TVA Nuclear Plants: Existing Reactors, Bellefonte, and What’s Next

The Tennessee Valley Authority operates three nuclear power plants — Browns Ferry in northern Alabama, Sequoyah near Chattanooga, and Watts Bar in east Tennessee — and together they supplied 41% of TVA’s electricity in the first half of fiscal year 2026.¹² The three stations hold roughly 8,600 megawatts of combined capacity, and TVA is now working to keep them running for decades longer while also pursuing small modular reactors, advanced reactor demonstrations, and a fusion project on top of that base.

Browns Ferry, Athens, Alabama

Browns Ferry sits on 840 acres beside Wheeler Reservoir, about 32 miles west of Huntsville. It houses three General Electric Type 4 Mark I boiling water reactors, each rated near 1,200 megawatts, for a plant total of nearly 3,954 megawatts. Unit 1 entered commercial service on August 1, 1974; Units 2 and 3 followed in 1975 and 1977.³ The plant currently provides about 20% of TVA’s total generating capacity.

Browns Ferry is best known outside the industry for a fire that reshaped American nuclear safety rules. On March 22, 1975, a worker using a candle to check for air leaks ignited polyurethane foam sealing electrical cable penetrations below the control room. The fire spread into the cable spreading room and disabled all emergency core cooling systems for Unit 1 and most of those for Unit 2. Workers averted core damage by improvising with non-emergency equipment. Unit 1 needed a year of repairs, and the NRC — established just two months before the fire — went on to issue new fire-protection rules, including 10 CFR 50.48 in 1980 and Appendix R in 1981, that required physical separation of safety cables and their backups.⁴

The plant’s troubles didn’t end there. TVA shut down its entire nuclear fleet in 1985 over management and safety concerns, and all three Browns Ferry units went dark. Unit 1 restarted in 2007 after a $1.8 billion overhaul.³

In December 2025, the NRC granted subsequent license renewals for all three units, authorizing operation for up to 80 years. The new expiration dates are December 2053 for Unit 1, June 2054 for Unit 2, and July 2056 for Unit 3.⁵⁶

Sequoyah, Soddy-Daisy, Tennessee

Sequoyah occupies 525 acres on Chickamauga Reservoir, about 9.5 miles northeast of Chattanooga. Its two Westinghouse four-loop pressurized water reactors each produce more than 1,160 megawatts of continuous electricity, making the site technically distinct from Browns Ferry’s boiling water design.⁷⁸

Unit 1 began commercial operation on July 1, 1981, Unit 2 on June 1, 1982. Both received first license renewals in 2015, extending operating authority to 2040 for Unit 1 and 2041 for Unit 2. As of mid-2026, no subsequent license renewal application has been filed for Sequoyah, though the current licenses still have roughly 14 to 15 years to run.⁷⁹

Watts Bar, Spring City, Tennessee

Watts Bar sits along the Tennessee River in east Tennessee. Its two pressurized water reactors have a combined capacity of about 2,260 megawatts — 1,109 for Unit 1 and 1,150 for Unit 2.¹⁰¹¹

The plant has an unusual place in American nuclear history. Construction began in 1973 and stopped in 1985 amid NRC concerns about TVA’s nuclear program. Unit 1 did not enter commercial operation until 1996. Unit 2 sat roughly 60% complete after TVA suspended its construction in 1988, citing reduced power demand. The TVA board authorized completion in August 2007, and work resumed that October. A 2007 study projected another five years and $2.5 billion on top of the $1.7 billion already spent. Construction instead ran until 2015, and total costs reached $4.7 billion. Unit 2 connected to the grid on June 3, 2016, achieved commercial operation that October, and became the first new U.S. nuclear reactor authorized to operate in the 21st century, as well as the first U.S. plant built to post-Fukushima NRC safety standards.¹¹¹²

Unit 1’s current operating license expires in February 2036 and Unit 2’s in October 2055. TVA plans to submit a joint license renewal application in the fourth quarter of 2026. Federal rules normally bar renewal applications more than 20 years before license expiration, so TVA has asked the NRC for an exemption to include Unit 2 on Unit 1’s schedule rather than wait until 2035.¹³

Watts Bar has also drawn most of the NRC’s recent enforcement attention at TVA. In December 2025, the NRC issued a Notice of Violation with a “White” finding after TVA failed to adequately address non-functional speakers in the plant’s public address system, an emergency-preparedness issue. Earlier actions included a proposed civil penalty of more than $903,000 in 2020 for a range of violations, later revised in 2021 when the NRC removed the “willfulness” factor and reclassified some findings; a $145,000 fine in 2019 for submitting inaccurate information about the offsite electric power system’s design basis; and a 2017 Confirmatory Order requiring independent oversight of TVA’s handling of employee safety concerns.¹⁴

Bellefonte: The TVA Plant That Never Ran

A fourth site often turns up in discussions of TVA’s nuclear program, but Bellefonte never generated commercial power. Construction permits were issued in December 1974 for two 1,256-megawatt pressurized water reactors near Scottsboro, Alabama. TVA mothballed the project in 1988 with Unit 1 at roughly 88–90% completion and Unit 2 at 58%. Several revival attempts, including a partnership with the French company Areva, failed. Proposed additional Bellefonte 3 and 4 units were canceled in 2011. By 2016, TVA concluded it had no need for additional baseload power for at least 20 years and auctioned the site.¹⁵¹⁶

A $111 million purchase contract with Nuclear Development LLC also collapsed. In 2021, a federal court held TVA had the right to terminate that contract after the developer failed to secure NRC permit transfers on time, ordered TVA to refund the $22.2 million investment with interest, and denied $30 million in claimed damages. TVA formally withdrew the site’s construction permits from the NRC in September 2021 and has said it is exploring other uses for the property.¹⁵ The project consumed roughly $6 billion over its lifetime.

