USA — Nuclear Fleet Overview

Operating Reactors (database): 12 tracked in platform Total Tracked Capacity: 2234 MWe Under Construction (database): 7 Planned: 28 Regulatory Body: NRC (Nuclear Regulatory Commission)

Fleet Summary

The United States operates the largest civilian nuclear power fleet in the world, with 93 operational reactors across 54 nuclear power plants as of 2023, generating approximately 95 GWe of net capacity. These reactors, primarily pressurized water reactors (PWRs) and boiling water reactors (BWRs), provide about 20% of the nation’s electricity, marking the U.S. as a cornerstone of global nuclear energy production. After a construction hiatus since the 1970s due to regulatory and economic challenges, recent completions like Vogtle Units 3 and 4 (each 1,117 MWe) signal a revival, alongside growing interest in small modular reactors (SMRs) and advanced designs. The fleet faces aging infrastructure, with many reactors approaching or exceeding their original 40-year design life, though license extensions to 60 or 80 years are common.

Policy & Outlook

U.S. nuclear policy is increasingly supportive of maintaining and expanding nuclear capacity as a key component of clean energy goals, with the Biden administration emphasizing nuclear in its net-zero by 2050 strategy. The Inflation Reduction Act of 2022 provides tax credits and funding for existing plants and new builds, while the Bipartisan Infrastructure Law allocates billions for advanced reactor demonstrations. Significant focus is on SMRs and microreactors, with projects like TerraPower’s Natrium (345 MWe) and X-energy’s Xe-100 (80 MWe) receiving Department of Energy (DOE) backing to decarbonize industrial sectors. Challenges remain, including high upfront costs, regulatory streamlining needs, and public perception hurdles, though restarts like Three Mile Island Unit 1 signal renewed industry momentum.

Key Sites

• Idaho National Laboratory (INL), Idaho: A hub for nuclear research, INL hosts the Advanced Test Reactor (ATR) and Transient Reactor Test Facility (TREAT), critical for testing fuels and materials for next-generation reactors.
• Vogtle Electric Generating Plant, Georgia: Home to the recently operational Vogtle Units 3 and 4 (AP1000 design, 1,117 MWe each), it represents the first new U.S. nuclear units in over 30 years, pivotal for modern nuclear expansion.
• Oak Ridge National Laboratory (ORNL), Tennessee: ORNL operates the High Flux Isotope Reactor (HFIR), a key facility for isotope production and materials research, supporting both medical and industrial applications.

Historical Context

The U.S. nuclear industry began in 1957 with the commissioning of the Shippingport Atomic Power Station in Pennsylvania, the first commercial nuclear power plant, marking the dawn of civilian nuclear energy. Rapid expansion followed in the 1960s and 1970s, with dozens of reactors built to meet growing energy demands, peaking at over 100 operational units by the 1990s. The 1979 Three Mile Island accident in Pennsylvania, a partial meltdown with no fatalities but significant public impact, led to tightened regulations and a halt in new construction for decades. Despite this, the industry has since focused on safety enhancements and license renewals, maintaining nuclear as a stable baseload power source.

Operating Reactors (Platform Database)

Reactor	Site	Type	Capacity (MWe)	Operator	Commercial Operation
Advanced Test Reactor (ATR)	—	Tank	—	Idaho National Laboratory	—
High Flux Isotope Reactor (HFIR)	—	Flux trap	—	Oak Ridge National Laboratory	—
NIST Center for Neutron Research (NCNR)	—	Pool	—	National Institute of Standards and Technology	—
MIT Research Reactor (MITR-II)	—	Tank	—	Massachusetts Institute of Technology	—
Missouri University Research Reactor (MURR)	—	Pool	—	University of Missouri	—
Oregon State TRIGA Reactor (OSTR)	—	TRIGA	—	Oregon State University	—
Penn State Breazeale Reactor (PSBR)	—	TRIGA	—	Penn State University	—
Kansas State University TRIGA (TRIGA Mark II)	—	TRIGA	—	Kansas State University	—
Rhode Island Nuclear Science Center (RINSC)	—	Pool	—	Rhode Island Nuclear Science Center	—
Transient Reactor Test Facility (TREAT)	—	Graphite	—	Idaho National Laboratory	—
Vogtle Unit 3	—	AP1000	1117	—	—
Vogtle Unit 4	—	AP1000	1117	—	—

Under Construction (Platform Database)

Reactor	Site	Type	Capacity (MWe)	Expected Operation
Palisades	—	PWR	805	TBD
Aurora (Oklo)	—	Microreactor	15	TBD
Hermes	—	Fluoride salt-cooled reactor	35	TBD
Aurora	—	Sodium-cooled fast reactor	15	TBD
Aalo-X	—	Sodium-cooled fast reactor	10	TBD
Mark-0	—	Sodium heat pipe microreactor	—	TBD
Isotope Production Reactor	—	Heat pipe microreactor	—	TBD

Sources

• IAEA PRIS — USA — IAEA Power Reactor Information System
• WNA Country Profile — World Nuclear Association
• NRC (Nuclear Regulatory Commission) — National nuclear regulator

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Enriched by Grok · Second Atomic Age Nuclear Wiki · 2026-05-10