The United States Department of Energy has announced a significant breakthrough in the domestic nuclear sector, confirming that three private startups have successfully reached nuclear criticality as part of an accelerated federal pilot program. This milestone, timed to coincide with the nation’s 250th anniversary celebrations on July 4, marks the first time in decades that multiple new reactor designs have moved from the conceptual phase to active, self-sustaining chain reactions within such a condensed timeframe. Energy Secretary Chris Wright characterized the achievement as the cornerstone of "America’s nuclear renaissance," a strategic initiative designed to modernize the nation’s energy grid and reclaim global leadership in advanced atomic technology.
The three companies—Valar Atomics, Antares Nuclear, and Deployable Energy—met a rigorous deadline established by a 2025 executive order. By reaching criticality, these firms have demonstrated that their reactor cores can maintain a steady state of nuclear fission, a prerequisite for generating usable thermal or electrical energy. While these reactors are currently operating as prototypes and test beds, their success signals a shift in the American nuclear landscape, which has long been defined by massive, multi-billion-dollar light-water reactors and stagnant regulatory timelines.
Understanding the Milestone: The Path to Criticality
In nuclear physics, criticality is the state in which a nuclear reactor sustains a fission chain reaction, where each fission event releases enough neutrons to cause a subsequent fission event at a constant rate. For the startups involved in the Department of Energy (DOE) pilot program, reaching this stage is the ultimate proof-of-concept. It transitions a design from a theoretical model or a digital twin into a functioning physical machine.
For decades, the high barrier to entry in the nuclear sector was defined by "The Ten-Year Rule"—a colloquialism among industry insiders suggesting that any new reactor design would take at least a decade and billions of dollars to license and build. The current pilot program aims to shatter this paradigm by utilizing "micro-reactor" and "small modular reactor" (SMR) designs. Unlike the traditional fleet of 94 large-scale reactors currently operating in the U.S., which use water as both a coolant and a moderator, these new designs often employ alternative substances such as liquid sodium, molten salts, or high-temperature gases. These alternatives allow the reactors to operate at higher efficiencies and lower pressures, significantly reducing the footprint and complexity of the facilities.
Chronology of the Accelerated Nuclear Program
The current surge in nuclear development can be traced back to a specific shift in federal policy. In May 2025, the administration issued an executive order that prioritized the rapid deployment of advanced nuclear technology. The order set an aggressive benchmark: at least three new reactor designs were required to achieve criticality by July 4, 2026.
To facilitate this, the DOE underwent a radical internal restructuring. In February 2026, the department quietly implemented a series of regulatory "fast-tracks" for experimental reactors operating under its direct purview. This included streamlining Environmental Impact Statements (EIS), which historically could take three to five years to complete. By narrowing the scope of these reviews for small-scale prototypes located on existing federal land, the DOE reduced the administrative wait time to less than 12 months.
The timeline of achievements for the startups is as follows:
- Late 2025: Valar Atomics becomes the first to reach criticality at the Los Alamos National Laboratory, using a core developed in collaboration with federal scientists.
- February 2026: The DOE slashes safety and environmental red tape for pilot participants, allowing for faster iterations of core testing.
- June 2026: Valar Atomics reaches criticality again with a second, more refined reactor at a state-funded site in Utah.
- July 1, 2026: Valar Atomics conducts a public demonstration where its reactor design provides the electricity necessary to power a high-end Nvidia AI chip, marking the first time an advanced SMR has powered modern computing hardware in the U.S.
- July 4, 2026: Antares Nuclear and Deployable Energy officially confirm they have reached criticality at their respective national laboratory test sites, meeting the executive order’s deadline.
The Role of Public-Private Partnerships
A critical component of this success has been the integration of private startup agility with the vast resources of the U.S. National Laboratory system. Rather than requiring startups to build their own multi-million-dollar testing facilities, the DOE provided access to sites like Los Alamos and Idaho National Laboratory.
