Nuclear Fission

Aalo Atomics

Private

Aalo Atomics is an Austin-based nuclear startup founded in 2023 by CEO Matt Loszak and CTO Yasir Arafat (former lead of INL's MARVEL microreactor) to mass-manufacture sodium-cooled reactors purpose-built for AI data centers. Its product line pairs the factory-built 10 MWe Aalo-1 reactor with the Aalo Pod, a 50 MWe plant of five reactors and shared turbines designed to install in months. Selected for the DOE's Reactor Pilot Program in August 2025, Aalo brought its Aalo-X Critical Test Reactor at Idaho National Laboratory to first criticality on July 4, 2026 - the fourth DOE-authorized advanced reactor to meet Executive Order 14301's deadline, less than eight months after groundbreaking. The company says it has grown from 2 people to about 200 and has raised over $300 million, including a $100M Series B led by Valor Equity Partners; a roughly $500M Series C at a $4-5B valuation was still being shopped as of September 15, 2026, with no close announced. Its 40,000 sq ft Austin pilot plant is slated to expand tenfold to 400,000 sq ft, with a longer-term one-million-square-foot Gigawatt Factory now described on the company site as ramping in 2030. On July 30, 2026 Aalo named cloud provider Crusoe as the partner for a 2027 INL proof-of-concept pairing a 50 MWe Aalo Pod with a Crusoe Spark modular data center, targeting commercial nuclear-powered AI deployments by the end of 2029. Aalo's own public timeline now puts first power from the integrated Aalo-X plant in Q1 2027 and the NRC application for the first commercial Aalo Pod in 2027 (slipped from a 2026 COLA target), with a long-term cost goal of 3 cents/kWh. The full-scale non-nuclear Aalo-0 sodium system was still listed as 65% complete and a Q3 2026 milestone as of September 15.

2023 · 🇺🇸 Austin, Texas

Antares Nuclear

Private

Antares Nuclear is a Torrance-based microreactor startup founded in 2023 by CEO Jordan Bramble and co-founder Julia DeWahl to factory-produce sodium heat-pipe fission reactors for defense and space missions. Its commercial R1 is a TRISO-fueled, graphite-core unit rated at 100 kWe to 1 MWe for 6+ years without refueling, using passive sodium heat pipes and a nitrogen closed Brayton cycle. On June 4, 2026 its Mark-0 zero-power demonstration reached initial criticality at Idaho National Laboratory's RACE facility - the first privately developed non-light-water reactor to go critical in the United States in more than four decades, and the first under DOE's Reactor Pilot Program. Antares has raised about $604M in disclosed equity and debt, including a $470M Series C ($370M equity + $100M debt) co-led by Paradigm and Caffeinated Capital on July 27, 2026. It has been selected to own, construct, and operate microreactor power at Fort Bragg under the Army's Janus Program, to site a prototype at Joint Base San Antonio under the Air Force ANPI initiative, and on September 11, 2026 won a $161M Space Force Strategic Breakthrough award for a ground demonstration of its R1-S space reactor. On September 17 it signed a multi-year HALEU supply contract with Centrus, with deliveries before the end of the decade. The company targets electricity from its Mark-1 reactor at INL in 2027 and first military deployments by 2028, against Executive Order 14299's September 30, 2028 deadline for an operating reactor on a U.S. installation.

2023 · 🇺🇸 Torrance, California

GE Vernova Hitachi Nuclear Energy

Subsidiary of GE Vernova (JV with Hitachi)

