Wolseong Unit 4, Partial Automatic Function Failure in Emergency Diesel Generator

Cause Identified as 'Engineering Safety Equipment Malfunction'... Reporting Subject Confirmed

Korea Hydro & Nuclear Power's Wolsong Headquarters announced, "On the 13th, during an inspection of electrical equipment at Wolsong Unit 4 (pressurized heavy water reactor, 70kW class), which is currently undergoing planned preventive maintenance, an incident occurred where the circuit breaker supplying internal power was opened."

Wolseong Nuclear Power Headquarters.

Fortunately, the standby diesel generator, which was operating for a routine test, supplied power normally, allowing the plant to remain in a stable condition.

However, at the time the circuit breaker opened, the automatic sequential connection device of the standby diesel generator did not operate, which falls under 'failure of engineered safety features to operate,' and it was confirmed on the 1st that this is a reportable event.

Currently, the plant is carrying out planned preventive maintenance stably, and Wolsong Headquarters plans to take necessary measures after checking the detailed cause.