Radioactive tritium in Fukushima sea, rivers same as pre-disaster levels: study

30 October 2015

Sea and river concentrations of tritium, a radioactive substance spewed during the 2011 nuclear accident at Tokyo Electric Power Co.’s Fukushima Daiichi plant, have been found to be at about the same levels or lower than those prior to the disaster, according to a study led by researcher Nagayoshi Shima at Fukushima University’s Fukushima Future Center for Regional Revitalization.

The researchers checked tritium levels in seawater in April-June 2013 at four locations along the Pacific coast of the northeastern Japanese prefecture -- Obama in Soma city, the Haramachi district of Minamisoma city, Hotokehama in Tomioka town and Yotsukuramachi in Iwaki city. The results showed concentrations below 0.25 becquerels per liter at all venues. As a similar survey conducted by the prefectural government in 2010 showed concentrations below the detectable limit of 0.4 becquerels, the researchers concluded that the current levels were about the same or even lower than prior to the nuclear disaster.

Tests of river water conducted in December 2011 after the disaster have also found tritium concentrations to have diminished to about 1 becquerel, which was about the same as the level recorded in a prefectural survey in 2002.

(Translated by Kyodo News)