A cracked oil duct has been found at a Fukushima nuclear power plant that was closed Sunday following an oil leak, plant operator Tokyo Electric Power Co. said Monday.
Tepco officials said they also found that 150 liters of water contaminated by low-level radiation have leaked from the plant's No. 2 reactor.
Sunday's oil leak at the Fukushima No. 1 plant, which is about 220 km northeast of Tokyo, was confined within the facility, said Tepco spokesman Ichiro Kudo. He said the leak posed no danger to the surrounding environment.
The plant was jolted Friday by earthquakes measuring 6.1 and 4 on the Japanese intensity scale of 7.
The firm has not connected the leaks to the quake.
The No. 2 reactor, which began operations in July 1974, is the sixth-oldest of the 51 commercial reactors in Japan.
The crack was found in a duct that carries oil to a valve controlling the amount of steam provided by the reactor to a turbine. At least 300 liters of oil was leaked.
The oil leak is believed to have started around 6 p.m. Sunday, and the reactor was manually shut down shortly after 9 p.m.
The water leaked had been used to move control rods in the reactor building by water pressure, the officials said.
The Fukushima plant, situated in the towns of Okuma and Futaba, has six reactors.
Concerns over nuclear power have escalated in Japan since September 1999, when the country experienced its worst nuclear accident. It was also classified as the world's worst since the 1986 Chernobyl accident.
The critical reaction at a uranium processing plant in Tokai, Ibaraki Prefecture, killed two plant workers and exposed 439 people to radiation.