After years of promise, a new generation of smaller, scalable nuclear power plants is closer to becoming a reality as two companies plan to have operational ­facilities by the end of the decade. One company is actively marketing its approach to industrial companies and utilities, raising the possibility of expanding nuclear energy beyond its traditional markets. Almost as significantly, these plans are accompanied by a recently announced effort to build the first fabrication plant outside Russia to manufacture the specific nuclear fuel the designs require. 

Nuclear power plants remain bedrock contributors to U.S. electricity supplies, support just under 20% of demand and provide almost half the nation’s carbon-free kilowatts. However, the industry has largely stalled. Only three units were completed in the last decade, and the youngest of the others is pushing 40. 

Three recent plants include Tennessee’s Watts Bar Unit 2, which began operating in 2016; Georgia’s Vogtle Unit 3, which began commercial operation in late July; and Vogtle Unit 4, with commercial operation expected by March 2024. The Vogtle plants have a combined output of approximately 2,200 megawatts (MW) and cost more than $30 billion to build, $17 billion above initial estimates, with construction taking seven years more than planned.

A new approach to nuclear

A decade or so ago, several startups began exploring smaller, modular approaches to nuclear generation, given the expense and regulatory complexity of large, ­megawatt­-scale reactors. Recognizing the changing U.S. energy market, these companies targeted designs that still offered base-load power production, but at a scale that addressed the growing contribution of comparatively inexpensive renewables in meeting energy demands. Now two of those operations, focused on high-assay, low-enriched-­uranium (HALEU) fuel, are nearing possible groundbreaking.

TerraPower’s Natrium small modular reactor (SMR) has garnered the most press, thanks to its famous financial backer, Bill Gates. However, the attention isn’t undeserved, given a unique design feature that will provide greater production flexibility than other nuclear designs. The 345 MW generators will incorporate a molten salt-based energy storage system that will boost output up to 500 MW for more than 5½ hours to support peak-demand needs. 

Additionally, Natrium uses liquid sodium, rather than water, as a coolant. That material’s significantly higher boiling point limits the possibility of China Syndrome-style meltdowns. Plus, the plants will operate at atmospheric pressure and use passive cooling methods that don’t require outside power to further enhance safety.

The company already has four units on order. The first is a demonstration project planned to replace the Naughton coal plant near Kemmerer, Wyo. Construction there is expected to begin this year. Startup was initially planned for 2028, but has been delayed to 2030 due to a lack of the HALEU fuel the design calls for. 

Work is now underway by Centrus Energy Corp. on a HALEU production facility in Piketon, Ohio, that should begin producing the material by the end of 2023. An additional three Natrium units are in the plans for the western utility PacifiCorp.

Future planning

X-Energy is a second startup well along with plans for operating reactors by the end of 2030. Its SMRs are 80-MW units that can be combined to create larger, commercial-scale plants or used individually in industrial applications. The company recently entered into a joint development agreement with Dow for a single unit to supply electricity and process steam for the chemical manufacturer’s facility in Seadrift, Texas. X-Energy also has signed an agreement for up to 12 units (960 MW) with Energy Northwest, a supplier to 28 public power utilities in Washington state. 

X-Energy subsidiary TRISO-X will be manufacturing the company’s proprietary fuel system, which wraps HALEU particles in alternating coating layers said to be meltdown­-proof. A fabrication plant is under development in Oak Ridge, Tenn., where a pilot facility is already up and running. X-Energy is also building its first support center for monitoring and managing its future plant fleet in Frederick, Md. The center will include real-time instrumentation and controls along with digital twin technology for use in training and predictive maintenance efforts.

Like TerraPower, X-Energy will be turning to Centrus Energy as their HALEU fuel supplier. This company, a longtime provider of enriched uranium fuel, is gearing up the nation’s only domestic HALEU production line, making it a critical cog for these two SMR manufacturers. 

In June, the Nuclear Regulatory Commission authorized the plant’s startup, and a demonstration project is expected to produce 20 kg of HALEU by the end of 2023, with an additional 900 kg expected by the end of 2024. This work follows a three-year project with the U.S. Department of Energy to manufacture and assemble the centrifuges the advanced uranium requires. Last November, the DOE awarded Centrus a $150 million contract to start up and operate the centrifuges.