Third Korean reactor taken offline as licence renewal decision awaited

KHNP said it has temporarily suspended the operation of Kori 4, whose initial operating permit expired on Wednesday. It noted the 1001 MWe pressurised water reactor, which entered commercial operation in April 1986, had achieved 2,059 consecutive days (five cycles) of trouble-free operation until its operating licence expired. Over the past 40 years the unit has generated about 277.3 billion kWh of electricity - enough to power the entire population of nearby Busan for about 12.7 years.

"Like Kori unit 3, a similarly ageing plant, KHNP is also pursuing the continued operation of Kori unit 4, which has long demonstrated its safety and technological prowess," the company said.

KHNP submitted a safety assessment report in September 2022 to the Nuclear Safety and Security Commission (NSSC) for continued operation of Kori 4. In July 2023, the company completed the public feedback process on the Radiation Environmental Impact Assessment for Continued Operation, and in November of the same year, it applied for a permit to change the operation of the reactor. 

"Continued operation is a key strategy for achieving a stable energy supply and carbon neutrality," said Kori Plant Director Lee Sang-wook. "We will prioritise the safety of our citizens and pursue continued operation through transparent and fair procedures. Through thorough safety reviews, safety equipment reinforcements, and state-of-the-art facility improvements, Kori unit 4 will become a safer and more efficient power plant."

The South Korean government is currently considering allowing reactors that have reached the end of their design lifespan to continue operating for an additional ten years, as permitted by the law.

KHNP suspended operation of Kori unit 2 in April 2023 and of unit 3 in September last year, when they reached 40 years of operation, respectively. When the company took unit 3 offline last year, it said it anticipated restarting the reactor in June 2026.

"The ongoing operation of Kori units 2, 3 and 4 is considered significant not only for KHNP but also for national energy policy and industry," KHNP said. "In particular, it is expected to significantly contribute to securing a sustainable and stable power infrastructure, which will help Korea become a leading artificial intelligence powerhouse."

Unit 1 of the Kori plant was permanently shut down in June 2017, after 40 years of operation, and become the first South Korean reactor to enter decommissioning. KHNP submitted its application to dismantle the unit to the NSSC in May 2021. The regulator approved the decommissioning of Kori 1 in June this year.