A spokesman for Tokyo Electric Power Co. said Saturday that heavy rain caused by Typhoon Phanfone probably affected the groundwater after the storm whipped through Japan last week.
Some 150,000 becquerels of tritium per liter were measured in a groundwater sample taken Thursday from a well east of the No. 2 reactor. The figure is a record for the well and over 10 times the level measured the previous week.
In addition, materials that emit beta rays, such as strontium-90, which causes bone cancer, also shattered records with a reading of 1.2 million becquerels, the utility said of the sample.