goingcritical:saeul-4South Korea · Power reactor
Saeul-4
Status: Under construction target criticality 2027 (confidence: low) 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. 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.
Site: Ulju County, Ulsan
Formerly Shin-Kori 6
Completion expected about a year after Saeul 3 (which went critical April 2026, commercial operation expected August 2026)
Details
| Design | APR1400 |
| Electrical output | 1,340 MWe |
Milestone history
- Announced —
- Construction start September 2018
- Fuel load —
- First criticality target 2027
- Grid connection —
- Commercial operation —