Showing posts with label Tomoya Yamauchi. Show all posts
Showing posts with label Tomoya Yamauchi. Show all posts

Thursday, March 8, 2012

3.43 Million Bq/Kg of Radioactive Cesium in "Black Dust" in Minami Soma City, Fukushima

Whatever this substance is, the number is extremely high.

About this "black dust" in Minami Soma, see my past posts, here, here, here.

Minami Soma City's Assemblyman Ooyama reports on his blog (3/8/2012):

試料:ID:080 鹿島区ジサ原C
Cs-134 1,498,000 ± 1,586 Bq/kg
Cs-137 1,932,900 ± 2,481 Bq/kg
TOTAL 3,430,900± 2,945 Bq/kg

It seems to be part of the report by Professor Tomoya Yamauchi of Kobe University who did the measurement. Mr. Ooyama lists the result of 11 samples tested by Professor Yamauchi.

The NGO in Minami Soma, HCR, seems to have some kind of a fallout with the assemblyman's volunteer group over the "black dust", and they've been making rather wild announcements (telling residents that the black dust was plutonium, when there was no alpha emission was detected, for example). I am still trying to get the overall picture on this matter.

Wednesday, October 5, 2011

Soil Survey of Watari District, Fukushima City Shows 5 Times Cesium Concentration in One Location

compared to the survey done in June.

From Professor Tomoya Yamauchi's survey result dated October 5, 2011, as published by the "FoE Japan":

Survey results 計測結果

(1) Ogura-ji Inariyama 小倉寺稲荷山
Cs-134: 604.66 eV; 108,450 +/- 247 Bq/kg
Cs-137: 661.64 eV; 131,250 +/- 282 Bq/kg
Total 総計:239,700 +/- 375 Bq/kg

(2) Hachiman Jinja 八幡神社
Cs-134: 604.66 eV; 71,293 +/- 171 Bq/kg
Cs-137: 661.64 eV; 85,981 +/- 198 Bq/kg
Total 総計:157,274 +/- 262 Bq/kg

(3) Storm drain on the school route 通学路西側住宅雨水枡
Cs-134: 604.66 eV; 44,294 +/- 135 Bq/kg
Cs-137: 661.64 eV; 54,010 +/- 156 Bq/kg
Total 総計:98,304 +/- 206 Bq/kg

(4) drain in Yakushi-cho 薬師町内の溝
Cs-134 604.66 eV; 137,490 +/- 236 Bq/kg
Cs-137 661.64 eV; 170,075 +/- 274 Bq/kg
Total 総計:307,565 +/- 361 Bq/kg

(5) backyard of a residence in Yakushi-cho 薬師町内民家の庭
Cs-134: 604.66 eV; 17,532 +/- 91 Bq/kg
Cs-137: 661.64 eV; 20,932 +/- 104 Bq/kg
Total 総計:38,464 +/- 138 Bq/kg

The location (1) is the one whose cesium concentration in the soil quintupled from the measurement in June of 46,540 Bq/kg of radioactive cesium.

The location (2) is right next to a nursery school with small children.

Professor Yamauchi's conclusion:

地域全体が非常に高いレベルで汚染している。側溝の泥を取除く程度の除染では線量は下がらない。各住宅や空き地の表土とともに、アスファルトやコンクリート、コンクリート塀、屋根も除去の対象にしなければ線量は下がらないと見られる。

The entire district is highly contaminated. The radiation level will not go down with decontamination that only involves removing the sludge from the drains. In addition to removing the top soil at houses and empty lots, asphalt, concrete, concrete fences and roofs would have to be removed in order to lower the radiation level.

The national government did survey the district, but managed to miss high radiation locations. It did only the air radiation survey, which does not necessarily reflect the contamination level of the ground.

Tuesday, October 4, 2011

#Radiation in Japan: 300,000 Bq/Kg of Radioactive Cesium from Soil in Fukushima City

NGO "FoE Japan (Friends of Earth Japan) did its own survey of radiation contamination in Watari District in Fukushima City with the help from Professor Tomoya Yamauchi of Kobe University. Watari District has high radiation levels throughout the district, but the national government has so far refused to designate anywhere in the district as "evacuation recommended" area.

If the government designate an area as such, the government has to pay for the relocation cost. As the result, the designation in other cities like Date City has been very arbitrary and spotty, rendering the whole exercise worthless. Often, the residents are simply moved to the other parts of the same city with slightly lower radiation.

Professor Yamauchi already released the result of the air radiation survey of Watari District, but today (October 5, 2011) FoE Japan held a press conference and announced the result of the soil contamination survey.

The links at the NGO's site are broken unfortunately, but the newspapers reporting the press conference, the highest contamination was 300,000 becquerels/kg of radioactive cesium. Here's one from Asahi Shinbun (10/5/2011), which is one of the better Japanese newspapers that tend to keep the links alive longer.

Judging from Professor Yamauchi's air radiation survey (in Japanese), this particular location looks like the one that had 23 microsieverts/hour radiation at 1 centimeter off the surface of the dirt in the roadside drain. Professor Yamauchi hypothesized that radioactive cesium from surrounding mountains and forests washes down the drain after the rain, and naturally gets concentrated in the dirt.

In my communication with Professor Yamauchi, I asked if the decontamination as currently practiced in Fukushima works at all, given the non-result in Watari District which he surveyed. He said the spot decontamination like removing the dirt and sludge is useless as radioactive materials simply come from somewhere else, so the district-wide decontamination including the surrounding mountains would be necessary to "decontaminate" in the true sense of the word - to remove radioactive materials, not reduce.

He also said that spraying water with high-pressure washers hardly work at all on concrete and asphalt surfaces, as radioactive cesium is now deeply embedded in the concretes and asphalt. The only way to decontaminate concrete and asphalt, the professor said, was to physically remove all concrete structures - houses, fences, pavement, etc., which he said would destroy the neighborhood. He is of the opinion that all the residents in the district should be evacuated first, with the government paying for the cost, and the experts should get to work to truly "decontaminate".

Professor Yamauchi also wryly observed the the word for "decontamination" in Japanese, 除染 (jo-sen), is misleading. Looking at the characters for the word, it does mean "removing the contamination". So by doing the "jo-sen" work people think they are removing the contamination, when all they may achieve is to reduce the level of contamination somewhat (not much, if Watari District is any indication). He even said it was as if the government was encouraging "decontamination" so as not to evacuate people.

Or in the case of Minami Soma City, it is as if the residents in contaminated areas could feel comfortable enough to remain there by doing the "decontamination" work, as one volunteer related in the US ABC News interview in August. "If this radiation is going to stick around here for five to 10 years, we have to learn to live with it,"she said, instead of moving away from the high radiation area. For her, shoveling dirt from the kindergarten playground was a way to live with "it".

17,000 people live in Watari District, with beautiful mountains and water. It is dubbed "hidden paradise" in Fukushima City for the scenery like this:

(Photo credit: SHEjapan.com, with permission)