Heavy Water Leak Occurs Inside Wolseong Unit 2 During Scheduled Preventive Maintenance

Published 19 Sep.2025 15:50(KST)

Wolseong Nuclear Power Headquarters of Korea Hydro & Nuclear Power (Director: Jung Wonho) announced that at approximately 4:30 a.m. on the 19th, during scheduled preventive maintenance, a portion of heavy water leaked inside the plant facilities while preparing to replace the moderator purification system filter in the auxiliary building of Wolseong Unit 2 (a 700,000 kW-class pressurized heavy water reactor).

Wolseong Nuclear Power Headquarters immediately shut down the relevant pump upon confirming the leak, thereby stopping further leakage. All of the leaked heavy water was collected in the reactor auxiliary building filter room and the internal sump, with no leakage to the outside. The amount of leakage identified so far is approximately 265 kg, and the exact amount is currently being verified.

Wolseong Unit 2 has been undergoing scheduled preventive maintenance since September 1, and there is no external radiological impact. Wolseong Nuclear Power Headquarters plans to investigate the detailed cause and take appropriate measures.

Wolseong Nuclear Power Headquarters.