An aerial view shows Onagawa Nuclear Power Plant is seen at Miyagi Prefecture in this photo taken by Yomiuri Shimbun on April 8, 2011. [Photo/Agencies]

TOKYO - Water leaks were found Friday at Onagawa nuke plant in Miyagi prefecture after the quake measuring 7.4 on Richter scale shook Japan's northeast Thursday night, Kyodo News quoted the plant's operator as saying.  

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The report didn't say where the water came from or whether it contains radioactivity.

The powerful aftershake knocked out two out of three external power supply units in Onagawa, operated by Tohoku Electric Power Co., leaving only one power source to cool the spent fuel.  

The cooling operations at the plant stopped once, but then resumed quickly.

Onagawa was the nearest nuclear power plant from the focus of the March 11 earthquake and the aftershock on Thursday. It still has its emergency backup generator to fall back on.