No way to find hot spots with dosimeter at 1m from the ground

We have published several articles in this blog saying that to protect the population the Japanese goverment should take into account the soil contamination as well as the radiation dose in the air.  The policy to open the evacuation zones and encourage the population to return to live there (with the end of financial compensation and relocation aid) is based only on the airborn radiation dose measurements (the evacuation order is lifted when the radiation dose is under 20mSv/year).  We have been saying that this is very dangerous, even  criminal, for the air radiation dose rate (indicating the amount of radioactive dose received by a person within a certin period time) is useful with a well-identfied fixed source of radiation, but is not adequate to reveal the overall environmental contamination after a nuclear accident. It doesn’t account for the internal radiation exposure induced health hazards (note 1).

Now we would like to point out another problem related to hotspots: it is nearly impossible to find hotspots by the usual measuring practice of the airborn radiation dose rate (in sieverts per unit of time).  To illustrate this difficulty, we are translating here a Facebook post of Mr Yoichi Ozawa of the citizen’s measurement group named the “Fukuichi Area Environmental Radiation Monitoring Project“.



Continue reading “No way to find hot spots with dosimeter at 1m from the ground”

Incredible contamination in Namie, Fukushima

The evacuation orders of the most populated areas of Namie, Fukushima were lifted on March 31st this year.

“Fukuichi area environmental radiation monitoring project” has published airborne radiation measurements map and soil surface density map. The results are simply incredible. This is far much worse than in Radiation Control Zone. Any area becomes designated as such when the total effective dose due to external radiation and that due to radioactive substances in the air is likely to exceed 1.3mSv per quarter – over a period of three months, or when the surface density is over 40,000Bq/m2. In the Radiation Control Zone, it is prohibited to drink, eat or stay overnight. Even adults are not allowed to stay more than 10 hours. To leave the zone, one has to go through a strict screening.

Namie’s radio contamination is far over these figures! And people are told to go back to these areas.



Here is the posting of “Fukuichi area environmental radiation monitoring project” in their FB page on April 20th.




We are uploading the map of airborne radiation rate map measured by GyoroGeiger, the Android supported Geiger counter, during the 38th monitoring action between 3 and 7 April 2017. Dose rate is measured at 1m from the ground.
At 56 points over 100 measuring points, the dose rate was over 1µSv/h. These points are indicated in red. The highest measure was 3.71µSv/h. Conversion to annual dose gives 32mSv. Is it allowed to make evacuees return to such areas?

Namie airborne


Here is the soil contamination map uploaded on April 15th. They even had to introduce 7 scales, for the contamination is so high and they couldn’t deal with the scales they were using before! It is a violation of human rights to let people live in such areas.

namie(2017.04-[38])ENGPixelise web