South Korea has stopped Tuesday operation of two of its 1,000-megawatt nuclear reactors because of unrelated system malfunctions, plant operators said, according to DPA. A reactor at the Shingori plant near the southern city of Busan was shut down at 8:10 am (2310 GMT Monday) after a warning signaled a problem in the reactor\'s control system, officials said. It is the first time that the reactor has been shut down due to a malfunction since it started commercial operation in February 2011. Another reactor at Yeonggwang, 260 kilometers south of Seoul, went into automatic shutdown at 10:45 am (0145 GMT Tuesday) due to a malfunction. The state-run plant operators said the two unrelated malfunctions involved no apparent risk of a radiation leak at either site. More than 35 per cent of South Korea\'s electricity needs are met with 23 nuclear power plants in operation.