The radiation was detected in a water tank at the facility on Saturday and the official confirmed that, "We shut down part of the facilities and are investigating what caused the leak."

The spokesperson believed that the probable cause for the radiation leak was the "leakage of coolant into a pipe linked to the reactor might have caused radiation to seep out."

The accident occurred at the plant, which is located around 400km south-west of Seoul in the South Jeolla province. The Yeonggwang No. 5 has a 1-million kilowatt reactor and is one of 18 that generate 40% of the country's electricity needs.