Four microreactors reach zero-power criticality under DOE Reactor Pilot Program by July 4 2026

The DOE selected 11 microreactor projects in August 2025 and supplied test sites plus national lab support. Antares reached criticality first in its Mark-0 unit in June; Valar, Deployable Energy, and Aalo followed, with Aalo crossing the threshold hours before the July 4 deadline. All tests operated at negligible thermal power and did not demonstrate sustained electricity generation or integrated cooling systems.

Zero-power criticality confirms only that a controlled chain reaction can be initiated. It supplies no data on fuel performance at operating temperature, heat-transfer loops, or grid interconnection. The four companies were founded between 2023 and 2025; their timelines project first grid or behind-the-meter power between late 2027 and 2028. Historical NRC licensing for novel designs has averaged 42 months from application to fuel load.

AI data-center load forecasts from EPRI and Lawrence Berkeley National Laboratory now exceed 8 percent of US electricity demand by 2030. Microreactor output in the 1-20 MW range matches co-located server racks without transmission upgrades. The milestone therefore marks the first physical hardware step toward dedicated nuclear supply for hyperscale facilities rather than incremental additions to the existing fleet.

The NRC microreactor framework proposed in Q1 2026 remains untested. If the first combined license review exceeds 24 months, commercial deployments will slip past 2028. Conversely, successful review of one Aalo or Valar unit would establish a repeatable template for the remaining seven pilot projects still in pre-critical testing.