Valar Atomics reaches cold criticality In NOVA test with DOE partnership

Valar Atomics said it achieved cold criticality under Project NOVA in work with Los Alamos National Laboratory. The company reported the milestone occurred at 11:45 a.m. Pacific Time on November 17 at the National Criticality Experiments Research Center in Nevada.

Cold criticality marks a self-sustaining chain reaction in uranium-235 at zero power. The stage allows researchers to study neutronic behavior without full operating temperatures or heat removal. It also verifies assumptions involving fuel performance, moderating materials, reactivity systems, and burnable poisons.

Valar is a new reactor developer that has raised $130 million from investors including Anduril founder Palmer Luckey and Palantir CTO Shyam Sankar. The company plans to mass-produce small modular reactors and deploy them in clusters to support data centers and industrial loads. Its designs use high-temperature gas reactor systems with TRISO fuel and helium cooling.

Project NOVA began its approach to criticality on November 12. The test uses a zero-power reactor built to collect physics data and confirm design traits of the Ward250, Valar’s reactor selected for the Department of Energy’s Reactor Pilot Project. The setup is not intended to generate thermal energy.

A statement from The Breakthrough Institute said the milestone satisfies a key target in a recent executive order and represents early progress for pilot program participants.

NCERC has conducted reactor and weapons physics experiments for decades. Its earlier Deimos experiment, the first in years to use TRISO pellets with HALEU, supplied benchmark data and structural components that supported the NOVA effort. LANL provided the critical assembly, safety envelope, instrumentation, experiment platform, reflectors, data work, and oversight. Valar supplied the core, TRISO fuel, and system layout.

Valar has not detailed the regulatory path for the test, though the effort relied on DOE authorization and the lower-risk nature of zero-power operations.

Radiant Nuclear, another micro-HTGR developer, has submitted its authorization request for the Kaleidos reactor and expects DOE approval this year for testing at Idaho National Laboratory.

The NOVA work precedes higher-power testing planned for Valar’s Ward250 in Utah. The cold criticality result is the first of six planned configurations to support Ward250 development and future NCERC research.