On the 26th, the Nuclear Safety And Security Commission began an investigation into an incident at the Hanul Nuclear Power Plant Unit 1 in Gyeongbuk Uljin, where power that should have been supplied to safety facilities was not properly provided during the operation of the emergency generator, which had been halted for equipment maintenance.
The Nuclear Safety And Security Commission noted that it received a report from Korea Hydro & Nuclear Power about an incident where, during the transformer replacement operation for the maintenance of the Hanul Unit 1 power facility, a circuit breaker malfunctioned, preventing the emergency diesel generator from supplying power to the safety bus (the line that supplies power to safety facilities).
There are two emergency diesel generators at Hanul Unit 1, and during the transformer replacement process, one of them was able to start normally.
However, when normalizing the power system afterwards, the emergency diesel generator was supposed to supply power to the safety bus, but it was confirmed that power was not supplied from 10:57 a.m. for 23 minutes due to the circuit breaker malfunction.
Hanul Unit 1 had entered scheduled preventive maintenance on the 23rd and was in a shutdown state.
However, the Nuclear Safety And Security Commission stated that this incident occurred in one of the two safety bus systems, and power continued to be supplied normally through the other safety bus, so it was confirmed that there was no impact on the safety of the nuclear power plant.