Kairos Power's next-generation nuclear reactor in Oak Ridge gets the green light

A new kind of commercial nuclear reactor is a big step closer to becoming a reality in the U.S., and it's being developed in Oak Ridge.

The U.S. Nuclear Regulatory Commission granted Kairos Power a construction permit for Hermes, a demonstration reactor, on Dec. 12.

Unlike every commercial nuclear reactor in the country, Hermes will not be cooled by water, but by a molten salt mixture that captures heat produced by fission.

While traditional water-cooled reactors require huge plants whose systems often operate under extreme pressure, the coolant in Hermes will stay liquid at high temperatures and low pressures, making the reactor design safer, more compact and more energy efficient.

Hermes is the first non-water-cooled reactor to be approved for construction in the U.S. in half a century. The last molten salt reactor was an experiment at Oak Ridge National Laboratory in the 1960s that laid the groundwork for the technology but was never commercialized.

The company plans to begin construction next year at the Heritage Center Industrial Park, a historical Manhattan Project site formerly known as the East Tennessee Technology Park, bringing $100 million of investment and 55 new jobs to Oak Ridge.

The park where Kairos will build the reactor was once public land owned by the Department of Energy, but now it's been turned over to private companies creating the next evolution of nuclear power.

Kairos must get a separate operating license from the NRC before it can fully operate Hermes. It expects the reactor will be up and running in 2026.

Hermes will not create power for the grid, but rather demonstrate the affordability and safety of the novel technology at a small scale. It is one step on California-based Kairos Power's path to commercialize the fluoride-salt-cooled, high-temperature reactor at full scale.

Kairos has enjoyed good relationships with the Nuclear Regulatory Commission, which it first engaged on Hermes licensing in 2018, and the community of Oak Ridge.

The two relationships came together at a mandatory hearing on the construction permit in October, where a letter of support from Oak Ridge leaders was read aloud and NRC Commissioner David Wright commended Kairos's engagement with local partners.

Hermes will use TRISO particle fuel, first developed at ORNL, and produced by Kairos Power in partnership with Los Alamos National Laboratory. One golf-ball-sized fuel pebble can produce the same energy as burning four tons of coal.

In 2020, the Department of Energy announced it would invest up to $303 million over seven years in the Hermes project, which will go to Kairos and its research partners. To date, the company says it has been funded almost exclusively by private investors.

Kairos born from decades of research at ORNL

Kairos hopes to build on increasing momentum for molten salt reactor technology as the U.S. races to develop advanced nuclear power to tackle the dual challenges of growing electricity demand and climate change.

The company owes much of its work to more than 60 years of research at ORNL, which pioneered molten salt reactors, first through an experiment to create nuclear-powered jets for the U.S. Air Force. In the early 1950s, the project was, for a time, the largest activity at the lab.

For five days in 1954, the lab achieved a self-sustaining fission chain reaction in a molten salt reactor, before high temperatures caused safety concerns. The nationwide program to make a nuclear jet that ran on liquid fuel was killed by President John F. Kennedy in 1961, but the lab proved the technology could work.

Then, from 1965 to 1969, ORNL operated the Molten Salt Reactor Experiment, which logged 13,000 hours at full power and became a lasting legacy of lab director Alvin Weinberg. Funding for the effort waned and the project ended in 1973.

Exactly 50 years later, the U.S. could be on the cusp of a nuclear renaissance with another wave of enthusiasm for molten salt technology. Kairos is leading the charge to build the first commercial molten salt reactor.

Of the 94 nuclear reactors licensed to operate in the U.S., 63 are pressurized water reactors and 31 are boiling water reactors, according to the NRC. TVA's two nuclear plants in East Tennessee, Watts Bar and Sequoyah, use pressurized water reactors and its third plant, Browns Ferry in Alabama, uses boiling water reactors.

The U.S. gets nearly 20% of its power from nuclear and is in a position to triple its nuclear output by 2050, according to the Department of Energy, though construction of traditional plants has slowed considerably since the 1970s and '80s. Because traditional nuclear plants often exceed their budgets enormously, there is little appetite among utility companies to build them. Instead, investments have shifted to developing next-generation nuclear technology.

A new exhibit at the American Museum of Science and Energy in Oak Ridge called "Reaction Time" tells the story of how molten salt reactor technology grew from ORNL to the Hermes demonstration reactor.

At the ribbon-cutting ceremony for the exhibit, Kairos CEO Mike Laufer said the city of Oak Ridge was a fitting partner for Hermes. The company has already submitted a construction permit application for Hermes 2, a two-unit demonstration plant in Oak Ridge that will build on the lessons of Hermes.

"What we are trying to do is really hard, really ambitious. We will work hard and tirelessly everyday to live up to the potential that we've set the stage for," Laufer said. "New technology is challenging. There's bumps and twists along the way. I'm confident that we have an approach that gives us what we think is the best shot of getting there."

Correction: An earlier version of this story misstated where Kairos will source its fuel. The company signed an agreement to produce TRISO particle fuel in partnership with Los Alamos National Laboratory.

Daniel Dassow is a growth and development reporter focused on technology and energy. Phone 423-637-0878. Email daniel.dassow@knoxnews.com.

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This article originally appeared on Knoxville News Sentinel: Kairos Power Hermes nuclear reactor approved for Oak Ridge