fission reaction at the core of most SMRs is the same as the one that takes place in conventional large reactors, which all use oxides of the heavy metal uranium for fuel. An atom of ²³⁶U, an unstable isotope of uranium made by bombarding ²³⁵U with neutrons, breaks apart, yielding two or more smaller atoms, more free neutrons, and heat. The neutrons go on to collide with other ²³⁵U atoms, which likewise turn into ²³⁶U. A chain reaction ensues, and the resulting heat is siphoned off to do useful work.

In some ways, nuclear plants are better suited to powering chemical operations and other heavy manufacturing facilities than they are to making electricity. An electric power plant uses heat to boil water to make steam to turn a turbine to generate electricity. Even the best systems capture less than half the heat as useful electrical energy, according to Jacopo Buongiorno, a nuclear science and engineering professor at the Massachusetts Institute of Technology. The rest is wasted, dumped into the air or water.

Chemical companies, in contrast, use heat directly to drive chemical transformations and distillations. The heat is usually in the form of pressurized steam blasting around facilities at temperatures up to 650 °C.

Alexander Koukoulas, a director at the energy and engineering firm AFRY Management Consulting, says a typical petroleum refinery or petrochemical plant needs twice as much steam energy as it does electrical energy. “Of all US manufacturing sectors, the petrochemical industry has the largest process-heating energy demand and, as result, is also the largest generator of on-site greenhouse gas combustion emissions,” Koukoulas says. By adopting SMRs, the chemical industry could cut its carbon footprint by 60%, he says.

On top of the CO₂ reduction, Koukoulas says, “if the industry can avoid the use of natural gas and waste gases like ethane and propane as sources of primary energy, it would increase the supply of these valuable chemical feedstocks, directing them to a better use in the production of resins and chemicals.”

What’s better about an SMR?

The notion of SMRs certainly has its challenges and skeptics. X-energy does not yet have a license for the Xe-100 design it plans to install for Dow. No SMRs other than NuScale’s 50 MW system are approved by the NRC, and the regulatory situation is similar in other countries. In another wrinkle, NuScale decided not to go to market with the 50 MW reactor and has applied to the US Department of Energy (DOE) for a 77 MW version instead.

Worldwide, only three SMRs are publicly known to be in operation, two on a power barge in Russia and one on land in China. India operates a fleet of fourteen 220 MW reactors, though their total size and design are more akin to those of conventional large power plants than SMRs. A utility in Argentina is working on a fourth SMR that is years behind schedule and billions over budget.

Blown timelines and budgets are common features of recent large-scale nuclear power projects, at least in the US and Europe. The first new US reactors since the Three Mile Island nuclear accident in 1979 are a pair of 1,250 MW units nearing completion outside Augusta, Georgia. Known as Plant Vogtle Units 3 and 4, the reactors were originally scheduled to connect to the grid in 2016. The project is nearly $17 billion over its $14 billion budget.

M. V. Ramana, who is a professor of public policy and global affairs at the University of British Columbia and studies nuclear power and weaponry, argues that Vogtle will probably be the last of the big reactors and that SMRs are doomed by the same basic problems. “I think we may see one or two projects funded by public money being built as a kind of prototype,” he says. “My prognosis would be that these will be expensive and take longer than expected, as has been the case with most nuclear projects, and that will be that.”

Ramana says the problem is one of economics. “Nuclear power is expensive,” he says. “And the reason it is expensive is that what you’re trying to do is to boil water using a very hazardous and complicated process, nuclear fission. And in order to keep that under control, one has to take a lot of precautions. Because of that technical challenge, there is no way it can ever be a cheap source of power.”

Other nuclear power experts disagree. Buongiorno says nuclear power has often been expensive compared with fossil fuel–based power and, more recently, renewable power sources like wind and solar. But he says the construction process is the main culprit. “The cost of the energy from a nuclear reactor is probably two-thirds associated with building the plant and then 20% operation and maintenance and 10% fuel,” he says.

Gigawatt-scale nuclear power plant projects in western Europe and the US are massive undertakings involving messy outdoor construction sites, variable weather, thousands of contractors, custom designs, and complex supply chains to deliver raw materials.

“This is an issue with the US and western Europe, and it’s primarily because our construction sector is very, very inefficient,” Buongiorno says. Indeed, major infrastructure projects of all types in those regions are chronically late and over budget, he says. South Korea, China, Russia, and India “deliver large nuclear power plants on time and on budget routinely, and they’ve been doing it for 30 years.”

Buongiorno says SMRs will help project developers avoid delays and cost overruns. The reactors will be built in dedicated factories and then shipped to the installation sites for final assembly. Companies will make the same reactor over and over, getting better at it each time and avoiding the need for fully bespoke engineering for each unit. And smaller projects are easier to manage and finance. Large companies can install them out of their regular capital expenditure budgets.

Dow’s deal with X-energy is structured to account for a key difference between SMRs and traditional big nuclear plants: the up-front costs of deploying the first reactor of any given design will be expensive, but they have to be paid only once.

