> ## Content Index > Fetch the complete content index at: https://www.edgewisely.com/llms.txt > Use this file to discover other available public pages before exploring further. # Top 7 Small Modular Reactor Companies in 2026 - URL: https://www.edgewisely.com/top-7-small-modular-reactor-companies-2026/ - Published: 2026-09-25T05:00:36.000Z - Updated: 2026-09-25T05:00:36.000Z - Description: For utilities, data-centre developers and investors tracking SMR nuclear. 2026 was the year the sector split in two: a handful of companies now have construction permits and poured concrete, while the rest still have letters of intent. - Author: John Karpentar - Tags: Roundups, Deep Tech A small modular reactor is a nuclear reactor of roughly 300 MWe or less, built in a factory and assembled on site rather than constructed piece by piece. The seven companies furthest along in 2026 are **GE Vernova Hitachi**, **TerraPower**, **X-energy**, **Kairos Power**, **NuScale Power**, **Oklo** and **Rolls-Royce SMR**. Only one of them has a grid-scale unit physically under construction in the West. ## How we picked these Ranking is by **demonstrated regulatory and construction progress**, not by announced pipeline. That distinction matters more in this sector than in any other we cover, because gigawatts of headline "demand" are routinely non-binding letters of intent. Criteria, in order: - **Construction status.** Is there a licensed site with concrete poured, or only a design? - **Regulator position.** Design certification, construction permit, or pre-application — and with which regulator, dated. - **Contract quality.** Signed power purchase agreements and government awards count. MOUs and LOIs are noted as such. - **Fuel supply realism.** Designs needing HALEU carry a supply-chain dependency that standard-LEU designs do not. - **Schedule credibility.** Has the stated first-power date already moved? Fission at this scale competes for the same capital and the same decade as [fusion energy](https://www.edgewisely.com/top-7-fusion-energy-companies-2026/) and grid-scale [solid-state batteries](https://www.edgewisely.com/top-7-solid-state-battery-companies-2026/). Those are different bets on the same problem, and we cover them separately. All regulatory, funding and schedule facts are **as of September 2026** and traced to the company, the regulator, or an SEC filing. No pricing appears below because no SMR developer publishes a per-unit price. ## Quick comparison | Company | Best for | Reactor type | Output per module | | ------------------ | ------------------------------------------ | ------------------------ | ---------------------- | | GE Vernova Hitachi | Utilities wanting the least technical risk | Boiling water reactor | 300 MWe | | TerraPower | Grid-scale with built-in storage | Sodium fast reactor | 345 MWe (500 MWe peak) | | X-energy | Industrial process heat | HTGR, pebble bed | 80 MWe | | Kairos Power | Hyperscaler power contracts | Fluoride-salt-cooled | 75 MWe | | NuScale Power | Buyers wanting a certified design | Pressurised water | 77 MWe | | Oklo | Fast deployment via the DOE route | Sodium fast microreactor | 75 MWe | | Rolls-Royce SMR | UK and European programmes | Pressurised water | 470 MWe | ## 1\. GE Vernova Hitachi Nuclear Energy (BWRX-300) [GE Vernova](https://www.gevernova.com/nuclear/carbon-free-power/bwrx-300-small-modular-reactor?ref=edgewisely.com) has the only grid-scale SMR actually being built in the Western world. Canada's regulator granted Ontario Power Generation a construction licence for a **BWRX-300** at Darlington in **April 2025**, and the first safety-related concrete went down in **May 2025**. OPG applied to the CNSC for a 20-year operating licence in **March 2026**. The design is deliberately unexciting, and that is the pitch. It is a 300 MWe boiling water reactor derived from GE's licensed ESBWR, running on standard low-enriched uranium fuel assemblies with a 60-year design life. No HALEU, no novel coolant, no new fuel form. **Best for:** utilities that want the shortest path to a licensed, financeable nuclear project. **Pros** - The only Western SMR with nuclear-grade concrete poured and construction underway. - Standard LEU fuel avoids the HALEU supply bottleneck constraining most advanced designs. - UK Generic Design Assessment **Step 2 completed December 2025**, opening a second major market. - TVA filed the first US construction permit application for a BWRX-300 at Clinch River in **May 2025**, backed by a **$400 million** DOE grant announced December 2025. **Cons** - Darlington Unit 1 is first-of-a-kind. Completion is targeted for late 2029 with commercial operation by end of 2030, and no BWRX-300 has ever operated. - Outside Canada, the order book is thin: Poland, Sweden, Estonia and Finland are MOUs, early-works agreements or downselections, not signed construction contracts. - The US path is an application only — no NRC permit yet. - Behind Rolls-Royce SMR in the UK regulatory queue. ![Cutaway rendering of the GE Vernova Hitachi BWRX-300 reactor pressure vessel](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-ge.png) Image: [GE Vernova](https://www.gevernova.com/nuclear/carbon-free-power/bwrx-300-small-modular-reactor?ref=edgewisely.com) ## 2\. TerraPower (Natrium) [TerraPower](https://www.terrapower.com/natrium/?ref=edgewisely.com) holds the single most significant US regulatory milestone in the sector. On **4 March 2026** the NRC issued a construction permit for Natrium Unit 1 at Kemmerer, Wyoming — the first NRC construction permit ever granted to a commercial-scale non-light-water reactor, and the first commercial reactor construction permit in roughly a decade. Construction began **23 April 2026**. Natrium is a sodium-cooled fast reactor rated at **345 MWe**, coupled to a molten-salt thermal storage system that lets output climb to **500 MWe** for several hours. That decoupling of reactor and turbine is the design's actual point: it turns a baseload plant into something that can follow a grid full of intermittent renewables. **Best for:** utility-scale generation on grids that need dispatchable output rather than flat baseload. **Pros** - First NRC construction permit for an advanced non-LWR reactor in over 40 years, granted ahead of schedule after a December 2025 safety evaluation. - Thermal storage provides load-following capability no conventional SMR offers. - Backed by DOE's Advanced Reactor Demonstration Program with cost-share of up to **$2 billion**. - Plant completion has held at its long-stated 2030 target without public slippage. **Cons** - The April 2026 construction start was site work. **First nuclear-grade concrete is targeted for 2027** — the nuclear island has not begun. - First-of-a-kind Gen IV construction carries schedule and cost risk with no precedent to benchmark against. - Private company: no audited public financials, and reported valuation figures come from third-party aggregators rather than TerraPower itself. - Heavy reliance on federal cost-share exposes the project to budget and policy change. ![TerraPower Natrium plant layout diagram showing the separated Nuclear Island and Energy Island](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-tp.png) Image: [TerraPower](https://www.terrapower.com/natrium/?ref=edgewisely.com) ## 3\. X-energy [X-energy](https://x-energy.com/xe-100/?ref=edgewisely.com) listed on Nasdaq under **XE** on 24 April 2026 at $23 a share, raising roughly **$1 billion**. Its Xe-100 is a helium-cooled, pebble-bed high-temperature gas reactor producing **80 MWe (200 MWt)** per module, usually sold as a four-pack of 320 MWe, with a 60-year design life. The strategic difference is fuel. X-energy owns TRISO-X, its own fuel fabrication subsidiary, whose TX-1 plant at Oak Ridge **completed vertical construction on 24 September 2026**. Few advanced reactor developers control their own fuel supply. The high outlet temperature also makes the Xe-100 usable for industrial process heat, which is why the lead customer is a chemical company rather than a utility. **Best for:** industrial sites needing high-temperature process heat alongside electricity. **Pros** - Construction permit application for Dow's Long Mott site was docketed in May 2025, and the NRC completed its environmental assessment ahead of schedule in **May 2026**; the permit is expected in Q1 2027. - Vertically integrated TRISO fuel manufacturing reduces exposure to third-party HALEU supply. - Signed a definitive HALEU and LEU supply agreement with Centrus in **August 2026**. - UK regulators began a design review for the Xe-100 with Centrica on **15 September 2026**. **Cons** - No construction permit yet — Seadrift remains pre-permit. - TX-1 is not finished, so fuel independence is a plan rather than a capability. - Newly public with a large raise implying substantial pre-revenue capital needs. - Customer agreements vary in maturity from LOI through joint development agreement; treat the widely quoted multi-gigawatt Amazon figure as an announced intent, not a confirmed binding order. ![Cutaway rendering of the X-energy Xe-100 high-temperature gas-cooled reactor module](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-xe.png) Image: [X-energy](https://x-energy.com/xe-100/?ref=edgewisely.com) ## 4\. Kairos Power [Kairos Power](https://www.kairospower.com/technology?ref=edgewisely.com) is building the