Sector Brief

Nuclear Fission

Companies developing next-generation nuclear fission reactors for clean, reliable energy.

State of the Industry

Updated 2026-10-16

12 Companies

Aalo Atomics logo

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.

2023 · 🇺🇸 Austin, Texas

Antares Nuclear logo

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.

2023 · 🇺🇸 Torrance, California

GE Vernova Hitachi Nuclear Energy logo

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.

2007 · 🇺🇸 Wilmington, North Carolina

Holtec International logo

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Private (HNUC S-1 withdrawn September 25, 2026)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

1986 · 🇺🇸 Jupiter, Florida

Kairos Power logo

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.

2016 · 🇺🇸 Alameda, California

NuScale Power logo

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.

2007 · 🇺🇸 Corvallis, Oregon

Oklo logo

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.

2013 · 🇺🇸 Santa Clara, California

Radiant Nuclear logo

Radiant Nuclear

Private

Radiant is still pre-revenue on Kaleidos sales.

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

TerraPower logo

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.

2008 · 🇺🇸 Bellevue, Washington

Valar Atomics logo

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.

2023 · 🇺🇸 El Segundo, California

Westinghouse Electric Company logo

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.

1999 · 🇺🇸 Cranberry Township, Pennsylvania

X-energy logo

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.

2009 · 🇺🇸 Rockville, Maryland

/ Upcoming Milestones

View all →

Reach first-module manufacturing and fuel readiness

NuScale says its main 2026 priority is ensuring full readiness to manufacture the first NuScale Power Module while scaling fuel and supply-chain support with partners such as Framatome. Components for 12 power modules are already in production; in June 2026 NuScale contracted Paragon Energy Solutions to complete final design of the module's safety-related instrumentation-and-control systems. On September 1, 2026 NuScale and MillenniTEK announced they had fabricated first-of-a-kind boron-oxide pellets for the module's passive emergency core cooling system, a concrete manufacturing-readiness step. The first physical module is still not complete.

2026

Ramp Groves to full power and start isotope production

With first criticality achieved on August 5, 2026, Oklo's next step is low-power testing and ascension to full power at the Groves Isotope Test Reactor in Lockhart, Texas, ramping toward R&D-scale isotope production over the following year. On its August 7, 2026 earnings call, management said it now expects Oklo's first isotope revenue in early 2027, and that it is more likely to come from the NRC-licensed Idaho Radiochemistry Laboratory than from Groves. Oklo's newsroom and isotopes page still describe Groves as having reached criticality in under a year, with no later public update on power ascension as of September 19, 2026.

2026-2027

Carry Aurora-INL through final safety review and construction

With the DOE's Preliminary Documented Safety Analysis approved on June 11, 2026 - the third of four major Reactor Pilot Program authorization steps - and a November 2025 binding Siemens Energy contract closing out major long-lead power-conversion equipment procurement, Oklo's near-term focus is securing the final Documented Safety Analysis, the last safety-basis document before DOE authorizes operation, while completing construction at Idaho National Laboratory ahead of fuel loading and first power. As of September 19, 2026, the final Documented Safety Analysis has not yet been approved; on its August 7, 2026 earnings call Oklo raised its full-year 2026 capital-expenditure guidance to $400-500 million to accelerate Aurora-INL procurement and grid-interconnection work while reaffirming a 2028 commercial start-up target.

2026-2027

Produce HALEU TRISO fuel for Hermes 1

Using DOE-allocated HALEU and Los Alamos National Laboratory's LEFFF capability to manufacture the first fuel pebbles needed for Hermes 1 startup and operation. As of late August 2026 Kairos has finished installing process equipment at LEFFF and is commissioning the pilot line with depleted uranium before introducing HALEU; no fuel pebbles for Hermes 1 have been reported produced yet. Company updates through September 10, 2026 (ETU 2 modular integration) did not announce a first HALEU pebble; the June 24 pebble campaign was surrogate (non-nuclear) fuel for ETU 2.

2026-2027

Complete ETU 2 integration and hot argon testing

Finish module installation and piping/electrical connections on Engineering Test Unit 2's more than 30 factory-built skids in Albuquerque, then run hot argon testing (valves, inert gas, temperatures and pressures) before heating the Flibe salt system. Kairos described ETU 2 as the world's largest planned Flibe molten-salt test once operations start later in 2026, and said the modular path will feed Hermes 2 construction.

Later in 2026

Convert pipeline and supply-chain reservations into projects

Having locked in a binding 16-unit Doosan Enerbility reservation, an expanded SGL Carbon graphite supply deal, an IHI Corporation MOU, and a definitive LEU/HALEU enrichment agreement with Centrus Energy (deliveries starting 2030), X-energy still needs to turn its 11.5 GW (144-unit) pipeline - including gigawatt-scale evaluations with Talen Energy and LG&E/KU - into named, financeable deployments. Q2 2026 remains the latest reported quarter ($54.6M revenue and grant income, $1.9B liquidity, up to $1B more ARDP). On the August 13 earnings call CEO Clay Sell said a roughly 1 GW investor-owned-utility agreement was in its final stages; as of September 18, 2026 that counterparty has not been named. Energy Northwest is still aiming to file a Cascade construction-permit application in the first half of 2027.

2026-2027

/ Latest News

View all →