Small modular reactors (SMRs)
Reactors of 300 MWe or less (under 20 MWe for microreactors) built from factory modules. WNA counts over 100 designs: light-water, fast, high-temperature gas and molten salt.
8 leading companies in small modular reactors (smrs), one segment of nuclear & small reactors — SMRs, reactor restarts, new large builds and the uranium/enrichment fuel chain behind them
new market segment · researched 2026-11-14
Small modular reactors (SMRs)Large nuclear reactorsReactor restarts & life extensionsUranium miningUranium enrichment & HALEUNuclear fuel & components
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Leading small modular reactors (smrs) companies
8 companies, with the scale each source states. Scale is the whole company's unless the row says otherwise.
| Company | Where | What they do | Scale |
|---|---|---|---|
| GE Vernova (GE Vernova Hitachi Nuclear Energy) GEV ↗ | Cambridge, MA, United States since 1892 | Designer of the BWRX-300 SMR being built at Darlington (via the GE Hitachi JV, Wilmington NC) | revenue (whole company): 38.07 USD billions (2025) ↗ |
| Ontario Power Generation ↗ | Oshawa, ON, Canada since 1999 | Owner/builder of Darlington New Nuclear (four BWRX-300 units); exploring large nuclear at Wesleyville | capital budget (4 SMR units): 20.9 CAD billions (2026) ↗ |
| NuScale Power SMR ↗ | Tigard, OR, United States since 2007 | Light-water SMR module designer (NuScale Power Module) | revenue: 31.479 USD millions (operating loss US$689.6M) (2025) ↗ |
| X-energy XE ↗ | Rockville, MD, United States since 2009 | Xe-100 pebble-bed high-temperature gas reactor and TRISO fuel; 4x80 MWe Seadrift, Texas project with Dow | proposed capacity (Seadrift): 320 MWe gross (4x80) (2026) ↗ |
| TerraPower ↗ | Bellevue, WA, United States since 2006 | Natrium sodium fast reactor; Kemmerer 1, Wyoming construction permit issued March 2026 | first-unit capacity: 345 MWe (2026) ↗ |
| Oklo OKLO ↗ | Santa Clara, CA, United States since 2013 | Fast-reactor microreactor/SMR developer and radioisotopes; pre-revenue | operating loss: -139.294 USD millions (2025) ↗ |
| Westinghouse Electric Company ↗ | Cranberry Township, PA, United States since 1999 | AP1000 large reactor and AP300 SMR designer, fuel and services; partner in the US$80B US government deployment deal | employees: 11,000 employees (">11,000") (2026) ↗ |
| Holtec International ↗ | Jupiter, FL, United States since 1986 | Restarting Palisades (805 MWe, Michigan); SMR-300 design planned for Palisades; spent-fuel storage | restart capacity (Palisades): 805 MWe net (2026) ↗ |
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In Canada
- 2026-06OPG's Darlington SMR-1 (GE Vernova Hitachi BWRX-300, 316 MWe gross) started construction on 26 June 2026, the first SMR in the G7. The CNSC licence to construct was granted on 4 April 2025. The total estimated cost for all four planned units is C$20.9 billion. ↗
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The nuclear & small reactors market
The whole market this segment sits in.
installed capacity (operable reactors, net) · world405,667
↗MWe (443 reactors) · 2026
Growth, segments, risks and every company in nuclear & small reactors →
Quick answers
- What is small modular reactors (smrs)?
- Reactors of 300 MWe or less (under 20 MWe for microreactors) built from factory modules. WNA counts over 100 designs: light-water, fast, high-temperature gas and molten salt. It is one segment of the nuclear & small reactors market.
- Who are the leading small modular reactors (smrs) companies?
- GE Vernova (GE Vernova Hitachi Nuclear Energy) (United States), Ontario Power Generation (Canada), NuScale Power (United States), X-energy (United States), TerraPower (United States), Oklo (United States), Westinghouse Electric Company (United States), Holtec International (United States).
- Which small modular reactors (smrs) companies are publicly traded?
- GE Vernova (GE Vernova Hitachi Nuclear Energy) (GEV), NuScale Power (SMR), X-energy (XE), Oklo (OKLO).
- Which Canadian companies are in small modular reactors (smrs)?
- Ontario Power Generation, Oshawa, ON.
- How big is the nuclear & small reactors market?
- For the whole nuclear & small reactors market, not this segment alone: installed capacity (operable reactors, net) (world) 405,667 MWe (443 reactors), 2026 — World Nuclear Association.