Air radiation levels have risen in Namie and other areas around the crippled Fukushima No. 1 nuclear power plant because the spring thaw has increased exposure to contaminated soil, the science ministry said.
Air radiation levels have risen in Namie and other areas around the crippled Fukushima No. 1 nuclear power plant because the spring thaw has increased exposure to contaminated soil, the science ministry said.
Ministry officials said other locations may show similar rises in radiation levels as the snow melts.
The Ministry of Education, Culture, Sports, Science and Technology has been operating measurement vehicles at 55 locations within a 20-kilometer radius of the Fukushima No. 1 nuclear plant since immediately after a crisis began to unfold in March 2011.
Although the readings show that radiation levels are generally declining, they have fluctuated at a number of snowy locations in Namie and elsewhere.
The highest radiation level in Namie was measured in the Kawabusa district, 19 km northwest of the plant.
The measurement station in Kawabusa recorded a reading of 30.6 microsieverts per hour on Jan. 17, but the figure dropped sharply to 21.7 microsieverts per hour over the following week, when about 20 centimeters of snow covered the ground.
The reading fell to 19.3 microsieverts per hour on March 6, when the snow depth was 13 cm.
But the level rebounded to 31.3 microsieverts per hour on March 21, by which time the snow had disappeared.
Radiation readings also jumped by about 5 microsieverts per hour because of the thaw near measurement stations in the Hirusone and Murohara districts of Namie.