What are the most valuable advanced nuclear startups?

Top startups in the advanced nuclear market ranked by valuation

Here is an updated table that ranks the top startups in the advanced nuclear market based on their latest reported or estimated valuations.

If you need to dig deeper and get more detailed data, please check our report covering the advanced nuclear market.

Which startups in the advanced nuclear market have been acquired or gone public?

These startups no longer have a private-market valuation of their own, so we list them separately, using their acquisition price or their current market capitalization.

1. Price for specific technology assets, not a sale of the company.
2. Technology-asset deal subject to closing conditions, not a company sale.

Why are advanced nuclear startup valuations rising so fast?

Advanced nuclear startups are attracting billion-dollar valuations because investors now see a real market for new reactors, especially from data centers, industrial companies and governments worried about electricity supply.

The biggest change comes from customers. In October 2024, Google signed an agreement with Kairos Power for up to 500 MW of future nuclear capacity. Amazon has gone further financially, investing $500M in X-energy and supporting plans for more than 5 GW of new nuclear capacity by 2039.

Government support has also become more substantial. The U.S. Department of Energy selected TerraPower and X-energy for cost-shared demonstration projects in 2020, while its January 2026 uranium-enrichment awards included a $900M task order for General Matter.

Then came the reactor tests. Antares reached zero-power criticality in June 2026, followed by Valar Atomics later that month and Aalo Atomics in July. These milestones showed that several young companies could build functioning experimental nuclear systems rather than merely propose them.

The investment story has broadened remarkably quickly. Investors are financing large power plants, transportable microreactors, nuclear fuel production and industrial heating systems. The industry has moved beyond a handful of expensive demonstration projects, although commercial revenue still trails the valuations by a considerable distance.

Which advanced nuclear startups are worth the most today?

TerraPower currently leads the private advanced nuclear ranking at $6.0B–$9.0B, followed by Valar Atomics at $5.8B–$6.2B and Aalo Atomics at $2.7B–$2.9B.

These three companies are pursuing quite different markets. TerraPower is building Natrium, a 345 MW sodium-cooled reactor intended for utility-scale electricity generation. Valar Atomics develops high-temperature nuclear systems, while Aalo Atomics is designing modular reactors that can supply electricity to data centers.

General Matter is valued at about $2B, even though it develops uranium enrichment infrastructure rather than nuclear reactors. Radiant, valued at $1.8B–$2.6B, specializes in transportable microreactors. Antares, at $2.0B–$2.1B, targets smaller nuclear systems suited to defense and remote-power applications.

One unusual feature of this market is that reactor size has surprisingly little to do with valuation. A company building a large power station can command a valuation similar to one developing much smaller nuclear systems, while an enrichment business can reach the same financial tier without manufacturing reactors.

For investors, the opportunities extend across the nuclear supply chain. For customers, these businesses are solving completely different problems. The ranking says a great deal about where capital is flowing, but much less about which reactor design will eventually win.

How many advanced nuclear unicorns are there?

Eight private advanced nuclear startups have valuation ranges starting at $1B or more, representing about 21% of the 39 companies in our private ranking.

Those eight companies are TerraPower, Valar Atomics, Aalo Atomics, General Matter, Radiant, Antares, CORE POWER and Blue Energy. A ninth company, Kairos Power, is valued at $900M–$1.4B, putting it partly above the unicorn threshold.

The variety is striking. TerraPower is developing a commercial power station, Radiant and Antares are working on compact systems, CORE POWER is pursuing maritime nuclear applications, and General Matter is building enrichment infrastructure. All can attract billion-dollar valuations despite having very different customers and development requirements.

Advanced nuclear has already produced a meaningful group of unicorns, even though most companies are still years away from generating electricity or supplying nuclear fuel at commercial scale. That is an aggressive financial starting point for such a capital-intensive industry.

Is TerraPower still the most valuable private nuclear startup?

TerraPower remains the highest-ranked private advanced nuclear startup, with a $6.0B–$9.0B valuation and one of the industry's most advanced commercial reactor projects.

