Micro-hotspots are still found all over Koriyama  いまだあちこちに点在するホットスポットin郡山

この記事はママレボ通信12月28日付記事、『いまだ、あちこちに点在するホットスポット in 郡山』の英訳です。

The original article is written by Hideko Wada, Mamarevo magazine.

To read the Japanese article: http://momsrevo.blogspot.fr/2014/12/in.html    

Playground in the park.
Playground in the park.

On October 25, I carried out radiation measurement in Koriyama City with a “hot spot finder”, together with Mrs. Toshie Nemoto, who runs an after-school program in the city. Mrs. Nemoto is a member of the ‘Protecting Health and Future of the Children’ project. We also asked the ‘Kodomo Mirai’ measurement center in Kokubunji, Tokyo, to measure cesium in soil samples that we collected from areas with high air-dose radiation. The air dose radiation level in decontaminated lawns in the park is 0.2-0.3 mSv/h (microSievert per hour), but many micro-hotspots still exist. 

"I have heard from my students in the after school program that they had been sent to a park with relatively high radiation levels to pick acorns. I wonder why the school deliberately makes their students expose themselves to radiation."


I received the phone call from Mrs. Nemoto in the middle of October. I decided to conduct a radiation measurement in Koriyama with Mrs. Nemoto. We borrowed a hotspot finder for the mission.

 It was a beautiful autumn day with splendid sunlight. The school outdoor activity that Mrs. Nemoto mentioned happened in the Heisei Anniversary forest park for Koriyama children.The park had a wide area of beautiful lawn and the trees had already started to change color to red and yellow. We saw many children playing in the field, accompanied by parents.

Lawn area in the park.
Lawn area in the park.

Our Hotspot finder showed 0.2-0.3 mSv/hour at the border of the play area and on the lawn. Considering that the air dose radiation used to be 0.05 mSv/h before the nuclear accident, this number cannot actually be seen as low, but still this is, for Koriyama, a relatively low dose of radiation. Mrs. Nemoto said that the radiation level was low in this area because the lawn had been replaced as a part of a decontamination process.


School outdoor activities are held in the park area, where the radiation level is equivalent to the level assuring Chernobyl residents the right of evacuation.

However, the situation was different in the area where the children took part in the acorn picking activity. This area is called the Forest of Bird and Insects, and it is located adjacent to the park. The area was damp and muddy, unlike that of the rest of the park.

The ground in the forest was moist, because it had rained the day before and it looked to be a typical ground condition which absorbs cesium very well. We first measured the air dose radiation and the counter said 0.4-0.6 mSv/h. We then collected the soil in the spot that showed the highest value and later sent it to Kodomo Mirai measurement center in Kokubunji, Tokyo.

The results were: 


Cesium137   5 250 bq/kg

Cesium134   1 670 bq/kg

Total              6 920 bq/kg



Comparing this value to the Ukrainian regulation standards after the Chernobyl accident, it is equivalent to Zone Three, which is an area where voluntary resettlement is guaranteed.

In Japan, soil with values above 8 000 bq/kg is supposed to be disposed of as ‘specified toxic waste under state control’. You will understand how high the contamination in this area is, even if it is not exactly classified as radioactive waste. Before the nuclear accident, waste with radioactivity higher than 100 bq/kg was supposed to be stored in a special area under severe control and was designated as low dose radioactive waste.

How come were children encouraged to pick acorns in such an area? A child who took part in the activity said that there hadn’t been an event like this before, it only started this year.

Along with picking acorns, a guiding person suggested children to pick leaves with special aroma and sniff them.

One of the parents speculated that the school, by giving lectures in the woods, intended to impart the impression that radiation isn’t a big deal.

Hotspots are scattered everywhere in a popular cherry blossom viewing spot

We had also been informed that there were other areas with high radiation spots. So we went off to Fujita River in Koriyama.

Cherry trees line the river banks and every April, small food booths are put up under the cherry blossoms for visitors who enjoy seeing cherry flowers. On this warm autumn day we could see children with parents playing on the river banks.

Despite the tranquil scenery, we found highly contaminated micro-hotspots.

(Photo: Right; The result from Kodomo Mirai measurement center. Left; Hotspot finder) 

We measured the air dose radiation underneath a bench situated by the river. The counter showed 1 mSv/h. We also collected some soil from the ground under the bench and sent it to be measured more precisely by Kodomo Mirai radiation measurement center. The result was 38,840 Bq/kg (Cs134 and Cs137 combined).


This value is way above the level indicating that the soil has to be stored as ‘specified toxic waste’. Comparing it to the Ukrainian regulation, the area is equivalent to the zone in Chernobyl where resettlement is compulsory.


A resident who lives near Fujita River said that there sometimes were children sitting on the bench. The resident knew that there were hotspots in this area and once asked the city of Koriyama to carry out decontamination. However, the city answered that the river was controlled by the Ministry of national land and water, so the city would not conduct decontamination.

Because municipal and national offices are not cooperating well with each other, children are left alone without being properly protected from radiation. The contamination with high radiation is not evenly spread around in this area, but rather exists as micro-hotspots. We think that local and national governments should act quickly to decontaminate the area as soon as they are aware of the actual radiological values.

We should know that the ‘recovery’ which is being repeated on TV and in other media does not fully explain what really is going on in the disaster affected areas. We should all make more effort to think what we can do for the sake of children who are at risk of radiation exposure, and have the courage to take action to protect them.

(Translation by WNSCR team)

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