South Korea’s authorities are investigating a possible leak after some 2.3 tonnes of stored water was released from the used fuel storage at unit 4 of the Wolsong NPP in Gyeongju. The Nuclear Safety & Security Commission (NSSC) said it received the report on the discharge of the water into the sea from plant operator Korea Hydro & Nuclear Power (KHNP) and immediately dispatched experts from the Korea Institute of Nuclear Safety (KINS) to investigate. After discovering a decrease in the water level at the storage KHNP immediately took measures to stop the leakage.
Radiation from the suspected leakage was estimated at 0.000000555 millisievert (mSv), far below the average radiation dose limit of 1 mSv to an individual for one year. An NSSC official said the agency suspects there was a problem between the coolant water, used to cool the used fuel, and the device used to cool this water. “We have blocked the storage to prevent any further leakage and are investigating the exact cause,” the official added.
The NSSC said it would announce the results of its investigations along with an environmental impact assessment. Wolsong 4 has been shut down for planned maintenance since 20 April.
