Valar Atomics is a California-based company that has been working on creating nuclear energy for America, and on November 17, 2025, they say that they have taken a major step forward.

Their NOVA Core reactor at the Nevada National Security Site reached cold criticality, which is an important milestone toward proving a nuclear technology.

Cold criticality is when a nuclear reactor is able to sustain a self-perpetuating chain of reactions from the fissionable material it is using for energy. For the NOVA Core reactor, the team was able to take atoms of uranium-235 and split them, which releases neutrons that then proceed to cause other atoms to split, causing the reaction to continue (until it is stopped or the uranium-235 atoms are gone).

This is also commonly called zero-power criticality as the process is done on a small scale that is not sufficient to generate the heat that would be required for power. It is essentially a test run of the reactor to show engineers and safety inspectors to see exactly how the core of the reactor works without the potential hazard of trying to run it at full scale.

In a statement about the event, the Founder and CEO of Valar Atomics, Isaiah Taylor, said:

“Zero power criticality is a reactor’s first heartbeat, proof the physics holds. I’m incredibly proud of the Valar team that took this from blueprint to splitting the atom, securing the first criticality ever achieved by a venture-backed company. This moment marks the dawn of a new era in American nuclear engineering — one defined by speed, scale, and private-sector execution with closer federal partnership.”

The company worked with technical assistance from the team at Los Alamos National Laboratory (LANL) and got $130 million of the funding needed from venture capital funds.

This accomplishment makes them the first private company to reach this stage, and it was done in response to the US Department of Energy’s (DOE) Reactor Pilot Program. This is an initiative that was developed from an executive order by President Donald Trump in order to encourage private companies to develop nuclear energy and technology.

The goal of the DOE is to have three or more startups reach this stage by July 4th, 2026. Valar Atomics is the first to hit this accomplishment. Max Ukropina is the Head of Projects at Valar Atomics, and in the statement, he said:

“President Trump asked industry and the labs to make nuclear great again. We got together and decided to start with the basics of fission. This team delivered incredible results safely so we can keep moving up the technical ladder. America should be thrilled, but wanting more.”

The team will continue to test and improve the NOVA Core reactor technology with the hopes of being able to bring it online for power generation in the near future. This is an important step in meeting the energy demands of the country, especially given the advancement of AI and the power-hungry data centers that power it.

If you think that’s impressive, check out this story about a “goldmine” of lithium that was found in the U.S. that could completely change the EV battery game.