South Korea has completely suspended power generation at the Kori-4 unit nuclear reactor in the southeastern city of Busan on Wednesday as its 40-year design life comes to an end.

According to the energy ministry and the Korea Hydro and Nuclear Power Company(KHNP), the KHNP, the nuclear operator, began reducing the unit's output by around three percent each hour from 4 a.m. Tuesday, before a complete shutdown by 2 p.m. Wednesday.

The 950-thousand-kilowatt reactor, which began commercial operation in November 1985, experienced no functional problems as it has consistently been upgraded.

The suspension, however, was decided as it nears the end of its lifespan.

The government is pushing to continue operation of Kori-4 and other facilities that have reached their lifespan under a legal extension of ten years in consideration of future power demand and the cost of building new facilities.

The Nuclear Safety and Security Commission is currently reviewing an approval of the extended operation for Kori-4, as well as Kori-3, which was halted last September, and Kori-2, which stopped in April 2023.

The Kori-1 reactor, which ran for some 40 years under a design lifespan of 30 years and an extension, became the nation's first commercial reactor to obtain approval for decommissioning last June.