Even as thousands of residents pondered the implications of the nuclear disaster in Fukushima Prefecture last year, Japanese government officials took little notice of up-to-the-minute high radiation measurements provided by the U.S. Energy Department.
The Energy Department used its Aerial Monitoring System (AMS) between March 17 and 19, 2011, and compiled a detailed map of radiation levels on the basis of 40 hours of flight time over Fukushima Prefecture.
The data was provided to Japanese government officials, but not released to the public.
The map clearly shows an area of high radiation levels extending in a northwesterly direction from the crippled Fukushima plant.
Thousands of Fukushima residents living near the plant, unaware of the danger they faced, evacuated in the direction of those high radiation areas.
This is not the first time the Japanese government has been shown to be slow to respond to the unfolding disaster at the Fukushima facility following last year's Great East Japan Earthquake and tsunami.
The central government also failed to quickly release forecasts of radiation spreading in Fukushima and beyond made by its System for Prediction of Environmental Emergency Dose Information (SPEEDI).
A major difference between the SPEEDI forecast and the Energy Department observations is that the U.S. data concerns actual radiation measurements taken over an area with a radius of about 45 kilometers from the Fukushima No. 1 plant.
The monitoring showed that communities in a northwestern direction from the plant, including Namie and Iitate, had radiation levels exceeding 125 microsieverts per hour over an area as wide as 30 kilometers.
Exposure to that level of radiation for eight hours would exceed what is deemed by the government to be safe over the course of a year.
According to Foreign Ministry officials, the U.S. Embassy in Tokyo twice provided data through e-mail messages. The radiation maps based on the results of the AMS were provided on March 18 and 20.
The Foreign Ministry immediately forwarded the data to the Nuclear and Industrial Safety Agency (NISA) and the science ministry, which is in charge of carrying out radiation measurements.
According to several science ministry officials, including Itaru Watanabe, the deputy director-general of the Science and Technology Policy Bureau, the science ministry and NISA not only failed to publicize the data, but neglected to pass it on to the prime minister's office or the Nuclear Safety Commission (NSC).
Continued at Asahi Shimbun