#Radioactive Apartment Update: Was Radiation from Crushed Stone Used in Foundation?

(Update: The stone pit operator, Futaba Saiseki Kogyo, sold the crushed stones to the concrete company in Nihonmatsu City in Fukushima which has since closed down. There is no record kept at the concrete company of where the concrete was sold and how much. The stone pit operator sold about 1000 tonnes to the concrete company, and the remaining 4000 tonnes or so to 20 construction companies inside Fukushima Prefecture.

The stone pit operator executive says he didn't know much about radiation, and that he would have stopped selling if the government had told him to. Information in Japanese, here and here.)

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For now, the media has decided to focus on the aggregate in the concrete used in the foundation of the apartment in Nihonmatsu City, Fukushima. The crushed stones from a stone pit in Namie-machi in the planned evacuation zone just outside the no-entry zone were freely shipped and sold until April 22, and several hundred job sites in Fukushima Prefecture may have used the stones.

Asahi reports slightly different numbers for radiation than reported in Fukushima TV news.

Nihonmatsu City may have known about the high radiation at the apartment since December last year, when the city had the result of the cumulative radiation exposure for children wearing glass badges.

Well, the city couldn't cast any shadow over the prime minister's declaration of "cold shutdown state" of Fukushima I Nuclear Power Plant, could it?

From Asahi Shinbun (1/16/2012):

福島県二本松市の新築マンションの工事に、東京電力福島第一原発事故で出た放射性物質に汚染されたコンクリートが使われていたことがわかった。マンション１階の床からは屋外より高い放射線量が測定された。同市と国が１５日発表した。

The concrete contaminated with radioactive materials from the Fukushima I Nuclear Power Plant accident was used in the construction of an apartment in Nihonmatsu City in Fukushima Prefecture. The radiation from the floor of the 1st floor of the apartment was higher than that of outside. The city and the national government announced on January 15, 2012.

　コンクリの材料に、計画的避難区域内の砕石場の石が使われたのが原因とみられる。同じ材料が数百カ所の工事に使われたとみられ、国は石やコンクリの流通経路を調査している。

The high radiation is thought to be coming from the stones used in the concrete mix; the stones came from a stone pit inside the planned evacuation zone. The same stones have been used in several hundred job sites, and the national government is investigating the distribution routes of the stones and the concrete.

　発表によると、汚染されたコンクリが使われたのは、昨年７月に完成した二本松市若宮地区の鉄筋コンクリート３階建て賃貸マンションの土台部分。１階の室内の高さ１メートルの線量が毎時１．１６～１．２４マイクロシーベルトで、屋外の同０．７～１．０マイクロシーベルトより高かった。２、３階の室内は同０．１０～０．３８マイクロシーベルトという。

According to the announcement, the contaminated concrete was used in the foundation of the 3-story apartment made of ferro-concrete in Wakamiya District of Nihonmatsu City. The apartment was finished construction in July last year. At 1 meter off the floor in a room on the 1st floor, the radiation level is 1.16 to 1.24 microsievert/hour. The radiation level outside is 0.7 to 1.0 microsievert/hour. On the 2nd and 3rd floors, the radiation level inside rooms is 0.1 to 0.38 microsievert/hour.

　コンクリの材料になった石は、計画的避難区域に入っている浪江町南津島の砕石場から搬出。コンクリ会社を通じ昨年４月１１日、マンションの基礎工事に５７．５立方メートルのコンクリが使われた。

The crushed stones used in the concrete were transported from a stone pit in Minami Tsushima in Namie-machi, inside the planned evacuation zone. 57.5 cubic meters of concrete was used in the foundation of the apartment building on April 11 last year.

　砕石場では原発事故前に採取した石を砕き、事故後も屋外に置いて避難区域に指定される同月２２日まで出荷を続けたという。経済産業省などによると、この砕石会社は県内の１９社に計５２００トンを出荷。このうち、マンションにコンクリを納入した二本松市の会社からは県内の百数十社に販売され、数百カ所の工事に使われたとみられるという。

At the stone pit, they crushed the stones that had been picked before the nuclear accident, and the crushed stones were kept outdoors and continued to be sold until the area was designated as evacuation zone on April 22. According to the Ministry of Economy, Trade and Industry, the stone pit operator sold 5200 tonnes of stones to 19 companies in Fukushima Prefecture. The concrete company in Nihonmatsu City who delivered concrete to the apartment site has sold concrete to over 100 companies in Fukushima Prefecture, and the concrete was used at several hundred job sites.

　二本松市は昨年９～１１月、子どもなどの積算線量を計測。マンションに住む女子中学生の３カ月間の線量が１．６２ミリシーベルトと比較的高かったため、市が調べた。マンションには１２世帯が入居している。

Nihonmatsu City measured the cumulative external radiation exposure of children from September through November last year. A female junior high school student who lives in the apartment was found with 1.62 millisievert cumulative radiation for the 3 months, and the city conducted the investigation. There are 12 families living in the apartment.

　マンション１階の室内に２４時間滞在する仮定で計算すると、年間の線量は１０ミリシーベルト前後になる。

If you stay inside a room on the 1st floor of the apartment for 24 hours, the cumulative radiation in one year would be about 10 millisieverts.

NHK runs a similar story, quoting the Ministry of Economy saying it must be the crushed stones from that particular stone pit in Namie-machi. That's the official story.

It's a bit hard to believe hard crushed stones has that much radiation on the surface considering the surface-to-volume ratio. On the other hand, small particles like ashes may. But the official story is set, and the net citizens on blogs and Twitter are left wondering "What about cement? What about additives in concrete? What about steel mesh or rebar?"

It is also convenient to blame everything on one stone pit operator than to have to check every bag of cement from the cement companies.

Another thing that strikes me as odd is the amount of crushed stones sold from this stone pit operator in such a short period of time between the March 11 accident and April 22. I suspect the situation may be similar to the cattle farmers in the planned evacuation zone who managed to sell their cows which were later found with high levels of radioactive cesium, before any rigorous testing started.

Hmmm. This is starting to feel like the radioactive beef and radioactive rice debacles from last year where first denying the problem and then insisting the problem was an exception, and doing perfunctory sample testing totally backfired on the government. We'll see if this story goes quiet very quickly.

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