Its strongest achievement is the Natrium project in Kemmerer, Wyoming. On March 9, 2026, the U.S. Nuclear Regulatory Commission issued a construction permit for the 345 MW sodium-cooled reactor. According to the Department of Energy, this was the first construction permit issued by the NRC for a commercial non-light-water power reactor.

TerraPower submitted its application in March 2024, and the NRC completed its safety review in December 2025. That is substantial progress for a reactor design that differs from the light-water technology used in most existing commercial nuclear plants.

Natrium also includes molten-salt thermal storage, allowing the facility to increase electrical output to 500 MW for limited periods. This gives the plant more flexibility to respond to changing electricity demand.

The project is expected to be completed around 2030, although TerraPower will still need an operating license before generating commercial electricity.

TerraPower's leading position looks justified by its regulatory and construction progress. Still, its valuation range overlaps Valar Atomics' $5.8B–$6.2B, despite the enormous difference between a utility-scale commercial project and a young developer advancing through experimental reactor tests.

Why is Valar Atomics worth so much?

Valar Atomics has reached a $5.8B–$6.2B valuation because it has moved unusually quickly from reactor development to a successful nuclear experiment.

On June 18, 2026, Valar's Ward 250 reactor achieved zero-power fueled criticality at the Utah San Rafael Energy Lab. The Department of Energy described it as the first DOE-authorized reactor built outside a national laboratory.

Criticality means that a controlled nuclear chain reaction can sustain itself. For an advanced reactor developer, this is a major technical milestone because it confirms important aspects of the nuclear core's behavior.

Valar's result came just two weeks after Antares achieved criticality at Idaho National Laboratory. Aalo Atomics followed in July, meaning three companies in our ranking reached this milestone within roughly one month.

That's quite a change for an industry that spent years talking mainly about designs, simulations and regulatory preparation.

There is a catch, though. The Ward 250 demonstration was conducted at zero power. Investors are still betting on Valar's ability to progress toward sustained high-temperature operation, commercial reactor manufacturing and electricity or industrial-heat delivery.

Valar's valuation reflects extraordinary confidence in its execution speed. The next serious test is whether it can operate a reactor under conditions much closer to what paying customers will need.

Is Aalo Atomics becoming a major nuclear startup for data centers?

Aalo Atomics is becoming a serious contender in nuclear power for data centers, with a $2.7B–$2.9B valuation and a successful experimental reactor test.

Aalo is developing approximately 10 MWe modular reactors that can be combined into 50 MWe Aalo Pods. This approach would allow customers to add generation capacity in smaller increments than a conventional nuclear power plant.

On July 4, 2026, its Aalo-X experimental reactor achieved zero-power fueled criticality at Idaho National Laboratory. The Department of Energy confirmed the achievement two days later.

The timing was impressive. Aalo built its test reactor in less than eight months, according to the company's development announcements. That's remarkably fast for a nuclear engineering project, even an experimental one.

Aalo's intended customers also have a clear reason to explore nuclear power. Large data centers require continuous electricity, and access to sufficient grid capacity can influence where new facilities are built.

Compared with TerraPower's utility-scale project, Aalo is aiming for smaller, repeatable installations. Compared with Radiant's approximately 1 MWe microreactor, its planned modules target substantially larger electricity loads.

Still, building an experimental reactor quickly doesn't establish what commercial units will cost. Aalo needs to show that its modular design can be manufactured repeatedly, licensed and connected to customers' electrical infrastructure.

The company has made serious technical progress. Its long-term valuation will depend on how cheaply and quickly it can actually deliver those first commercial installations.

Are Radiant and Antares actually close to selling nuclear microreactors?

Radiant and Antares are making credible progress toward commercial nuclear microreactors, but their valuations still reflect substantial future revenue expectations.

Radiant has a $1.8B–$2.6B valuation and is developing Kaleidos, a transportable reactor designed to produce approximately 1 MWe of electricity. Antares, valued at $2.0B–$2.1B, is pursuing microreactors for demanding environments, including defense installations.

Antares achieved zero-power criticality with its Mark-0 reactor at Idaho National Laboratory on June 4, 2026. This established an important technical foundation for its later reactor designs.

