The company began monitoring at that spot in August, after it acknowledged in July that contaminated groundwater had been seeping into the ocean.
One-point-four becquerels per liter of cesium-137 was found in the sample. This is the first time that the radioactive material has been detected in seawater taken at that spot.TEPCO officials say the radiation level is lower than the safety standard for drinking water set by the World Health Organization, which is 10 becquerels per liter.
They say a seawater sample taken from the spot on Thursday did not contain a detectable level of cesium.They will continue to monitor seawater to find out whether contaminated groundwater is affecting the seawater outside the plant's port. Oct. 10, 2013 - Updated 17:25