GE Vernova Hitachi Nuclear Energy (GVH, formerly GE Hitachi Nuclear Energy) is the Wilmington, North Carolina-based nuclear alliance formed by GE (60%, now GE Vernova) and Hitachi (40%) in 2007, combining reactor design, services for the global boiling-water-reactor fleet, and fuel manufacturing through Global Nuclear Fuel. Its flagship BWRX-300 small modular reactor - a 300 MWe natural-circulation design derived from the NRC-certified ESBWR - is the first grid-scale SMR under construction in the Western world, with Ontario Power Generation building the first of four units at Darlington for service by the end of 2030. In the US, the NRC issued TVA Construction Permit CPAR-2 for Clinch River Unit 1 on September 28, 2026 (TVA and GVH announced it September 29; Federal Register notice October 5), the first US BWRX-300 CP and only the second US advanced-reactor CP. The permit sets construction completion between October 1, 2031 and September 30, 2032 and is not an operating license. TVA announced no construction start. ENR quoted spokesperson Scott Fiedler that nuclear construction has not begun, no new construction packages or long-lead procurement were authorized, the board still must approve a final commitment to build ($350 million authorized to date), and TVA did not reaffirm a 2032 commercial-operation target while cost-share talks continue so ratepayers do not bear first-of-a-kind costs. In March 2026 the US and Japanese governments announced up to $40B to deploy up to 10 BWRX-300s (3 GW) in Tennessee and Alabama under the US-Japan strategic investment framework. The order book extends across Poland (ORLEN Synthos Green Energy, including a June 2026 agreement for up to six units at Wloclawek), the UK (Generic Design Assessment completed December 2025; an SGE-led team bid in mid-2026 to build 14 units), a new US project with Elementl Power in Meigs County, Ohio (up to five units, agreed June 2026), Estonia, Hungary, Saskatchewan, Lithuania and Bulgaria, plus a March 2026 MOU with Hitachi to explore Southeast Asia. GVH lost Sweden's first new-nuclear competition in June 2026, when Vattenfall's Videberg Kraft venture picked Rolls-Royce SMR over the BWRX-300 for its Ringhals project, but returned to the Swedish market on September 3, 2026 when Studsvik selected GVH and Samsung C&T to advance a separate proposed four-unit, 1.2 GW BWRX-300 project. On September 15, 2026 Blue Energy filed the first part of an NRC construction permit application for the first BWRX-300 at its Port of Victoria, Texas gas-plus-nuclear plant. GVH also co-developed the Natrium sodium-cooled fast reactor with TerraPower, which began construction in Wyoming in 2026. Jason Cooper became President and CEO in January 2026. GE Vernova's Q2 2026 10-Q separately disclosed Nuclear Power segment revenue for the first time - $1,575M for H1 2026, up from $1,310M in H1 2025.

2007 · 🇺🇸 Wilmington, North Carolina

Holtec International

Private (HNUC S-1 withdrawn September 25, 2026)

Holtec International is a vertically integrated nuclear technology and services company whose core businesses include used-fuel storage and transport systems, plant decommissioning, manufacturing, and nuclear project execution. Its flagship growth program is the restart of the Palisades plant in Michigan, which would be the first U.S. nuclear plant to return from decommissioning to operations status: on August 30, 2026 Holtec began loading fuel into the 204-assembly reactor core, the most visible physical milestone yet. Engineering News-Record reported on September 18, 2026 that the plant was still in Mode 6 (refueling) with no grid-restart date, while Holtec communications describe Palisades as an 805 MW unit. Its other flagship program is the SMR-300 small modular reactor platform, which Holtec is advancing at Palisades and in the UK with EDF. Holtec is also pursuing a large SMR-300 program in India - where a March 2025 U.S. DOE 10CFR810 authorization lets it share the design with partners Tata Consulting Engineers, Larsen & Toubro, and its Holtec Asia subsidiary - with a February 2026 plan to build up to 200 SMR-300s from an expanded manufacturing hub in Gujarat, and in Rwanda, where a May 2026 Comprehensive Development Agreement with the country's Atomic Energy Board targets up to roughly 5 GW of capacity, Holtec's first sub-Saharan African market. After a confidential filing in February 2026, Holtec publicly filed a Form S-1 on July 10, 2026 for a Nasdaq / Nasdaq Texas IPO under the ticker HNUC. On September 8, 2026 Holtec launched the IPO roadshow at $15 to $18 per share for 50 million Class A shares (up to $900 million, plus a 7.5 million-share greenshoe), targeting a valuation of up to $10.2 billion. On September 17, 2026 Holtec postponed the offering after talks with its banking syndicate, citing a retreat in IPO and nuclear-sector markets driven primarily by uncertainty over data-center development. On September 25, 2026 Holtec Nuclear filed Form RW withdrawing File No. 333-297395; the registration had not been declared effective and no securities were sold. CEO Kris Singh told the Financial Times, as reported by Engineering News-Record on September 18, that Holtec has other capital options and could return to the IPO market in three to six months depending on conditions. Holtec's SMR-300 pipeline now spans Palisades, the Green River, Utah revival project, a newly cleared Oyster Creek, New Jersey site (NRC approved the plant's license termination plan on July 30, 2026, opening the way for four more SMR-300 units there), the Cottam, UK proposal with EDF, and Rwanda - and on August 4, 2026 Holtec signed a non-binding memorandum of agreement with Entergy and Hyundai Engineering & Construction to evaluate further SMR-300 projects across Entergy's Gulf South territory. On September 15, 2026 Holtec said the NRC had granted an August 28 exemption authorizing permanent support-of-excavation and cutoff-wall work for Pioneer 1 and 2 at Palisades before a Limited Work Authorization is issued. Engineering News-Record also reported on September 18 that the NRC was targeting completion of its final safety evaluation and environmental impact statement for Pioneer by March 31, 2027. On September 30, 2026 Holtec submitted the Pioneer 1 and 2 Preliminary Safety Analysis Report, completing construction-permit Part 2, and said a draft safety evaluation for the limited-work authorization is anticipated in December 2026. The same day Palisades Energy filed emergency license amendment PNP 2026-052 to retrieve fuel assembly DD41 and asked for approval by October 2. ANS Nuclear Newswire reported on October 8 that the public comment period expired that afternoon while the NRC was still reviewing the request.