Radiant is working toward an integrated nuclear testing program for Kaleidos. The company has also developed manufacturing plans in Tennessee, reflecting its ambition to produce multiple transportable reactors rather than build each installation as an entirely separate engineering project.

The commercial opportunity is particularly interesting in locations where diesel generators, fuel transport or grid extensions are expensive. A remote military installation can have very different electricity economics from a conventional urban customer.

The first microreactor businesses will ultimately be judged by installation cost, fuel logistics, operating reliability and the total price customers pay for electricity. Compact nuclear reactors are impressive engineering achievements, but repeat orders will depend on those practical results.

Radiant and Antares have reduced important technical uncertainties. Commercial deployments will determine whether microreactors can become attractive businesses at scale.

Why is General Matter worth billions without building nuclear reactors?

General Matter has an estimated $2B valuation because uranium enrichment is becoming one of the most strategically important parts of advanced nuclear power.

Many advanced reactor designs require high-assay low-enriched uranium, known as HALEU. This fuel contains more uranium-235 than conventional commercial reactor fuel, but commercial HALEU production capacity in the United States remains limited.

General Matter received a $900M task order from the Department of Energy in January 2026 to help expand domestic HALEU enrichment capacity. American Centrifuge Operating received a separate $900M award under the same federal initiative.

The total package announced by the department amounted to $2.7B across three enrichment companies, including an additional award for low-enriched uranium production.

That's an enormous federal commitment to a supply chain supporting an industry whose first commercial advanced reactors are still being developed.

The attraction of General Matter is straightforward: it could serve several reactor developers rather than depend on the success of one particular reactor design.

There is a similar strategic logic behind LIS Technologies, Hexium and Clean Core Thorium Energy, although these companies work on different enrichment technologies or advanced fuel products.

One important distinction: General Matter's $900M federal task order is tied to performance and project milestones. It doesn't mean the company has already earned $900M in revenue.

Even so, General Matter could become a major nuclear supplier if domestic enrichment capacity expands as planned. Reactor developers will need qualified fuel, and the companies capable of producing it may hold considerable bargaining power.

Could uranium fuel shortages slow down advanced nuclear startups?

Uranium fuel shortages could delay advanced nuclear deployment, especially for companies that need HALEU before their first reactors can operate.

The U.S. Government Accountability Office examined the problem in August 2026. Its report found that projected HALEU availability might fall short of near-term demand, while emphasizing that demand remains uncertain because many proposed reactor projects have not yet been built.

The Department of Energy expected approximately 21.2 metric tons of HALEU to be available by the end of 2028 and about 23.4 metric tons by 2030 under the supply assumptions examined by the GAO.

Several reactor developers are therefore competing for a relatively limited supply of qualified fuel. Additional production capacity requires enrichment equipment, regulatory approvals, investment and long-term customer commitments.

The problem creates a difficult cycle. Enrichment businesses want confirmed reactor demand before making enormous investments, while reactor developers need confidence that fuel will be available before committing to commercial schedules.

This helps explain why nuclear fuel companies are gaining attention alongside reactor manufacturers. A supplier capable of delivering qualified domestic fuel could become commercially important well before advanced nuclear electricity production reaches a large scale.

Fuel supply milestone	Evidence	Why it matters
October 2020	DOE selects TerraPower and X-energy for demonstration awards	Creates demand for advanced reactor fuel
January 2024	DOE begins soliciting domestic HALEU enrichment services	Establishes a federal procurement pathway
October 2024	DOE selects four suppliers for HALEU enrichment contracts	Expands the potential supplier base
January 2026	General Matter receives a $900M task order	Supports planned enrichment capacity
January 2026	American Centrifuge Operating receives a separate $900M task order	Adds another major domestic investment
August 2026	GAO warns that projected HALEU supply may be insufficient	Confirms an important deployment constraint
By 2030	DOE's examined plans indicate about 23.4 metric tons of available HALEU	Shows the limited near-term scale of expected supply

Is Kairos Power worth less than Aalo Atomics despite having more permits?

