On the 3rd of March, the Shin Hanul Unit 2 nuclear power plant in Uljin County, North Gyeongsang Province, which stopped operating due to a reactor coolant leak, will be restarted.
On the 14th, the Nuclear Safety And Security Commission approved the restart of the Shin Hanul Unit 2 reactor, which underwent regular inspections since April, at the 218th Commission meeting.
Earlier, at around 6:30 a.m. on March 12, a preliminary alarm was triggered at the radiation monitor inside the Shin Hanul Unit 2 reactor building, which led to a reduction in reactor output starting from 10:30 a.m. An investigation confirmed that a reactor coolant leak occurred near the reactor coolant pump. At that time, there were no radiation-related anomalies, including alarms from radiation monitors outside the power plant.
Two days later, on March 14, an alarm was triggered at the radiation monitor located at the discharge purification unit in front of the stopped Shin Hanul Unit 2 reactor containment building. It was confirmed that inactive gas, which had remained in the piping during sample collection and cooling water drainage operations, leaked into the containment building air purifier.
Korea Hydro & Nuclear Power manually shut down the Shin Hanul Unit 2 reactor and replaced the piping where the leak was confirmed with new piping. Additionally, procedures were improved to ensure that the coolant is drained through a route where there is no possibility of inactive gas leakage. The Commission confirmed that the welding condition of the replaced piping and the results of non-destructive testing were appropriate and that there have been no inactive gas leaks since the measures were taken.
The Commission stated, "We have determined that the safety of Shin Hanul Unit 2 has been secured and resolved to restart the reactor," adding, "We will allow criticality and verify safety through 11 subsequent tests, including power ascend tests." Criticality refers to the state in which the number of neutrons in a nuclear fission chain reaction reaches equilibrium, indicating that the reactor is ready to operate.