Valar Atomics, for instance, utilized fuel and structural components provided directly by federal labs to expedite their first core. Matt Loszak, co-founder and CEO of Aalo Atomics—another company in the pilot program—noted that the change in government attitude has been the primary driver of speed. "Before, you’d try to get a signature, and maybe it would sit on someone’s desk for five weeks," Loszak stated. "Now, it’s like, done the next day, because it’s a priority for the nation."
This level of cooperation is intended to de-risk the technology for private investors. Silicon Valley has taken notice, with venture capital firms pouring billions into "hard tech" and energy independence. The primary motivator for this sudden interest is the exponential growth of artificial intelligence.
The AI Factor: Driving Demand for 24/7 Power
The resurgence of nuclear interest is inextricably linked to the massive energy requirements of the tech sector. Data centers powering AI models require immense amounts of electricity, and unlike wind or solar, nuclear power provides "baseload" energy—consistent, 24/7 power that does not fluctuate with weather conditions.
The demonstration by Valar Atomics, in which an Nvidia chip was powered by a micro-reactor, was a calculated signal to the market. Tech giants are increasingly looking to bypass the traditional energy grid, which is often bogged down by aging infrastructure and interconnection delays. By co-locating small reactors directly with data centers, tech companies can secure a carbon-free, independent power source. This "behind-the-meter" strategy is viewed by many in the industry as the most viable path to commercialization for these startups.
Regulatory Hurdles and the "Commercialization Gap"
Despite the celebrations, industry experts caution that reaching criticality in a lab setting is vastly different from deploying a commercial product. Adam Stein, director of the Nuclear Energy Innovation program at the Breakthrough Institute, described these prototypes as "everything and nothing." While they prove the physics of the design, they do not yet prove the economics or the long-term reliability required for the commercial market.
The next major hurdle is the Nuclear Regulatory Commission (NRC). While the DOE can streamline rules for experimental reactors on federal land, the NRC governs the commercial sale and operation of reactors. The NRC licensing process remains one of the most stringent in the world. Energy Secretary Chris Wright has indicated that the NRC is currently working on a "fast timeline" for the commercialization of these pilot reactors, but critics worry that cutting too many corners could compromise safety or public trust.
Furthermore, the supply chain for advanced nuclear fuel remains a significant bottleneck. Many of these new designs require High-Assay Low-Enriched Uranium (HALEU), a type of fuel that is not currently produced in significant quantities in the United States. Historically, Russia has been a primary supplier of this material, creating a geopolitical complication that the U.S. is currently rushing to solve through domestic enrichment initiatives.
Economic Realities and Historical Context
The "nuclear renaissance" must also contend with the ghost of the industry’s past. Brett Rampal, senior director of nuclear and power strategy at Veriten, pointed out that the U.S. nuclear industry has a history of over-promising and under-delivering on costs. "If you go back and you look at all the nuclear power plants we built throughout the country, on average, they were over cost and over budget," Rampal noted.
The most recent example is the Vogtle Electric Generating Plant in Georgia. The expansion of the plant, featuring two new AP1000 reactors, was delayed by seven years and saw costs balloon from an initial estimate of $14 billion to over $30 billion. The startups in the DOE pilot program argue that their small, modular approach avoids these pitfalls by allowing for factory-based manufacturing and smaller, more manageable capital outlays. However, until a commercial unit is built and operated profitably without heavy federal subsidies, the economic viability of SMRs remains a subject of intense debate among energy economists.
Future Outlook: A New Era for Atomic Energy
The success of Valar Atomics, Antares Nuclear, and Deployable Energy represents a psychological victory for an industry that has been largely dormant for forty years. By meeting the July 4 milestone, the DOE has demonstrated that the federal government can move at the speed of private industry when national security and energy independence are at stake.
As the program moves into its next phase, the focus will shift from "can it work?" to "can it scale?" The goal for 2027 and beyond is to move these reactors out of the national labs and into industrial parks, data centers, and remote communities. If the regulatory and supply chain challenges can be navigated, the "fireworks" provided by these three startups may indeed be the start of a new, carbon-free chapter in American industrial history. For now, the successful achievement of criticality serves as a potent reminder of the country’s renewed commitment to being at the forefront of the global energy transition.
