A leak of heavy water occurred from the Wolsong-4 reactor in Gyeongju city, totaling 208 kilograms, but it remained inside the plant. Authorities confirmed no abnormal radiation levels and dispatched experts for inspection.
On 2 July 2026, South Korea's Nuclear Safety and Security Commission announced that heavy water, used as a coolant, leaked from the Wolsong-4 reactor in Gyeongju, in the country's southeast. However, no radioactive material leak or environmental impact was detected.
The Korea Hydro & Nuclear Power reported the incident occurred around 14:26 on Wednesday. Officials stated that by 21:00 the same day, approximately 208 kilograms of heavy water had leaked, but the liquid remained inside the nuclear power plant building without escaping outside. Initial checks found no abnormal radiation levels in the surrounding area. The commission is preparing to send experts to thoroughly investigate the cause of the leak.
They also noted that the Wolsong-4 reactor has been offline for scheduled inspection and maintenance since early July. After detecting the leak, officials immediately shut down the related pump systems to control the situation.
Source: Yonhap