Saturday, July 28, 2012

The science ministry has claimed it was appropriate to withhold radiation fallout forecasts from the public immediately after the Fukushima reactor meltdowns because the data were "based on assumptions."

In a report released Friday, the ministry said the data on the predicted spread of radioactivity compiled by the System for Prediction of Environmental Emergency Dose Information (SPEEDI) did not necessarily reflect the actual situation.

After analyzing its response to the crisis, the ministry believes it was "not in a position to release the data to the public" once the nuclear crisis started in March 2011, officials said. The process included interviews with then science minister Yoshiaki Takaki and other officials.

The government has drawn fire for failing to promptly announce the SPEEDI forecasts, with critics charging the delay exposed residents near the Fukushima No. 1 plant to radiation that could have been avoided.

In a separate report published Monday, a government-appointed panel investigating the disaster said that disclosing the data could have allowed residents to make a more informed decision about when to evacuate — and where.

But the ministry's report claimed it is "doubtful" it could have provided trustworthy information to the public, even though the same data from the purpose-built ¥11 billion computer simulator was quickly passed onto the U.S. military and international bodies.

It admitted, however, that "the significance of providing predictions cannot be denied."

The report also admitted that the ministry "did not offer enough explanations and caused misunderstandings" regarding the maximum radiation level acceptable in schoolyards. A threshold of 3.8 microsieverts per hour was imposed so students wouldn't be exposed to more than 20 millisieverts a year, based on guidelines issued by the International Commission on Radiological Protection, according to the ministry.

At times of emergency, the British-based advisory body recommends that radiation exposure be limited to a range of between 20 and 100 millisieverts per year.

The report claimed that the 3.8-microsievert limit, which triggered harsh protests from alarmed parents who felt the threshold was too high, does not necessarily mean that children playing in schoolyards received a dose approaching 20 millisieverts.

However, it conceded that the ministry "failed to promptly respond to concerns aired by parents" of elementary and junior high school students in connection with the upper limit of radioactive substances detected in school lunches.

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