The government on March 11 decided to allow local bodies to use SPEEDI, a computer system designed to predict the spread of radiation in the event of a nuclear disaster, when they are evacuating their residents.
The decision was reached by Cabinet ministers in a meeting on nuclear power. It will be incorporated in the government's basic disaster prevention plan in the near future.
In its guidelines for nuclear emergency preparedness, the Nuclear Regulation Authority (NRA) has a policy of not using SPEEDI, formally known as the System for Prediction of Environment Emergency Dose Information. But bodies including the National Governors' Association have made strong calls to utilize the system, prompting a change in government policy.
SPEEDI was not put to use in evacuations following the outbreak of the Fukushima nuclear disaster, and the NRA has therefore decided to base evacuation decisions on such factors as state of the nuclear reactor and actual measurements in surrounding areas, without using SPEEDI.
With the NRA set on its policy of not using SPEEDI data for evacuations, in the event of a nuclear disaster there may be discrepancies between the decisions of the NRA and local bodies over the evacuation of residents, resulting in confusion.
The government says that it will make arrangements with local bodies over how SPEEDI is used in the future. According to a government plan, when local bodies are instructing residents on evacuation routes and destinations in the event of a nuclear disaster, central government officials will not obstruct the use of SPEEDI as a source of information.
Government officials are set to discuss concrete application of the system in the future, including whether local bodies will use SPEEDI of their own accord or whether they will have the Japan Atomic Energy Agency, which holds SPEEDI information, provide data. If local bodies operate the system, then the government will provide financial support.
Separately, the government has decided to allow local bodies at their own discretion to provide stable iodine tablets to residents within 30 kilometers of a nuclear power plant to prevent thyroid gland radiation exposure to prepare for a nuclear accident. As a rule, officials had previously restricted distribution to a radius of 5 kilometers from a nuclear plant. The government will cover distribution expenses.
SPEEDI, which incorporates weather patterns in its dispersion predictions, was developed following the Three Mile Island nuclear accident in the United States in 1979. Roughly 12.4 billion yen has been spent on the system.