1494 Days of Failure-Free Operation Sets New Record... Wolsong Unit 4 Begins Maintenance for Another Milestone

Maintenance Begins After Achieving the Most Consecutive Failure-Free Safe Operation Cycles in Korea

Korea Hydro & Nuclear Power Wolsong Headquarters announced that Wolsong Unit 4 (pressurized heavy water reactor, 70 kW class) halted power generation at 9:00 a.m. on July 18 and began its 21st scheduled preventive maintenance, which will take approximately 73 days.

Korea Hydro & Nuclear Power Wolsong Nuclear Power Headquarters.

Wolsong Unit 4 achieved four consecutive cycles of failure-free safe operation from October 8, 2020, to July 18, 2025 (approximately 1,494 days), and has set a new domestic record by achieving a total of 16 failure-free safe operation cycles since the start of commercial operation.

During this scheduled preventive maintenance period, Wolsong Unit 4 will undergo a regular inspection in accordance with the Nuclear Safety Act, improvements to the 345 kV switchyard gas-insulated switchgear facilities, enhancements to the Class A protection relay trip circuit, and a disassembly inspection of the low-pressure turbine. Power generation is scheduled to resume around September 28.