Advancing the Next Generation of Nuclear Technology

As various stakeholders debate the possibilities for a future electric system, a new generation of nuclear generating technology is coming into the fold. These demonstrations of advanced nuclear technologies will help many across the industry – and policymakers – understand how the next generation of nuclear can provide the clean, affordable, safe, and reliable baseload power that is urgently being sought after.

And just as public power played a key role in seeing the first generation of nuclear facilities in the U.S. come online, public power entities are again taking part in projects that might set the course for the next generation of nuclear power.

First generation still at work, but retiring

In 2019, public power generated more than 62 terawatt-hours of electricity from nuclear plants, or 16.4% of total generation – which is roughly half of the total public power generation from natural gas. Nationwide, just under 20% of generation comes from nuclear facilities, the majority of which began operation in the 1970s and 1980s. More than half of public power’s nuclear generation currently happens in the southern half of the country, with some southeastern states sourcing almost a quarter of their power from nuclear facilities.

Nuclear facilities have made up less than 1% of capacity additions since 2014 and have accounted for about 4% of all capacity retirements in that timeframe. In 2020, two nuclear reactors - nearly 2,000 MW in nameplate capacity – retired. Over the next few years, owners have announced plans to prematurely retire more than 3,100 MW of nuclear through 2025, putting it among the biggest share of capacity getting retired, behind coal and natural gas. These announced retirements would bring down the total nameplate capacity by 3% (for contrast, about 15% of current coal capacity is planned to be retired through 2025).

Enter the next generation

Nuclear projects under construction today total more than 2,200 MW, but the future of the nuclear industry looks different from today’s large light water reactors. Looking deeper into the pipeline, this decade is poised to see technologies that have been in the earlier stages of research and development move into the demonstration stage.

Most of the focus on advanced nuclear is on small modular reactors, which consist of several linked nuclear reactors with a capacity of up to a few hundred megawatts. The reactors are designed to be built in a factory setting to bring down the development time and cost.

x-energy nuclear facility rendering
Rendering of X Energy facility in Washington

Notably, the Department of Energy’s Advanced Reactor Demonstration Program awarded about $4 billion in four grants to demonstrate new nuclear technologies. As a condition for the awards, the developers must match development costs with DOE funding and had to show that they could reasonably have the demonstration facilities in operation by 2027. Three of the grants involve public power partners. Energy Northwest, a joint action agency serving 27 public utilities in Washington state, and Utah Associated Municipal Power Systems, a joint action agency serving 49 members in seven Western states, are utility partners in the DOE-funded demonstrations.

The bipartisan infrastructure bill, as passed by the Senate in August, would funnel another $6 billion into research and development activities around advanced nuclear technology.

These projects were discussed during a panel at the American Public Power Association’s virtual National Conference in July 2021, which featured Maria Korsnick, president and CEO of the Nuclear Energy Institute; Greg Cullen, vice president of energy services and development at Energy Northwest; and Doug Hunter, CEO & general manager of UAMPS.

Snapshot of SMR projects under development




Natrium (TerraPower and GE Hitachi)


Six 77 MW reactors

Four 80 MW reactors

Single reactor

Total Capacity

462 MW

320 MW

345 MW (500 MW with salt storage)

Public power partner


Energy Northwest/Grant County PUD

Energy Northwest (consulting)


Air condenser



Of note

First SMR design to receive approval from Nuclear Regulatory Commission

Fuel “pebbles” containing uranium inside a hard graphite shell

Salt storage of excess energy

X Energy’s design for the facility would feature four reactors each with 80MW each, for a total of 320 MW for the facility. The plan is for the facility to be sited adjacent to the Columbia Generating Station, and to come online before 2030. Energy Northwest is a technical consultant on the project, with Grant County Public Utility District stepping in to be the likely utility owner. Cullen described the X Energy design as having fuel “pebbles,” each about the size of a billiard ball, which contain the uranium inside a thick graphite shell to prevent from being melted. Each reactor contains about 200,000 pebbles that move through the reactors “like a gumball machine,” getting rerouted about six times before being fully spent.

The TerraPower and GE Hitachi design for the Natrium facility is a bit unique in that it has a single reactor that has a molten salt storage capacity between the reactor and the turbine generators. This design allows for energy to be fed directly to the turbines or diverted to salt storage, based on needs, while keeping the operations at a steady state. The planned site for the facility is at a retired coal plant in Wyoming. Cullen said that Energy Northwest is consulting on the project and will possibly manage operations of the project in the future.

cross section of NuScale modular design, courtesy NuScale Power LLC
Cross section of NuScale reactor building. Courtesy NuScale Power, LLC.

The NuScale facility with UAMPS, known as the Carbon Free Power Project, will be sited in Idaho, and feature six reactors of 77-MW each, for a total of 462 MW. Given the water shortages in the West, Hunter stressed that it was important that this technology could avoid using water for cooling. Hunter also shared some of the different project capabilities, which include being able to decrease the heat and bypassing the steam from the steam generator directly to the condenser to allow for greater integration of renewable resources. “It really gives us a lot of flexibility inside the grid,” said Hunter.

