A nuclear reactor along the west coast suddenly halted operation due to a malfunction caused by problems in the coolant pump, the state-run Korea Hydro & Nuclear Power Co. said Saturday.

 The Hanbit No. 2 reactor at the nuclear power plant in Yeonggwang, 320 kilometers southwest of Seoul, stopped at 2:59 a.m., the company said.

One of the four coolant pumps was found to have a problem, which led the reactor to shut down automatically. A fire also broke out caused by overheating in a circuit breaker, but it was extinguished by workers.

The company added the reactor's condition is currently stable, and there was no leak of radioactive materials. The reactor will resume operation after replacing the circuit breaker, it added. (Yonhap)