What would a 10-year lifespan extension allow Kori-3 and Kori-4 to do?

If the Nuclear Safety and Security Commission approves the request, Kori-3 could operate until September 2034 and Kori-4 until August 2035. The request covers restarting and operating the two reactors beyond their designed 40-year lifespans.

When did Kori-3 and Kori-4 stop operating or reach the end of their lifespans?

Kori-3 was suspended on Sept. 28, 2024. Kori-4’s operational lifespan expired on Aug. 6, 2025.

What safety preparations did regulators review for Kori-3 and Kori-4 before considering their lifespan extensions?

Earlier this month, the commission approved an accident management program for the two reactors. The document outlines preparations to maintain safe conditions, prevent accidents and mitigate fallout if a nuclear accident occurs.

Nuclear watchdog set to decide on 10-year lifespan extension for Kori units 3, 4

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Summary

The Nuclear Safety and Security Commission was set to decide Tuesday in South Korea whether to allow Kori units 3 and 4 to restart and operate for an additional 10 years. The two 950-megawatt pressurized water reactors have passed their designed 40-year lifespans. If approved, Kori-3 could operate until September 2034 and Kori-4 until August 2035.

Key Facts

Kori-3 was suspended on Sept. 28, 2024, while Kori-4’s operational lifespan expired on Aug. 6, 2025.
Korea Hydro and Nuclear Power plans to seek lifespan extensions for nine aging plants.
The commission approved the accident management program for both reactors earlier this month, covering preparations to maintain safe conditions, prevent accidents and mitigate their effects.
The watchdog approved a 10-year lifespan extension for the Kori-2 lightwater reactor last year.

By Yonhap

Published Oct 27, 2026 1:57 pm KST

The Kori nuclear reactor units 3 and 4 on the northeastern coast of Busan / Yonhap

The country's nuclear watchdog was set to decide Tuesday whether to extend the lifespan of two nuclear reactors by an additional 10 years.

The Nuclear Safety and Security Commission (NSSC) plans to hold a meeting to review a request to restart and operate two 950-megawatt capacity pressurized water reactors — Kori units 3 and 4 — that have reached beyond the 40-year designed lifecycle.

The Kori-3 reactor was suspended in Sept. 28, 2024, and the operational lifespan of the Kori-4 reactor expired on Aug. 6, 2025.

The two reactors are among nine aging plants for which the Korea Hydro and Nuclear Power (KHNP), the state-run power operator, plans to seek life extensions. Korea's nuclear watchdog had approved a 10-year lifespan extension for the Kori-2 lightwater reactor last year.

The latest deliberation comes after the commission early this month approved the accident management program for the two nuclear reactors, a document that outlines preparations, including strategies to maintain safe conditions, to prevent accidents and mitigate any fallout if a nuclear accident occurs.

If approved, Kori-3 will be able to operate till September 2034 and Kori-4 will run until August 2035.

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