Three Nuclear Startups Achieve Criticality: Significance and Challenges

The U.S. Department of Energy (DOE) announced on July 4, 2026, as part of the 250th Independence Day celebrations, that three nuclear startups have achieved criticality with their newly designed reactors. Criticality refers to the state in which a nuclear reactor can sustain a chain reaction of nuclear fission, representing a crucial technical milestone toward power generation. This accomplishment is part of a pilot program initiated by an executive order from former President Donald Trump in May 2025, which set an ambitious goal to achieve criticality in “at least three reactors” by the 250th anniversary of the United States.

Overview of the Pilot Program

The program, spearheaded by the DOE, aims to accelerate the development and deployment of next-generation nuclear technologies. Energy Secretary Chris Wright has described this initiative as the catalyst for “America’s nuclear renaissance,” designed to spark a new wave of nuclear innovation. Other companies participating in the program are expected to achieve criticality in the weeks following July 4. However, it is crucial to note that these reactors are experimental and not yet commercial power plants.

Significance and Limitations of the Milestone

The achievement of criticality holds symbolic importance for the long-stagnant U.S. nuclear industry. However, Adam Stein, Director of the Nuclear Energy Innovation Program at the Breakthrough Institute, cautions that “these prototypes mean everything and nothing at the same time.” While achieving criticality is a significant step forward for the participating companies, these are test reactors, not commercial products. The success of these experimental reactors demonstrates technical feasibility but does not translate into immediate commercialization.

A Turning Point from Historical Stagnation

For decades, the U.S. nuclear industry has been dominated by large-scale light-water reactors, which use water to transfer heat and sustain nuclear reactions. While these reactors have a proven track record in safety and efficiency, escalating construction costs and extended project timelines have posed significant challenges. The concept of building smaller, innovative reactors has long been stymied by slow regulatory processes and massive upfront investments.

Stein reflects, “The industry has been described as being in a perpetual state of stagnation, with reactors always being a decade away.” This perception has been challenged by the recent pilot program. “It shows that deliberate, expedited action can change the narrative and perceptions, which is significant for the investment community,” he said. Overcoming technical and regulatory barriers could drastically shorten the timeline for nuclear energy development.

Challenges to Commercialization

Despite the milestone, the path to commercialization remains a long one. Achieving criticality in a test reactor does not mean that power generation has commenced. Further steps, such as power ramp-up tests, safety evaluations, and accumulation of long-term operational data, are required. Moreover, obtaining commercial reactor licenses involves rigorous review by the Nuclear Regulatory Commission (NRC), which differs from the DOE’s oversight of the test reactors. Even if the DOE has streamlined some safety regulations, the NRC’s stringent criteria for commercial reactors remain unchanged.

Policies and Regulatory Reforms

The Trump administration pursued policies to accelerate nuclear development through regulatory reforms. In February 2025, the DOE quietly eased certain environmental and safety regulations for reactors under its jurisdiction, including those in the pilot program. This included measures like shortening the preparation period for environmental impact statements (EIS). Stein highlighted the years-long process of creating these assessments and noted that procedural streamlining could benefit the industry. Similar regulatory reforms are reportedly under consideration by the NRC.

These policy changes are a response to strong lobbying from Silicon Valley investors and tech firms. As power consumption in data centers surges, driven by the expansion of artificial intelligence and cloud computing, there is growing interest in small modular reactors (SMRs) as a 24/7 carbon-free power source. High-tech industries had urged the Trump administration to implement significant regulatory rollbacks and expedite SMR development.

Silicon Valley’s Demand and the Reality of a

Nuclear Renaissance

In recent years, the rapid growth of AI and cloud computing in Silicon Valley has led to an unprecedented increase in electricity demand. Given the intermittent nature of renewable energy sources, there is mounting interest in nuclear energy as a reliable baseload power source. SMRs and microreactors, which can be manufactured in factories and transported to sites, hold the promise of reducing construction costs and risks.

Despite the optimism, Stein emphasizes that these milestones are still limited to “test reactors.” Commercialization will require years of effort and billions of dollars in funding. Additionally, fundamental challenges such as spent fuel disposal and public acceptance remain unresolved.

Editorial Opinion

In the short term, the achievement of criticality represents a positive development for nuclear startups, likely boosting their ability to attract funding and investor interest. It is also probable that other participating companies will announce similar milestones within the next three to six months. However, as it will take at least several years before commercial operations and grid integration can begin, this milestone will not lead to an immediate increase in power supply. How the market assesses this gap will be key. From a long-term perspective, the continuation of regulatory reforms could enable the commercial deployment of SMRs by the early 2030s, allowing them to capture a share of the market for data center and industrial power. However, without societal agreement on safety and nuclear waste management, a true nuclear renaissance remains out of reach. The editorial team believes that achieving a balance between technological advances and societal acceptance will be the most critical issue over the next one to three years. Continuous monitoring is necessary to ensure that the recent regulatory reforms do not compromise safety.

References

• Wired — Published on 2026-07-03T18:13:15.000Z
• Wired: 3 Nuclear Startups Hit a Big Milestone. Why It Matters—and Why It Doesn’t — Published on 2026-07-03
• Official Announcement by the U.S. Department of Energy (Related to the Pilot Program)