A nuclear reactor in South Korea\'s southwestern nuclear complex was abruptly shut down due to a technical glitch, an official said Wednesday, raising fears that the nation\'s protracted electric power shortage could take a turn for the worse amid the summer heat wave. The 1-million-kilowatt \"Hanbit 6\" reactor stopped operating at 2:44 p.m., said Kim Tae-seok, an official of the Korea Hydro and Nuclear Power, the state-run operator of nuclear power plants.