KP-FHR, a fluoride-salt-cooled high-temperature reactor using TRISO fuel pebbles in a molten Flibe salt coolant at near-atmospheric pressure and 650°C outlet temperature. Commercial modules are 150 MWe as twin 75 MWe units; the KP-450 configuration reaches 450 MWe. Kairos holds two NRC construction permits — **Hermes** (December 2023) and **Hermes 2** (November 2024), the latter being the first electricity-producing Gen IV plant approved for construction in the US. It also has the sector's most concrete hyperscaler relationship: a signed master plant development agreement with Google from **October 2024** targeting 500 MW by 2035, with a TVA power purchase agreement signed in **August 2025** covering the first deployment. **Best for:** teams tracking which SMR developer converts data-centre interest into signed offtake first. **Pros** - Two NRC construction permits in hand, ahead of every peer except TerraPower on the non-LWR path. - Google agreement and TVA PPA are signed contracts, not letters of intent. - Near-atmospheric operating pressure removes a major class of accident scenario from the safety case. - Uses 19.75% LEU+ TRISO now, with the company stating it will move to HALEU only as supply broadens. **Cons** - Hermes produces no electricity. It is a 35 MWth test reactor, so nothing Kairos has built generates power. - The NRC extended Hermes's construction completion deadline on **13 May 2026**, moving it from 31 December 2026 to **30 April 2029** — a confirmed slip of roughly two and a half years. - Private, with no disclosed funding or valuation, which limits any read on runway. - No published cost data, so the fleet economics behind the 500 MW Google target are unverifiable. ![Architectural rendering of the Kairos Power Hermes reactor facility](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-kp.png) Image: [Kairos Power](https://www.kairospower.com/technology?ref=edgewisely.com) ## 5\. NuScale Power [NuScale](https://www.nuscalepower.com/products/nuscale-power-module?ref=edgewisely.com) remains the only company with a fully NRC-certified SMR design, and the NRC approved the uprated **77 MWe** version in May 2025\. Modules scale into plants of 462 to 924 MWe, use ordinary light water, and run on standard LEU below 5% enrichment — no HALEU exposure at all. Commercially the picture is harder. NuScale reported **$1.9 billion** in cash and investments at 30 June 2026, but second-quarter revenue of **$0.1 million**, down 98.8% year on year. Its flagship agreement — a January 2026 deal with TVA and ENTRA1 for up to 6 GW — was still described in the company's own August 2026 results as advancing toward a definitive power purchase agreement rather than signed. **Best for:** buyers who want a design the regulator has already certified end to end. **Pros** - The only NRC design certification held by any SMR developer, now covering the uprated 77 MWe module. - Standard LEU fuel and light-water design mean no novel coolant or fuel supply chain. - Strong balance sheet: $1.9 billion in cash and investments as of 30 June 2026. - Modular plant sizing from 462 MWe to 924 MWe gives utilities configuration flexibility. **Cons** - No unit-specific construction permit anywhere, and no reactor under construction. - Its original customer, the UAMPS Carbon Free Power Project, cancelled in November 2023 — still the sector's most cited cost-escalation failure. - Revenue has effectively collapsed, down 98.8% year on year in Q2 2026. - Both flagship deals — TVA/ENTRA1 and Romania's RoPower — remain conditional, per NuScale's own disclosure. ![Cutaway rendering of the NuScale Power Module small modular reactor](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-ns.png) Image: [NuScale Power](https://www.nuscalepower.com/products/nuscale-power-module?ref=edgewisely.com) ## 6\. Oklo [Oklo](https://oklo.com/technology/aurora-powerhouse?ref=edgewisely.com) is pursuing the Aurora Powerhouse, a sodium-cooled fast microreactor using metal fuel, with the first commercial unit at Idaho National Laboratory rated at 75 MWe. Its route to construction is unusual: rather than wait on NRC licensing alone, Oklo is building under the **DOE Reactor Pilot Program**, which authorises test and demonstration reactors on DOE sites outside the standard NRC process. It broke ground at INL in September 2025. The NRC track runs in parallel. The agency **denied** Oklo's original combined licence application in 2022 for insufficient detail; the resubmitted application has since been accepted for review. **Best for:** watching whether the DOE authorisation pathway genuinely compresses timelines. **Pros** - Groundbreaking already done at INL under a federal pathway