Kairos Power has a lower estimated valuation than Aalo Atomics despite having a longer regulatory track record and a major customer agreement with Google.

Kairos is valued at $900M–$1.4B, compared with Aalo Atomics' $2.7B–$2.9B range.

The regulatory comparison is revealing. Kairos received construction permits for its Hermes demonstration reactor in December 2023 and its Hermes 2 test facility in November 2024. Those approvals came before Aalo's July 2026 criticality demonstration.

Kairos also signed a development agreement with Google in October 2024 covering up to 500 MW of nuclear electricity capacity by 2035. The plan involves multiple reactors and a sequence of projects, beginning with an initial deployment targeted around 2030.

Aalo, meanwhile, has attracted a considerably higher valuation after rapidly developing and testing its own reactor technology.

Does that make Kairos undervalued? Possibly. Its permitting history and named customer commitments are unusually strong for a company in this valuation range.

The two businesses have different reactor designs and commercialization strategies, but the gap is still worth examining. If regulatory progress and customer commitments were the only considerations, Kairos would look particularly competitive.

Are Google and Amazon really spending money on advanced nuclear power?

Google and Amazon have moved beyond casual interest in advanced nuclear power, although the electricity covered by their agreements is largely scheduled for future delivery.

Google's October 2024 arrangement with Kairos Power targets up to 500 MW of capacity by 2035, with the first deployment planned around 2030. It creates a commercial framework for a fleet of advanced reactors.

Amazon has made a more direct equity commitment through its $500M investment in X-energy. It is also working with Energy Northwest on a project in Washington state initially targeting 320 MW, potentially expandable to 960 MW.

In October 2026, Amazon, X-energy and American Electric Power announced a proposed project in Indiana involving twelve 80 MW Xe-100 reactors. Together, they would produce 960 MW of generation capacity if completed.

These are serious commitments, particularly because Amazon is supporting both nuclear technology development and individual projects.

But the quantities need some perspective. A 500 MW development target is different from 500 MW of operating electricity generation. Even a signed power-purchase agreement leaves permitting, construction and commissioning work ahead.

Hyperscalers have become genuine financial and commercial partners for advanced nuclear developers. Their involvement improves the industry's prospects considerably, although most of the expected electricity production remains years away.

Which advanced nuclear technologies are attracting the highest valuations?

Sodium-cooled reactors, high-temperature systems and modular reactor designs currently dominate the upper end of private advanced nuclear valuations, with uranium enrichment emerging as another major category.

TerraPower's Natrium project uses sodium cooling. Valar Atomics develops high-temperature reactor technology, and Aalo Atomics is pursuing compact modular systems. General Matter has built its investment case around fuel enrichment.

Other reactor designs are receiving investment at smaller valuation levels. Kairos Power develops fluoride-salt-cooled reactors, Copenhagen Atomics works on thorium molten-salt systems, and Blykalla focuses on lead-cooled reactors.

Thorizon, Stellaria and Saltfoss Energy are also developing molten-salt concepts, while ARC Clean Technology and HEXANA pursue sodium-cooled designs.

These technologies have different trade-offs involving operating temperature, fuel, materials, reactor size and industrial applications. For example, reactors operating at higher temperatures may be useful for supplying industrial heat alongside electricity.

However, no reactor category has established a broad commercial manufacturing lead. Today's valuations tell us considerably more about fundraising and project progress than they do about the eventual cost per megawatt-hour.

It is far too early to declare which reactor technology will dominate in twenty years. Some of the eventual winners may not even be among today's most valuable startups.

Can nuclear microreactors compete with conventional nuclear power plants?

Nuclear microreactors could become competitive in specialized locations, especially where reliable electricity is expensive or difficult to obtain. Competing with large power plants on ordinary wholesale electricity prices will be harder.

The differences in reactor size are substantial. TerraPower's Natrium project targets 345 MWe, Aalo Atomics is designing approximately 10 MWe modules, and Radiant's Kaleidos is intended to generate about 1 MWe.

A large nuclear plant can spread many fixed costs across greater electricity production. Smaller reactors offer potential advantages in transport, installation and the ability to match local demand.

