#Radiation in Tokyo: It's Already a Secondary Radiation Contamination in Koto-Ku

So the Tokyo Metropolitan government finally admitted to the high air radiation level in "Nanbu Sludge Plant" in Ota-ku in Tokyo, after, it turns out, a Tokyo Metropolitan Assemblyman from Ota-ku went inside the plant and measured the radiation.

"Tobu" or Eastern, Sludge Plant in Koto-ku in Tokyo has an even higher level of radioactive cesium, and the plant may have been spewing radioactive cesium from the incinerator where the radioactive sewage sludge is burned, and has been contaminating the air and the soil in the areas around the plant and downwind (upstream) areas along the Arakawa River.

So it's a secondary radiation contamination.

The eastern part of Tokyo has been registering higher air radiation levels than the western part of Tokyo. Unchecked cesium dispersion from the sludge plant ever since the start of the Fukushima I Nuke Plant accident may be good part of the reason.

And we wouldn't have known if it were not for the very concerned parents in Koto-ku who decided to organize themselves and ask a researcher from Kobe University to help them measure the radiation.

From Tokyo Shinbun (6/8/2011):

江東区の保護者でつくる「江東こども守る会」は七日、都庁で記者会見し、都の汚泥処理施設「東部スラッジプラント」（同区新砂三）近くのグラウンドの土から高濃度の放射性セシウムを検出したとする独自調査の結果を発表した。

"Koto Association to Protect Children (江東こども守る会)" held a press conference in the Tokyo Metropolitan Government Building on June 7, and announced the result of its own survey showing the high level of radioactive cesium detected from the athletic ground near the sewage sludge processing plant "Tobu (eastern) Sluge Plant".

　調査は、同会が神戸大大学院の山内知也教授（放射線計測学）と実施。検出されたセシウムは一平方メートル当たり二三万ベクレルで、放射線障害防止法で、放射線管理区域からの持ち出しが制限される汚染基準の約六倍という。また、プラント周辺と同区の荒川、旧中川沿いでは、放射線量が毎時〇・二マイク ロシーベルトを超える地点が多くあった。山内教授は「値が高い地域の位置と風向きを考慮すると、下水を通じてプラントに集まった放射性物質が処理過程で再 び大気中に放出されている可能性が高い」と主張。同会は同日、プラントの稼働停止と調査などを求め、都に要望書を提出した。

The survey was done by the Association and Professor Tomoya Yamauchi of Kobe University (radiation measurement). Cesium detected was 230,000 becquerels per square meter, 6 times as high as the limit set for the radiation control zone to restrict one from taking an item out of the control zone. Also, in the area around the plant and along the Arakawa river and the old Nakagawa river, there were many locations that registered high air radiation levels exceeding 0.2 microsievert/hour. [The "official" number measured in Shinjuku-ku is about 0.06 microsievert/hour.] Professor Yamauchi says, "Considering the locations with high air radiation levels and the wind direction, it is highly likely that the radioactive materials in the sewage collected at the plant are being released into the atmosphere through the treatment process." The Association submitted the petition to the Tokyo Metropolitan government demanding the halt of sludge processing at the plant and thorough investigation.

If they are demanding the halt, that means it is still in operation. The plant is located near the river mouth of the Arakawa River in eastern Tokyo as it flows into the Tokyo Bay. Prevailing wind is from the south, going upstream from the plant.

Tokyo Disney Land is about 5 kilometers southeast of the plant, by the way.

The Association uploaded the test result of the samples from 2 locations - athletic ground right next to the sludge plant, and a park 5 kilometers north of the plant; the test was done by a French laboratory (Association pour le Contrôle de la Radioactivité dans l’Ouest). It shows the soil in the park upstream (and downwind) from the plant having higher concentration of radioactive tellurium, iodine, and cesium than the soil taken from the athletic ground right next to the plant.

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#Radioactive Sewage Sludge and Slag in Tokyo

It was big news when the radioactive sewage sludge and slag were found in Fukushima Prefecture earlier this month (see my posts here, here and here).

And it is almost no news when the highly radioactive (170,000 becquerels per kilogram) sewage slag was found in TOKYO, and the slag's been already sold as construction materials.

Here's a report from a week ago by Nippon Television (3;48PM JST 5/13/2011):

東京都の下水処理施設から出た汚泥の焼却灰から、一キロあたり１７万ベクレルという高濃度の放射性物質が検出されていたことが日本テレビの取材でわかった。

Nippon Television's investigation has revealed that the radioactive materials in very high concentration, 170,000 becquerels per kilogram, had been found in the sewage slag from a sewage treatment facility in Tokyo.

　 東京都によると、江東区の下水処理施設「東部スラッジプラント」で３月２５日に採取した汚泥の焼却灰から、一キロあたり１７万ベクレルの放射性物質が検出 されていた。同じ時期に採取した別の２つの施設の焼却灰からも、一キロあたり１０万ベクレル以上検出されていたという。これらの焼却灰は、すでにセメント や建築資材などに再利用されている。

According to the Tokyo Metropolitan government, 170,000 becquerels per kilogram radiation was detected in the sewage slag sample taken on March 25 at Tobu Sludge Plant, a sewage treatment facility in Koto-ku. The samples taken at two additional facilities also showed radiation over 100,000 becquerels per kilogram. The slag has already been recycled into cement and other construction materials.

　国は、１２日になって福島県に対しては一キロあたり１０万ベクレルを超える汚泥は県内で焼却するなどした上で、焼却灰は容器に入れて保管すべきとの指針を出したが、福島県以外に対する基準は現在もない。

The national government issued a guidance on May 12 as to how to dispose the radioactive sludge and slag in Fukushima Prefecture, which is to burn the sludge and store the burned sludge (slag) in containers. However, there is no such standard for radioactive sewage treatment outside Fukushima Prefecture.

In comparison, the sewage slag from Koriyama City in Fukushima measured 334,000 becquerels per kilogram, and Koto-ku is 225 kilometers away from Fukushima I Nuke Plant.

In the latest test (done on May 10-12), the result for the slag at the Koto-ku facility was lower, at 18,470 becquerels/kg (cesium-134 and cesium-137). Instead, the treatment facility in Edogawa-ku (east of Koto-ku) tested high radiation at 53,200 becquerels/kg.

And the highly radioactive sludge in Fukushima is to be burned. That's just great. According to Sankei News, the national government will allow the radioactive sludge and slag with low radiation (few thousands becquerels per kilogram) to be used as cement materials, as before, as long as the radioactive materials are diluted enough to the level that has no immediate effect on health. Between 10,000 becquerels/kg and 100,000 becquerels/kg, they should be put in a temporary storage. The government guideline doesn't say what will happen when the temporary storage becomes full.

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