South Korea extends life of nuclear units, Kori 3 and 4 cleared to restart

Two South Korean nuclear units have been cleared to restart by the nuclear regulator. Kori units 3 and 4, which were shut down in 2024 and 2025 after their original 40-year operating licences expired, will begin generating electricity in the first half of next year. The extended licence for the units, with a combined installed capacity of 2 GW, is valid for 10 years and follows on from the previous licence. In addition to extending the lifetimes of old nuclear units, South Korea is also building and planning new nuclear capacity.

South Korean utility KHNP (Korea Hydro & Nuclear Power) announced that the nuclear regulator had extended the operating licences for units 3 and 4 at the Kori nuclear power plant. The two nuclear units, with a combined installed capacity of 2 GW, are set to restart in the first half of next year. They can now generate electricity until September 2034 (unit 3) and August 2035 (unit 4), respectively.

0ngoing operation will contribute to the national economy by responding to growing energy demand in advanced sectors such as semiconductors and artificial intelligence. It will also support a stable energy supply and play a key role in carbon neutrality. We will do everything we can to ensure the safe restart of Kori units 3 and 4, prioritising safety and carrying out subsequent procedures, such as equipment upgrades and regular inspections," said Kim Hoe-cheon, president of Korea Hydro & Nuclear Power (KHNP).

Kori nuclear units 3 and 4 began commercial operation in 1985 and 1986. KHNP shut both down after their 40-year operating licences expired in September 2024 and August 2025. The company applied for a 10-year extension of their operating licences in 2023. The units subsequently underwent a series of inspections by the nuclear regulator and investments to improve safety. KHNP permanently shut down Kori 1, while Kori 2 was cleared to restart this April.

"Approval of the extended licence is significant because it confirms that units 3 and 4 at the Kori nuclear power plant have met the safety standards and requirements necessary for continued operation," KHNP said in a press release.

The future of South Korean nuclear power

South Korea has 26 operable reactors, which account for around one-third of its energy mix. In addition to extending the lifetimes of existing nuclear units, the country is building four new pressurised water reactors, APR1400s, at the Shin Hanul and Saeul power plants.

Between 2017 and 2022, nuclear power faced opposition from the South Korean president, delaying new-build projects. After 2022, however, the country revived its nuclear plans and, in addition to existing projects, is targeting the construction of two more conventional nuclear units, alongside small modular reactors.