That makes remote industrial sites, military facilities and isolated communities promising early markets. A customer currently dependent on delivered diesel fuel may be willing to pay considerably more for dependable power than a customer connected to a large electricity grid.

Specialized developers are pursuing similar opportunities outside conventional electricity generation. Jimmy targets industrial heat, CORE POWER develops maritime nuclear applications, and Bluecore Energy works on floating nuclear power systems.

These specialized markets could give smaller reactors a practical entry point. The tougher challenge comes later, when manufacturers try to compete with conventional power generation across larger and more price-sensitive markets.

Can advanced nuclear startups really manufacture reactors at scale?

Advanced nuclear startups are getting closer to repeatable reactor manufacturing, but no private company in our ranking has yet demonstrated a large commercial fleet built at predictable unit costs.

Aalo Atomics wants to produce standardized modules, Radiant is developing manufacturing infrastructure for transportable systems, and Last Energy promotes factory-built nuclear plants.

Blue Energy is pursuing an especially different construction model by developing modular plants assembled using shipyard infrastructure. Prodigy Clean Energy is also working on transportable nuclear facilities.

These approaches share a common goal: reduce the amount of specialized work performed at individual construction sites.

Yet manufacturing a reactor involves much more than producing its core. Companies need qualified components, fuel supply, quality-control systems, transport arrangements and regulatory approval for the finished installation.

The industry's first genuinely useful manufacturing comparisons will come from building successive commercial units. The real question is whether the second, fifth or tenth reactor costs less and takes less time to deliver than the first.

Until those results are available, factory-production plans remain difficult to value precisely. Making one reactor work is hard enough. Making dozens at a competitive price is an entirely different industrial challenge.

Are European advanced nuclear startups falling behind American companies?

European advanced nuclear startups are developing plenty of interesting technology, but American companies currently dominate the highest private valuation tier.

Of the eight companies whose valuation ranges begin at $1B, seven are based in the United States. CORE POWER, from the United Kingdom, is the only European representative.

Across the full private ranking, 22 of the 39 startups are American, accounting for about 56%. European companies represent most of the remaining group, with businesses operating in France, Sweden, Denmark, the Netherlands, Switzerland, Germany, Norway, Estonia and the United Kingdom.

France has five private companies in the ranking: Jimmy, Stellaria, Otrera, HEXANA and Blue Capsule Technology. Their technologies include industrial nuclear heating, molten-salt reactors and sodium-cooled systems.

Northern Europe has another cluster. Copenhagen Atomics is working on thorium molten-salt reactors, Blykalla is developing lead-cooled technology, and Thorizon is pursuing reactors designed to use recycled nuclear materials.

The United States has several advantages that translate more directly into large private valuations: major government demonstration programs, a deep venture-capital market and concentrated demand from technology companies building data centers.

Europe has technological depth but fewer companies reaching the same financial scale. Closing that gap will depend on bringing reactor projects through licensing, securing enough construction capital and converting industrial partnerships into actual facilities.

Are advanced nuclear startups raising enough money to justify their valuations?

Advanced nuclear startups are raising substantial amounts of capital, but their valuations depend on much more than the money already invested.

TerraPower has approximately $1.5B in reported funding against its $6.0B–$9.0B valuation. Aalo Atomics has raised $133M and is valued at $2.7B–$2.9B. Antares has $479M in funding against a $2.0B–$2.1B valuation.

The differences are large because investors price ownership based on expected future value, rather than simply adding up historical investments.

However, nuclear companies face a financial challenge that many software startups do not. Reactor construction, manufacturing infrastructure, testing facilities and fuel production can require considerable additional capital before meaningful commercial revenue appears.

Government awards also need to be separated from equity funding. A cost-shared construction grant or a federal procurement contract can reduce financing pressure, but its total value should not be added directly to a company's equity valuation.

Public companies show how far market values can diverge from historical financing. NuScale Power has a $2.42B market capitalization against $3.8B+ in reported funding, while NANO Nuclear Energy has a $589M market capitalization against $680M in funding. In both cases, market value sits below cumulative reported funding as investors reassess future prospects, and because reported funding can include financing categories beyond equity capital.

