More than 200kg of heavy water has leaked from the Candu-6 reactor at unit 4 of South Korea’s Wolsong NPP in Gyeongju, North Gyeongsang Province. The unit had been shut down for scheduled maintenance work. According to the Wolsong Nuclear Power Headquarters of Korea Hydro & Nuclear Power (KHNP), 208kg of heavy water leaked inside the reactor building. At the time, work was underway at the site to replace the ion-exchange resin of the heavy water purification system. However, an abnormality occurred in a part of the facility, causing the heavy water to flow out into the collection sump.
Immediately after the accident, the Wolsong Headquarters took emergency response measures, recovering all of the leaked heavy water and confirming that no additional leak had occurred. “The leaked heavy water was immediately collected, and there is absolutely no impact on the external environment,” an official stated. “We will thoroughly analyse the cause of the failure in the facility in question and prepare measures to prevent a recurrence.”
The Nuclear Safety & Security Commission (NSSC) is conducting on-site inspections and will urgently dispatch an investigation team composed of experts from the Korea Institute of Nuclear Safety (KINS) to the site to establish the specific sequence of the accident. In particular, since a heavy water leak is an issue directly linked to the reliability of internal systems at the plant, it is necessary to meticulously examine the ageing of equipment and whether operational procedures were complied with.
The NSSC is expected to inspect the repair status of the facility based on the detailed diagnostic results of the investigation team and approve follow-up procedures only after final safety is secured.
