Modular next-gen US nuclear reactor goes critical

[Marlin]

Modular next-gen US nuclear reactor goes critical

https://newatlas.com/energy/antares-modular-next-gen-us-nuclear-reactor-critical/

[Core Content]

Source: New Atlas.

The Antares Nuclear Mark-0 test reactor reached initial criticality at Idaho National Laboratory on June 4, 2026. This milestone fulfills a Department of Energy mandate for advanced reactor development using HALEU fuel and passive liquid-sodium heat pipes. The project aims to validate core physics for modular microreactors intended for military deployment by 2028.

Nuclear energy in the West took another step forward as the first privately developed, non-light-water reactor to go critical in the United States in more than 40 years reached a major milestone when the Antares Nuclear Mark-0 test reactor came online at Idaho National Laboratory.

The milestone, achieved on June 4, 2026, was what is known as "initial criticality" or "zero-power fueled criticality," which means the reactor was only brought to the minimum power level required to start a nuclear chain reaction. The goal is to validate the reactor's computational physics models, core geometry, control rod performance, and initial neutronic behavior without generating significant thermal energy or requiring active coolant flow.

Read the full article at New Atlas:
https://newatlas.com/energy/antares-modular-next-gen-us-nuclear-reactor-critical/