As of March 2026, at least 66 companies across 15 countries are actively building the SMR and advanced nuclear industry. This directory covers every major reactor developer, fuel fabricator, uranium miner, enrichment provider, and nuclear utility in the space. NuScale Power (NYSE: SMR) remains the only company with full NRC design certification. Oklo (NYSE: OKLO) is the largest SMR pure-play by market cap. TerraPower broke ground on the first US advanced reactor at Kemmerer, Wyoming. Kairos Power holds the first NRC construction permit for an advanced reactor. 20 companies trade on public exchanges, and the sector has attracted billions in private and government funding.
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| Aalo Atomics | Aalo-X (10 MWe experimental), Aalo Pod (50 MWe commercial) | PWR | USA | 2023 | — | $100M+ (Series B Aug 2025) | TIER 1 |
| Antares Nuclear | Antares R1 | HTGR | USA | — | — | $96M Series B (Dec 2025) | TIER 1 |
| China National Nuclear Corporation | Linglong One / ACP100, HTR-PM | PWR | China | 1999 | — | — | TIER 1 |
| Deep Fission | Gravity Reactor | PWR | USA | — | — | — | TIER 1 |
| EDF / Nuward | Nuward SMR | PWR | France | — | EDF.PA | — | TIER 1 |
| GE Vernova / GE Hitachi Nuclear Energy | BWRX-300 | BWR | USA | 2007 | GEV | — | TIER 1 |
| General Atomics | EM2 | GCFR | USA | 1955 | — | — | TIER 1 |
| Holtec International | SMR-300 | PWR | USA | 1986 | — | — | TIER 1 |
| Jimmy Energy | Jimmy HTR | HTGR | France | — | — | EUR80M (March 2026) | TIER 1 |
| Kairos Power | Hermes, KP-FHR | FHR | USA | 2016 | — | $300M+ | TIER 1 |
| Korea Hydro & Nuclear Power | i-SMR | PWR | South Korea | 2001 | — | — | TIER 1 |
| Naarea | XAMR | MSR | France | — | — | — | TIER 1 |
| Natura Resources | MSR-1, MSR-100 | MSR | USA | — | — | — | TIER 1 |
| NuScale Power | VOYGR | PWR | USA | 2007 | SMR | — | TIER 1 |
| Oklo Inc. | Aurora Powerhouse | SFR | USA | 2013 | OKLO | — | TIER 1 |
| Rolls-Royce SMR Ltd | Rolls-Royce SMR | PWR | UK | 2017 | — | — | TIER 1 |
| Rosatom State Nuclear Energy Corporation | KLT-40S, RITM-200 | PWR | Russia | 2007 | — | — | TIER 1 |
| Saltfoss | CMSR | MSR | Denmark | — | — | $60M+ cumulative | TIER 1 |
| Steady Energy | LDR-50 | PWR | Finland | — | — | — | TIER 1 |
| Stellaria | Stellarium | MSR | France | — | — | EUR23M (2025) | TIER 1 |
| TerraPower | Natrium | SFR | USA | 2008 | — | $2B+ (DOE + private) | TIER 1 |
| Thorizon | Thorizon One | MSR | Netherlands | — | — | — | TIER 1 |
| Valar Atomics | Nova (prototype), Ward 250 (test reactor) | HTGR | USA | 2024 | — | $149M | TIER 1 |
| Westinghouse Electric Company | AP300, eVinci, LFR | PWR | USA | 1886 | — | — | TIER 1 |
| X-energy | Xe-100, TRISO-X | HTGR | USA | 2009 | — | $700M Series D (Nov 2025) | TIER 1 |
| Ansaldo Nucleare / EAGLES Consortium | EAGLES-300 | LFR | Italy | 1963 | — | — | TIER 2 |
| ARC Clean Technology | ARC-100 | SFR | Canada | 2014 | — | — | TIER 2 |
| BARC / NPCIL | BSMR-200, SMR-55 | PHWR | India | 1954 | — | — | TIER 2 |
| Blykalla | SEALER-55, SEALER-E | LFR | Sweden | 2019 | — | $50M | TIER 2 |
| BWX Technologies | BANR, TRISO fuel | Microreactor | USA | 2015 | BWX | — | TIER 2 |
| China General Nuclear Power Group | ACPR50S | PWR | China | 1994 | — | — | TIER 2 |
| CNEA (Comision Nacional de Energia Atomica) | CAREM-25 | PWR | Argentina | 1950 | — | — | TIER 2 |
| Copenhagen Atomics | Copenhagen Atomics MSR | MSR | Denmark | 2014 | — | — | TIER 2 |
| CORE POWER | Maritime MSR | MSR | UK | 2018 | — | — | TIER 2 |
| Dual Fluid Energy | Dual Fluid Reactor | LFR | Canada | 2021 | — | — | TIER 2 |
| KEPCO Engineering & Construction | BANDI-60 | PWR | South Korea | 1975 | — | — | TIER 2 |
| Korea Atomic Energy Research Institute | SMART100 | PWR | South Korea | 1959 | — | — | TIER 2 |
| Last Energy | PWR-20, PWR-5 | Microreactor | USA | 2020 | — | $100M+ Series C (Dec 2025) | TIER 2 |
