The BBC informs: Radioactive water is leaking into the sea from a 30-centimetre (12-inch) crack in a containment pit at Japan's quake-hit Fukushima nuclear plant, its operator Tepco have said.
The crack under reactor 2 may be the source of recent radiation in coastal waters, Tepco officials said.
They are preparing to pour concrete into the pit to try to stop the leak.
Japanese PM Naoto Kan has been visiting the area of north-eastern Japan worst affected by the tsunami.
Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, told a separate news conference that Tepco was planning to pour concrete into the pit to seal the crack.
"With radiation levels rising in the seawater near the plant, we have been trying to confirm the reason why, and in that context, this could be one source. We're testing samples of water from the pit and from the sea near the plant, and we can't really say for certain until we've studied the results," Hidehiko Nishiyama, deputy director-general of the Nuclear and Industrial Safety Agency, said.