Oklo, a developer of a micro nuclear reactor design that it claims will be a technological leap ahead of current operating power reactors, has become the first of the so-called "advanced reactors" to submit a combined construction and operating license application to the Nuclear Regulatory Commission, the company said Tuesday.

The submission comes weeks after NRC staff decided to begin work on a streamlined process for reviewing the environmental impacts of advanced reactors, a move that the staff estimated could cut the length of the years-long approval process by 25%, but also a decision that has been criticized by nuclear watchdog groups.

This streamlined regulatory process would apply only to reactors that can generate up to 30 MW thermal, which includes Oklo's Aurora design, but excludes many of the other advanced reactor developers that have been in talks with the NRC.

Like small modular reactors (SMRs), advanced reactors aim to solve the problem of prohibitively high capital costs for new nuclear power plants that have made replacing the aging and gradually retiring U.S. nuclear fleet very difficult.

The potential of ​advanced reactors

The role of nuclear energy in the U.S. grid has been flat or slightly declining in recent years, despite the increase in demand for energy sources that do not produce CO2 emissions, like nuclear. Developers of SMRs and advanced reactors aim to cut costs through a simplified, standardized design, a smaller footprint, and the ability to flexibly generate power to run in tandem with renewable energy from the grid.

But while SMRs are light water reactors like the fleet of reactors running today, the concept of "advanced reactors" refers to non-light-water designs that use a completely different kind of reactor core, such as a molten salt-cooled reactor like a design being developed by TerraPower, a startup founded by Bill Gates. This fundamental design difference, molten salt reactor developers say, will allow these reactors to safely operate at significantly higher temperatures than current nuclear power plants, therefore adding thermal energy storage and industrial heating as additional revenue streams for nuclear power on top of selling electricity.

The technology proposed by Sunnyvale, California-based company Oklo, however, is different still. Oklo's Aurora reactor would only be 1.5 MW in capacity, compared to around 200 MW and 300 MW for designs from advanced reactor developers Terrestrial Energy and Moltex Energy, respectively, and over 1,000 MW for TerraPower's molten chloride fast reactor. These capacity numbers are megawatts electric, which tend to be smaller than the equivalent megawatts thermal for a reactor.

The Aurora would use metal fuel to produce heat, which would then go through a heat exchanger and be converted into electricity. The company says the technology has a number of attributes that current reactors cannot achieve, such as the ability to run for decades without needing to refuel and the use of a type of nuclear fission that allows waste to be recycled. The Aurora could be used as an alternative to a diesel generator, saving 1 million tons of CO2 over its lifespan compared to burning diesel, according to Oklo.

An NRC spokesman confirmed to Utility Dive that Oklo's combined construction and operating license application represents the first non-light-water design to apply for a license under the Part 52 process established in 1989 to allow a plant to request construction approval and operation approval concurrently.

A step toward the next generation

The filing of Oklo's application, the product of pre-application work that had been going on since 2016, came shortly after the NRC's Feb. 28 decision to follow through on a proposal from last year to streamline the review of advanced reactors by developing a generic environmental impact statement.

The "generic" statement means that the staff is able to use a "technology-neutral" approach to determine many of the environmental impacts from a proposed reactor. For example, the proposed reactor would have a certain site acreage, and the NRC staff would judge the land use and water use impacts of the proposed reactor based on a generic plant of the same size.

This process would save staff resources that would otherwise be spent on "duplicative review," the staff said. Developing the generic environmental impact statement itself will take 24 months, according to the staff's decision.

Oklo Chief Operating Officer and Co-Founder Caroline Cochran said that it is appropriate for regulators to look at the "general" impacts of a small plant like the Aurora, which would have the square footage of a "large home."

"The environmental reviews for many types of clean energy have evolved over recent decades in order to be more efficient, to allow the power to get onto the grid faster for the climate imperative, or in order to take into account environmental benefits with the negatives," Cochran told Utility Dive.

Both the nuclear industry and members of Congress have called on the NRC to speed up the review for advanced reactors. A bill signed into law by President Donald Trump at the end of 2019 orders the NRC to create a new regulatory structure for advanced reactors, and the Nuclear Energy Institute, the trade association representing the nuclear industry, urged the NRC to move ahead with a generic environmental impact statement.

While many advanced reactors will not be subject to the generic environmental impact statement the staff is working on, "given the strong interest in commercial deployment of next-generation reactors, we believe [it] will need to encompass all advanced reactors to the maximum extent possible, and we see this limited scope focused on micro-reactors as a good first step," Nuclear Energy Institute spokeswoman Mary Love told Utility Dive.

Moltex Energy Chief Executive for North America Rory O'Sullivan also called the decision "a step in the right direction."

While the Moltex design, which the company is attempting to build in New Brunswick, Canada, is over 30 MW, Moltex is "keenly watching the rapid advances of the NRC in preparing themselves to license advanced reactors and commends the updates made so far," O'Sullivan said in an email statement to Utility Dive. "There is extensive spent fuel in the USA which could generate larger amounts of clean energy if converted for use in the Moltex Stable Salt Reactor."

TerraPower President and CEO Chris Levesque also praised the NRC's decision. "The NRC's effort to right-size environmental reviews of advanced reactor technology will enable companies like TerraPower to provide broad access to carbon-free energy," he said in an email to Utility Dive.

A small advanced reactor design that could be affected by the NRC's new process is the eVinci from Westinghouse Electric, the company that developed the AP1000 reactor that will be used in Southern Co.'s Vogtle nuclear power plant expansion.

The 15-MW eVinci design uses solid materials to regulate nuclear reactions instead of liquid coolant, and will be able to run and shutdown "without the need for additional controls, external power source or operator intervention, enabling highly autonomous operation," Westinghouse said in a statement when the design received $5 million in funding from the U.S. Department of Energy's ARPA-E program in 2018. Westinghouse did not respond to a request for comment.

A 'Noah's Ark' of reactor technologies

In the lead up to the NRC's decision, several groups, such as the Union of Concerned Scientists and Uranium Watch, argued that the agency should not have a simpler process for licensing advanced reactors and should, if anything, move with extra caution due to the unknowns about the technologies being considered.

"It is hard to imagine a facility category for which development of a generic [environmental impact statement] would be less appropriate," Union of Concerned Scientists Nuclear Power Safety Director Edwin Lyman said in formal comments filed with the NRC. "The proliferation of new reactor designs being put forward today is practically a Noah's Ark of diversity. The vast range of power levels, fuel and coolant materials, structural materials, core designs, auxiliary systems, spent fuel characteristics, and proposed applications would result in a correspondingly diverse range of environmental impacts."

Since the NRC is governed by commissioners who are appointed by the president and confirmed by the Senate, the agency could be a very different place after the two-year period in which the generic environmental impact statement will be developed.

While noting that it is impossible to predict what the future composition of the commission could be or how the commissioners would vote regardless of their partisan backgrounds, Lyman told Utility Dive he hopes "that Democrats would be opposed to fast-tracking environmental reviews based on such a flimsy technical justification as the staff has offered."

In response to Lyman's filed comments, the NRC staff said it is not trying to address "the entire breadth of advanced reactor sizes and technologies," which is why the generic environmental impact statement will apply only to small reactors that use only "limited" amounts of land and water. But the environmental reviews "could be expanded to encompass some categories of larger advanced reactors as more information on new technologies becomes available," the staff said.