A nuclear reactor in a southern coastal city of South Korea stopped operations due to a glitch in the coolant pump late Tuesday, but no radioactivity leaks were reported. The Unit-6 reactor in Uljin, 330 kilometers southeast of Seoul, came to a standstill around 6:05 p.m due to a glitch found in its reactor coolant pump, according to the Uljin branch of Korea Hydro & Nuclear Power Co., the nuclear power agency.