The Korean Hydro & Nuclear Power Co. said there is no risk of radiation leaks but the shutdown of the Yonggwan reactor will present problems for the country's already stretched power supply going into the winter months.
The company said it detected microscopic cracks in tunnels for six control rods -- used to regulate the speed of nuclear reactions taking place inside reactors -- at its nuclear plant in the southwest of the country, CNN reported Friday.
The discovery follows a recent scandal involving the use of unverified parts in two other nuclear plants, where thousands of parts were supplied with forged quality certificates.
The shutdown of those two plants, along with the Yonngwan reactor, could create an "unprecedented level" of strain on the nation's power supply, experts said.
"Winter here is brutal, and I am now very concerned that the unexpected shutdowns of three nuclear units will cause power shortages," Huh Kyun-young, a nuclear engineering professor at Kyung Hee University, said.