goingcritical:ziacoreUnited States · Microreactor
ZiaCore
Status: Critical since May 2026 Reactor status full glossary → Announced Publicly announced — a site and design are proposed, but construction has not begun. Site preparation Early site and civil works are under way; the first safety-related ("nuclear") concrete has not yet been poured. Under construction Formal construction has begun, marked by the first nuclear concrete. Fuel loaded Nuclear fuel has been loaded into the core. The reactor is fuelled but has not yet gone critical. Critical Has reached first criticality — a self-sustaining chain reaction, usually at low power — but is not yet connected to the grid. Grid connected Synchronised to the electrical grid and exporting power for the first time, but still in commissioning and power-ascension testing — not yet in commercial service. In commercial operation — the operator has formally declared the unit in regular commercial service. Shut down Permanently shut down and no longer generating; may be defuelled, undergoing decommissioning, or preserved in place. Canceled Abandoned before completion.
Site: NCERC (Deimos testbed), Nevada National Security Site, Nevada
First heat-pipe, zirconium-hydride-moderated LEU microreactor to reach criticality — a high-temperature (>800°C) zero-power physics validation run over four weeks in April–May 2026 on the Deimos testbed at NCERC in Nevada; a Los Alamos National Laboratory design, announced 30 July 2026
Details
| Design | Heat-pipe-cooled, zirconium-hydride-moderated LEU (uranium dioxide) microreactor; HALEU-compatible |
| Capacity | Undisclosed |
Milestone history
- Announced —
- Construction start —
- Fuel load —
- First criticality May 2026