that avoids the NRC critical-path bottleneck. - Resubmitted COLA accepted for NRC review after the 2022 denial — a real recovery. - Metal fuel design can use recycled or reprocessed material, not only freshly enriched HALEU. - Publicly listed, so financials and risk disclosures are visible in SEC filings. **Cons** - A prior outright NRC application denial is a genuine track-record mark, not a procedural footnote. - Most headline demand is non-binding. The Equinix agreement — 500 MW with a $25 million prepayment — is an LOI whose rate is left to future PPAs, and the Diamondback agreement is likewise an LOI. - Pre-revenue with substantial ongoing cash burn and consequent dilution risk. - On **2 September 2026** Oklo filed an emergency FERC complaint alleging PJM improperly dropped its Virginia interconnection project from the queue — an unresolved dispute over grid access, which is increasingly the real constraint on [data-centre power](https://www.edgewisely.com/ai-data-center-power-nuclear-timeline-gap/). ![Architectural rendering of an Oklo Aurora Powerhouse building at dusk](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-ok.png) Image: [Oklo](https://oklo.com/regulatory?ref=edgewisely.com) ## 7\. Rolls-Royce SMR [Rolls-Royce SMR](https://www.rolls-royce-smr.com/?ref=edgewisely.com) is 57.8% owned by Rolls-Royce Holdings, with BNF Resources, Constellation and the Qatar Investment Authority holding the remainder. Its design is a conventional pressurised water reactor at **470 MWe** per module (1,358 MWth) on standard LEU — by some margin the largest output in this list, which stretches the definition of "small" but makes the per-megawatt economics easier. It leads the UK regulatory queue. The design completed Step 2 of ONR's Generic Design Assessment in July 2024 and entered **Step 3**, the final stage, the same month. As of the regulator's February 2026 update it is the only SMR design to have reached Step 3. **Best for:** UK and European deployments tied to national nuclear programmes. **Pros** - The only SMR design in ONR's final GDA step, ahead of every competitor in the UK. - Selected by the UK government's nuclear programme, with an Early Works Agreement confirmed **13 April 2026** and Wylfa named as the first site. - The National Wealth Fund has committed up to **£599 million** in financing alongside broader UK programme backing. - Czech expansion is progressing: an Early Works Contract with ČEZ for Temelín and a control-systems supply contract with ŠKODA JS signed in September 2026. **Cons** - No construction has started anywhere, and GDA Step 3 is not complete, so there is no certified design yet. - Schedule is vague by the programme's own account: final investment decision is not expected until around the turn of the decade, with first power in the mid-2030s. - The ČEZ agreement is a preliminary early-works contract, not a construction order. - Commercial viability is heavily underwritten by UK state funding; the unsubsidised economics are untested. ![Rolls-Royce SMR branded test rig equipment inside a development facility](https://storage.ghost.io/c/54/5a/545a66b3-60ef-480c-80ae-765bac52f6ec/content/images/2026/09/smr-rr.png) Image: [Rolls-Royce SMR](https://www.rolls-royce-smr.com/?ref=edgewisely.com) ## How to choose If you are a utility, a data-centre developer or an investor, the useful question is not which design is best but which stage of risk you can carry. - **Lowest technical risk, nearest to operating.** GE Vernova Hitachi's BWRX-300\. It is the only one with concrete poured, and the only one using an already-licensed reactor lineage. - **Dispatchable grid-scale output.** TerraPower's Natrium, for the thermal storage that lets it follow load. - **Industrial heat, not just electricity.** X-energy's Xe-100, whose high outlet temperature is the whole point. - **Signed hyperscaler offtake as a proof signal.** Kairos Power. The Google agreement and TVA PPA are contracts, not intentions. - **Regulatory certainty above all.** NuScale, the only certified design — accepting that certification has not yet converted into a single construction start. - **Testing the federal fast lane.** Oklo, which is building under DOE authorisation rather than waiting on the NRC. - **UK or European programme exposure.** Rolls-Royce SMR, by a wide margin. Two things to check on any SMR announcement. First, **is the contract binding?** A gigawatt figure attached to an LOI is a marketing number. Second, **does the design need HALEU?