Key takeaways
- Top pick: GE Vernova Hitachi Nuclear Energy, best for: Utilities that want an SMR already licensed for construction. The NRC issued TVA a construction permit for a BWRX-300 at Clinch River, Tennessee on 29 September 2026.
- Also near the top: NuScale Power, best for: Utilities and large energy users planning multi-module plants; and TerraPower, best for: Utilities that want nuclear power with built-in storage.
- How it was ranked: 10 deep tech companies compared. Each verdict is below.
Best Small Modular Reactor Companies: Top 10 Ranked. GE Vernova Hitachi Nuclear Energy ranks first, with a Lister Score of 97.2.
GE Vernova Hitachi's BWRX-300 leads globally, with construction licensed in both Canada and the US. NuScale was the first SMR design approved by the US regulator,
TerraPower is building the first commercial non-light-water power reactor licensed in the US, and
Rolls-Royce SMR is the chosen design for the UK's first SMR plant at Wylfa.
Best Small Modular Reactor Companies in 2026, compared| RANK | ENTRY | BEST FOR | SCORE | FROM |
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| 1 |  GE Vernova Hitachi Nuclear EnergyThe NRC issued TVA a construction permit for a BWRX-300 at Clinch River, Tennessee on 29 September 2026. | Utilities that want an SMR already licensed for construction | 97.2 | Custom |
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| 2 |  NuScale PowerNuScale's 77-megawatt design received US NRC standard design approval in May 2025. | Utilities and large energy users planning multi-module plants | 95.9 | Custom |
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| 3 |  TerraPowerThe NRC approved the Kemmerer Unit 1 construction permit in March 2026, its first for a commercial non-light-water power reactor. | Utilities that want nuclear power with built-in storage | 94.8 | Custom |
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| 4 |  Rolls-Royce SMRRolls-Royce SMR signed its contract for three Wylfa units with Great British Energy Nuclear in April 2026. | Governments planning fleets of larger SMRs | 93.6 | Custom |
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| 5 |  Kairos PowerKairos started construction of Hermes 2 in Oak Ridge in April 2026 after receiving an NRC construction permit. | Tech companies buying nuclear power for data centres | 92.3 | Custom |
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| 6 |  X-energyThe NRC completed its environmental assessment for the Long Mott project in May 2026 with a finding of no significant impact. | Industrial sites that need both power and process heat | 91.0 | Custom |
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| 7 |  Holtec InternationalThe NRC accepted Holtec's partial construction permit application for the Palisades SMR-300 units in February 2026. | Utilities adding SMRs at existing nuclear sites | 89.7 | Custom |
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| 8 |  OkloOklo broke ground on its first Aurora powerhouse at Idaho National Laboratory on 22 September 2025. | Data centres and industrial sites wanting small on-site reactors | 88.3 | Custom |
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| 9 |  WestinghouseWestinghouse says eVinci is the first microreactor with an NRC-approved instrumentation and control system. | Utilities that want an SMR from an established reactor vendor | 86.9 | Custom |
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| 10 |  Aalo AtomicsAalo's Aalo-X Critical Test Reactor reached criticality at Idaho National Laboratory on 4 July 2026. | Data centre developers planning on-site nuclear power | 85.4 | Custom |
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How to choose
Start from what you need it for. Where each entry fits best:
- GE Vernova Hitachi Nuclear Energy (#1): Utilities that want an SMR already licensed for construction
- NuScale Power (#2): Utilities and large energy users planning multi-module plants
- TerraPower (#3): Utilities that want nuclear power with built-in storage
- Rolls-Royce SMR (#4): Governments planning fleets of larger SMRs
- Kairos Power (#5): Tech companies buying nuclear power for data centres
- X-energy (#6): Industrial sites that need both power and process heat
- Holtec International (#7): Utilities adding SMRs at existing nuclear sites
- Oklo (#8): Data centres and industrial sites wanting small on-site reactors
- Westinghouse (#9): Utilities that want an SMR from an established reactor vendor
- Aalo Atomics (#10): Data centre developers planning on-site nuclear power
Each entry's full verdict is below.
The ranking, in detail
01
BWRX-300 boiling water SMR
GE Vernova Hitachi Nuclear Energy, a joint venture of GE Vernova and Hitachi based in Wilmington, North Carolina, designs the BWRX-300, a 300-megawatt boiling water SMR. Canada's regulator licensed construction of the first unit at Ontario Power Generation's Darlington site in April 2025, and the US NRC issued a construction permit for TVA's Clinch River unit in September 2026.
PROS- Licensed for construction in Canada and the US
- Builds on proven boiling water reactor technology
CONS- First units not yet operating
- Costs of first plants still unproven
- Best for
- Utilities that want an SMR already licensed for construction
- Where it falls short
- First units are not yet operating, so costs remain unproven.
- Pick something else if
- you need proven operational track records.
97.2
02
NuScale Power Module light water SMR
NuScale Power, listed on the New York Stock Exchange, designs the NuScale Power Module, a 77-megawatt light water reactor module that can be grouped into larger plants. The US NRC granted standard design approval for the 77-megawatt design in May 2025, and NuScale's partner ENTRA1 has a non-binding agreement with TVA for up to 6 gigawatts of NuScale capacity.
PROS- First SMR design approved by the US NRC
- Modules can be grouped to scale output
CONS- No plant under construction yet
- TVA agreement not yet binding
- Best for
- Utilities and large energy users planning multi-module plants
- Where it falls short
- No plant under construction yet.
- Pick something else if
- you need a proven track record of completed projects.
95.9
03
Natrium fast reactor with built-in energy storage
TerraPower, based in Bellevue, Washington and founded by Bill Gates, is building its first Natrium plant, a 345-megawatt sodium-cooled fast reactor with molten salt energy storage, in Kemmerer, Wyoming. The NRC approved its construction permit in March 2026.
