goingcritical:duane-arnoldUnited States · Restart

Duane Arnold Energy Center

Status: Under construction target criticality Q1 2029 (confidence: medium) ? Reactor status full glossary → Announced Publicly announced — a site and design are proposed, but construction has not begun. Site preparation Early site and civil works are under way; the first safety-related ("nuclear") concrete has not yet been poured. Under construction Formal construction has begun, marked by the first nuclear concrete. Fuel loaded Nuclear fuel has been loaded into the core. The reactor is fuelled but has not yet gone critical. Critical Has reached first criticality — a self-sustaining chain reaction, usually at low power — but is not yet connected to the grid. Grid connected Synchronised to the electrical grid and exporting power for the first time, but still in commissioning and power-ascension testing — not yet in commercial service. Operating In commercial operation — the operator has formally declared the unit in regular commercial service. Shut down Permanently shut down and no longer generating; may be defuelled, undergoing decommissioning, or preserved in place. Canceled Abandoned before completion.

Developer: NextEra Energy

Site: Palo, Iowa

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NextEra anticipates restart of operations in early 2029; NRC plans to issue its bundle of restart licensing actions by January 2028. Restart restoration work and NRC restart inspections underway since late 2025.

Details

Design	GE BWR-4 (Mark I containment)
Electrical output	601 MWe

Milestone history

1. Announced October 27, 2025
2. Construction start —
3. Fuel load —
4. First criticality target Q1 2029
5. Grid connection —
6. Commercial operation —