2.3 tons of ”used nuclear fuel storage water” leaked from Wolsong Nuclear Power Plant... ”Currently under investigation” = South Korea

On the 22nd, 2.3 tons of water stored in a spent nuclear fuel storage tank at Unit 4 of the Wolseong Nuclear Power Plant in Gyeongsangbuk-do, South Korea, was released into the sea through a drain.
The Korea Nuclear Safety and Security Commission said, "At 7:53 a.m. on the 22nd, Korea Hydro & Nuclear Power, which operates the nuclear power plant, announced that water used to store nuclear fuel had leaked from Wolsong Unit 4, which was undergoing planned preventive maintenance.
Following the report of the leak, experts from the Korea Institute of Nuclear Safety (KINS) were dispatched to the plant to investigate the exact amount of water leaked and its cause.
The Wolsong 4 reactor was shut down on April 20 and was undergoing a routine inspection. According to the report, Korea Hydro and Nuclear Power Co. (KHNP) shut down the reactor at around 4:34 a.m. on the same day after it was taken out of service.
The company discovered that the water level in the nuclear fuel storage tank was decreasing and took measures to prevent leakage. Korea Hydro and Nuclear Power said, "We assessed the impact on the environment based on the estimated amount of leakage and found that the effective radiation dose was 0.0000 per year.
The radiation exposure limit for the general public is 1 millisievert per year.
The Nuclear Safety Commission launched an investigation immediately after the report.
The Nuclear Safety Commission said, "The cooling water that cools the nuclear fuel after use and the heat exchanger that cools this cooling water are
"It is believed that a problem such as a leak occurred between the storage tank and the storage facility," he said. "We have temporarily blocked the leak with valves to prevent further leakage of the stored water, and are currently investigating the exact cause."
The Nuclear Safety Commission plans to make public the results of its investigation into the appropriateness of safety measures, along with the specific results of its environmental impact assessment.