Unit 1 of the Shin Wolseong nuclear power plant in the nation’s southeastern region stopped operations on Tuesday due to a malfunction, according to the Korea Hydro and Nuclear Power Co.

“The cause of the problem has yet to be identified, but the reactor is in stable condition without risk of a radiation leak,” a KHNP official said.

The 1-million-kilowatt reactor, located near Gyeongju, North Gyeongsang Province, began commercial operations in July 2012.

With the temporary closure of the Shin Wolseong reactor, the country’s power reserve level dropped to less than 4.5 million kilowatts, forcing Korea Electric Power Corp. to issue a preliminary power shortage warning, according to KEPCO officials.

The reduction of power supply in the off-season is attributed to a series of shutdowns of seven of the nation’s 23 nuclear reactors, which generate one-third of the nation’s power supply.

Currently, five reactors are temporarily closed for scheduled maintenance, and two more reactors are stopped due to technical problems.

By Seo Jee-yeon (jyseo@heraldcorp.com)