12 Août 2015
August 12, 2015
The government has decided not to use the SPEEDI network system as a basis for making decisions regarding evacuations, drawing objections from municipal governments and residents.
The decision, which was made in July, is reflected in the government's Basic Disaster Management Plan, which informs the central and local governments' disaster measures.
The government came under fire following the outbreak of the March 2011 Fukushima nuclear crisis when it delayed the public release of information generated by the System for Prediction of Environment Emergency Dose Information (SPEEDI) -- which predicts the volume and the extent to which radioactive materials are spread in the event of a nuclear disaster based on data such as the volume of radioactive materials released, weather conditions and terrain -- and needlessly exposing residents to radiation as a result.
In new nuclear disaster prevention guidelines established in 2012, the Nuclear Regulation Authority (NRA) stipulated that residents within five kilometers of a stricken nuclear power plant be evacuated immediately in the event of a nuclear incident, while residents between five and 30 kilometers from a nuclear plant take shelter indoors and evacuate once actual measurements of air radiation doses reach 500 microsieverts per hour. The guidelines stated that SPEEDI would be used as a reference, and the government's Basic Disaster Management Plan also stated that SPEEDI's prediction results would be publicly released.
However, the use of SPEEDI was deleted from the nuclear disaster prevention guidelines this past April, and the system was eliminated from the Basic Disaster Management Plan in July as well.
"Because the actual flow of radioactive materials can differ from predictions, SPEEDI results are uncertain," a senior official at the NRA explained as the reason for SPEEDI's omission as a tool for deciding evacuation policy. "Using actual radiation measurements as criteria for evacuation does not allow us to completely prevent residents from being exposed to radiation, but it's a standard method that's accepted worldwide."
At a Central Disaster Management Council meeting in July, Niigata Gov. Hirohiko Izumida argued that residents would not support evacuation criteria that presuppose that residents will be exposed to a certain level of radiation. At briefing sessions regarding evacuation plans held for residents of the Kagoshima Prefecture city of Satsumasendai, where the No. 1 reactor of the Sendai Nuclear Power Plant was reactivated on Aug. 11, the municipal government had conveyed its intent to use SPEEDI information.