South Korea's oldest nuclear unit gets green light to restart. It will return to operation after 3 years

South Korean company Korea Hydro & Nuclear Power (KHNP) has received approval to restart its Kori 2 unit. It was shut down in spring 2023 after its original 40-year operating license expired. Over the past three years, the unit has undergone extensive upgrades and reviews, enabling KHNP to secure a 10-year license extension.

Nuclear power plants are a significant source of electricity in South Korea, with 26 operable reactors providing around a third of the country's electricity generation. The country's oldest nuclear units are already more than 40 years old, including Unit 2 at the Kori nuclear power plant. Kori is the country's oldest nuclear power plant, although operation of its first unit ended in 2017.

Kori 2 thus became the country's oldest operating reactor, but its operation was temporarily suspended in April 2023 after its 40-year operating license expired. Since then, the unit has undergone modifications to extend its life and improve operational safety, including design changes to accident-management systems, such as an external circuit for injecting coolant into the reactor and the installation of equipment to supply power to key accident-response systems.

The unit's operator, KHNP, submitted a safety assessment report to support a life extension in spring 2022. South Korea's nuclear regulator, the NSSC, according to World Nuclear News, approved operation of the unit until 2033 last November and has now completed its inspections, confirming that it can be restarted. Given the unit's relatively long shutdown, extensive inspections of its safety systems were carried out, confirming that it is ready to operate beyond its original design life.

As with Unit 2, Units 3 and 4 at the plant were also shut down, in September 2024 and last August, respectively, after their 40-year operating licenses expired. KHNP plans to extend the lives of these units as well, along with those of seven other nuclear units whose licenses expire by the end of this decade.