Microreactor race 2025: How Westinghouse, Oklo, X-Energy, and Ultra Safe Nuclear compare

Why Are Microreactors Gaining Traction in 2025?

As nations seek to decarbonize without sacrificing grid resilience, microreactors are emerging as a promising technology for distributed, clean energy generation. These factory-fabricated, small-scale nuclear units are designed to deliver steady power and industrial heat in places where conventional energy infrastructure cannot reach—remote communities, defense sites, mining hubs, and even lunar missions. The year 2025 marks a crucial turning point as several U.S. microreactor developers move from lab testing toward early licensing and deployment stages.

Westinghouse Electric Company‘s recent approval for its eVinci microreactor’s Preliminary Safety Design Report (PSDR) by the U.S. Department of Energy (DOE) set an industry precedent. But it is far from alone in the race. Oklo Inc., X-Energy, and Ultra Safe Nuclear have also gained ground, each offering unique designs, commercial strategies, and regulatory paths.

This feature compares these four major players, unpacking the technology, licensing progress, deployment readiness, and investor sentiment shaping the global microreactor race.

What Sets Westinghouse’s eVinci Microreactor Apart?

Company: Westinghouse Electric Company

Backer: Brookfield Business Partners

Reactor: eVinci Microreactor

Thermal Capacity: 3–5 MWt (3 MWt in test phase)

Core Tech: Heat pipe, solid-state, transportable

Regulatory Status: First to receive PSDR approval under DOE’s NRIC-DOME program

Westinghouse’s eVinci microreactor has positioned itself as a nuclear battery—self-contained, sealed, and built to deliver carbon-free electricity and heat for over eight years without refueling. With no moving parts, it is engineered for reliability in off-grid or hostile environments. The recent PSDR approval marks the first formal DOE green light for a microreactor test unit at the Idaho National Laboratory (INL), giving Westinghouse a regulatory lead.

From a commercialization standpoint, eVinci is designed to serve a wide range of markets—from Arctic villages and mining operations to Department of Defense sites and future lunar bases. The company anticipates test operations at INL by 2027, followed by full-scale deployment in the early 2030s.

Investor sentiment is bolstered by Westinghouse’s legacy in nuclear services and manufacturing, as well as Brookfield’s infrastructure-oriented capital backing. While the firm is not publicly traded, analysts view its supplier ecosystem and project partnerships as strong secondary beneficiaries.

How Is Oklo Trying to Disrupt the Nuclear Industry?

Company: Oklo Inc.

Backers: Sam Altman, DOE grants, DOE site use rights

Reactor: Aurora Powerhouse

Thermal Capacity: ~1.5 MWt

Core Tech: Fast-spectrum metal-fueled reactor

Regulatory Status: First-ever combined license application rejected by NRC; resubmission in progress

Oklo Inc. stands out for its Silicon Valley-style ambition and unconventional approach to nuclear innovation. Its Aurora microreactor features a fast reactor design using recycled nuclear waste as fuel—an attractive but technically complex proposition. Oklo gained early attention for being the first company to submit a combined license application (COLA) for a microreactor to the Nuclear Regulatory Commission (NRC), although the application was later rejected in 2022 due to insufficient technical data.

Since then, Oklo has worked to rebuild its licensing pathway. It signed an agreement with the DOE for a site at INL and continues to receive strong private investor backing, notably from OpenAI’s Sam Altman. In 2024, the company filed to go public via a SPAC merger, though the transaction was later delayed. As of 2025, Oklo remains pre-licensure but highly watched by early-stage investors and clean tech enthusiasts.

Despite regulatory setbacks, Oklo’s vision for a nuclear-powered clean tech revolution continues to attract attention. The Aurora reactor’s minimal operational footprint and waste recycling pitch remain core to its branding.

Where Does X-Energy Stand on the Path to Commercial Deployment?

