Another reactor at South Korea's Yeonggwang nuclear plant will see an extended outage after a routine inspection found microscopic cracks in the control rod tubing of a reactor pressure vessel.

Units 5 and 6 at the plant were taken offline a week ago as part of an investigation into nearly 7,700 parts delivered with improper documentation. Now unit 3 will be shut down 47 days beyond its normal outage period. Half of Yeonggwang's six units will remain offline, raising the specter of winter power shortages.

CNN International quoted Korea Hydro and Nuclear Power Co. as saying the cracking was detected in six of the tubes that control rods pass through in unit 3, but there was no risk of leakage.

According to the World Nuclear Association, unit 3 is a 997 megawatt Combustion Engineering System 80 pressurized water reactor that entered operation in late 1995. Units 5 and 6 are OPR-1000 reactors.