1986 · 🇺🇸 Jupiter, Florida

Kairos Power

Private

Kairos Power is commercializing its fluoride salt-cooled, high-temperature reactor (KP-FHR), which combines TRISO pebble fuel with FLiBe coolant in a compact, low-pressure design aimed at grid and AI-data-center loads. The company runs an iterative, vertically integrated development model centered on Hermes 1, a 35 MWth demonstration reactor under safety-related construction in Oak Ridge, and Hermes 2, an electricity-producing demonstration plant for the TVA grid under a Google fleet agreement totaling up to 500 MWe by 2035. A May 2026 NRC amendment extended Hermes 1's construction-completion deadline to April 2029 (Kairos still expects to finish building the test reactor in 2028); Hermes 2 broke ground April 17, 2026 and is targeted for first grid power around 2030. In August 2026 Kairos launched NuCAMP, a 12-month manufacturing and workforce partnership at Oak Ridge, and named former SpaceX launch-operations director Dr. Mike McGuire as VP of Operations and Site Delivery. On September 2, 2026 it appointed Ignacio Redondo, formerly SVP of Finance at Nextracker, as its first CFO. On September 4 it completed the first phase of its ETU 3 hardware demonstration - a reduced-scale Hermes 2 reactor-cavity mockup used to test modular precast shielding and remote handling. A September 10, 2026 company update said Engineering Test Unit 2 in Albuquerque comprises more than 30 factory-built skids whose module integration is underway, with hot argon testing next, and that Hermes 2 will use skids fabricated in Albuquerque and shipped to Oak Ridge. Kairos's careers page still lists 500+ employees, and a June 24, 2026 manufacturing update said the Albuquerque Pebble Development Lab had produced more than 60,000 annular surrogate fuel pebbles at about 950 per day for ETU 2 and other tests. On October 7, 2026 the Albuquerque Pebble Development Lab commissioned an automated inspection and tracking line with a near-term target of 70,000 inspected pebbles for ETU 2 and other tests. The company still has not reported a first HALEU TRISO pebble at LANL LEFFF, a Hermes 1 operating-license application, or a closed Samsung C&T investment with a disclosed cash-versus-in-kind split.