Outside of the technology exploration, Hunter explained the importance of a contract design that allowed for cost controls and multiple off-ramps for UAMPS if the development does not go as planned. UAMPS’ contract with NuScale specifies that the energy produced will not exceed $58/megawatt-hour at the interconnection, a price that Hunter called competitive for carbon-free, dispatchable generation. The first reactor is scheduled to be operational in 2029, with the full plant operational in 2030.

Avoiding overbuild

In Washington, the Clean Energy Transformation Act pushes for the electric system to be 100% carbon neutral by 2030, with at least 80% of electric generation coming from non-emitting resources, and 100% carbon free by 2045. Cullen noted that the distinction for the “clean” energy requirement, instead of being a renewable requirement, was a helpful distinction for utilities in the state facing concerns over future resource adequacy.

Energy Northwest’s 100% clean energy portfolio is supported by the Columbia Generating Station, a 1,200 MW nuclear facility that came online in 1984. Currently, said Cullen, the plant’s license is set to expire in 2043, and the JAA hopes to have that extended another 20 years.

Cullen mentioned how several years ago, public power utilities across the Pacific Northwest commissioned a study regarding the feasibility and costs to bring down emissions across the region. The study, developed by E3, calculated that the capacity factor for wind and solar in the region was only about 26%, and that the effective load carrying capability of these sources was even lower – 7 and 12% percent, respectively – since they generate the most in the spring and fall, when hydroelectric facilities in the region are traditionally able to offer the most output, and demand is lowest. Relying solely on wind, solar, and storage, E3 forecasted that utilities in the Pacific Northwest would need to build more than 150 GW capacity of these resources to reach a 100% clean energy system by 2050.

The study posited that adding clean baseload technology, such as small modular reactors, could bring down these new capacity needs. Energy Northwest commissioned a follow-up study that found adding 6.5 GW of nuclear capacity – 5.3 GW of small modular reactors and 1.2 GW to Columbia Generating Station – would allow the agency to reach the state’s 2045 goal and avoid building about 91 GW of wind, solar, and storage if only those resources are allowed.

Hunter also sees advanced nuclear generation as being able to fulfill anticipated future capacity needs. “We have lost a lot of coal out here in the West over the last 10 years, and we're destined to lose more than what we've already lost in the next 10 years,” he said. “This idea of having something that can follow load for us and meet those requirements is very important.”

Making the case

In a speech in March 2021, NEI’s Korsnick stated that nuclear facilities have been operating at 90% capacity factor for more than two decades. The entities involved in developing advanced nuclear technologies expect to achieve even greater efficiency, plus allow for more flexibility in integrating with variable resources.

“Governments, NGOs, and the private sector all agree: ambitious climate plans only work with nuclear energy,” said Korsnick.

She asserted that advanced nuclear technologies can “bring clean electricity to hard-to-reach places where traditional reactors just don’t make sense” – either because of size, waste storage needs, or proximity to necessary infrastructure.

Cullen pointed to significant advancements in safety and design that make SMRs more accessible for regions that haven’t worked with nuclear generation. He called out attributes including the modular construction techniques and flexible operation design for making the technology more economically viable.

And while advanced nuclear facilities are just moving into demonstration, Korsnick, Cullen, and Hunter all emphasized how the technology today is building off of decades of research and development. “These aren't just concepts that are trying to go straight from the drawing board into operations,” stressed Cullen. “They're building on decades of work.”

Getting the technology into operations is one hurdle, other challenges include ensuring the supply chain is solid and building public support for and understanding of the technology.

“The next generation of nuclear will only work if we have the supply chain to build, operate, and maintain new reactors at home and abroad,” said Korsnick in the March 2021 speech. For NEI, building this supply chain means renegotiating trade agreements around nuclear fuels, having policies and regulations that support nuclear exports, and having the federal government sign onto long-term contracts for enriched uranium to spur the supply and demand needed for advanced nuclear globally. Korsnick stressed the importance of having the U.S. ready to meet such demand, so that facilities need not rely on fuel or other supply chain needs from China and Russia.

“The U.S. industry can offer unparalleled expertise and technological capabilities to countries that choose nuclear energy. We also offer the world’s highest safety standards and safeguards and a promise to enhance—not lessen—our partners’ energy independence as they reduce emissions,” she said.

In conducting some customer polling on nuclear topics, Energy Northwest found that about half of its customer base was neutral on whether or not they supported nuclear projects. Cullen sees this as an opportunity to provide some public education on the technology, sharing some of the enhanced safety aspects of advanced nuclear as well as how the technology can help achieve clean energy goals. Cullen hopes that such education can influence the majority of the population to become supportive of the technology.

“There's such a focus now on climate and carbon and cleaning up the energy sector that people are really open to anything that can help with that,” said Cullen.