The Seadrift project is supported by an $80 million grant from the DOE. The grant will support efforts by Dow and X-energy to get the first four-reactor system up and running. But the grant, which the two firms are matching, is doing more than just helping pay for the work at Seadrift. More than half the money will go toward the engineering of the reactor, getting it approved by the NRC, and building a separate facility to make the nuclear fuel. Those are onetime expenses that could enable dozens of SMR installations.

For now, Young says, Dow is contributing $25 million toward preparing the NRC application, which she expects will be submitted next year. The firm also purchased a minority stake in X-energy in August 2022. “We’re very committed to doing this. We’re very excited about it,” she says. “We need to work down that path, but we can’t write a blank check.”

Dow is moving away from fossil fuels on a site-by-site basis, Young says. “The timelines for decarbonizing each of our sites is different, and it’s based on the end of life of the assets that are at that site,” she says. “I think, assuming this all goes the way that we expect it to go and the way that we want it to go, nuclear is going to be a tool we’re going to look to again.”

X-energy’s SMR differs significantly from conventional nuclear reactors and NuScale’s SMR design, both in the form of fuel it uses and the way it harvests heat from the reactor core.

The Xe-100 is what’s known in the industry as a pebble-bed high-temperature gas-cooled reactor. The nuclear fuel is in the form of billiard-ball-size spheres. The balls have a uranium core enriched to 15.5% ²³⁵U surrounded by three containment layers made of silicon carbide and pyrolytic carbon. Those “pebbles” flow slowly but continuously down through the reactor core while helium gas flows up at high pressures. The helium carries heat released during nuclear fission out of the core and into heat exchangers that generate steam at 565 °C.

That’s a big departure from more familiar, water-cooled reactors, which include NuScale’s as well as those found in military submarines and civilian power stations. Water-cooled reactors use uranium enriched to 3–5% ²³⁵U that is pressed into pellets and packed into metal tubes. Uranium’s natural 235U abundance is around 0.7%. The heat-transfer fluid is regular water, which limits the output temperature to 275–325 °C.

It’s probably not a coincidence that the only NRC-approved SMR design is a water-cooled reactor similar to conventional nuclear power plants. The DOE strongly supports new reactor types, and its Idaho National Laboratory is an international hub for research into civilian nuclear power. But the NRC, which is a separate agency, has been less welcoming of new technology.

In 2022, the NRC took the rare step of rejecting outright a 1.5 MW reactor design from the reactor technology firm Oklo that uses liquid metal as a coolant and can recycle some spent fuel. In a scathing memoir published in 2019, former NRC chairman Gregory B. Jaczko says it’s more common for the agency to hint that rejection is likely, prompting companies to withdraw an application. Jaczko describes all nuclear power as a failed technology and, like Ramana, says SMRs don’t solve anything.

Nonetheless, Oklo is working with the NRC on a new application for its SMR, which, like X-energy’s, can produce high-grade heat suitable for industrial applications. The firm recently announced plans to go public through a merger with a special purpose acquisition company, or SPAC, and has the backing of Sam Altman, who founded the company that is behind the artificial intelligence tools ChatGPT and Dall-E 2.

Chemical customers

If SMR makers such as X-energy, Oklo, and NuScale can get their reactors permitted and rolling off the factory floor, they could win customers in several heavy manufacturing sectors. GE Hitachi Nuclear Energy (GEH) has already signed contracts to supply its BWRX-300 SMR design to utility companies in Canada, Poland, and Estonia that are planning electricity and hydrogen production. GEH also says it is in talks with companies in the US, Sweden, and the Czech Republic.

Charles Forsberg, who like Buongiorno is a nuclear science and engineering professor at MIT, held a workshop in July in Charlotte, North Carolina, to talk about nuclear-assisted pulp and paper mills. The meeting was attended by a cross section of paper mill owners and suppliers, nuclear developers and utility companies, and researchers.

Papermaking is an energy-intensive process because multiple steps require reducing watery pulp slurries to dry powders and sheets. Forsberg says pulp and paper mills burn for heat about half the wood that comes through their gates. “The game is, If you have an external energy source, can you sell every carbon atom coming in instead of letting half the carbon atoms go up to the atmosphere as carbon dioxide?” he says.

Forsberg says papermaking is a good market for SMRs because almost every pulp and paper plant uses the same technology, the kraft process. Success at one site could be quickly replicated across the industry—the same basic song that SMR makers are singing.

Instead of burning large amounts of biomass for heat, paper mills could produce more paper, or they could convert the freed-up biomass into renewable fuels and chemicals, Forsberg explains. Similarly, pyrolysis and gasification, processes also powered by heat, could convert paper mill waste into biobased oil and syngas—feedstocks the chemical industry knows how to use.

If paper mills had an on-site hydrogen source, they could upgrade their waste streams to higher-value hydrocarbon products such as sustainable aviation fuel, Forsberg says. SMRs could be a good way to make hydrogen because their power output is expected to pair well with the energy needs of water electrolysis, further tightening the fit at a paper mill.

