Small Modular Nuclear Reactors

Public utilities explore nuclear power to meet electricity demands

By Stephen Ernst

Utah Associated Municipal Power System is working with NuScale Power to develop what could be the nation’s first operational small modular nuclear reactor. This illustration shows a full VOYGR-12 SMR plant layout, including parking and administration buildings, left; the main energy production buildings, center; and cooling towers and a switchyard surrounded by a perimeter security fence. Illustrations Courtesy of Nuclear Power.

With a growing demand for electricity—and in a state with aggressive decarbonization policies—Grant Public Utility District (PUD) in Moses Lake, Washington, is considering adopting a new spin on an old energy resource.

Grant PUD and Energy Northwest—a consortium of public utilities—are among those in the West studying the feasibility of developing a small modular nuclear reactor, known as SMR, that could be online before 2030.

The first civilian nuclear reactor went into service in the United States in 1969. Today, 93 commercial reactors operate in the country, generating about 95 gigawatts of power—or about 20% of the country’s total annual electricity generation.

But those traditional nuclear plants—which generate more than 1,000 megawatts (MW) each—are expensive to build and don’t have the flexibility to ramp up or down to help balance rapid changes in generation from solar and wind projects.

As more coal-fired power plants are retired in the West and states move away from developing new natural gas-fired generation, grid operators are left with a limited number of dispatchable resources, or power plants that can be turned up or down depending on what the grid needs.

Grant (PUD) is studying a Small Modular Reactor (SMR) designed by Maryland-based X-Energy that would initially generate 320 megawatts of power but could be expanded as needed.

The facility would be capable of quickly increasing or decreasing output to match the rise and fall of solar and wind facilities in the region.

The X-Energy-designed reactor operates at extremely high temperatures that could also produce hydrogen the utility could burn in a regular natural gas power plant.

Today, Grant PUD generates all the electricity it uses to serve 53,213 meters in central Washington with emissions-free hydroelectricity, generated primarily from 2 dams it owns on the Columbia River.

But the utility is quickly outgrowing its hydro portfolio. The PUD has grown about 3% a year during the past decade and expects that trend to continue. The utility projects it will be short of energy by 2025 and forecasts a capacity deficit starting in 2026.

NuScale Power’s VOYGR-12 SMR plant can generate 924 megawatts of electric capacity on 0.05 square miles, making it ideal for generating power in locations with space constraints. This image shows a cross sectional view inside the VOYGR-12 plant reactor building.

Rich Wallen, general manager at Grant PUD, says SMR technology fits the profile the utility seeks in a generating resource. It is emissions-free, dispatchable and capable of meeting the utility’s energy and capacity needs.

“We have an aggressive carbon reduction policy in this state, and traditional renewable energy has intermittency concerns that, frankly, won’t necessarily meet the needs in front of us,” Wallen says. “That doesn’t mean they can’t be a part of the overall solution, but we need clean, firm and dispatchable generation. SMR technology checks all of those boxes.”

Grant PUD expects to have an engineer estimate the costs of developing an SMR in the first quarter of 2023. Wallen says the cost needs to be between $55 per megawatt-hour (mWh) and $60 per MWh for an SMR to be competitive.

One of the promises of SMR technology is it could be cheaper and less risky to build than traditional reactors. But rising inflation and higher interest rates may undercut that promise.

The Utah Associated Municipal Power System—a collection of 50 small public utilities, municipalities and electric cooperatives in the intermountain West—is further along in its exploration of SMR technology.

The organization is working with Portland-based NuScale Power to develop what could be the nation’s first operational SMR.

The 462-MW Carbon Free Power Project would be at the Idaho National Laboratory near Idaho Falls. It has received the first of three key regulatory approvals from the Nuclear Regulatory Commission.

About one-third of the expected generation from the project is already under contract to 27 UAMPS members, but the projected cost of that power is rising.

Initial projections from 2016 calculated the energy cost at $55 per MWh. That was revised to $58 per MWh in 2020, and now the levelized cost of energy from the project is nearly $100 per MWh.

The organization attributes the price hike to increasing costs for steel and higher interest rates. UAMPS is finishing a new cost estimate and hopes final costs come closer to $90 per MWh.

UAMPS says it carefully investigated all other forms of nonintermittent, noncarbon, dispatchable energy sources and has found the SMR project to be cost-competitive with each of them. These include renewable energy with battery backup, green hydrogen, and fossil fuel with carbon capture and storage.

Hydroelectricity, geothermal and waste-heat resources are part of UAMPS’ portfolio but won’t provide the scale needed to back up renewables and provide the amount of energy needed as electrification occurs in transportation and other sectors, the organization says.

A third SMR project is under development in Wyoming.

Bellevue, Washington-based TerraPower has proposed a demonstration plant in Kemmerer, Wyoming, near PacifiCorp’s retiring coal-fired Naughton Power Plant.

The project features a 345-MW sodium-cooled fast reactor with a molten salt-based energy storage system. The storage technology can boost the system’s output to 500 MW when needed and facilitate integrating the plant with renewable resources.

PacifiCorp and TerraPower announced recently they are studying the feasibility of developing five more SMR projects within PacifiCorp’s service territory by 2035.

So far, the three proposed SMR projects have been financed mostly by the U.S. Department of Energy’s Advanced Reactor Demonstration Program, which requires projects to be operational by 2028.

“I have a super-high level of confidence that an SMR will be built,” Wallen says. “I don’t know if Grant PUD will be the first, but I hope someone in public power is. I think the technology works and can meet the needs of a nation trying to decarbonize its electrical grid. I think it’s just a matter of time.”

How Do SMRs Work?

Nuclear power plants generate heat through nuclear fission. The process begins in the reactor core. Atoms are split apart, releasing energy and producing heat as they separate into smaller atoms. The cycle repeats again and again through a fully controlled chain reaction.

Control rods made of neutron-absorbing material are inserted into the core to regulate the heat generated by the chain reaction.

Reactor coolant water picks up heat from the reactor core. Reactor coolant pumps circulate the hot water through a steam generator, which converts water in a secondary loop into steam.

The steam is used to drive a turbine, which generates electricity.

Throughout the process, the pressurizer keeps the reactor coolant water under high pressure to prevent it from boiling.

Information courtesy of the Department of Energy.