Which nuclear power companies will achieve criticality before Aug 2026? [Subquestion: Antares Nuclear]

probability: 99%

rationale:

This event has already occurred, effectively ensuring a "Yes" resolution. On June 4, 2026, Antares Nuclear's Mark-0 microreactor achieved initial criticality at the Idaho National Laboratory (INL) under the U.S. Department of Energy (DOE) Reactor Pilot Program, nearly two months ahead of the August 1, 2026 deadline.

Evidence suggests that this milestone is thoroughly documented by multiple designated resolution sources. Antares' official update explicitly stated that the Mark-0 "achieved initial criticality" and became the first private company to bring an advanced reactor to criticality under the DOE program antaresindustries.com. The DOE officially reported that the reactor "successfully completed a zero-power fueled criticality demonstration" energy.gov. Furthermore, World Nuclear News—an explicitly allowed resolution source—corroborated that the Mark-0 "completed a zero-power fuelled criticality demonstration" at INL world-nuclear-news.org.

The only remaining uncertainty is procedural rather than substantive: whether the resolution authority might interpret a "zero-power fueled criticality demonstration" as failing to meet the threshold of "achieves criticality." However, because a self-sustaining chain reaction is the precise technical definition of criticality, and the exact term is uniformly used across the company's announcements antaresindustries.com, the DOE energy.gov, and independent industry reporting world-nuclear-news.org, this risk is vanishingly small. The 99% probability reflects this near-certainty while reserving a nominal margin for unforeseen market resolution anomalies.