Wednesday, January 11, 2012

Disaster Debris from Onagawa, Miyagi: 133 Bq/Kg of Radioactive Cesium

which, if incinerated all by itself, would become ashes with maximum 4389 becquerels/kg of radioactive cesium, using the calculation by the Ministry of the (Destruction of) the Environment (multiply by 33).

The image below is from the information handed out to the residents who live near the incineration plants in Ota-ku and Shinagawa-ku in Tokyo, where the disaster debris from Onagawa-cho, Miyagi Prefecture was taken and burned in December. The entity in charge of burning the disaster radioactive debris from Miyagi in the 23 Special Wards ("ku") in Tokyo is the Clean Association Tokyo 23, who created the handout.

As you see, in the test conducted at Ishinomaki Clean Center, Onagawa-cho's regular waste is already radioactive, resulting in fly ashes with 2,200 becquerels/kg of radioactive cesium. Then, they measured the radioactivity by mixing the disaster debris to the regular waste, with 20% of the mix from the disaster debris, and burning. That resulted in fly ashes with 2,300 becquerels/kg of radioactive cesium.

This official information doesn't say whether the radioactivity of the disaster debris is the average or from one sample, or whether it was wood, plastic, or something else. It doesn't even say whether it was the debris with 133 becquerels/kg that was mixed and burned.

Now, many people who are all for bringing disaster debris from Miyagi and Iwate to Tokyo argue that since Tokyo is contaminated so much already, it doesn't make any difference, that Miyagi's disaster debris is less radioactive than Tokyo's regular garbage.

Is it?

Here's the latest test result (December 2011) of fly ashes at the municipal incinerators under the management of the Clean Association:

There are only three incineration plants whose radioactive cesium in fly ashes exceeds that of Onagawa-cho (circled in red), with two of them exceeding the level of Onagawa debris.

If we listen to those who believe it is logical to bring low-contamination debris/garbage to high-contamination areas and process, then most of the regular garbage should be shipped to Miyagi and be burned and buried there.

The mayor of Rikuzen Takata City in Iwate Prefecture thought it would be much better to process disaster debris in the city and wanted to build a new plant dedicated to disaster debris. He consulted the Prefectural government who turned down his request by saying the application procedure alone would take at least 2 years.

Disaster debris is as good as money. There are enough municipalities throughout Japan in a dire financial condition and willing to accept debris in exchange for subsidies. As Haruki Madarame of the Nuclear Safety Commission said 7 years ago, "It's all about money, isn't it?" He was talking about nuclear waste then.


Hélios said...

Found this (in japanese, if you please...:

What is it ?

Anonymous said...

So the ashes produced after the debris from Onagawa is processed contain 133 Bq/Kg?

arevamirpal::laprimavera said...

@anonat 1:48PM, No.

Debris before burning: 133 Bq/kg
Fly ashes after burning disaster debris mixed with regular garbage: 2300 Bq/kg

Anonymous said...


But it says 焼却灰等 (incineration ashes): 133 Bq/Kg (Measured in Ishinomaki)

I seems adding 20% of debris from Onagawa only adds 100 Bq/Kg to the already contaminated fly-ash (from 2,200 to 2,300 Bq/Kg) from processing Tokyo garbage.

Anonymous said...

@anon at 2:57AM, "But it says 焼却灰等 (incineration ashes): 133 Bq/Kg (Measured in Ishinomaki)" - no it doesn't. 133 bq/kg is not from the ashes. It's from the debris before being burned.

Also, they are measuring FLY ASHES.

Read English and do the math. If you do read Japanese and still write what you wrote, you are trying to mislead.

1 kg of FLY ASHES resulting from burning debris (20%) and regular garbage (80%) is 2300 bq/kg. Regular garbage (100%) results in 2200 bq/kg

Math question: What would be the becquerel of fly ashes if debris (100%) were burned?

Middle-school math, I believe.

Anonymous said...

If adding 20% of debris from Onagawa adds 100 Bq to the total contamination in the fly ashes, it means that burning only the debris for would generate fly ashes with 2700 Bq/Kg? Seeing the ratio of contamination between bulk ashes and fly ashes at the incineration facilities in Tokyo, that figure of 133 Bq/Kg from Ishinomaki it's clearly from the bulk ashes.

arevamirpal::laprimavera said...

No, 133 bq/kg of cesium is from ONAGAWA DISASTER DEBRIS itself, BEFORE BEING BURNED at Ishinomaki incineration plant.

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