Radioactive Strontium Found in Central Tokyo

(UPDATE-2) Asahi Shinbun carried the news:



(UPDATE) So far, it is dead silence from the Japanese MSMs; even the critical papers like Tokyo Shinbun is mum on strontium in Tokyo.

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A citizen group did the soil survey of three locations in central Tokyo, and had the soil samples tested for radioactive cesium and strontium. All three had both.

Summary of reporting by Yasumi Iwakami, independent journalist:

Locations and amounts of radioactive materials:

Kiyosumi Shirakawa Station, Koto-ku:
Radioactive cesium (134 and 137 combined): 19,126 Bq/kg
Radioactive strontium (89 and 90 combined): 44 Bq/kg

Yurakucho Station, Chiyoda-ku:
Radioactive cesium (134 and 137 combined): 20,955 Bq/kg
Radioactive strontium (89 and 90 combined): 51 Bq/kg

Front of the Ministry of Economy, Trade and Industry, Chiyoda-ku:
Radioactive cesium (134 and 137 combined): 48,176 Bq/kg
Radioactive strontium (89 and 90 combined): 48 Bq/kg

It's a poetic justice that the amount of radioactive cesium is the highest at METI. I hear TEPCO's headquarter building in Tokyo also enjoys rather high radiation.

Iwakami cautions that radioactive strontium may be confirmed to have come from Fukushima only after the detailed analysis at a laboratory that can separately measure strontium-89 and strontium-90. The presence of cesium-134 seems to prove that at least radioactive cesium found in the soil samples is of Fukushima origin.

I believe there is only one or two laboratories in Japan that does that; one of them is the laboratory that TEPCO uses for the radionuclide analysis (Japan Chemical Analysis Center).

It looks like the national government may make a comment or two on this discovery later, some people are hoping that the government does. What would the government say? Let me guess... How about "No immediate effect on health", and "We should only worry about cesium, forget the rest".

By the way, you may recall the discovery of radioactive strontium on the rooftop of an apartment building in Kohoku-ku in Yokohama City in October. There has been no response from the city to the citizen who measured it, and no action from the city whatsoever on removing the highly radioactive sediment from the rooftop or decontaminating.

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Three Plutonium Brothers Revisited

Now that the national government has finally owned up to the existence of plutonium and strontium outside Fukushima I Nuclear Power Plant (in case of strontium-89, as far as Shirakawa City, 79 kilometers from the plant), it seems like a good time to revisit what the government researchers were saying about "heavy" plutonium that we didn't need to worry about a bit, back in March and April.

Particularly the second guy, Keiichi Nakagawa of Tokyo University, said plutonium was so heavy it wouldn't disperse, and only the workers at the plant needed to worry.

(From my post on 8/8/2011)

Nakagawa: To begin with, this material is very heavy. So, unlike iodine, it won't disperse in the air. Workers at the plant MAY be affected. So, I'd caution them to be careful. But I don't think the public should worry.

My original post has the transcript (translation) of the video, which was captioned by Tokyo Brown Tabby. The Japanese video was compiled by sievert311.

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Ministry of Education Maps of Plutonium and Strontium Show Wide Dispersion of Supposedly Heavy Nuclides

On September 30 the Ministry of Education and Science posted the blurry maps plotting the locations where plutonium and strontium have been detected.

(On the same day, September 30, the national government abolished the evacuation-ready zone between the 20 and 30 kilometer radius from the plant, "allowing" the residents to return.)

The Ministry's 10-page document is in Japanese only for now.

According to the Ministry, the survey for plutonium and strontium was carried out in early June to early July in 100 locations within the 80-kilometer radius from Fukushima I Nuclear Power Plant by government researchers. One location each in 59 municipalities within the 80-kilometer radius was picked, based on the air radiation level and the high population density. The remaining 41 locations were picked from within the 20-kilometer radius evacuation zones.

The Ministry claims it is the first time plutonium has been detected outside the plant, but all that means is that it is the first time a government ministry has admitted to the existence of plutonium outside the plant. As the readers of this blog already knows, as early as April the researchers were taking soil samples outside the plant and have them tested for plutonium and found it (see here and here).

The Ministry's conclusion is that the amount of plutonium is not that big to cause any alarm, and that they should focus more on the decontamination of cesium-134 and -137.

As for strontium, the Ministry does sound a bit more nervous. It says the ratios of radioactive strontium to cesium-137 in these locations were calculated; the ratios varied too much, indicating there was no correlation between the deposition of radioactive strontium and radioactive cesium. The Ministry will conduct further, more detailed study in locations that had higher strontium ratios.

Plutonium-238 (top number in the map), Plutonium-239+240 (bottom number):

Strontium-89 (top number in the map), -90 (bottom number):

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#Fukushima I Nuke Plant: Radioactive Strontium from Ocean Soil Off the Plant

Strontium-89 and strontium-90 have been detected in soil and ocean water, but for the first time they have been detected in ocean soil 3 kilometers off the coast where Fukushima I Nuclear Power Plant is located. The samples from 2 locations were taken on June 2.

The Ministry of Education and Science have announced the detection of radioactive cesium from the ocean soil, but has been silent about strontium.

Strontium-89 (half-life 51 days) was detected at 140 becquerels/kg at one location (off Minami-Soma City), 42 becquerels/kg at the other (off Naraha-machi). Strontium-90 (half-life 29 year) was detected at 44 becquerels/kg at one location, 10 becquerels/kg at the other.

There is no safety standard set for radioactive strontium. The amount detected in regular sampling surveys from 1999 to 2008 at Fukushima II (not I) was ND (not detected) to 0.17 becquerel/kg.

The survey also detected a minute amount of plutonium-239+plutonium-240.

Clearly, no one cares any more in Japan. No major news outlet carried the news, not at least on line. The only paper that carried this news was the Japan Communist Party's newspaper, Akahata (red flag).

Here's TEPCO's press release on June 25, 2011:

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#Radioactive Strontium from Groundwater at Fukushima I Nuke Plant for the First Time

Radioactive strontium (strontium-89 and -90) was detected from the sub-drain pits at the Reactor 1 turbine building and the Reactor 2 turbine building. The samples were taken on May 18.

It is the first time that radioactive strontium was detected from the groundwater at Fukushima I Nuclear Power Plant.

The sub-drain pits are located outside the turbine buildings to collect groundwater so that the basements don't get flooded.

From TEPCO's press release on June 12, English labels added by me (measurement unit: becquerel/cubic centimeter):

In addition, strontium-89 and -90 were detected from the seawater samples taken on May 16 at 3 locations: at the water intake canals for the Reactors 1 through 4, inside the silt screen for the Reactor 2, and inside the silt screen for the Reactor 3.

From TEPCO's English press release on June 12 (measurement unit: becquerels/liter, or 1000 cubic centimeters):

The amount of strontium-90 in the seawater inside the silt fence for the Reactor 3 was 240 times as high as the legal limit allowed for nuclear plant operations.

Note that the sub-drain water analysis is in becquerels/cubic centimeter, and the seawater analysis is in becquerels/liter (1000 cubic centimeter). Obfuscate, obfuscate. I'll translate the numbers for the sub-drains into liters to compare. (Or if someone can do it for me, I'd much appreciate.)

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