Ho New / ReutersThe Kori nuclear power plant in Busan, southeast of Seoul, is seen in this picture released by the plant to Reuters on April 14, 2011. South Korea's oldest nuclear reactor has been shut down due to a glitch in the plant's electric circuits, an official said on Thursday, amid rising concerns about nuclear safety after Japan's nuclear crisis. There were no radiation leaks from the plant on the peninsula's southeast coast, the operator said. Reactor One at the Kori nuclear power plant, which began operation in 1978, has been down since Tuesday when the electric circuit malfunction was discovered and repairs will likely continue through Friday, the power plant official said, asking not be named. REUTERS/Kori Nuclear Power Plant/Handout (SOUTH KOREA - Tags: ENVIRONMENT BUSINESS ENERGY) FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS