A report estimates accumulated radiation exposure of more than 1 millisievert in eastern Fukushima Prefecture for the two months following the Fukushima No. 1 nuclear power plant accident.
A report estimates accumulated radiation exposure of more than 1 millisievert in eastern Fukushima Prefecture for the two months following the Fukushima No. 1 nuclear power plant accident.
One millisievert is considered the maximum safe exposure level for one year.
The report was submitted by the Japan Atomic Energy Agency to the Japan Atomic Energy Commission, which is under the Cabinet Office, on June 28.
The estimate includes external and internal exposure. Internal exposure occurs when radiation enters the body through the mouth or nose.
The calculation is based on the assumption that residents stayed outdoors 24 hours a day for two months from March 12, the day after the Great East Japan Earthquake, through May 12.
The radiation map factored in weather conditions and geographic features to estimate exposure levels of radioactive iodine and cesium.
The map shows that external radiation exposure exceeded 1 millisievert--the safe standard for an entire year--only in a part of eastern Fukushima Prefecture.
Radiation levels rose above 0.01 millisievert in the central and southern areas of the Tohoku region as well as the Kanto region. The results are largely in line with the measurements taken by the science ministry.
When it comes to internal exposure of iodine-131, only part of eastern Fukushima Prefecture shows more than 1 millisievert of estimated exposure.
When the 00.1 millisievert standard is applied, the central and eastern areas of the Kanto region as well as the southern part of the Tohoku region fall into the exposure zones.
However, the results serve only as reference data because the actual radiation exposure could be a maximum of five times or a minimum of one-fifth the estimated data.
The data has been published on the agency's website. (http://www.jaea.go.jp)