Aug 02

#Radioactive Fallout in Tokyo in March: Iodine, Cesium, Tellurium, Radioactive Silver (EX-SKF, August 1, 2011):

Silver-110m, half life about 250 days, wouldn’t have been discovered unless the control rods had melted at Fukushima I Nuclear Power Plant.

There was the news in early April that radioactive silver was detected in South Korea. There was no way the same nuclide wasn’t falling in Japan if it could fly all the way to Korea, I thought.

Sure enough.

It was not until 2PM on July 29 that the Ministry of Education and Science announced the “reading of environmental radioactivity level by prefecture [Fallout]” for March 2011.

What’s the point of telling us now? Just for the record?

Radioactive materials that were falling in the Kanto region in March, other than iodine-131, cesium-134 and -137, are: Continue reading »

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Jun 07

#Fukushima I Nuke Accident Tellurium-132 Conundrum: Case of Missing Iodine and Cesium (EX-SKF, June 6, 2011):

This blog posted on June 3 that the Nuclear and Industrial Safety Agency revealed tellurium-132 had been detected 6 kilometers from the plant on the morning of March 12, before the venting of the Reactor 1.

Well, that Yomiuri Shinbun article in that post was incomplete, to say the least. It turns out that it was not only one location in Namie-machi where radioactive tellurium was detected but also at 3 other locations: one more location in Namie-machi, one location in Okuma-machi, and one location in Minami-Soma City.

Moreover, the same air radiation survey done by Fukushima Prefecture detected more volatile iodine-131 at half as much as tellurium, but it hardly detected any cesium-137 except at one location.

It’s not supposed to happen that way, if what we’ve been told about the circumstance is correct, as a Kyoto University professor says in the article in Tokyo Shinbun, below.

(I’ll go look for the information at NISA, and update if I find more data.)

Tokyo Shinbun (6/5/2011; emphasis added) reports the puzzling detection of tellurium-132 on March 12:

東日本大震災の発生翌日、福島第一原発で爆発が起きる前に福島県が行ったモニタリング調査で、金属性で飛散しにくい放射性のテルルが原発から約七 キロ離れた同県浪江町などで検出されていたことが分かった。拡散しやすい揮発性の放射性ヨウ素より多く検出されており、早い段階で金属性の放射性物質が広 く飛散していた。テルルはレアメタル(希少金属)の一種で、放射性同位体のテルル132の半減期は三日余り。主にベータ線を出す。

It has been revealed that radioactive tellurium, a metal that is hard to disperse in the atmosphere, was detected on the next day [March 12] of the earthquake in Namie-machi, 7 kilometers from the plant, and other locations according to the result of the monitoring survey done by Fukushima Prefecture before the explosion at Fukushima I Nuclear Power Plant that day. More tellurium was detected than more volatile radioactive iodine. It shows that metallic radioactive materials [like tellurium] dispersed wide from an early stage [of the accident]. Tellurium is a rare metal, and tellurium-132 has a half-life of about 3 days, emitting beta rays.

データは保安院が三日夜に公表。三月十二日朝から十三日夜までの大気を調べたもので、大半がこれまで未公表だった。テルル132は十二日朝から昼 すぎにかけ、浪江町の二カ所と大熊町、南相馬市で検出。濃度は一立方メートルあたり法定限度の二〇ベクレルを超える一一九~二三ベクレルだった。

The data was revealed on June 3 evening by the Nuclear and Industrial Safety Agency. The monitoring survey of the air was done from March 12 morning till March 13 night, and the most of the data had been withheld until June 3. Tellurium-132 was detected from the morning till the early afternoon on March 12 at 2 locations in Namie-machi, and Okuma-machi and Minami-Soma City. The concentration was between 23 to 119 becquerels per cubic meter, exceeding the safety limit of 20 becquerels per cubic meter.

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May 23

ACRO is a NPO that was created just after the Chernobyl disaster in 1986 and has been monitoring radioactivity in the environment for 25 years together with the concerned populations. It runs a laboratory with the highest scientific standards that is accredited by the French authorities. Its activity is complementary to the official monitoring because it is aimed to answer to the questions of the population.

ACRO was involved during several years in a project in the contaminated areas of Byelorussia to implement radioactivity measurement stations in villages and develop a culture of radioprotection. The European Union and the Swiss ministry of foreign affairs supported our contribution.

Results of ACRO’s monitoring in Japan (05/17/2011 update):

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After the nuclear disaster of Fukushima, ACRO has extended its Citizen Watch of Radioactivity in the Environment to Japan.
We have received samples from the Fukushima and Miyagi prefectures that show an alarming contamination.

• Soil and water were collected by Japanese citizens on the 31st of March 2011.

• Vegetables and mushrooms taken on the 2nd of April in the Sendai area by French journalists.

Vegetables bought on the 22st of April in a supermarket in Osaka.

Analysis of the soil in various locations in Japan (12-18th april 2011)

Seawater collected on the 16th of april in Soma (Fukushima prefecture)

Comments :

The contamination is very large and comparable to the environment of Chernobyl.
The Maeda field of Iitate-mura is the most contaminated place.
Iodine contamination is the largest and it is better to evacuate the population.
On the long time range, cesium 137 is the most worrying element because it has a half-life of 30 years.

Regarding the results expressed in Bq/kg of soil, most of them are higher than the limit fixed by the Japanese authorities at 5 000 Bq/kg for agriculture. Rice cannot be cultivated.

The data expressed in Bq/m² can be compared to the definition of the zones in Byelorussia after the Chernobyl disaster (law of 1991) :
185 000 – 555 000 Bq/m²: migration allowed
555 000 – 1 480 000 Bq/m²: right to rehousing

Most of the results are higher than one of these limits.

Read the press release in French (11th of April 2011)

Download the analysis report for the first samples

(Click on images to enlarge.)


Comments :

The results show that the four samples collected in the Sendai area (80 km from Fukushima dai-ichi) are tainted with artificial radionuclides released from the crippled NPP.

Densities of cesium 137 measured in the vegetables (Chinese cabbage, komatsuna and tsubomina) are above the limits set by Japanese authorities (500 Bq/kg). These vegetables should not be eaten.


ND: Not Detected


Comments :

ACRO has analyzed samples collected in various locations in Japan by Japanese citizens. Except for Kobe, all these samples are contaminated by numerous radioelements coming from the fallouts of Fukushima.
The large densities in the straw are due to the fact that straw is light: the same amount of pollution falling on a square meter gives a contamination per kilogram far larger with straw than with soil.
The previous analysis that we did on soil samples coming from Fukushima prefecture showed that iodine 131 was dominating. But this element has a quite short half-life (8 days) and disappears relatively quickly: the densities measured this time are lower than the ones for caesium.
The tellurium 129m decays into iodine 129 that has a very long half-life: 16 millions years. This element should be carefully monitored in the surrounding the nuclear power plant.
A mid-term, caesium 137 will be the most problematic element: the densities measured are all below the limit of 5 000 becquerels per kilogram fixed by the Japanese authorities for the culture of rice.
If we calculated the contamination of the caesium 137 in becquerels per square meters, all the values in Fukushima prefecture are higher that the limit of 185 000 becquerels per square meter that gives right to migration in Byelorussia.
The contamination in the Miyagi prefecture is also quite large, confirming the large contaminations of the vegetables that we measured in this prefecture.

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