The operator of the Fukushima Daiichi nuclear plant says radioactive water leaked from a water treatment facility may have reached the sea through a gutter.
Tokyo Electric Power Company says slightly elevated levels of cesium were detected on Sunday in seawater around an outlet from the gutter.
Earlier in the day, workers found that at least 45 tons of water had leaked from a desalinization device at the plant. The water then apparently seeped out of the building and flowed into the gutter.
The leaked water also contained radioactive strontium at levels that could pose health risks in case of internal exposure. TEPCO says it will take about 2 weeks to complete its analysis of the situation.