** Centrus remains the only US-owned HALEU producer, and its capacity expansion depends on financing that is not yet committed — a genuine constraint on every HALEU-dependent developer, and a reason the standard-LEU designs look less exciting and more deliverable. ## Frequently Asked Questions ### Are there any small modular reactors in operation? Very few. China's HTR-PM twin-unit gas-cooled plant at Shidao Bay has been in commercial operation since December 2023, and Russia's floating Akademik Lomonosov has run two KLT-40S units since 2020, passing a billion cumulative kilowatt-hours. China's Linglong One missed its first-half 2026 target and is not yet operating. No SMR operates commercially in North America or Europe. ### What are small modular reactors? Small modular reactors are nuclear reactors producing roughly 300 MWe or less per module, built as repeatable factory units and assembled on site. The modularity is the economic argument: factory serial production should cut the cost overruns that plague bespoke gigawatt-scale plants. Designs range from conventional light-water reactors to sodium fast reactors, gas-cooled reactors and molten-salt systems. ### What companies make small modular reactors? GE Vernova Hitachi, TerraPower, X-energy, Kairos Power, NuScale Power, Oklo and Rolls-Royce SMR lead the Western field. Holtec and Westinghouse are also advancing designs, and microreactor developers including Radiant, Aalo Atomics and Last Energy target smaller output. Outside the West, Rosatom and CNNC are the established builders. ### How do small modular reactors work? The same way as any fission plant: a controlled chain reaction heats a coolant, which drives a turbine. What differs is scale and assembly. Modules are factory-built and shipped, and many use passive safety — natural circulation and gravity rather than pumps — so the reactor shuts down safely without operator action or external power. ### How much does a small modular reactor cost? No SMR developer publishes a per-unit price, so any figure you see is an estimate rather than a quote. The most instructive public data point is a negative one: the NuScale UAMPS project was cancelled in November 2023 after its projected cost rose, and that remains the sector's clearest evidence that first-of-a-kind SMR economics are not yet settled. ## Editor's note — sources - [CNSC Darlington New Nuclear Project](https://www.cnsc-ccsn.gc.ca/eng/reactors/new-reactor-power-plant-projects/new-reactor-power-plant-facilities/darlington-new-nuclear-project/?ref=edgewisely.com) and [GE Vernova BWRX-300](https://www.gevernova.com/nuclear/carbon-free-power/bwrx-300-small-modular-reactor?ref=edgewisely.com) - [TerraPower: NRC approves Natrium construction permit](https://www.terrapower.com/NRC-Approves-Natrium-Reactor-Construction-Permit?ref=edgewisely.com) and [DOE Office of Nuclear Energy](https://www.energy.gov/ne/articles/nrc-issues-construction-permit-terrapowers-natrium-advanced-reactor?ref=edgewisely.com) - [X-energy Xe-100](https://x-energy.com/xe-100/?ref=edgewisely.com), [TRISO-X TX-1 construction update](https://x-energy.com/news/triso-x-completes-vertical-construction-of-tx-1-fuel-fabrication-facility/?ref=edgewisely.com), [Centrus HALEU supply agreement](https://x-energy.com/news/x-energy-centrus-sign-haleu-supplyagreement-for-xe-100-advanced-small-modular-reactor-development/?ref=edgewisely.com) - [NRC Hermes construction deadline extension, 18 May 2026](https://www.federalregister.gov/documents/2026/05/18/2026-09880/in-the-matter-of-kairos-power-llc-hermes-test-reactor-extension-of-latest-date-for-completion-of?ref=edgewisely.com) and [Kairos Power / Google agreement](https://www.kairospower.com/updates/google-and-kairos-power-partner-to-deploy-500-mw-of-clean-electricity-generation?ref=edgewisely.com) - [NuScale Q2 2026 results](https://www.nuscalepower.com/press-releases/2026/nuscale-power-reports-second-quarter-2026-results?ref=edgewisely.com) - [Oklo regulatory page](https://oklo.com/regulatory?ref=edgewisely.com) and [ANS on the PJM interconnection complaint](https://www.ans.org/news/2026-09-02/article-8362/oklo-claims-pjm-improperly-dropped-its-virginia-project/?ref=edgewisely.com) - [ONR Generic Design Assessment: Rolls-Royce SMR](https://www.onr.org.uk/generic-design-assessment/assessment-of-reactors/rolls-royce-smr?ref=edgewisely.com) and [National Wealth Fund commitment](https://www.nationalwealthfund.org.uk/news-and-publications/news/national-wealth-fund-commits-up-to-599m-to-rolls-royce-smr/?ref=edgewisely.com) - [World Nuclear News: Akademik Lomonosov passes one billion kWh](https://www.world-nuclear-news.org/articles/russias-floating-nuclear-power-plant-passes-one-billion-kwh?ref=edgewisely.com) - [Centrus HALEU production milestone, DOE](https://www.energy.gov/ne/articles/centrus-reaches-900-kilogram-mark-haleu-production?ref=edgewisely.com)