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):
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.
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.