Advanced nuclear online
Definition of done
Done when a reactor in the United States that is not a conventional large light-water plant (a small modular reactor, a microreactor, or a non-light-water design such as molten salt, sodium or high-temperature gas) first delivers electricity to a grid or to a paying customer. A construction permit, groundbreaking, fuel load or first criticality is a milestone, not done, and that includes DOE, DoD or university test reactors that go critical without sending power out. Restarts and uprates of existing plants, new large reactors such as the AP1000, and SMRs operating abroad do not count.
Where it stands
No US advanced reactor or SMR is producing power yet; the furthest commercial step is the construction permit the NRC granted on Sep 29, 2026 for TVA's 300-MW BWRX-300 at Clinch River, and TVA has not yet committed to build and still needs a separate operating license. Kairos Power has broken ground on its Hermes 2 demonstration plant in Oak Ridge, reported Oct 21, 2026. In the test lane, Oklo says its Groves isotope test reactor reached criticality earlier in 2026, Last Energy's micro-reactor at Texas A&M-RELLIS cleared its DOE safety analysis in early October, and the Molten Chloride Reactor Experiment aims for criticality as early as 2027. Larger plans such as AEP and X-energy's 960-MW Indiana project remain at the evaluation stage.
Milestones
2026-10-21: Kairos Power was reported to have broken ground on its Hermes 2 molten-salt demonstration plant. — newgen — SMR industrial base: fuel cycle + supply chain stacking
2026-10-19: Oklo reported that its Groves Isotope Test Reactor had reached criticality earlier in 2026, building on its work in DOE's Reactor Pilot Program. — newgen — Oklo's Groves-2: DOE follow-on, medical isotopes first
2026-10-08: Last Energy's micro-modular reactor at Texas A&M-RELLIS cleared its DOE Documented Safety Analysis, leaving a readiness review before fuel and operation. — newgen — DoD nuclear demos: Army leases, Aberdeen IMSR, Antares space reactor
2026-09-29: The NRC granted TVA the first US construction permit for a BWRX-300 small modular reactor, Unit 1 at Clinch River in Oak Ridge. — newgen — Clinch River: the country's first BWRX-300 construction permit
Related claims
- TVA/NRC — NRC approves the Clinch River SMR construction permit by Sep 30, 2026 (said 2026-09-09; due 2026-09-30): hit.
- MCRE (Southern Company and Core Power) — the Molten Chloride Reactor Experiment reaches first criticality as early as 2027 (said 2026-10-14; review by 2027-07-15): pending.
- Antares/Centrus — HALEU deliveries under their multi-year contract begin by the end of the decade (said 2026-09-18; review by 2029-07-01): pending.
- IAEA — projection of up to about 1,000 SMRs worldwide by 2060 (said 2026-09-14; review by 2031-06-30): pending.