2016 · 🇺🇸 Alameda, California

NuScale Power

Public (NYSE: SMR)

NuScale Power is a public small modular reactor developer, headquartered in Corvallis, Oregon, commercializing its NRC-approved 77 MWe NuScale Power Module through ENTRA1-led deployments. In 2025-26 it advanced a nonbinding program with TVA for up to 6 GW of NuScale capacity (CEO John Hopkins still targeting a binding PPA by year-end 2026, last restated on the August 5 earnings call, with no definitive agreement as of mid-September), secured a Final Investment Decision for the Romanian RoPower project, and launched a strategic petrochemical process-heat partnership with Ebara Elliott Energy. The Romania path now has a sharper political overhang: a July 2026 government control-body audit alleged schedule slippage and cost overruns at Doicesti, Nuclearelectrica CEO Cosmin Ghita resigned on August 26, 2026 amid those findings, and the Extraordinary General Meeting that failed for lack of quorum on September 10 reconvened on September 11 and voted unanimously to publish the control-body report. Ghita's mandate ends October 2, 2026, with Mihai Laurentiu Gioara taking over as interim CEO on October 3. A September 14 Bursa recap of the published report said Doicesti is blocked by disputes among Nuclearelectrica, RoPower, and Nova Power & Gas (contractual disagreements, litigation, contested evaluations); the recommendations are to resolve the disputes and resume implementation, not to cancel the NuScale-based project. Energy Secretary of State Cristian Busoi said the ministry will still evaluate RoPower FID conditions at the end of September before mandating how its shareholder representatives vote. Shares closed at $8.61 on September 11 after UBS cut the stock to Sell with a $6 target and were still trading in the mid-$8 to low-$9 range through September 17, with no new company press release after the September 1 MillenniTEK pellets announcement. NuScale remains pre-deployment (minimal engineering and licensing revenue; no commercial reactor order) and ended Q2 2026 with about $1.9B in cash, cash equivalents and investments, on Q2 revenue of $75,000 and a net loss of $50.1M. 2026 work is centered on first-module manufacturing readiness - components for 12 modules are in production - and on September 1, 2026 NuScale and MillenniTEK said they had fabricated first-of-a-kind boron-oxide pellets for the module's passive emergency core cooling system.

2007 · 🇺🇸 Corvallis, Oregon

Oklo

Public (NYSE: OKLO)

Oklo is developing fast-fission power plants under its Aurora product line while building a vertically integrated nuclear business around power sales, fuel recycling, and radioisotopes. Aurora units are designed to produce 15-75 MWe and run on fresh, recycled, or down-blended fuel, targeting customers such as data centers, industrial sites, military facilities, utilities, and remote communities. Its first plant, Aurora-INL at Idaho National Laboratory, is advancing under DOE's Reactor Pilot Program - the DOE approved its Preliminary Documented Safety Analysis on June 11, 2026, leaving the final Documented Safety Analysis as the last safety-basis step before authorization. Oklo is deepening vertical integration through the June 2026 acquisitions of Oak Ridge precision manufacturer ARMEC and sodium-systems engineering firm Creative Engineers, plus its May 2026 selection for DOE's Surplus Plutonium Utilization Program, while Atomic Alchemy builds U.S. isotope supply around the Groves test reactor in Lockhart, Texas, which reached first criticality on August 5, 2026.

2013 · 🇺🇸 Santa Clara, California

Radiant Nuclear

Private

Radiant is still pre-revenue on Kaleidos sales. A 9 October 2026 deep audit found no public announcement that the Kaleidos Development Unit was installed, fueled, or taken to zero-power criticality at INL DOME after Q3 closed on 30 September. The news index still tops out at the 9 September Centrus HALEU contract and the 12 August El Segundo departure. Wikipedia still records the August shipment, not criticality. The NRC Kaleidos page, last reviewed 15 September, remains pre-application; the KDU commissioning plan is under review and the R-50 Part 70 application is in RAI. NRIC says DOME is currently hosting Kaleidos and next availability begins July 2027, while another FAQ line still says testing likely in 2027; neither is a criticality result. No sourced revised campaign date. Janus is up to $750 million for 15 units; Fort Benning remains three 1 MW units with the pad still under evaluation; Buckley remains the 2028 ANPI site.

