Tuesday, October 25, 2011

Elevated Radiation Level in the Center of Tokyo, in Ginza

An elementary school located in Ginza, Chuo-ku, Tokyo was found with a 0.80 microsievert/hour radiation spot, and a kindergarten, also in Chuo-ku, was found with 0.56 microsievert/hour spot. So-called "decontamination" effort using a power washer achieved only a modest success in lowering the radiation levels.

In both cases, the asphalt surface resisted decontamination effort, indicating radioactive materials are no longer on the surface after more than 7 months since the Fukushima I Nuclear Power Plant accident started.

From Tokyo Shinbun Tokyo local edition (10/25/2011):


Chuo-ku announced on October 24 that Taimei Elementary School (located in 5 Ginza) and Chuo Kindergarten (2 Minato) had high radiation spots that exceeded the level that the national government uses as standard for doing decontamination (0.23 microsievert/hour). It also said the decontamination was carried out.


According to Chuo-ku, 0.31 microsievert/hour radiation was measured on October 21 in part of the drain on the school yard of Taimei Elementary. Decontamination was carried out on October 22 using a high pressure washer, and the radiation level dropped to 0.22 microsievert/hour. However, the asphalt surface next to the drain measured 0.80 microsievert/hour, and despite the decontamination it only dropped to 0.56 microsievert/hour.


At Chuo Kindergarten, two locations under the rain gutter were found with 0.56 microsievert/hour and 0.42 microsievert/hour respectively on October 21. After decontamination, one location dropped to 0.22 microsievert/hour, but the other location, asphalt surface, remained high at 0.46 microsievert/hour.


The city carried out measures to keep pupils out of the area, and is planning to replace the asphalt surface.


In response to the reports of high radiation spots being discovered, the city started on October 21 to measure radiation levels in the drains and shrubs in schools and parks.


Anonymous said...

If you could get straightforward answers or advice from nuke plant operators, they would doubtless have told you power washing has a minimal effect.

We can presume TEPCO already knew this.

jmdesp said...

It sounds like the cesium got inside the melting asphalt during the hot summer. Retrospectively it's quite obvious.

Well Japanese civil engineering companies always manage to obtain some completely useless works from the government, so this time just let them remove the surface of asphalt and put a new one instead everywhere needed to lower the radioactivity level in school !

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