| Mitsubishi Heavy Industries | Integrated Small Reactor | PWR | Japan | 1884 | 7011.T | — | TIER 2 |
| Moltex Energy | SSR-W | MSR | UK | 2014 | — | — | TIER 2 |
| Nano Nuclear Energy | KRONOS, LOKI, ZEUS, ODIN | Microreactor | USA | 2021 | NNE | $400M private placement | TIER 2 |
| Newcleo | LFR-AS-200 | LFR | France | 2021 | — | $755M+ since 2021 | TIER 2 |
| Radiant Industries | Kaleidos | Microreactor | USA | 2020 | — | $300M+ Series D (Dec 2025) | TIER 2 |
| Terrestrial Energy | IMSR | MSR | Canada | 2013 | IMSR | — | TIER 2 |
| Ultra Safe Nuclear Corporation | MMR | HTGR | USA | 2011 | — | — | TIER 2 |
| Elysium Industries | MCSFR | MSR | USA | 2015 | — | — | TIER 3 |
| ThorCon International | ThorCon MSR | MSR | USA | 2011 | — | — | TIER 3 |
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| TRISO-X (X-energy subsidiary) | TRISO pebble fuel | TRISO Fuel | USA | 2018 | — | — | TIER 1 |
| Lightbridge Corporation | Lightbridge Fuel | Advanced Fuel | USA | 1992 | LTBR | — | TIER 2 |
| Standard Nuclear | TRISO fuel, HALEU fuel | TRISO Fuel | USA | — | — | $186.5M | TIER 2 |
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| Centrus Energy Corp | HALEU enrichment, LEU enrichment | HALEU | USA | 1998 | LEU | — | TIER 1 |
| Orano | Uranium enrichment, Fuel fabrication, Reprocessing | LEU | France | 2018 | — | — | TIER 1 |
| Urenco | LEU enrichment, LEU+ enrichment, HALEU (planned) | LEU | UK | 1971 | — | — | TIER 1 |
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| Cameco Corporation | Uranium concentrate (U3O8) | Mining | Canada | 1988 | CCJ | — | TIER 1 |
| Denison Mines Corp | Uranium (ISR) | Mining | Canada | 1997 | DNN | — | TIER 2 |
| Energy Fuels Inc | Uranium, Rare earth elements | Mining | USA | 1987 | UUUU | — | TIER 2 |
| NexGen Energy Ltd | Uranium (conventional mining) | Mining | Canada | 2012 | NXE | — | TIER 2 |
| Uranium Energy Corp | Uranium (ISR) | Mining | USA | 2003 | UEC | — | TIER 2 |
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| Constellation Energy | Nuclear power generation | Utility | USA | 2022 | CEG | — | TIER 1 |
| Ontario Power Generation | Nuclear power generation, BWRX-300 deployment | Utility | Canada | 1999 | — | — | TIER 1 |
| Dominion Energy | Nuclear power generation | Utility | USA | 1983 | D | — | TIER 2 |
| Energy Northwest | Nuclear power generation | Utility | USA | 1957 | — | — | TIER 2 |
| Talen Energy | Nuclear power generation | Utility | USA | 2015 | TLN | — | TIER 2 |
| Vistra Corp | Nuclear power generation | Utility | USA | 2016 | VST | — | TIER 2 |
| COMPANY | REACTOR / PRODUCT | TYPE | COUNTRY | FOUNDED | TICKER | FUNDING | TIER |
|---|---|---|---|---|---|---|---|
| Fluor Corporation | Nuclear EPC services | EPC | USA | 1912 | FLR | — | TIER 2 |
| Prodigy Clean Energy | Marine Power Platform | Marine | Canada | 2013 | — | — | TIER 2 |
The SMR industry in 2026 is no longer a handful of startups with PowerPoint reactors. 66 companies across 15 countries are building, licensing, or deploying small modular reactors and advanced nuclear technology. The sector has bifurcated into clear tiers: 32 Tier 1 companies with NRC certifications, construction permits, or multi-billion-dollar contracts (NuScale, TerraPower, Oklo, Kairos Power, X-energy, GE Hitachi, Rolls-Royce SMR), and a growing Tier 2/3 bench of microreactor developers, advanced fuel startups, and international players. 20 companies trade publicly, giving investors direct exposure from uranium mining (Cameco, NexGen) through enrichment (Centrus) to reactor developers (NuScale, Oklo) and nuclear utilities (Constellation, Vistra). The capital flowing into the sector is unprecedented: TerraPower alone has over $2 billion in DOE and private funding, X-energy raised $700 million in a single round, and Holtec is targeting a $10 billion+ IPO. The nuclear renaissance is not coming. It is here.