2020 · 🇺🇸 1921 E. Maple Ave, El Segundo, California

TerraPower

Private

TerraPower is a nuclear innovation company founded by Bill Gates with two business lines: the Natrium sodium fast reactor with integrated molten-salt energy storage, and TerraPower Isotopes, a medical-isotope business producing actinium-225 for targeted cancer therapies. In March 2026 the NRC issued Kemmerer Unit 1 the first construction permit for a commercial-scale advanced nuclear plant in the U.S., and on April 23, 2026 TerraPower and then-contractor Bechtel officially began plant construction in Wyoming, a build expected to mobilize roughly 1,600 workers; on July 21, 2026 TerraPower became the first advanced-reactor developer accepted into the Institute of Nuclear Power Operations. A Bechtel WARN notice signed September 13, 2026 and reported September 17 says the two companies could not agree terms for the next phase of the Natrium Demonstration Project and have decided to move forward separately, with Bechtel planning about 200 Reston layoffs from around November 16; TerraPower has not named a replacement contractor for Kemmerer Unit 1. In January 2026 TerraPower signed a landmark agreement with Meta to develop up to eight Natrium plants in the U.S., marking a shift from a single demonstration toward a commercial fleet, and on August 14, 2026 it deepened its Korean industrial supply chain with a preliminary joint-business agreement with SK Innovation for South Korea's first commercial Natrium plant, selection of Hyundai Engineering & Construction as EPC contractor for up to eight future Natrium reactors, and a reactor-vessel manufacturing contract with Doosan Enerbility. In August 2026 it named George Wilson, previously SVP of Regulatory Affairs, as its first Chief Nuclear Officer to oversee nuclear safety, licensing, and regulatory strategy, and on August 31 it awarded 12 additional supplier contracts for Kemmerer Unit 1 and an on-site sodium test and fill facility. CEO Chris Levesque told Reuters on September 7, 2026 that Natrium could generate UK electricity by 2034, TerraPower's first market outside the United States, and has said the company still plans to announce a second Natrium project - this one for an unnamed AI data-center customer - before the end of 2026, with construction targeted for 2027. The core reactor business remains pre-revenue, but Natrium has moved from development into full project execution under DOE's ARDP cost-share program, while TerraPower Isotopes already sells actinium-225 commercially to pharmaceutical partners and is building a $450 million second production facility in Philadelphia.

2008 · 🇺🇸 Bellevue, Washington

Valar Atomics

Private

Valar Atomics is an El Segundo-based nuclear startup founded in 2023 by Isaiah Taylor that develops small, mass-manufacturable high-temperature gas-cooled reactors (TRISO fuel, graphite moderator, helium coolant) intended to be deployed by the hundreds on grid-independent 'gigasites' producing power, hydrogen, and carbon-neutral synthetic fuels. As one of 11 projects in the DOE Reactor Pilot Program, its 100 kWt Ward250 test reactor at the Utah San Rafael Energy Lab achieved fueled criticality on June 18, 2026 - the first DOE-authorized reactor built and operated outside a national laboratory - then became the first of the pilot reactors to ramp to full power on June 23, and on July 1 generated 100 kW while powering Nvidia Blackwell chips in a live demo. The company and Nvidia are now exploring a 30 MW nearly waterless nuclear-powered AI data center in Orangeville, Utah. On September 18, 2026, Utah's Trust Lands Administration Board unanimously approved a Special Use Lease Agreement covering up to 640 acres of state trust land in Carbon County (starting with a 480-acre, 50-year lease near Wellington and Price), Valar's first named expansion site beyond the Emery County test lab; construction still needs development plans and permits. Valar has raised roughly $1.6B total, after closing a $1B Series B on August 3, 2026 led by Sequoia Capital (Shaun Maguire, who joins the board) that tripled its valuation to $6B, alongside a separate $200M credit facility led by Erebor Bank and J.P. Morgan (with Crescent Cove and Hercules Capital participating); the company says the round funds reactor-manufacturing factories to scale output toward thousands of units a year plus in-house TRISO fuel production, building on its September 2025 selection for DOE's Fuel Line Pilot Program. The round follows a $450M equity-and-debt round at a $2B valuation in March 2026 backed by Palmer Luckey and Palantir CTO Shyam Sankar, a $130M Series A led by Snowpoint Ventures, and a $19M seed led by Riot Ventures. It is also building Ward One, a 100 kW research microreactor in the Philippines with the Philippine Nuclear Research Institute, and is a co-plaintiff (alongside Texas, Utah, Louisiana, Florida, Arizona, Last Energy, and Deep Fission) in a lawsuit seeking to exempt small test reactors from full NRC licensing, stayed until September 29, 2026 for settlement talks. CEO Isaiah Taylor says Valar hopes to start selling power on a test basis in 2027 and become fully commercial in 2028.

