2011.06.19
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ガイガーカウンター片手に地道に調査された研究者の方の論文がサイエンスに掲載されました。
ご紹介します。
http://www.sciencemag.org/content/332/6036/1368.fullより引用
Science 17 June 2011:
Vol. 332 no. 6036 p. 1368
DOI: 10.1126/science.332.6036.1368
News & Analysis
Japan Disaster
Citizens Find Radiation Far From Fukushima
Frustrated by a dearth of information on what happened to all of the radiological isotopes released from the ravaged Fukushima nuclear power plant, civic groups and individuals have been monitoring radiation on their own. Collectively, they have produced a worrisome picture of contamination throughout eastern Japan, with some hot spots surprisingly far from the crippled reactors.
“Authorities don't want to tell people about the real dose rates,” says Atsuhito Ennyu, a geochemist at Itochu Oil Exploration Co. in Tokyo who has spent most of his free time for the past 10 weeks taking radiation measurements and posting them on a Web site.
The distrust extends to academia. On 13 June, 40 University of Tokyo faculty members petitioned the school to revise what they say is misleading information posted on its Web site regarding radiation at its Kashiwa, Chiba, campus. “University of Tokyo has a big impact on society; the information it disseminates should be accurate,” says Masaki Oshikawa, a physicist based in Kashiwa and one of the petition organizers.
Figure
View larger version:
In this page
In a new window
Have meter, will travel.
Armed with his own dosimeter, geochemist Atsuhito Ennyu is measuring radiation levels throughout eastern Japan.
"CREDIT: D. NORMILE/SCIENCE"
Public faith in the government's handling of the crisis took another hit last week with new revelations indicating that the situation was much worse than official pronouncements had portrayed. On 6 June, the Nuclear and Industrial Safety Agency (NISA) announced that, contrary to previous conclusions, a large proportion of the nuclear fuel in the reactors melted and then probably breached containment vessels. NISA also doubled its previous estimate of the amount of radiation released in the week after the earthquake to 770,000 terabecquerels. The same day, the government announced that it is again considering widening the evacuation zone northwest of the plant where radiation doses could accumulate to more than 20 millisieverts over a year.
It shows one wide belt of radiation reaching 225 kilometers south from the stricken reactors to Tokyo and another extending to the southwest. Within those belts are localized hot spots, including an oval that encloses northeast Tokyo and Kashiwa and neighboring cities in Chiba Prefecture.
Radiation in this zone is 0.4 microsieverts per hour, or about 3.5 millisieverts per year. That is a fraction of the radiation found throughout much of Fukushima Prefecture, which surrounds the nuclear power plant. But it is still 10 times background levels and even above the 1-millisievert-per-year limit for ordinary citizens set by Japanese law. The health effects of such low doses are not clear and are passionately debated. But it is known that children are more susceptible to radiation than adults, and few parents want to take chances with a child's health. Besides, “The law should be observed,” Yamauchi says. Kyo Kageura, an information scientist at the University of Tokyo, says there should be a public discussion of the issue, “based on a scrupulous presentation of the data, including to what extent the 1-millisievert limit can be achieved.”
Kageura is among those urging the university to be part of the discussion. The university's Web site implies that background radiation accounts for the high measurements in Kashiwa, something Oshikawa says is inaccurate. The Web site also says health effects are “no problem whatsoever,” which Oshikawa denounces as misleading. The petitioners would like to see the university post a detailed but understandable explanation of the uncertainties about the effects of low radiation doses.
The freelance monitoring efforts are starting to have an impact. The Tokyo Metropolitan Government will start monitoring radiation at 100 locations. Other local governments have announced similar plans. The scientists involved think the first step is simply making residents aware of the situation they are facing.
ご紹介します。
http://www.sciencemag.org/content/332/6036/1368.fullより引用
Science 17 June 2011:
Vol. 332 no. 6036 p. 1368
DOI: 10.1126/science.332.6036.1368
News & Analysis
Japan Disaster
Citizens Find Radiation Far From Fukushima
Frustrated by a dearth of information on what happened to all of the radiological isotopes released from the ravaged Fukushima nuclear power plant, civic groups and individuals have been monitoring radiation on their own. Collectively, they have produced a worrisome picture of contamination throughout eastern Japan, with some hot spots surprisingly far from the crippled reactors.
“Authorities don't want to tell people about the real dose rates,” says Atsuhito Ennyu, a geochemist at Itochu Oil Exploration Co. in Tokyo who has spent most of his free time for the past 10 weeks taking radiation measurements and posting them on a Web site.
The distrust extends to academia. On 13 June, 40 University of Tokyo faculty members petitioned the school to revise what they say is misleading information posted on its Web site regarding radiation at its Kashiwa, Chiba, campus. “University of Tokyo has a big impact on society; the information it disseminates should be accurate,” says Masaki Oshikawa, a physicist based in Kashiwa and one of the petition organizers.
Figure
View larger version:
In this page
In a new window
Have meter, will travel.
Armed with his own dosimeter, geochemist Atsuhito Ennyu is measuring radiation levels throughout eastern Japan.
"CREDIT: D. NORMILE/SCIENCE"
Public faith in the government's handling of the crisis took another hit last week with new revelations indicating that the situation was much worse than official pronouncements had portrayed. On 6 June, the Nuclear and Industrial Safety Agency (NISA) announced that, contrary to previous conclusions, a large proportion of the nuclear fuel in the reactors melted and then probably breached containment vessels. NISA also doubled its previous estimate of the amount of radiation released in the week after the earthquake to 770,000 terabecquerels. The same day, the government announced that it is again considering widening the evacuation zone northwest of the plant where radiation doses could accumulate to more than 20 millisieverts over a year.
It shows one wide belt of radiation reaching 225 kilometers south from the stricken reactors to Tokyo and another extending to the southwest. Within those belts are localized hot spots, including an oval that encloses northeast Tokyo and Kashiwa and neighboring cities in Chiba Prefecture.
Radiation in this zone is 0.4 microsieverts per hour, or about 3.5 millisieverts per year. That is a fraction of the radiation found throughout much of Fukushima Prefecture, which surrounds the nuclear power plant. But it is still 10 times background levels and even above the 1-millisievert-per-year limit for ordinary citizens set by Japanese law. The health effects of such low doses are not clear and are passionately debated. But it is known that children are more susceptible to radiation than adults, and few parents want to take chances with a child's health. Besides, “The law should be observed,” Yamauchi says. Kyo Kageura, an information scientist at the University of Tokyo, says there should be a public discussion of the issue, “based on a scrupulous presentation of the data, including to what extent the 1-millisievert limit can be achieved.”
Kageura is among those urging the university to be part of the discussion. The university's Web site implies that background radiation accounts for the high measurements in Kashiwa, something Oshikawa says is inaccurate. The Web site also says health effects are “no problem whatsoever,” which Oshikawa denounces as misleading. The petitioners would like to see the university post a detailed but understandable explanation of the uncertainties about the effects of low radiation doses.
The freelance monitoring efforts are starting to have an impact. The Tokyo Metropolitan Government will start monitoring radiation at 100 locations. Other local governments have announced similar plans. The scientists involved think the first step is simply making residents aware of the situation they are facing.
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