PROS- Construction permit in hand
- Storage lets output follow demand
CONS- Relies on specialist HALEU fuel
- First plant still years from operation
- Best for
- Utilities that want nuclear power with built-in storage
- Where it falls short
- First plant is still years from operation.
- Pick something else if
- you need immediate nuclear capacity.
94.8
04
470-megawatt pressurised water SMR
Rolls-Royce SMR, majority owned by Rolls-Royce and based in Derby, UK, designs a 470-megawatt pressurised water SMR. In April 2026 it signed a contract with Great British Energy Nuclear for three units at Wylfa in North Wales, backed by up to £599 million from the National Wealth Fund.
PROS- Chosen for the UK's first SMR plant
- Factory-built modules
CONS- Larger than most SMRs
- First units still years from operation
- Best for
- Governments planning fleets of larger SMRs
- Where it falls short
- First units are still years from operation.
- Pick something else if
- you need immediate deployment.
93.6
05
Salt-cooled reactors for data centre power
Kairos Power, based in Alameda, California, develops fluoride salt-cooled high-temperature reactors. It began building Hermes 2, a 50-megawatt plant in Oak Ridge, Tennessee, in April 2026 as the first project under its agreement to supply Google.
PROS- Google as anchor customer
- NRC construction permits in hand
CONS- Novel coolant and fuel
- Small output per unit
- Best for
- Tech companies buying nuclear power for data centres
- Where it falls short
- Each unit provides only 50 megawatts of output.
- Pick something else if
- you need higher power capacity per reactor.
92.3
06
Xe-100 high-temperature gas-cooled reactor
X-energy, based in Rockville, Maryland and publicly listed, designs the Xe-100, an 80-megawatt high-temperature gas-cooled reactor. Dow's subsidiary Long Mott Energy applied for an NRC construction permit for four Xe-100 units at its Seadrift site in Texas in March 2025.
PROS- Supplies industrial steam as well as power
- Backed by Dow and Amazon
CONS- Construction permit still under review
- Relies on specialist TRISO fuel
- Best for
- Industrial sites that need both power and process heat
- Where it falls short
- It relies on specialist TRISO fuel.
- Pick something else if
- you need standard fuel types.
91.0
07
SMR-300 pressurised water reactor
Holtec International designs the SMR-300, a pressurised water SMR of about 340 megawatts. It filed the first part of a construction permit application for two SMR-300 units next to the Palisades plant in Covert, Michigan in December 2025, and the NRC accepted it for review in February 2026.
PROS- Site next to an existing nuclear plant
- Large nuclear services business behind it
CONS- Construction permit not yet granted
- Second part of application still to file
- Best for
- Utilities adding SMRs at existing nuclear sites
- Where it falls short
- It lacks a granted construction permit for its SMR-300 units.
- Pick something else if
- you need immediate regulatory approval to proceed with deployment.
89.7
08
Aurora fast microreactor powerhouses
Oklo, based in Santa Clara, California and listed on the New York Stock Exchange, designs the Aurora powerhouse, a sodium-cooled fast reactor. It broke ground on its first Aurora unit at Idaho National Laboratory in September 2025, under the Department of Energy's reactor pilot programme.
PROS- Construction under way in Idaho
- Also developing fuel recycling
CONS- Earlier NRC licence application was denied
- No commercial NRC licence yet
- Best for
- Data centres and industrial sites wanting small on-site reactors
- Where it falls short
- It lacks a commercial NRC license yet.
- Pick something else if
- you need immediate regulatory approval for deployment.
88.3
09
AP300 SMR and eVinci microreactor
Westinghouse, based in Cranberry Township, Pennsylvania, offers two small reactors: the AP300, a 300-megawatt SMR based on its AP1000 design, and the eVinci microreactor. The NRC has approved eVinci's principal design criteria and its instrumentation and control platform.
PROS- Builds on the licensed AP1000 design
- Range from microreactor to SMR
CONS- No SMR under construction
- AP300 deployment still years away
- Best for
- Utilities that want an SMR from an established reactor vendor
- Where it falls short
- It has no small modular reactors currently under construction.
- Pick something else if
- you need a reactor ready for immediate deployment.
86.9
10
Modular sodium-cooled reactors for data centres
Aalo Atomics, based in Austin, Texas, designs factory-built sodium-cooled reactors, including the 50-megawatt Aalo Pod for data centres. Its Aalo-X Critical Test Reactor reached criticality at Idaho National Laboratory on 4 July 2026 under the Department of Energy's reactor pilot programme.
PROS- Test reactor already reached criticality
- Fast build pace
CONS- Early commercial stage
- No commercial power plant built yet
- Best for
- Data centre developers planning on-site nuclear power
- Where it falls short
- It has no commercial power plant built yet.
- Pick something else if
- you need proven commercial deployment.
85.4
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Frequently asked questions
What are the best Small Modular Reactor Companies?
GE Vernova Hitachi Nuclear Energy ranks first on Lister. GE Vernova Hitachi Nuclear Energy, a joint venture of GE Vernova and Hitachi based in Wilmington, North Carolina, designs the BWRX-300, a 300-megawatt boiling water SMR. Canada's regulator licensed construction of the first unit at Ontario Power Generation's Darlington site in April 2025, and the US NRC issued a construction permit for TVA's Clinch River unit in September 2026.
What are the top 10 Small Modular Reactor Companies?
1. GE Vernova Hitachi Nuclear Energy; 2. NuScale Power; 3. TerraPower; 4. Rolls-Royce SMR; 5. Kairos Power; 6. X-energy; 7. Holtec International; 8. Oklo; 9. Westinghouse; 10. Aalo Atomics.
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