A joint Los Alamos National Laboratory and Valar announcement (posted on Valar's site, dated November 18, 2025) says the NOVA core reached zero-power ('cold') criticality at 11:45 a.m. PT on November 17, 2025, at LANL's National Criticality Experiments Research Center on the Nevada National Security Site, after approach-to-criticality work began November 12. Valar built the central core and supplied the TRISO fuel; LANL operated it on NCERC's Comet critical assembly and supplied the facility safety envelope, instruments, reflectors and analysis, under NNSA Nevada Field Office oversight. The core is graphite-moderated, HALEU TRISO-fueled, with boron-carbide control elements, and was configured to model the Ward 250 core. The release itself stresses there was no power production, grid connection or full-temperature operation. The claim of the first criticality by a venture-backed company is the company's. POWER magazine (June 2026) independently describes the same November 2025 campaign and notes it ran under NNSA oversight at LANL, not under the Reactor Pilot Program authorization.

• Los Alamos National Laboratory and Valar Atomics Announce Project NOVA Criticality Milestone in Nevada (Valar Atomics (joint announcement with LANL), 2025-11-18) primary company “without power production, grid connection, or full-temperature operation”
• Valar Atomic’s Ward 250 Becomes Second Reactor to Go Critical Under DOE Pilot Program (POWER Magazine, 2026-06-19) news “NOVA reached zero-power criticality in November 2025 during a week-long campaign”