Valar Atomics

Rule Changes

First to achieve criticality in DOE Reactor Pilot Program

The Nuclear Regulatory Commission finalized a rule on October 22 that lets reactor applicants reuse analyses and test data from projects already authorized by the Energy or Defense departments. The agency targets about 18 months for a first-of-a-kind review and 12 months for later applications.

Updated Oct 23

Built World

As of August 2026: Second company in the pilot program to reach criticality

On June 4, 2026, Antares Nuclear's Mark-0 reactor at an Idaho desert lab started a self-sustaining nuclear reaction. It was the first privately built non-light-water reactor to do that in the U.S. in more than 40 years, and four rival startups matched the feat within nine weeks.

Updated Aug 8