2016-04-13 10:29 | カテゴリ:未分類

China Times 


   

 4月10日のThe China Post  (英文中国郵報)という台湾の英字新聞に、われわれの『放射線像」が5枚掲載されました。ヒノキ、はさみ、お賽銭,ネズミ、不明の野生植物、などです。周知のように台湾でも福島の事故を受けて脱原発運動が盛んです。この英字新聞を通して、世界中の華僑や香港の中国人も『放射線像』に注目してくれることを願っています。これを契機に、原発を稼働している韓国や中華人民共和国の新聞にも「放射線像」が掲載されることを期待しています。まだアメリカの新聞からは「放射線像」掲載のオファーが来ないようですが、ねばり強く、呼び掛けています。

          
  このThe China Post の新聞記者は、フォトジャーナリストの加賀谷雅道氏が現在諸外国各地での『放射線像』の展示会で使用している原稿を、「あくまで新聞記事作成の参考のために」と送ったところ、この新聞社はその原稿をまるまる無修正で掲載しています。だから少し内容に奇妙な表現のところがありますが、読者には大意は通じると思います。以下がその本文です。あえて翻訳いたしませんが、あしからず。

  
 
By Masamichi Kagaya
(Photographer) and Dr. Satoshi
Mori (University of Tokyo)
As a consequence of the Great
East Japan Earthquake and ensuing
tsunami on March 11, 2011,
the cores of the first to third nuclear
reactors at the Fukushima Daiichi
Nuclear Plant underwent meltdowns
as external power for the cooling
pumps was lost. As a result, a huge
amount of radioactive particles was
released into the air. These particles
were carried by southeasterly winds
to Iitate Village, Fukushima City, and
Nakadori, a central region of Fukushima
Prefecture, leaving high levels
of radioactive contamination in their
wake. The particles were further
carried along multiple routes creating
radioactively contaminated areas
in regions from Ibaraki to Tokyo and
Kanagawa Prefecture, as well as in
Northern Kanto and the Tohoku Region
(Northeastern Japan).
Whether we are in Tokyo, Fukushima,
or even in front of the
damaged nuclear reactor buildings,
we are exposed to radiation that
we are unaware of. It is too small
to see, it cannot be heard and it is
odorless. Therefore, despite living in
a region contaminated with radioactive
particles, to this day, we are not
consciously aware of the radiation.
NaI (TI) scintillation detectors and
germanium semiconductor detectors
are used to measure the amount of
radioactive contamination in soil,
food, and water in units called Becquerels
(Bq). Radioactivity is further
measured in Sieverts (Sv), which is
an index of the effects of radioactive
levels in the air, doses of exposure,
and so on. Nevertheless, from such
values, it is impossible to know how
the radioactive particles are distributed
or where they are concentrating
in our cities, lakes, forests, and in
living creatures. These values do not
enable us to “see” the radioactivity.
Thus, radioactive contamination has
to be perceived visibly, something
that can be done with the cooperation
of Satoshi Mori, Professor
emeritus at Tokyo University. Professor
Mori is using autoradiography
to make radioactive contamination
visible.


Today, dozens of radiographic
images of plants created by Professor
emeritus Mori since 2011 are on
display together with radiographic
images of everyday items and animals.
This collection of radiographic
images (autoradiographs) is the first
in history to be created for objects
exposed to radiation resulting from a
nuclear accident. I hope that visitors
will come away with a sense of the
extent of contamination in all regions
subject to the fallout — not just those
in and around Fukushima. At the
same time, I hope that this exhibition
will remind visitors of the large
region extending from the Fukushima
Daiichi Nuclear Power Plant to
Namie Town, Iitate Village and the
dense forests of the Abukuma Mountain
Area that, to this day, remain restricted areas. The radiation affects
animals that continue to live in
these areas and be exposed to heavy
radiation, as well as the 140,000
people that had to evacuate and who
lost personal assets (homes, property,
work, interpersonal relationships).
These people are in addition
to the victims who directly breathed
in the radioactive materials, subjecting
them to internal exposure —
victims that include anyone from the
residents near the plant to people in
Tokyo and the Kanto Region.


Although what can be done is
limited, new progress has made it
possible to record the otherwise invisible
radioactivity and make it visible.
The history of needless nuclear
accidents occurring in the United
States, the Soviet Union (Russia) and
Japan over the last several decades
may still potentially be repeated elsewhere
in the world, but hopefully
future generations will see the cycle
be broken. Through exhibitions and
other means of disseminating knowledge
about radioactivity, future generations
may learn to leave behind
dependence on nuclear power and
be free from the dangers of nuclear
accidents and nuclear waste.


