Current state

Status	Commissioning
Design	APR1400 (PWR)
Net capacity	1,340 MWe
Country	South Korea
Vendor	KEPCO E&C
Owner / operator	KHNP
Construction start	2017-04
Original COD target	—
Current COD estimate	2026
Schedule slippage	—

Notes

Status moved to commissioning 2026-09-28 (fuel loaded + critical + power ascension; 9th APR1400 to reach criticality worldwide). Nine-year odyssey: 2017 Moon-era halt at 28.8%, 471-citizen jury resumption vote Oct 2017, Gyeongju-quake seismic upgrades, aircraft-impact/air-cooled-generator design adds. Apr-22 auxiliary-building smoke incident + Aug-4 turbine-system issue (both non-nuclear-island, per PowerMag/NSSC). Commercial target Oct 2026 at risk after Aug-11 trip — watch.

Milestone log

2026-06-16 — Listed as under construction in the WNA world table, grid connection estimated 2026 (source)
2025-12-19 — NSSC grants operating licence (5-1 vote) after 5+ year review (source)
2026-01-20 — Initial fuel loading ceremony (first APR1400 fuel load at Saeul 3&4) (source)
2026-04-12 — First criticality ('first start') — stable self-sustaining chain reaction (KHNP) (source)
2026-08-11 — Automatic reactor shutdown during 80%-power transmission-trip test; NSSC investigation team dispatched; commercial operation (targeted Oct 2026) expected to slip (ministry notice via MK News) (source)

The milestone log is append-only: corrections are recorded as new entries, never rewrites. Full history via /api/v1/changes.

NNN coverage

On the APR1400 design

US, South Korea outline $120bn plan for eight reactors 2026-10-02
South Korea nears $100B deal to build eight US reactors 2026-09-11
South Korea weighs $120B for eight US reactors in tariff pact 2026-09-08
The 7 nuclear stories that mattered this week 2026-10-03
The 6 nuclear stories that mattered this week 2026-09-12

Saeul-3 (ex Shin-Kori 5)

Current state

Notes

Milestone log

NNN coverage

On the APR1400 design

Sources