新聞週間特集:「原発事故と報道」報告(その2止) 放射線知る一助に

(Mainichi Japan) October 21, 2011
Journalists strived to get truth about nuclear fallout to public (Part 2)
新聞週間特集:「原発事故と報道」報告(その2止) 放射線知る一助に


The question of how much and where radioactive materials were dispersed by the hydrogen explosions at the Fukushima No. 1 nuclear plant have been of the utmost importance to residents of both Fukushima Prefecture and beyond, and one we began to pursue soon after the nuclear disaster started to unfold.

The government initially designated the area within a 20-kilometer radius of the power plant an evacuation zone, while those living between 20 kilometers and 30 kilometers from the plant were instructed to remain indoors.  政府は当初、原発から半径20キロを避難区域、20~30キロを屋内退避区域に指定していたが、

However, high levels of radiation were being detected even beyond those areas.

A long-term advisory to stay indoors had not been a part of the government's disaster preparedness guidelines, and would pose too great a burden on residents.

It seemed to us that a designation of evacuation zones based on actual radiation measurements was necessary.

That was when we came up with the idea of calculating cumulative radiation levels at various locations.

At the time, radiation monitoring results released by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) and municipal governments were limited to the amount of radiation detected in the atmosphere per hour (dosage rate).

But since local residents would continue to be exposed to radiation, we felt it far more important to provide information on cumulative radiation levels.

When we appealed to MEXT to provide this information, we were told it was not something they could do right away.

It was decided then that the Mainichi would crunch the cumulative radiation level numbers by adding together dosage rates released by public sources.

Between March 14 and March 21, the cumulative radiation level in the city of Fukushima reached 1770.7 microsieverts.

The figure was 299.7 microsieverts for the Fukushima prefectural city of Iwaki and 34.1 microsieverts for the Tochigi Prefecture capital of Utsunomiya for the same period, and 33.2 microsieverts in the Ibaraki Prefecture capital city of Mito between March 15 and March 21.

Having found the cumulative radiation in the city of Fukushima to exceed the average 1500 microsieverts of natural background radiation that we are normally exposed to annually, the Mainichi's Science and Environment News Department debated what to do with the information, concerned about the public response the information could spark.

Ultimately, we decided to release the information along with the explanation that cumulative radiation levels indicate how much radiation one would be exposed to if they stayed outdoors all day, and that radiation levels in general were trending downwards.

We also added commentary from multiple experts that the radiation levels posed no health risks for people "stepping out to shop" for groceries, and published the information in the March 23 morning issue of the Mainichi's Japanese edition.

Following publication, we received inquiries from various municipal governments in Fukushima Prefecture, and were criticized by some readers for "causing panic among Fukushima city residents."

We maintain, however, that by contributing information on cumulative radiation levels -- which until then had been largely ignored -- we helped residents come to their own conclusions on what to do next.

On March 25, MEXT began releasing cumulative radiation figures.

Since then, it has gone on to conduct detailed monitoring of radiation levels, and has posted predicted cumulative radiation levels through March 2012.


We still regret not having been able to predict that radioactive contamination would spread to the extent that it has.

We keep asking ourselves if there was any way we could've sounded a more precise alarm when large volumes of radioactive materials were released on March 14 and March 15, as we continue working toward protecting the public from unnecessary exposure.

(By Taku Nishikawa, Science and Environment News Department)

(This is part two of a six-part series on coverage of the Fukushima nuclear crisis.)
毎日新聞 2011年10月18日 東京朝刊

by kiyoshimat | 2011-10-23 07:16 | 英字新聞

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