2023 · 🇺🇸 El Segundo, California

Westinghouse Electric Company

Private (Brookfield & Cameco)

Westinghouse Electric Company is the largest Western nuclear technology company, owned 51% by Brookfield (with institutional partners) and 49% by uranium miner Cameco since their $7.9B acquisition closed in November 2023. Westinghouse technology powers 57% of the world's operating nuclear plants, maintains nearly two-thirds of the fleet, and fuels 40%, and its fuel and operating-plant-services businesses generated about $5.0B of revenue in 2025. Its flagship AP1000 reactor is the only fully licensed advanced large reactor operating in the US (Vogtle Units 3 and 4 in Georgia), with four more units operating in China and orders or advanced programs in Poland, Bulgaria, and Ukraine. On September 23, 2026 the Westinghouse-Bechtel consortium and PEJ agreed on the main commercial terms of the EPC contract for three AP1000 units totaling 3,750 MWe at Lubiatowo-Kopalino; PEJ said remaining terms should be finished by year-end and that this is not a finalized contract, with first electricity still expected in 2036. In October 2025 the US government announced an $80B+ strategic partnership with Westinghouse, Brookfield, and Cameco, followed in June 2026 by a conditional $17.5B DOE loan commitment for long-lead components for up to 10 AP1000s. On July 31, 2026 Westinghouse confidentially filed a draft S-1; Bloomberg reported September 18 a targeted valuation of more than $50 billion and a public filing as soon as October, though timing could still change. Alongside the large-reactor buildout, Westinghouse is developing the 330 MWe AP300 small modular reactor and the 5 MWe eVinci microreactor, which reached zero-power high-temperature criticality at 663 C on September 3, 2026. Under CEO Dan Sumner, appointed in April 2026, the company sits at the center of the US nuclear renaissance.

1999 · 🇺🇸 Cranberry Township, Pennsylvania

X-energy

Public (NASDAQ: XE)

X-energy is an advanced nuclear and fuel company commercializing the 80 MWe Xe-100 reactor and its TRISO-X fuel platform. In April 2026 the company priced an upsized IPO to begin trading on Nasdaq under the ticker XE, raising ~$1.1B in net proceeds, and on August 13, 2026 reported Q2 2026 revenue and grant income of $54.6M (up 154% year over year) alongside $1.9B of total liquidity, while the DOE formally notified X-energy that its ARDP cooperative agreement will receive up to an additional $1B, raising the government's total ARDP cost-share to as much as $2.115B. Shares closed at $16.34 on September 17, 2026 (~$6.64B market cap on 406.37M shares), still below the $23 April IPO price after a 12% bounce from the prior close. The NRC held the uncontested Long Mott construction-permit hearing on September 22, 2026 in Port Lavaca. The August 20, 2026 Federal Register notice kept the hearing record open for written comments through October 6, 2026, and that deadline has passed with no later NRC notice extending it. The NRC Long Mott project page, last reviewed September 14, 2026, still lists Hearing TBD, a November 2026 target for the final safety evaluation (not issued), and a construction-permit decision of TBD. TRISO-X holds the first-ever Part 70 HALEU fuel license, expanded its Oak Ridge campus to roughly 180 acres, started TX-1 interior buildout on August 24, and on August 11 extended its Oak Ridge National Laboratory fuel CRADA by 30 months. The company also joined DOE's Project Prometheus AI initiative with NVIDIA and AWS, doubled nuclear-grade graphite supply with SGL Carbon, and signed a definitive LEU/HALEU enrichment agreement with Centrus Energy - underpinning an 11.5 GW, 144-unit pipeline that includes the Amazon-backed Cascade project. A promised ~1 GW investor-owned-utility agreement has still not been named. The company remains pre-revenue from commercial reactor operations.

2009 · 🇺🇸 Rockville, Maryland