Aug 8, 2025

The third Korean reactor has been shut down while waiting for a decision on its license renewal.

Korea Hydro & Nuclear Power has halted operations at unit 4 of the Kori nuclear power plant while awaiting a government decision on allowing reactors to function beyond 40 years. Units 2 and 3 have already been shut down after their 40-year design lives expired.

KHNP announced the temporary suspension of Kori 4, whose operating permit expired on Wednesday. The 1001 MWe pressurized water reactor, which started commercial operations in April 1986, had operated without issues for 2,059 consecutive days (five cycles) until its license expired. Over its 40-year lifespan, it has produced approximately 277.3 billion kWh of electricity, sufficient to power the entire population of Busan for about 12.7 years.

KHNP stated that it aims to continue operating Kori unit 4, similar to unit 3, highlighting its established safety and technological reliability.

In September 2022, KHNP submitted a safety assessment report to the Nuclear Safety and Security Commission (NSSC) for Kori 4's continued operation. By July 2023, the company had finished the public feedback process for the Radiation Environmental Impact Assessment and applied for an operational permit in November.

Kori Plant Director Lee Sang-wook emphasized that continued operation is crucial for ensuring stable energy supply and achieving carbon neutrality. He assured that safety for citizens will be a priority in pursuing this through transparent procedures and comprehensive safety reviews, enhancements of safety equipment, and modern facility upgrades.

The South Korean government is currently evaluating the possibility of allowing reactors that have finished their design lifespans to operate for an additional ten years, in line with legal provisions.

KHNP previously suspended unit 2 in April 2023 and unit 3 in September 2022 after they reached 40 years of operation. When taking unit 3 offline, it was projected to restart in June 2026.

KHNP noted that the continued operation of units 2, 3, and 4 is important not just for the company but also for national energy policy and industry, contributing significantly to a sustainable and stable power framework, which is vital for Korea's ambition to become a leading hub for artificial intelligence.

Kori unit 1 was permanently shut down in June 2017 after 40 years of service, becoming the first South Korean reactor to begin decommissioning. KHNP submitted a decommissioning application to the NSSC in May 2021, which was approved in June this year.