TVA receives first U.S. construction permit for a small modular reactor

Overview

Updated 2 hours ago

The U.S. Nuclear Regulatory Commission on September 29 granted Tennessee Valley Authority a construction permit for a small modular reactor at its Clinch River site near Oak Ridge, Tennessee. It is the first SMR construction permit issued in the United States, clearing TVA to build a 300-megawatt BWRX-300 designed by GE Vernova Hitachi Nuclear Energy.

The permit is only the second advanced-reactor construction permit in U.S. history, after TerraPower's Natrium approval in March 2026. The NRC completed its review in 14 months, four months ahead of schedule, helped by an Early Site Permit TVA already held for the property. The permit authorizes construction but not operation — TVA must complete the build and win a separate operating license before loading fuel.

The decision establishes a repeatable licensing pathway for the BWRX-300 design, with Ontario Power Generation already building one in Canada and Blue Energy applying for another in Texas. At roughly a third the size of a traditional reactor, SMRs are built from factory-made modules that are shipped to the site, which proponents say cuts construction cost, time, and complexity compared with gigawatt-scale plants.

Why it matters

First U.S. small modular reactor permit opens a licensing path to bring a new class of nuclear plants online by the early 2030s.

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Key Indicators

300 MWe

Reactor capacity per unit

BWRX-300 output, about one-third of a traditional nuclear unit.

14 months

NRC review time

Completed four months ahead of schedule.

Advanced reactor construction permits issued in the U.S.

Clinch River follows TerraPower's Natrium approval in March 2026.

Reactor units the Clinch River site can host

Current permit covers Unit 1; the Early Site Permit allows a combined 800 MWe.

Voices

Curated perspectives — historical figures and your fellow readers.

Ever wondered what historical figures would say about today's headlines?

People Involved

Jason Cooper

Chief executive, GE Vernova Hitachi Nuclear Energy

Leads the joint venture behind the BWRX-300

Adam Stein

Director of Nuclear Energy Innovation, Breakthrough Institute

Analyst tracking nuclear licensing reform

Organizations Involved

Tennessee Valley Authority

Federal utility

Permit holder and project owner

The largest U.S. public power company, serving about 10 million people across Tennessee and parts of six neighboring states.

GE Vernova Hitachi Nuclear Energy

Nuclear technology vendor

Reactor designer and manufacturer

Joint venture behind the BWRX-300, a 300-MWe boiling water reactor design built from factory-made modules.

U.S. Nuclear Regulatory Commission

Federal regulator

Issuing authority for the permit

The independent federal agency that licenses and oversees civilian nuclear reactors in the United States.

Ontario Power Generation (OPG)

Provincial utility

Leads the Canadian BWRX-300 deployment at Darlington

Ontario's public electricity generator, building the first BWRX-300 at its Darlington site.

Timeline

February 2022 September 2026

8 events Latest: Today

Tap a bar to jump to that date

September 2026
NRC issues first U.S. SMR construction permit
Today Regulatory

Approved TVA's Clinch River BWRX-300, the first small modular reactor permit and second advanced-reactor permit in the U.S.
Today
Blue Energy files Texas BWRX-300 application
Filing

Submitted the first part of its construction permit application for a gas-plus-nuclear project in Texas.
September 2026
March 2026
NRC issues TerraPower Natrium permit
Regulatory

First advanced-reactor construction permit in the U.S., for TerraPower's Wyoming plant.
March 2026
OPG applies to operate Darlington reactor
Filing

Ontario Power Generation submitted its License to Operate application for the first Darlington BWRX-300.
March 2026
May 2025
TVA files second part of application
Filing

Submitted the second half, completing the construction permit application under an NRC exemption.
May 20th, 2025
April 2025
TVA files first part of construction permit application
Filing

Submitted the first half of its Clinch River construction permit application to the NRC.
April 28th, 2025
Canada licenses first BWRX-300 construction
Regulatory

Canadian Nuclear Safety Commission issued Ontario Power Generation a license to build the first BWRX-300 at Darlington.
April 2025
February 2022
TVA board launches SMR program
Decision

Board approved exploring advanced reactors and announced intent to pursue the BWRX-300 at Clinch River.
February 2022

Scenarios

TVA breaks ground and begins building Clinch River Unit 1

Likely Resolves by End of 2027

Discussed by: TVA and project partners, who are negotiating cost-sharing for the build

TVA finalizes financing partnerships, announces a construction start, and pours first structural concrete on schedule. The permitted site, factory-built modules, and an existing 800 MWe site allowance make this the most direct path, if TVA secures funding and partners.

BWRX-300 fleet grows as more U.S. permits follow

Possible Resolves by Q3 2028

Discussed by: GE Vernova Hitachi Nuclear Energy, citing Blue Energy's pending Texas application

The Clinch River permit becomes the template for a fleet. The NRC dockets Blue Energy's Texas BWRX-300, and other applicants cite the Clinch River review to shorten their own. A repeatable pathway, rather than one-off reviews, is what the vendor says makes the design economical.

Cost or schedule trouble stalls Clinch River construction

Possible Resolves by End of 2027

Discussed by: Historical pattern; the project was nearly terminated in 2023 as costs rose and subscribers dropped out

Construction stalls or slows on rising material costs, supply-chain bottlenecks, or financing gaps, echoing the NuScale UAMPS project that was cancelled in 2023. TVA has stressed it is negotiating 'responsible cost sharing' with partners, signaling cost discipline but also acknowledging financial risk.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1970–1983

Clinch River Breeder Reactor Project (1970–1983)

Congress funded a prototype fast breeder reactor at the same Clinch River site in Oak Ridge, seeing it as the future of nuclear power. The project ran for over a decade as costs ballooned, then Congress terminated it in 1983 after more than a billion dollars had been spent, with nothing built.

Then

The site sat undeveloped for decades, and the cancellation discouraged new U.S. reactor orders.

Now

The empty Clinch River site, already studied and zoned for nuclear, remained available for a later project.

Why this matters now

The same land that hosted America's most famous cancelled reactor now hosts the first approved small modular reactor — a second chance at the same site, 43 years later.

2009–2024

Vogtle Units 3 and 4 (2009–2024)

Georgia Power built the first new U.S. reactors in decades, two AP1000s at Plant Vogtle. The project came online from 2023 to 2024 after running years late and billions of dollars over its original budget.

Then

Vogtle showed the U.S. still knows how to finish a nuclear build, but at enormous cost.

Now

Its cost overruns are the cautionary tale for every large nuclear construction project that follows.

Why this matters now

The BWRX-300's factory-built, smaller-scale design is marketed as the answer to Vogtle-style overruns; the permit is the first test of whether that promise holds.

2020–2023

NuScale UAMPS project terminated (2023)

NuScale planned the first U.S. SMR deployment, six modules in Idaho for a group of municipal utilities. Costs kept rising as the target power price climbed, and the project was cancelled in November 2023 when not enough utilities committed to buy the power.

Then

The U.S. was left without any SMR under construction, and skepticism about the design class grew.

Now

It set the benchmark for the cost and subscription risk any new SMR project must overcome.

Why this matters now

Clinch River is the first U.S. project to get past the permitting stage NuScale never reached, but it faces the same market test: finding partners willing to fund and buy from a first-of-a-kind plant.