Company: X-Energy LLC

Backers: U.S. DOE ARDP grants, Centrus Energy, private equity

Reactor: Xe-Mobile (micro) and Xe-100 (modular)

Thermal Capacity: Xe-Mobile: ~3–5 MWt

Core Tech: High-temperature gas-cooled reactor (HTGR) using TRISO fuel

Regulatory Status: Xe-100 design under NRC review; Xe-Mobile in conceptual phase

X-Energy has built its microreactor plans atop a more established reactor program—the Xe-100 small modular reactor (SMR). While its Xe-Mobile microreactor is still in early development, the company’s credibility stems from its Department of Energy funding and active licensing effort for the larger Xe-100. That program includes utility partnerships (e.g., Dow Chemical) and advanced fuel supply agreements with Centrus Energy for TRISO fuel fabrication.

X-Energy’s Xe-Mobile is expected to mirror the Xe-100’s core principles: passive safety, high-temperature output (750–850°C), and load-following capability. While deployment is likely further out than Westinghouse’s eVinci, X-Energy benefits from a relatively mature organizational structure and a pipeline of industrial end-use partnerships.

Institutional interest remains high due to the firm’s blend of government backing, dual-track reactor strategy, and high-heat applicability for industrial processes, including hydrogen and synthetic fuels.

How Is Ultra Safe Nuclear Targeting Niche Global Markets?

Company: Ultra Safe Nuclear Corporation (USNC)

Backers: Private equity, U.S. military R&D, NASA collaborations

Reactor: Micro Modular Reactor (MMR)

Thermal Capacity: 5 MWt / 1.5 MWe

Core Tech: High-temperature gas-cooled reactor with FCM fuel

Regulatory Status: Canadian pre-licensing complete; U.S. pilot planning in progress

Ultra Safe Nuclear Corporation (USNC) is betting on geographic diversification and niche energy ecosystems. Its Micro Modular Reactor (MMR) is based on high-temperature gas-cooled reactor technology and uses Fully Ceramic Micro-encapsulated (FCM) fuel—a variation on TRISO. With early traction in Canada, USNC plans to deploy the first commercial MMR at Chalk River Laboratories by 2026 through a partnership with Global First Power.

What makes USNC stand out is its international strategy. In addition to the Canadian rollout, the company is actively exploring partnerships in South Korea, the United Kingdom, and even potential lunar or Martian missions via its collaboration with NASA.

The reactor is small enough to be deployed at research centers, industrial parks, and remote mining sites. It is also one of the few projects nearing site-specific construction outside the U.S., giving it a head start in regulatory diplomacy and export positioning.

Which Company Is Most Likely to Deploy First?

Among the four, Westinghouse currently leads in regulatory milestones within the U.S., thanks to its PSDR approval and proximity to test-bed deployment at INL. Ultra Safe Nuclear may be the first to achieve a commercial deployment globally, with construction in Canada potentially beginning in 2026.

X-Energy remains on track for larger-scale industrial deployment, particularly through its Xe-100 reactor, which could inform Xe-Mobile’s eventual design. Oklo, while bold and innovative, is still in regulatory recovery mode, though its branding and Silicon Valley backing keep it in the spotlight.

How Nuclear Licensing Milestones Are Shaping Investor Sentiment

Investor enthusiasm for microreactors has grown alongside increased DOE support, decarbonization mandates, and demand for resilient infrastructure. While none of these microreactor companies (aside from indirect stakeholders like Brookfield and Centrus) are currently publicly traded, investor flows have been clustering around advanced nuclear ETFs, ESG infrastructure plays, and fuel supply chain providers.

From a sentiment standpoint, Westinghouse’s PSDR approval is a bullish signal, triggering renewed attention from institutional investors toward microreactor-adjacent firms. At the same time, the rejection of Oklo’s earlier COLA filing continues to serve as a cautionary example of regulatory hurdles in the nuclear innovation space.

The Microreactor Race Is Heating Up, and Westinghouse Just Took the Lead

The U.S. microreactor landscape in 2025 is defined by rapid innovation, regulatory experimentation, and high-stakes investment. Westinghouse’s DOE-approved test reactor marks a tangible step forward in a space long stalled by licensing complexity and public skepticism. Yet competition remains robust, with Oklo, X-Energy, and Ultra Safe Nuclear each offering differentiated paths to commercialization.

As these companies navigate testing, licensing, and early deployment, their success could redefine how the world thinks about distributed nuclear power—offering a clean, scalable, and secure energy future far beyond the grid.