EVERETT — TerraPower, an energy firm that operates a 65,000-square-foot research facility in Everett near Paine Field, plans to build a prototype nuclear reactor in southwest Wyoming.

The decade-old Bellevue-based company, launched by Microsoft co-founder Bill Gates, recently chose Kemmerer, Wyoming, as the production site for the company’s new Natrium reactor demonstration plant.

The prototype is intended to test the power plant’s engineering, construction and function.

TerraPower received an initial $80 million to build the plant through a competitive grant offered by the U.S. Department of Energy’s Advanced Reactor Demonstration Program.

TerraPower is one of two companies to secure funding through the program.

X-energy, a nuclear engineering company, in Rockville, Maryland, also received $80 million.

TerraPower’s Everett laboratory supports a variety of research, including materials development and testing, a company spokeswoman said in an email statement.

To support the Natrium project, TerraPower “is and will be hiring for a variety of positions” at the Everett lab and the company’s main office in Bellevue, the spokeswoman said.

The energy department expects to invest $3.2 billion over a seven-year period in the two firms. The aim is to make the nuclear reactors operational by 2028.

Terra Power and X-energy will match the federal investment dollar-for-dollar, the two companies said.

“The awards are the first step of a new program that will strengthen American leadership in the next generation of nuclear technologies,” U.S. Secretary of Energy Dan Brouillette said in an agency statement. “These partnerships will help maximize the Department of Energy’s investment in advanced reactors, which play a vital role in our clean energy strategy.”

The long-term goal is to develop commercially viable power plants.

Because nuclear power does not emit carbon dioxide or greenhouse gases, it is considered a carbon-free source.

TerraPower’s sodium-cooled fast reactor uses liquid metal — sodium — as a coolant, unlike typical nuclear power plants that use water as a coolant.

The use of liquid sodium allows the coolant to operate at lower pressures and higher temperatures, improving the safety and efficiency of the system, according to the U.S. Office of Nuclear Energy.

Terra Power, which developed the technology with GE-Hitachi, said the reactor’s design should reduce the plant’s overall cost.

The completed plant is expected to produce up to 500 megawatts, enough energy to power 400,000 homes.

Nuclear reactors currently supply about 20% of the electricity consumed in the United States. According to Gates, nuclear power “is the only carbon-free energy source that can reliably deliver power day and night, through every season, almost anywhere on earth, that has been proven to work on a large scale.”

Terra Power selected Kemmerer, which is near the Naughton Power Plant, after an extensive evaluation process and meetings with community members and leaders, the company said.

The Naughton Power Plant is coal-fired and operated by PacifiCorp. The facility’s two remaining coal-fired units are scheduled to retire in 2025.

“People across Wyoming welcomed us into their communities over the past several months, and we are excited to work with PacifiCorp to build the first Natrium plant in Kemmerer,” said Chris Levesque, president and CEO of TerraPower, in a company statement. “Our innovative technology will help ensure the continued production of reliable electricity.”

Gary Hoogeveen, president and CEO of Rocky Mountain Power, a division of PacifiCorp, called the project, “an exciting opportunity to explore what could be the next generation of clean, reliable, affordable energy production while providing a path to transition for Wyoming’s energy economy, communities and employees.”

TerraPower expects to submit a construction permit application to the Nuclear Regulatory Commission in 2023.

Janice Podsada; jpodsada@heraldnet.com;425-339-3097; Twitter: @JanicePods.