TerraPower bullish on Natrium plant construction, NRC says ‘not so fast’

TerraPower officials said last week to expect "dirt moving" at its Wyoming site come June-and for operations to begin there as early as 2030-as it advances plans to build new nuclear in the United States. But 40-plus pages of initial commentary back from the Nuclear Regulatory Commission, in the form of a preapplication readiness assessment report, may slow TerraPower's plans.

The Bill Gates-backed company filed construction application materials for Kemmerer Power Station Unit 1, which will utilize TerraPower's Natrium sodium fast reactor technology. The site neighbors a retiring coal plant in Kemmerer, Wyo.

What's next? Chris Levesque, chief executive of TerraPower, told the Financial Times that his firm will start building in June, even if it hasn't received a construction permit from regulators by then. Most of the initial work at the Kemmerer site won't be related to nuclear activity, he added.

The NRC's response response to TerraPower's application suggests there are still gaps around the technical and licensing process for the Natrium reactor approval. "References to report for which the reviews have not yet been completed represents a potential application review schedule risk," the NRC said in its letter.

Edwin Lyman, a physicist and director of nuclear power safety for the Union of Concerned Scientists, said questions raised by the NRC in its feedback "will be hard to remedy" between now and June, when TerraPower wants to start construction.

"There are a lot of issues with a first-of-its-kind reactor," Lyman added. "For these unique designs-some that are not new but don't have much, if any, operating experience in the U.S.-my concern is that there's too much of a rush."

The specs: The Natrium reactor demonstration project, a collaboration between TerraPower and GE Hitachi, is a 345-MW sodium-cooled fast reactor design with a molten salt-based energy storage system. The demonstration plant is intended to validate the design, construction, and operational features of Natrium technology and HALEU fuel.

The reactor would generate 345 MW of electricity, but actual electricity generation will vary between 100 MW and 500 MW, depending on wholesale prices on the grid. The longer-term idea is that this will depend on whether the sun is shining and the wind is blowing.

Natrium is one of two advanced reactor demonstration projects selected for competitive funding through the Department of Energy's Advanced Reactor Demonstration Program. (X-energy's Xe-100 is the other.) TerraPower also received $1.6 billion in funding from the Bipartisan Infrastructure Law signed by President Biden in November 2022, which is to be used to ensure the completion of the plant. The company also raised over $1 billion in private funding.

The technology: Gates helped found TerraPower in 2006 and has been its chair ever since. The company's aim is to provide the world with a more affordable, secure, and environmentally friendly form of nuclear energy. The Natrium plant is roughly one-third the size of the larger U.S. operating plants and is even a smaller footprint, compared with other advanced reactors.

TerraPower touts the cheaper cost and safety attributes of using liquid sodium rather than water to cool its Natrium reactors. Liquid sodium has a significantly higher boiling point-882°C-than water, which is used to cool most conventional reactors.

But the use of sodium has raised some concerns due to its explosive reaction if it touches water. There has not been a sodium-cooled reactor in the U.S. since several experimental reactors were attempted in the 1960s and 1970s. After several failures, including a partial meltdown of Fermi-1 in Michigan in 1966, all of these reactors were decommissioned, and most were replaced with conventional boiling water reactors.

Natrium's design also relies on natural forces, like gravity and hot air rising, to cool the reactor if an unexpected shutdown occurs.