Story perspectives

Three Microreactors Hit Criticality, Meet DOE Deadline

7/2/2026

Summary

Microreactors Achieve Criticality

Three advanced microreactors achieved criticality in June 2026, meeting the DOE’s July 4 deadline under Executive Order 14301.
Antares Nuclear’s Mark-0 sodium heat-pipe reactor reached zero-power criticality at Idaho National Laboratory on June 4, 2026.
Valar Atomics’ Ward 250 high-temperature gas microreactor achieved self-sustaining criticality near Orangeville, Utah, on June 18, 2026.
The reactors were funded through the DOE’s Nuclear Energy Launch Pad program, which opened applications in June 2026 and anticipates further criticality tests in July 2026.

Summary

Oklo Shares Surge

Oklo's shares rose 5% after Department of Energy (DOE) design safety approval, keeping a $9.1 billion valuation despite a 27% decline.
The firm will produce medical and industrial radioisotopes, not electricity.
Oklo bought Creative Engineers, Inc., gaining sodium and alkali-metal cooling technology.
A Letter of Intent with Centrus Energy secures high-assay low-enriched uranium (HALEU) for Aurora starting 2029.
An MOU with Standard Nuclear will study fuel reprocessing at Oak Ridge.

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Microreactors Achieve Criticality

Three advanced microreactors achieved criticality in June 2026, meeting the DOE’s July 4 deadline under Executive Order 14301.
Antares Nuclear’s Mark-0 sodium heat-pipe reactor reached zero-power criticality at Idaho National Laboratory on June 4, 2026.
Valar Atomics’ Ward 250 high-temperature gas microreactor achieved self-sustaining criticality near Orangeville, Utah, on June 18, 2026.
The reactors were funded through the DOE’s Nuclear Energy Launch Pad program, which opened applications in June 2026 and anticipates further criticality tests in July 2026.

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