The operation of a nuclear reactor in Uljin, North Gyeongsang Province, came to a halt for an unverified reason on Thursday.

The 950,000-kilowatt light water reactor stopped operating at 6:41 p.m., the Korea Hydro & Nuclear Power Co. said. Officials said that no radioactive leakage has so far been detected, and that there is no safety problems caused by the stoppage.

The KHNP said that it is currently trying to ascertain the exact cause of the problem.

The reactor came into service in September 1988.

The safety of nuclear power plants has been called into question following a meltdown at the crippled Fukushima Daiichi nuclear power plant in Japan in 2011.

Korea now has 22 nuclear reactors in operation with its reliance on atomic energy accounting for some 35 percent of its electricity generation.

By Song Sang-ho (sshluck@heraldcorp.com)