Thursday, February 23, 2012

23,300 Bq/Kg of Radioactive Cesium from a Mix of Wet Soil and Dead Leaves in Mizumoto Park in Tokyo

(Sorry, you can't just multiply the number by 65 and compare it to the Chernobyl evacuation level. Read on to find out why.)

The Mizumoto Metropolitan Park is located in the eastern Tokyo with elevated radiation levels. The Communist Party delegation of Tokyo Metropolitan Assembly, who has done the survey of radiation levels in Tokyo from very early on in the nuclear crisis, released the result of the latest survey in one of the Metropolitan parks in Tokyo.

The survey found 23,300 becquerels/kg of radioactive cesium from a wet mix of dirt and dead leaves in one location in the Mizumoto Park in Katsushika-ku, Tokyo (No. 4 location in the table posted below).

The delegation did three tests at this location with 2 samples taken on February 15. The third test was done on February 18 by combining the two samples taken on February 15 and tested on February 16 and 17.

It may be important to note that the Communist Party delegation tested the top 1 centimeter of the soil, and the top 1 to 2 centimeters of the soil and dead leaves mixture. The measured numbers may therefore be higher than the samples taken from the top 5 centimeters, which is a normal procedure in the government tests.

To derive "becquerel/square meter" from "becquerel/kg", you multiply "becquerel/kg" number by 65, but that only applies if the soil is taken from the top 5 centimeters. (Ibaraki Prefecture's measurement page as reference, here.)

From the Communist Party delegation of Tokyo Metropolitan Assembly website (English translation is mine; the last two rows are the reference):


According to Yomiuri Shinbun article (2/22/2012), "the Ministry of Education and Science sets the standard of radiation that requires decontamination as locations that test "1 microsievert/hour higher than the surrounding areas", and the Tokyo Metropolitan Bureau of Environment says "There is no need for decontamination at this point.""

Never mind that the Ministry of Environment's decon standard is 0.23 microsievert/hour.

The surface radiation levels and the air radiation levels at 1 meter off the ground all exceed 0.23 microsievert/hour. The highest surface radiation level was 1.54 microsievert/hour, and the highest radiation level at 1 meter was 0.74 microsievert/hour.

Before the nuclear accident, the average background radiation level in Tokyo was slightly above 0.03 microsievert/hour. That was the level right before something very radioactive arrived from Fukushima on March 15, 2011 sometime between 4AM and 4:59AM. (See the Tokyo Metropolitan government's own measurement, here, as the radiation in Shinjuku went from 0.0347 microsievert/hour average between 3AM and 3:59AM to 0.1 microsievert/hour average in the next hour. )

What the Tokyo Metropolitan government needs to do is to scrape 1 centimeter of the soil under the trees and shrubs and remove dead leaves to lower the radiation. But they openly say they are not going to do anything.

================

(UPDATE from Kontan Bigcat on Twitter: the 65 multiplier applies only to soil taken from 5 centimeters AND with the soil density (dry) of 1.3 gram/cubic centimeter.

17 comments:

Yosaku said...

Great post, ex-skf.

I would also point out that even if they were to take soil from the top 5 centimeters as prescribed and multiply by 65 to obtain Bq/m^2, the comparison to the Chernobyl evacuation standards would still not be appropriate because the Chernobyl standards applied to broad area levels, not hot spots.

Similarly, the Japanese ministries seem to have taken the position that the applicable clean-up level for hot spots is 1 uSv/hr, while the applicable level for broader areas is 0.23 uSv/hr. Prefectures and wards can have their own limits, however. Kawasaki, for example, cleans up anything exceeding 0.19 uSv/hr.

(http://ajw.asahi.com/article/0311disaster/fukushima/AJ201201030001z)

Anonymous said...

The only thing that has to be 'cleaned up' are the Japanese goverment and their officials.

Anonymous said...

