Monday, June 27, 2011

#Radiation in Japan: Radioactive Cesium from Ashes from Household Garbage at Waste Disposal Plant in Edogawa-Ku, Tokyo

Not a water purification plant or at a waste water treatment plant, but a plant that burns regular, household garbage in eastern Tokyo was found with a high level of radioactive cesium in the fly ashes caught in the incinerator filter.

Edogawa-ku is located at the eastern end of Tokyo. Along with its northern neighbor Katsushika-ku, Edogawa-ku seems to have been in denial of the elevated radiation levels throughout the ward, and has only recently (June 18) started to measure the radiation at multiple locations within the ward.

The Edogawa waste disposal plant is located by the Edogawa River that separates Edogawa-ku and Chiba Prefecture. The plant can burn 600 tonnes of garbage per day with 24-hour operation, with 2 incinerators. It's in a mixed residential/commercial neighborhood, with 2 elementary schools nearby, and a nursery school right next to the plant, according to the Google Map.

From Sankei Shinbun (6/27/2011):

東京都と東京23区清掃一部事務組合は27日、一般家庭ゴミなどを処理する23区内の清掃工場のうち、江戸川清掃工場で発生した焼却灰から、1キロ グラムあたり8千ベクレルを超える放射性セシウムが検出されたと発表した。同組合によると、灰はフィルターで集められ、運搬時などは密閉しているほか、施 設周辺の空間放射線量の測定結果からも、外部環境への影響はないとみている。

The Tokyo Metropolitan government and the "Clean Association Tokyo 23" (organization of waste disposal facilities in Tokyo's 23 "ku" or wards) announced on June 27 that radioactive cesium in excess of 8,000 becquerels/kilogram was detected from the fine ashes from the waste disposal plant in Edogawa-ku. The plant burns regular garbage collected from households in Edogawa-ku. According to the Association, the ashes are collected by the filter, and the filter is in a sealed container during transport. The air radiation levels have been measured around the plant, and there appears to be no effect on the environment.


According to the Tokyo Metropolitan government, it was the first time that any municipal government measured the ashes from the regular waste disposal.



There are two types of ashes as the result of incineration at the waste disposal plants: "main ashes" that collect inside the incinerator, and "fly ashes" that are collected by the filter.


Rradioactive cesium of over 8,000 becquerels/kilogram was detected from the fly ashes produced at the Edogawa Waste Disposal Plant. Cesium from the main ashes from the plant, or the fly ashes and main ashes from the other waste disposal plants was less than 8,000 becquerels/kilogram.


The fly ashes at the Edogawa plant will be stored temporarily at a facility at the plant that can shield radiation. The main ashes will be buried in the final waste processing facility.


The Tokyo Metropolitan government will continue the survey of the ashes, and will ask municipalities in Tama region [western part of Tokyo] to conduct the survey.

There is no safety standard for radioactive materials in wastes OUTSIDE Fukushima Prefecture. So, the Tokyo Metropolitan government is using the standard that the national government has set for Fukushima Prefecture, and it will bury the main ashes and fly ashes as long as the radioactive materials detected are less than 8,000 becquerels per kilogram.

Now, here's the actual survey result, dated June 27. The amount of cesium detected from the fly ashes at the Edogawa plant is 9,740 becquerels/kilogram.

Other high but below 8000 numbers (page 3):

  • Katsushika: 6,610 becquerels/kg

  • Ota: 6,030 becquerels/kg

  • Koto: 4,850 becquerels/kg

  • Meguro: 4,180 becquerels/kg

Looking at the numbers for the air radiation in the surrounding areas (page 5), contrary to what Sankei reports, the areas do seem to have elevated levels of air radiation.

For the Edogawa Plant, the air radiation level inside the plant is between 0.07 to 0.16 microsievert/hour. Outside the plant, the level is much higher, between 0.21 to 0.24 microsievert/hour.

As I said above, a nursery school is right next to the plant, and there are 2 elementary schools nearby.

Ashes, ashes, we all fall down...


Ian Goddard said...

Anyone know if all the fly ash stopped from entering the atmosphere, or does the filter just collect some of it?

This suggests that fallout is more prevalent than officials are assuming based on air-sample readings. And this is why dosimeter readings from the ground like those taken by youtube user asuperdry are most meaningful because the radionuclides fall and collect like and with dirt.

Presumably such fallout-settling is how household waste gets contaminated.

Anonymous said...

Well, even in Saitama you can easily find quite some radiation in the remains (mud) of the puddles. Especially on larger concrete or asphalt areas you will find puddles that give you a reading of up to 1 uSv/h at less than 1cm distance. At 1m you will detect nothing, since beta radiation has some difficulty to travel far in the air.

According to my Geiger counter, I get 41 cpm/0.1g (at a distance of ~5mm). If I consider the background radiation (~10 cpm) I still end up with about 5250 Bq/kg.

My experience with my Geiger counter tells me that it is roughly 10 times less sensitive than a liquid scintillation counter. This would result in a really highly contaminated hot spot more than 250km away from Fukushima.

By the way, especially small kids love to jump into these puddles and get dirty from top to bottom...

By the way, the drains in Saitama are usually at about 50% of the above value. That actually also clarifies where all the highly radiative sludge in the waste water treatment plants comes from. It is washed by the rain into the server system of Tokyo. So the good thing is that that radioactive garbage is at least getting removed from concrete areas, but the parks and playgrounds are a different story.

Anonymous said...

Sorry - correction

Please exchange the 'server' in the last paragraph of my previous post into a 'sewer'.


Anonymous said...

@ Anon 6:29 AM

You're probably right, but the post says "Not a water purification plant or at a waste water treatment plant, but a plant that burns regular, household garbage" so it is not about stuff in the sewer. The question is what are they burning that has these levels of contamination?

Anonymous said...

@ Anon 6:32 AM

My guess is grass, leafs and small twigs from gardens and parks. They are usually collected with the household garbage and they are already cutting them in the area around Tokyo.

Lets hope it is not from the contaminated dust in the vacuum cleaner bags or from the remains of the biological waste - like the peels of the healthy food from Fukushima, Ibaraki, ....

Anonymous said...

@ Anon 7:08,

let us also hope it is not from sitting at curbside waiting for pickup !

"Lets hope it is not from the contaminated dust in the vacuum cleaner bags or from the remains of the biological waste - like the peels of the healthy food from Fukushima, Ibaraki, ...."

tony smyth said...

Gardens? You'll be hard pressed to find a garden in Tokyo!!!

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