The International Atomic Energy Agency kicked off a week-long inspection of the Gori-1 nuclear power plant Monday in Korea's southern city of Busan.
The plant has been on lockdown since a blackout in February.
Upon a request from the plant's operator, Korea Hydro and Nuclear Power Corporation, the eight-member team is checking the status of the emergency generator and the power grid, which caused the power failure.
The operator says it hopes the inspection will mitigate public concerns and enhance safety at the site.
Environmental activists and local residents, however, are calling for the plant, which is the oldest in the country, to be closed immediately, saying that the inspection is a mere formality for the operator to continue operations.
The plant opened in 1978 and completed its life span in 2007 but a 10-year extension was granted the following year, after an inspection by the UN nuclear watchdog.