THIS IS GREAT NEWS, TOKYO'S NOT THAT CONTAMINATED AND IT'S EASY TO CLEAN UP RADIATION, i SEEN THEM CLEAN RADIATION IN USA AND EUROPE. I BET THE UNAGI IS NOT THAT CONTAMINATED EITHER SO LITTLE OF NUCLEAR FUEL PARTICLES WILLNOT HURT ANYONE, IT'S OK TO HAVE A LITTLE BIT OF NUCLEAR FUEL AND ISOTOPES IN YOU AND AROUND YOU, WATCH, JAPAN WILL BE OK, IS ONLY SMALL AMOUNTS RIGHT.

Anonymous said...

COPS?RETARDS, WORKERBEES?< RETARDS, 100%?<RETARDS!!!! WATCH YOUR CHILDREN DIE< RETARDS

Chibaguy said...

Caps only person, leave because you have nothing to add. You contribute so little to the discussion that if I was Ex skf I would send your comments to daiichi.

Anonymous said...

Finnish troll strikes again.

Anonymous said...

ur dum










/fer real

Steveo said...

This one from the Frying Dutchman, a Japanese musician.

19 minutes dialogue type musician rant on the street in Japan.

He really "nails it" with good subtitles. He hit on the whole farce and back room dealings involved with nuclear power.

The simple fact is---we do not need nuclear energy anyone.

Watch it and drop a comment or two.

Yes he nailed it, another nail in the coffin of nuke, good riddance!

http://nukepimp.blogspot.com/2012/02/drying-dutchman-nails-nuclear-power.html

Anonymous said...

Finnish troll changes his so called "style" to all caps tech lingo but still writes the same imperseptive nonsense crap. How many places have you been banned from dude? Take a hint already you bombastic dolt.

Anonymous said...

Tokyo background levels before the accident were not 0.03 micro/hour. Those numbers are from a NaI scintillator measuring station located on the top of a 10-story building. With a geiger counter at ground level you would have probably measured around 0.07-0.09 micro/hour before March 2011: http://roseparsley.iobb.net/hotart/radiation.html

arevamirpal::laprimavera said...

@anon at 2:00PM, background in Tokyo as measured by citizens using personal survey meters borrowed from the Ministry of Education before March 11, 2011 shows 0.038 microsievert/hour.

http://rika.s58.xrea.com/wiki.xcg?page=%B4%C4%B6%AD%C4%B4%BA%BA%A5%DE%A5%CB%A5%E5%A5%A2%A5%EB%A1%A1%A1%C1%A1%A1%BC%AB%C1%B3%CA%FC%BC%CD%C0%FE%CE%CC%A4%CE%C2%AC%C4%EA

Anonymous said...

That Hakarakun device seems to be a scintillator, not a geiger counter.

Anonymous said...

But anyway, just check Hino's geiger counter, which was measuring 0.11 micro/hour on December 2010: http://park30.wakwak.com/~weather/geiger_index.html
Or the measurements by Dr. Hasegawa in Odawara, which are around the same levels: http://www.geocities.jp/pinealguy/physics/2011/2011.html

Anonymous said...

Many people in Tokyo use scintillation survey meters today to measure the radiation levels now, and they are above 0.06 microsievert/hour in most locations.

Anonymous said...

Anon, I know. The Tokyo metropolitan government is one of those measuring more than 0.06. Check here to see the differences between different models of scintillators and geiger counters taking readings at 1m and 5cm from the ground: http://monitoring.tokyo-eiken.go.jp/radiation_measurement.html

This is for Shinjuku. Had they done the same experiment in eastern Tokyo or, even more, the hotspot around Kashiwa/Matsudo they would have gotten higher numbers.

arevamirpal::laprimavera said...

Tokyo Metropolitan government now measures radiation levels at 3 locations in Tokyo: Shinjuku, Edogawa-ku (east), and Kodaira City (west). http://monitoring.tokyo-eiken.go.jp/

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