The government shelved the Nuclear Safety Commission‘s proposal to evacuate residents around the damaged Fukushima Daiichi power plant and provide iodine to them after receiving a forecast on the spread of radioactive materials, government sources said Tuesday.

On November 25, the Ministry of Education, Culture, Sports, Science and Technology (MEXT) released SPEEDI simulations of the radioactive contamination spread from all nuclear plants in Japan.

The SPEEDI maps, which stands for “System for Prediction of Environment Emergency Dose Information,” were made to support emergency preparedness drills of local and central government authorities, calculate the concentration of radioactivity in the air, contamination on the ground, and dose to the population within a range of 10 kilometers. Based on these maps, drills on evacuation or sheltering of the population, or distribution of iodine pills are organized.

However, the maps showed only extremely low releases of radioactivity over a 10 kilometer area around the plants in the event of meltdown.

When Greenpeace met with officials from MEXT and the SPEEDI program on Tuesday this week, officials confirmed that the current simulations are limited to low-level releases, and that the system needed upgrading to cover larger releases and wider areas beyond 10 kilometers from the plants.

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University of Tokyo professor Toshiso Kosako, who was then a adviser to the Cabinet on radiation, proposed on March 16 to make use of SPEEDI, but Nuclear Safety Commission Chairman Haruki Madarame told then-Prime Minister Naoto Kan and his aides that SPEEDI wasn’t ready. SPEEDI comes up with an estimate by weather data and the total amount of released radiation, but the latter was undetectable then.

Researchers from the Japan Atomic Energy Agency, which developed SPEEDI, and aides to Kan proposed calculating the total radiation release from atmospheric dust samples. But early attempts to collect dust samples from March 16 to 19 failed because of changes in wind direction.

They later managed to collect a sample, the data from which was used to calculate the total amount of radiation released from March 12 to 23. The SPEEDI estimate was then reported to the prime minister’s office on March 23.

The data detected high levels of radiation in Iitate and other municipalities northwest of the Fukushima No. 1 plant and outside the 20-km evacuation area

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The government determined that it would be too late to take such measures as around 10 days had already passed since the first of a series of hydrogen explosions occurred at the Fukushima complex, the sources said.

The forecast was based on data from a government computer system known as the System for Prediction of Environmental Emergency Dose Information, or SPEEDI, designed to predict the spread of radioactive materials released in a nuclear plant accident. The prime minister’s office received the first SPEEDI-based report on March 23, according to the sources.

Iitate and the municipalities became designated evacuation areas April 22, about a month after SPEEDI’s estimate was calculated. The government has been criticized for not being able to put the SPEEDI data to faster use after the March 11 earthquake and tsunami triggered the nuclear crisis. At the meeting on Dec. 16 of its task force dealing with the nuclear crisis, the government is expected to decide that it has completed “Step 2″ of the roadmap to contain the nuclear crisis with the crippled Fukushima nuclear plant being brought under control by achieving a stable state called a ”cold shutdown” and unveil plans to review the current scheme of evacuation zones by the end of the year. Source: Asian Scientist Source: Japan Times

Source: Mainichi

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