What TVA Is Building Next

Clinch River Small Modular Reactor

TVA’s most advanced new-build project is a GE Vernova Hitachi BWRX-300 small modular reactor planned for a 1,200-acre site along the Clinch River near Oak Ridge. The NRC issued an early site permit in 2019. In May 2025, TVA became the first U.S. utility to submit an SMR construction permit application to the NRC.¹⁷

The 300-megawatt reactor is designed to be simpler and cheaper to build than a conventional large plant, though the cost claim is contested. TVA is targeting commercial operation by the end of 2032, and the NRC has already granted an exemption allowing site excavation before the construction permit is issued. The NRC’s advanced safety evaluation was completed in May 2026; the final safety evaluation is targeted for November 2026, with mandatory hearings and a final permit decision not yet scheduled.¹⁸

In December 2025, the Department of Energy selected TVA for $400 million in federal cost-shared funding to help de-risk the project. The award came from a $900 million DOE solicitation issued in March 2025. TVA has separately applied for an $800 million DOE grant.¹⁹

The ENTRA1 Agreement

In September 2025, TVA and ENTRA1 Energy announced a plan to develop up to 6 gigawatts of new nuclear capacity across TVA’s seven-state territory, described as the largest SMR deployment program in U.S. history. Under the arrangement, ENTRA1 would finance, build, and own six plants using NuScale Power’s 77-megawatt modules, and TVA would buy the electricity through future power purchase agreements.²⁰²¹

NuScale’s 77-megawatt module received standard design approval from the NRC on May 29, 2025, making it the only SMR design with NRC approval at the time. Modules can be configured up to 12 per plant, yielding 924 megawatts per site.²²²³ No project timeline or financial terms have been disclosed publicly, and the memorandum of understanding is confidential. NuScale has indicated its technology could potentially be deployed as early as 2029.²¹

Kairos Power and Google

TVA is partnering with Kairos Power on Hermes 2, a commercial-scale demonstration of Kairos’s fluoride salt-cooled, high-temperature reactor at Oak Ridge. It is not a water-cooled design; it uses TRISO fuel particles and molten fluoride salt as a coolant. The NRC issued construction permits in November 2024, groundbreaking was on April 17, 2026, and operations are targeted for 2030.²⁴²⁵

In August 2025, Kairos, TVA, and Google announced a collaboration under which Kairos will sell electricity from Hermes 2 to TVA, and TVA will deliver equivalent clean power to Google’s AI data centers in Montgomery County, Tennessee, and Jackson County, Alabama. It is part of a broader Kairos-Google deal to bring 500 megawatts of advanced nuclear online by 2035, and TVA became the first U.S. utility to sign a power purchase agreement for electricity from a Generation IV reactor.²⁶

Type One Energy Fusion

TVA is also working with Type One Energy on “Project Infinity,” a fusion initiative at the site of the retired Bull Run coal plant near Clinton, Tennessee. The project envisions a 350-megawatt baseload fusion plant, “Infinity Two,” using stellarator technology, with operations targeted for the mid-2030s. A prototype testbed, “Infinity One,” is scheduled for commissioning in 2029. TVA issued a letter of intent in September 2025. Final approval for construction and any energy purchase agreements remain subject to TVA Board approval and regulatory review.²⁷²⁸

The Cost Question

TVA describes its existing nuclear plants as having low operating costs second only to hydroelectric power, and credits nuclear generation with keeping rates competitive for more than 4.5 million homes and businesses.¹ That framing glosses over a complicated build history. A Government Accountability Office report found that TVA’s nuclear construction program saw costs rise to $31.6 billion, 166% higher than original estimates, driven by design changes, scope additions, and delays. From 1970 to 1980, TVA rates rose about 9.2% annually in real terms, and production costs plus interest on construction debt accounted for 86% of what ratepayers paid in fiscal year 1980.²⁹

The new generation of small modular reactors raises fresh cost questions. TVA’s own filings put the base construction cost of the BWRX-300 at $17,949 per kilowatt in 2024 dollars, excluding financing and construction-period inflation. Independent analyses have estimated electricity from such plants could cost between $115 and $251 per megawatt-hour by 2035.³⁰ The recent history of nuclear megaprojects is instructive: the Vogtle expansion in Georgia, the only other recent U.S. nuclear construction, finished seven years late at $35 billion, and Watts Bar Unit 2 itself came in at nearly double its projected budget.

What’s Pushing the Expansion

TVA has repeatedly cited surging electricity demand from artificial intelligence data centers, hyperscale computing, semiconductor manufacturing, and national security operations as the reason for its nuclear push. The Clinch River SMR, the ENTRA1 agreement, and the Kairos partnership all reference the need for round-the-clock power to those facilities. The $400 million DOE award was framed as part of a broader federal effort to expand domestic nuclear capacity.¹⁹

Whether TVA can carry out an expansion this ambitious without repeating the cost overruns and delays that have marked its nuclear construction for decades remains open. Clinch River has a credible regulatory pathway and federal funding. The ENTRA1 program dwarfs anything else in the U.S. SMR pipeline but has no public timeline or cost projections. And the fusion and advanced reactor partnerships rely on technologies that have never operated at commercial scale.

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