Image Explanation
The radiographic images were
created by a method called “autoradiography.”
Major universities
and research facilities in Japan
and throughout the world have
autoradiography equipment, which
is commonly used in biological,
biochemical, and microbiological
research to quickly view, with high
sensitivity, the distribution of radioactive
substances in a sample.
These images are frequently used
in research papers and in conference
presentations. The radiationsensitive
imaging plate developed
in 1987 by Fuji Film Industries and
Kasei Optics is approximately 100
to 1000 times more sensitive than
x-ray film.


The imaging process involves
placing a radioactive sample on the
imaging plate for a given period, after
which the imaging plate is read
by a device called a BAS. The contrast
of the read image is carefully
adjusted, whereby the distribution
of radioactive substances gradually
becomes apparent. Radiation emitted
by radioactive particles appears
as black areas in the radiographic
image. The darker the area is, the
stronger the radioactive contamination
is. An autoradiographic image
exhibits the same phenomenon as
an x-ray image taken at a hospital,
where bones, which block radiation,
appear white and portions through
which the radiation passes without
being blocked appear black.


When viewing a radiographic image,
one point to keep in mind is that
since each image is individually adjusted
for contrast, the images cannot
be compared with one another
to determine which indicates greater
contamination. In this exhibition,
records concerning specimens indicate
β radiation levels in both “cpm”
measured using a survey meter in
the sampling of each specimen, and
in “becquerels” (Bq/kg) measured
using a gerimanium semiconductor
detector. These values express the
degree of contamination of the specimens
and therefore, I hope that you
will keep these values in mind while
viewing the images.


For example, an area is determined
to be radioactively contaminated
if the measured cpm value is
twice the usual background level,
in this case, 25 to 40 cpm. Further,
as a reference for measurements
in becquerels, naturally occurring
radioactive potassium K40 is on
the order of 33 Bq/kg for white
rice, 1600 Bq/kg for dried kelp,
and 66 Bq/kg (dry weight, excluding
water content: 165 Bq/kg) for
the human body.

以下は写真の詳細な説明です。
1.2. Black parts dispersed throughout the proximal end of the branch in this set of cypress leaves and cones, found in Iitoi, Iitate Village in 2014, are highly contaminated by fallout from March 2011. The branches that grew from those parts in 2012 exhibit
slight secondary contamination by radioactive particles carried by the wind, while the black hue emitted around the cones that developed in 2013 indicate a remarkable level of contamination. Further, the young leaves that grew in 2014 have higher internal
radioactive contamination than the other leaves. In another cypress, we found that while the leaves and cones had the same level of contamination, the seeds in the cones had one-third the level of contamination, indicating that the radioactive cesium is
being passed onto the next generation.

3. These scissors were found outdoors in Namie Town in June 2013. The rusted blades are six times more contaminated than the coated handles. The microstructures (unevenness) caused by rusting readily store the radioactive particles. The same
phenomenon has occurred on other rusted samples as well. Radiation Level: Blade - 3000 cpm, Handle - 500cpm.

4. This is a comparison of macrophyll from Hiroshima and weed from Namie. The weed, right, came from Namie town in 2015, 10 km from the damaged nuclear plant. The macrophyll, left, is from Hiroshima, 840 kilometers from the plant. Radiation levels
are as follows: the weed reads at 100-150 cpm, while the macrophyll reads 50 cpm (background levels).

5. After the nuclear accident in Fukushima prefecture, empty houses in the restricted area became infested by rats. This rat was caught in a trap in Warabidaira, Iitate Village in 2013. We find radioactive materials on the body surface and contamination
in the muscles of the thigh. Looking at the internal organs, we see a high level of contamination in the kidneys and the gall bladder surrounded by the live. Because Cesium is carried out with urine and the kidneys are the final step in the urinary system,
radioactive cesium accumulates here. Radiation levels for the rat are as follows: Body, Internal organs 100-150cpm, Body 286.5 Bq/kg, Heart 2521 Bq/kg, Liver 4937 Bq/kg, Lungs 3134 Bq/Kg, Stomach and Intestines 6111 Bq/kg, Spleen 4334 Bq/kg, Kidneys
11750 Bq/kg (total Cs-134, Cs-137)

6. These coins, found in Akougi, Namie Town, 25 kilometers from the nuclear plant in October 2014 were offerings in a small roadside shrine. Nearly all the coins were exposed for imaging on the side that was facing upward at the site. The three coins that appear
faintly were exposed on the opposite side. Although scientists expected differences between coins made of differing metals, they did not find that to be the case. The coins were returned to the shrine. Radiation levels read 550 cpm on upside, 210 cpm underside. 

秘密

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