It has been revealed that waste from the liquid radioactive material storage tank of Unit 2 at Wolsong was discharged into the ocean without undergoing sampling analysis.
The Nuclear Safety Commission noted that it received this report from Korea Hydro and Nuclear Power Corporation at 10:23 a.m. on the 12th.
According to the Nuclear Safety Commission, Korea Hydro and Nuclear Power Corporation confirmed that the valve at the tank outlet was open during the preparation process for discharging liquid waste into the ocean (mixing work for sampling analysis) in the morning and immediately closed the valve to prevent leakage. Subsequently, Korea Hydro and Nuclear Power Corporation analyzed the remaining samples in the tank and reported that the concentration of radioactive materials and the estimated radiation level discharged were at normal discharge levels.
The concentration of tritium, a radioactive material remaining in the tank, was reported to be 3.79×108 Bq (becquerels)/㎥, and the gamma radionuclide was reported at 1.219×104 Bq/㎥. The amount discharged was approximately 29 tons, with the included radioactivity estimated at 1.116×1010 Bq for tritium and 3.589×105 Bq for gamma radionuclides. The radiation exposure to residents from this incident is assessed to be 6.97×10-8 mSv (millisieverts, a unit representing radiation exposure dose) annually. The allowable dose for the general public is 1 mSv per year.
Following Korea Hydro and Nuclear Power Corporation's report, the Nuclear Safety Commission dispatched experts from the Korea Institute of Nuclear Safety to investigate the exact leakage amount and causes. They plan to also collect seawater near the nuclear power plant for a precise assessment of environmental impact. In the future, the Nuclear Safety Commission will investigate and disclose the specific environmental impact assessment results and the appropriateness of safety measures.