**Scientists just brought us one step closer **to the dream of unlimited power. On November 17 at the Nevada National Security Site, a nuclear energy startup called Valar Atomics achieved zero-power criticality, a crucial step in nuclear energy development.

Also known as cold criticality, the term refers to a self-sustaining chemical reaction of uranium-235, a radioactive uranium isotope. As the name suggests, cold criticality means the fission system doesn’t reach full operating temperatures (which are hotter than 1300°F), and therefore doesn’t generate power. Instead, cold criticality is the foundational step that precedes operational status. Still, the recent achievement is an opportunity for researchers to understand the behavior of the core, which could mean we’re closer than ever to unlocking true unlimited energy.

“Zero power criticality is a reactor’s first heartbeat, proof the physics holds,” Isaiah Taylor, founder and CEO of Valar Atomics, says in a press release. Taylor believes this achievement is ushering in “the dawn of a new era in American engineering”—one that he believes will evolve rapidly.

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The recent tests are a part of Project NOVA (Nuclear Observation of Valar Atomics), a campaign to verify the physics of cold criticality. The startup worked in partnership with the Los Alamos National Laboratory (LANL) National Criticality Experiments Research Center (NCERC), which has its roots in the Manhattan Project, the program that developed nuclear weapons during World War II. Valar Atomics designed the central part of the core, which features a high-temperature gas reactor (HTR) design. Typically, HTR cores rely on helium gas and ceramic material to stabilize the fission, or atom splitting, process.

Valar Atomics’ success is also part of a larger national effort in the United States. The DOE’s Nuclear Reactor Pilot Program seeks to expedite the nuclear reactor testing process, attempting to reinstate the U.S. as a global leader in nuclear energy. The current goal of the program is for several advanced reactors to reach full criticality—or operational status—by July 4, 2026.

“ZERO POWER CRITICALITY IS A REACTOR’S FIRST HEARTBEAT, PROOF THE PHYSICS HOLDS.”

As exciting as the recent achievement may seem for proponents of nuclear energy, there are still many obstacles for Valar Atomics to clear before its reactors are viable for commercial use.

“It is much easier to achieve a zero-power criticality than to actually make power in a reactor. There’s a huge technical gap between those things,” Taylor confesses in an interview with Inc. “But I certainly wouldn’t underestimate the value of the data that we’re going to get out of this test.”

According to the press release, zero-power criticality experiments allow the research team to better understand the core’s “neutronic behavior,” which is simply the physics of the reactor. The team is also studying variables such as the reactivity control, or the rate of reactions within the core, and burnable poisons, which act as buffers in reactors.

Next, the Valar Atomics team will test their core at extreme temperatures and progressively higher power levels. The reactor will also have to undergo safety and regulatory processes with the DOE, according to the Valar Atomics communications team. Should the U.S. achieve its goal and see several reactors reach full criticality by this summer, it would allow the country to “to stay competitive in AI, rebuild industrial capacity, keep a stable grid, maintain reasonable prices, and cut emissions at the same time,” the team explains.

However, two major hurdles remain for clean, commercial nuclear energy: scaling the reactors to industrial sizes and actually harnessing power for the grid. Still, progress must start somewhere, and Valar Atomics’ recent experiments are a promising test run.

Max Ukropina, head of projects Valar Atomics, puts it simply in the release: “America should be thrilled, but wanting more.”

Emma Frederickson graduated from Pace University where she studied communication and media. Prior to her time as an editor, she was a freelance science reporter. She enjoys covering everything from shipwrecks to pimple popping, but her favorite topics include climate change, conspiracy theories, and weird biology. When she’s not writing, Emma can be found hopping between coffee shops on the hunt for the world’s best oat milk cappuccino.