● To bring together citizens’ abilities and knowledge to ensure that radioactivity measuring data is not concealed.
● To obtain factual knowledge by accumulating as much accurate and independent data as possible.
● To provide comprehensive and user-friendly information.
We hope that this measurement data can be a barometer for thinking about a no-nuke society.
We also hope to increase the use and support of independent radioactivity measurements laboratories in Japan.
The data forms a valuable record from the unfortunate accident we have encountered.
We want to continue the activity of MDS with all the people in the nation so that we will not forget the accident at the
Tepco Fukushima Daiichi Nuclear Power Plant on March 11, 2011.
What the peak after 10 years in Chernobyl has taught us
Be prepared for the long lasting fight against the radiation Pass onto the future,
Written by Junichi Ohnuma, Toukai Net Civilian Radiation Measuring Center (C-Lab)
The social impact of Fukushima Daiichi nuclear power plant’s accident is fading
Fukushima Daiichi nuclear power plant’s accident, which occurred in March 11th 2011, has not been settled down yet.
The melting nuclear fuel debris has not been found in the plant. Nor the contaminated water that is used to cool down
the plant have still been produced and released into the ocean. The decontamination has not shown much successes.
Yet, the evacuation order in the highly contaminated areas has been lifted. Compensation and housing aids for the evacuee
have been cut that is forcing those people to go back to the area.
People from Minami Souma city has brought a collective lawsuit for this issue against TEPCO and the government.
People from Fukushima are known to be very calm, but they are starting to stand up for themselves.
However, the government has carried out a campaign to tell that “radiation is not dangerous.
Stress caused by being worried about the radiation is worse for your health”.
It is supported by international nuclear lobbying organizations such as IAEA and ICRP.
Foods that are harvested in Fukushima are used in school lunches in Fukushima.
Children are faced with risks of being internally exposed to the radiation. “Fukushima Ethos Movement” that encourages people
to stay in Fukushima by keeping the exposure at minimum level but also the worry at the minimum level has apparently been
active under the support of ICRP. There were TV show of pro-government scientists and celebrities going on a bus tour to eat
edible mountain plants from Fukushima as the propaganda. Under those situations, the social impact of the accident is
definitely fading. There is a story from some volunteers from Tokai area. They had been to Iidate village and the local people
offered them mushroom soup from the area.
Radiation remains for 300 years
The main reason for high dose of air contamination is radioactive cesium (cesium 134 and cesium 137).
Half-life for cesium 134 is 2 years, so it has already decreased to ¼ of the amount compared to the beginning.
This is the reason why it feels like the contamination has decreased since the accident.
However, half-life for cesium 137 is 30 years, so it does not decrease much. It means that from now on,
decrease in radioactive air contamination is going to be very slow along with the half-life of cesium 137.
We have to know that the contamination will last about 100-300 years from now. Cesium releases beta radiation
when it collapses. Therefore, we need to be aware of and avoid the internal exposure by inhaling or eating them
on top of air contamination.
The peak after 10 years in Chernobyl
It has been 30 years since the accident in Chernobyl. We had an opportunity to see a very shocking data from Kiev,
Ukraine by the chief of whole body detector laboratory in internal exposure department in national medical radiation
research center, Mr. Vasilenko Valentina (graph 1).
The graph shows the secular trends of internal exposure to radiation (average rate) by intake of cesium 137 in people
who live in Ragovka village, Kiev from 1986 to 2008.
The vertical axis is dose of internal exposure to radiation (mSv/year), the red bars (on the left) represent adults
and the green bars (on the right) represent children. In 1986, it was 1.5 mSv/year for adults and 1.3 mSv/year for children.
It gradually decreased and became less than 0.5 mSv/year for both of them by 1990. However, since 1994 it reversed and
started to increase. In 1998, it had become 2.3 mSv/year for adults and 1.3 mSv/year for children.
Then it started to decrease again, and in 2004 it went back to be less than 0.5 mSv/year.
＜Graph1 Internal irradiation Doses Dynamics (mean values) due to Cesium in residents with abnormally high internal irradiation level＞
This tendency is not unique to people in Ragovka village. Graph2 shows secular trends of accumulated dose of cesium in people
by internal exposure (average rate for adults) from 16 villages in Ukraine. The vertical axis is kBq/body, and the red line shows
when it is 30kBp/body. If the body mass was average of 60kg, then it becomes 500 Bq/kg. Mr.Vasilenko said that the data might
be the result of people starting to eat wild berries and wild mushrooms again as the social impacts of the accident had faded.
Graph 3 is a transition of average internal contaminated dose (Bq/kg) by cesium 137 among variety of groups from 1986 to 1992
presented by Swedish radiation protection laboratory. Those researchers who were cautious of what they eat and tried to avoid
inhaling dusts had maximum internal exposure of 10Bq/kg. Non-famers had maximum 40 Bq/kg of internal exposure while farmers
had 80 Bq/kg. In contrast, Sami people from Lapland who eat reindeers that eat contaminated lichen reached internal exposure
to radiation of 1000 Bq/kg.
＜Graph2 Incorporated cesium content dynamics (medians) for adults in several settlements in Ukraine within＞
We need to be cautious about accumulation of radiation in our body
It is an alarming reality towards Japanese society where the social impacts of nuclear power plant’s accident are also fading.
Contaminated foods are being distributed around Japan secretly. 100 Bq/kg is used as a uniform limitation standard for
how contaminated foods can be in most of the foods.
Under this situation, we need to be cautious of foods around Japan not limited to areas that are highly contaminated
such as Fukushima, Miyagi and Tochigi. We need to especially look out for children.
However, the government is not willing to increase the amount of food sample they measure, or to measure strontium-90.
Our role as citizen’s radiation measuring laboratory becomes even more important in those situations.
People’s caution towards radiation has become less so the request to measure samples in citizen’s radiation measuring laboratory
has decreased dramatically. Most of the laboratories are facing difficulties of operating the place. That is why it is a crucial point
especially from now on. The value of operating “Minna no Data Site” that allow people to search radioactive contamination in food
is significant. “Measuring Becquerel level in Soil Project in East Japan” which implemented during 2014-2016 had huge role to play,
we believe. We would also like to acknowledge the importance of quality control by standard brown rice to increase the quality of data
measurement. This is what “Citizen Science” looks like. The battle to protect us from possible damages by radiations that have been
spread by the government and TEPCO will last at least for 50 years. Let’s accompany each other, share the knowledge and
keep this movement for long time together.