goingcritical:darlington-bwrx-300-1Canada · SMR

Darlington New Nuclear Project Unit 1 (BWRX-300)

Status: Under construction target criticality 2030 (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: Ontario Power Generation

Site: Darlington New Nuclear Project site, Clarington, Ontario

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OPG targets construction complete by end of 2029 and commercial operation by end of 2030 (criticality target not separately stated); operating licence application filed March 2026

Details

Design	GE Vernova Hitachi BWRX-300
Electrical output	300 MWe

Milestone history

1. Announced —
2. Construction start May 2025
3. Fuel load —
4. First criticality target 2030
5. Grid connection —
6. Commercial operation —