Tokyo Electric Power Co. is considering spending of tens of billions of yen extra to ensure the safety of its Kashiwazaki-Kariwa nuclear plant in Niigata Prefecture, which it hopes to restart in fiscal 2013, sources said.

As Tepco has already pledged to spend around ¥70 billion after the March 2011 meltdowns at its Fukushima No. 1 power station, total expenditure on safety measures at Kashiwazaki-Kariwa, the world's biggest atomic energy power complex, could climb above ¥100 billion, the sources said Friday.

The utility has already spent considerable time and resources on countermeasures against tsunami, including to fortify the plant's seawalls, and it also plans to install upgraded ventilation facilities, the sources said.