For private startups, the question is how much capital must still be raised before cash generation becomes dependable. A high valuation can coexist with substantial future financing needs, and existing shareholders may face significant dilution along the way.

What does an advanced nuclear startup need to become a unicorn?

An advanced nuclear startup can reach a billion-dollar valuation well before operating a commercial power plant, provided investors believe it has a credible path to licensing, customers and large-scale deployment.

The clearest examples show three different approaches.

Aalo Atomics reached $2.7B–$2.9B through a modular reactor strategy and rapid experimental progress. Valar Atomics reached $5.8B–$6.2B while advancing high-temperature reactor technology. General Matter reached about $2B by focusing on uranium enrichment, a strategically important part of the nuclear supply chain.

None of those companies needed an operating commercial reactor to achieve unicorn status. They convinced investors that their technology addresses an important problem and that their teams can execute demanding development programs.

The path becomes more difficult as the business grows. Experimental success must eventually be followed by regulatory approvals, qualified manufacturing, customer contracts and reliable operations.

For fuel companies, the milestones are different. Production capacity, customer commitments and actual enrichment output may matter more than reactor construction.

Reaching $1B is therefore possible at a relatively early commercial stage. Keeping that valuation through the far more expensive construction and deployment stages is another matter entirely.

Which advanced nuclear startups have gone public or been acquired?

Several major advanced nuclear businesses have already entered public markets, while others have been acquired through transactions that reveal the financial risks of nuclear technology development.

Oklo currently has a $4.7B public market capitalization, X-energy stands at $4.33B, and NuScale Power at $2.42B. These companies are valued through publicly traded shares rather than private startup financing rounds.

Standard Nuclear has a $1.87B market capitalization, followed by newcleo at $1.3B and NANO Nuclear Energy at $589M. Smaller public-market valuations include Steady Energy, Terrestrial Energy, Terra Innovatum, Deep Fission and Hadron Energy.

The acquisition category tells a much harsher story. Ultra Safe Nuclear's specified technology assets were acquired for $9M after the company had attracted approximately $300M in funding, following financial distress. That low price reflects an asset transaction rather than the acquisition of a healthy operating company.

Moltex Energy's technology-asset transaction was estimated at $7M–$10M and remained subject to closing conditions. Kärnfull Next had an acquisition value of $8M.

These outcomes illustrate how sharply financial results can differ within advanced nuclear. Some businesses have gained access to public equity markets, while other technologies have changed hands at prices far below their historical investment requirements.

Public-company capitalizations also offer useful comparisons for private valuations, although share prices can change quickly. They are a reminder that even after a nuclear startup reaches the stock market, investors can radically revise what its technology and future commercial projects are worth.

Are advanced nuclear startups overvalued right now?

Advanced nuclear startups are not uniformly overvalued, but some of today's multibillion-dollar valuations assume that companies will overcome several expensive engineering and commercial challenges.

The strongest businesses now have measurable achievements. TerraPower has a commercial reactor construction permit. Kairos Power has regulatory approvals and a long-term agreement with Google. Several microreactor developers have demonstrated nuclear criticality, while General Matter has secured a major federal enrichment award.

These developments make the sector more credible than it was a few years ago.

Yet commercial nuclear construction remains expensive, and most advanced designs still lack a track record of repeated, profitable deployment. Companies also face financing dilution, fuel availability constraints, component manufacturing challenges and regulatory requirements that continue after initial construction permits.

The market could therefore separate sharply between companies that successfully commission operating facilities and those that remain stuck in development.

A successful first reactor would strengthen a company's case, but investors will eventually want evidence that subsequent units can be built faster, operated reliably and sold at a price customers accept.

Our assessment is that advanced nuclear startup valuations have a real foundation, especially at companies making measurable progress toward deployment. The speculative part is how quickly investors expect those projects to become profitable businesses.

The next few years should make those differences much clearer. Today, nuclear startups are being valued for an industrial future that is beginning to take shape, but has yet to prove itself at commercial scale.