Overall, Forsberg says, pulp and paper mills could double or even triple the revenue they get from every metric ton of wood they bring in if they added an ample zero-carbon energy source. And the switch to nuclear power at pulp and paper mills could free up enough biomass to supply 48% of the energy needs of the US via biofuels. “All we want to do is decarbonize half the US economy,” he jokes. “We’ll leave the other half for somebody else.”

Forsberg is not the only person talking about nuclear-powered hydrogen production. Water electrolysis is more efficient at high temperatures, so the steady combination of heat and electricity from nuclear plants should be great for electrolytic hydrogen production. Earlier this year, the utility company Constellation started up a 1 MW hydrogen plant at its 2 GW Nine Mile Point nuclear generating station in Oswego, New York. Constellation is working with Rolls-Royce on SMR hydrogen projects in the UK.

Rolls-Royce, which has had the contract for building England’s nuclear submarines for 60 years, is also in talks with the industrial conglomerate Sumitomo Corporation about nuclear hydrogen. The firms told World Nuclear News in June that an SMR’s“compact footprint and flexible modular design means it can be located alongside energy intensive industrial processes. . . . For the production of hydrogen via Solid Oxide Electrolytic Cell technology it is possible to use the thermal output of the power plant to radically boost the overall efficiency of the hydrogen production cycle.”

At a smaller-yet scale, the microreactor start-up Nano Nuclear Energy is eyeing remote hydrogen-fueling stations as an application for a high-temperature SMR it is developing. The semitruck-size system would yield 2.5 MW of heat or 1 MW of electricity.

Nuclear hydrogen projects of all sizes are getting government support. The U.S. National Clean Hydrogen Strategy and Roadmap, which the DOE published in June, places nuclear right alongside wind and solar as desirable sources of clean energy for hydrogen production. The Joe Biden administration is making hydrogen generated from nuclear power eligible for all the same production tax credits and other subsidies as wind- and solar-based hydrogen.

The Czech government is similarly supportive, and France successfully fought earlier this year for the European Union to recognize nuclear hydrogen as low carbon in its green-energy legislative framework.

The nuclear debate

It’s not all rosy, though. The opinion gap between nuclear pessimists and optimists is a chasm. Ramana, the professor from the University of British Columbia, writes the section on SMRs for theWorld Nuclear Industry Status Report. In the 2022 edition, University of Antwerp emeritus engineering management professor Aviel Verbruggen describes these annual publications as “a barrier against utopian fantasies and wishful thinking, a tool to connect with reality.”

Ramana tells C&EN, “The people who you might think of as more critical are, in my opinion, more realistic,” because they are looking at the troubled history of nuclear power economics. “I think what’s happening is a kind of wishful thinking. It’s a straw they’re holding on to, to make sure that some technology is going to be there that will deliver us from climate change.”

In particular, Ramana cautions SMR advocates not to get too excited about direct heat use. Though an application that needs only heat could theoretically skip the water tanks, steam pipes, and turbines needed to turn heat into electricity, all the current projects being planned—including Dow’s—involve steam and electricity generation.

Ramana is similarly critical of the safety benefits that SMR makers claim. When you add up all the reactors in an SMR multipack, he says, concerns about accidents, fuel theft, and nuclear waste start to creep back in.

But the global push to cut CO₂ emissions may change the equation for SMRs enough to get a better result. Dow’s Young stresses that nuclear power today is competing with other low-carbon energy sources, such as solar, wind, and fossil fuels paired with carbon capture. Until very recently, nuclear was competing with unmitigated combustion of coal, oil, and natural gas.

Sam Dale, an analyst at the market research firm IDTechEx, says SMRs are already competitive, at least on paper, after accounting for the batteries or other energy storage devices needed to make solar and wind work as baseload power suppliers. He estimates that SMRs will attract upward of $200 billion in investment over the next 2 decades.

Dale expects to see several early SMRs come on line by 2033. Among them will be so-called fourth-generation designs, a category that includes X-energy’s gas-cooled reactor, Oklo’s liquid-metal-cooled design, and molten salt reactors that can use thorium and nuclear waste in addition to fresh uranium. “By 2043, we’re expecting about 2% of the world’s electricity to come from SMRs, which sounds insignificant until you realize that’s coming from zero today,” Dale says.

Other industry watchers are even more bullish. Mason Lester, an analyst at S&P Global, said in a recent episode of the consulting firm’s podcast Platts Future Energy that he expects 5 GW of new nuclear power in North America and 23 GW in the European Union by 2050—most of it from SMRs.

Dale predicts that direct heat use of SMRs, which is also one of Dow’s aspirations, will grow alongside electricity generation and that wide adoption by heavy industry is possible by the late 2030s.

AFRY’s Koukoulas says SMRs give the chemical industry an opportunity to rethink its primary energy supply in a way that significantly cuts greenhouse gas emissions.

“The savings in purchased power and CO₂ emissions avoidance could be enormous,” he says. “Additionally, SMRs may actually derisk plant operations by providing secure, uninterrupted baseload energy supply to chemical plants and petroleum refineries. SMRs could pave the way for a more sustainable and resilient future for the chemical industry.”