A nuclear power generator at the Wolseong Nuclear Power Plant in Korea's southeastern city of Gyeongju automatically shut down on Monday evening.
The state-run operator, Korea Hydro & Nuclear Power, says Reactor number 1 stopped generating at around 9:40PM after a turbine stop signal.
No radiation leak has been reported.
The operator says it is looking into the exact cause of the shutdown, but added the nuclear reactor is in a safe condition.
The reactor has been operational since 1983,and its THIRTY-year life span is scheduled to end next month.