Japan earthquake - contamination & consequences outside Fukushima NPP

[tsutsuji]

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201206140067 "There are two major theories on why the cyanobacteria in the black soil has such high levels of radiation, but nothing has been confirmed."

 

[Azby]

(This has been cross-posted)
I attended the talk at Temple Univ. in Tokyo on Tues. night (July 3), at which Dr. Ryu Hayano, Nicholas Sternsdorff, and Satsuki Takahashi spoke. I was particularly interested in hearing what Dr. Hayano had to say, because he has been spearheading many important efforts in Fukushima, such as measuring the radiation in school lunches and measuring people's internal contamination with whole body counters. His name has come up quite often here. His work has been extremely conscientious and reliable, and has brought him into conflict with the government and his university at several points. His presentation was a model of clarity, and he engaged the audience very well by dotting it with questions which we answered by holding up sheets of paper with "T" or "F." *Such as, "About 10% of food from Fukushima has exceeded the 100Bq/kg standard," *(F, only 2%), and "No milk from Fukushima has been shown to be contaminated" (T, none has). His slides are available here:

http://www.slideshare.net/safecast/temple-u-20120703

Hopefully a video of his talk will be posted soon as as well. I'd like to give a brief summary of what he said.

--Their WBC measurements in Minamisoma and Hirata have been very extensive and accurately performed. *Between Nov 2011 and May 2012 they've measured about 10,000 people. In Hirata, about 15,000 people have been measured. The vast majority have shown no internal contamination. The levels of others has been extremely low compared to people in Russia, Ukraine, and Belarus 5-10 years after the Chernobyl accident. In fact the levels are much lower than the average internal contamination of Japanese people measured in 1964 at the height of nuclear weapons testing. More on that below.

--He spoke a lot about calibration issues and how they solved them. He said that around the end of last year, CRMS, who had been conducting WBC measurements in Fukushima, was about to release a report claiming that the entire population of Fukushima had 20Bq/kg of internal cesium contamination. Dr. Hayano insisted on re-analyzing the data himself to see if their measurements were accurate or not. By calibrating their machine with a plastic "phantom" known to have 0Bq/kg, he determined that their reading of "20" should have been "0." He likened it to using a scale that was set to "20kg" when no weight was on it to weigh people. So the internal contamination of almost everyone CRMS had measured was 0Bq/kg! *This has been borne out in subsequent measurements. (Imagine what we'd be dealing with if CRMS had released that report!)

--They have remeasured everyone who showed internal contamination after a period of months, and based on that have shown that in almost every case people's body burden of cesium has been sharply decreasing; the slopes of the decrease indicate that most of these people are consuming close to 0 Bq/day. Therefore he concludes that the food screening has been very effective. *Of 10,000 people only 2 showed an increase between Nov 2011-May 2012, and they were farmers who have been eating a lot of their own food.

-- "Duplicate portion" measurements of food were conducted with 100 families in Fukushima in April 2012. Only 10 consumed any contaminated food; of those, only one family received more than 10Bq/kg --12 Bq/kg to be exact (the natural radioactive potassium each family consumed however ranged from about 20-50 Bq/kg). Based on the WBC measurements and these studies he expects that very few people in Fukushima will have more than 0.01mSv/yr internal exposure. This is so vastly lower than the 100mSv/yr risk level or even the stricter 10mSv/yr level promoted by others, that he concludes that "there is no health risk." This is an unpopular stance as we all know, but it's based on very solid measurements.

--Only 2% of the 53,000 food samples tested by local gov'ts since the new 100 Bq/kg standards came into effect have exceeded this standard. *No milk from Fukushima has been shown to be contaminated yet; no contamination has been found in school lunches in Minamisoma since they started measuring them in Jan 2012.

--On the other hand, soil in Fukushima is very contaminated, and items like wild boar, wild berries, etc. show high levels, so people will have to be very careful to continue effective monitoring for years to come.

--Because the internal contamination has been so low, he thinks that external contamination may present a relatively greater risk (but still very small). Based on glass badge results from Fukushima City, Minamisoma City, Koriyama City, and Soma City, most people there are receiving less than 1mSv/yr.

--In 1964, due to nuclear testing, the entire population of Japan was consuming 5 Bq/kg of Cs137 in their food every day, and this continued for over a year, with average body burdens of 550 Bq. This is much greater than the average levels they have seen in Fukushima so far. He suggested that the exposure in 1964 has not been directly linked to any measurable increase in illness, even after almost 50 years, and that the Fukushima exposures will not either.

--Afterward, I asked him his opinion about the recent WHO report on exposures, and he got very agitated and said it was terrible, because it overestimated exposures so blatantly. *He will be bringing his findings to the UN in a few weeks to push for the data to be included in the WHO Fukushima health risk report due out in a few months.

 

[tsutsuji]

http://radioactivity.mext.go.jp/ja/contents/6000/5269/24/203_0518.pdf.pdf Shikoku helicopter map
http://radioactivity.mext.go.jp/ja/contents/6000/5445/24/203_0608Kin.pdf Kinki region helicopter map
http://radioactivity.mext.go.jp/ja/contents/6000/5515/24/203_0615.pdf Chugoku region helicopter map

 

[zapperzero]

RT reports 300 contaminated Japanese cars were stopped by Russia at the border since the accident.

http://www.rt.com/news/radioactive-japanese-cars-russian-border-624/

 

[tsutsuji]

http://pubs.rsc.org/en/content/articlelanding/2012/ee/c2ee22019a John E. Ten Hoeve and Mark Z. Jacobson, "Worldwide health effects of the Fukushima Daiichi nuclear accident", Energy Environ. Sci., 2012, Advance Article, DOI: 10.1039/C2EE22019A, Received 23 Apr 2012, Accepted 26 Jun 2012.

http://green.blogs.nytimes.com/2012/07/19/trying-to-tally-fukushima/ Some comments about the above article.

 

[Azby]

http://pubs.rsc.org/en/content/articlelanding/2012/ee/c2ee22019a John E. Ten Hoeve and Mark Z. Jacobson, "Worldwide health effects of the Fukushima Daiichi nuclear accident", Energy Environ. Sci., 2012, Advance Article, DOI: 10.1039/C2EE22019A, Received 23 Apr 2012, Accepted 26 Jun 2012.

http://green.blogs.nytimes.com/2012/07/19/trying-to-tally-fukushima/ Some comments about the above article.

Thanks for the links, Tsutsuji.
The paper has generated a lot of commentary. Quite a few people I know have dismissed the mortality and morbidity findings as impossibly low, while quite a few others think they are wildly over-stated. For those who haven't read it yet, the authors predict between 15 to 1,300 cancer mortalities (with a mean of 130) and from 24 to 2,500 cancer cases (with a mean of 180). They point out that approx. 600 deaths have been attributed to the evacuation itself.

This article by Mark Lynas, which attacks the paper as "junk science," has a very lively comments section with a strong back and forth between Jacobson and Lynas, as well as many others:

http://www.marklynas.org/2012/07/fukushima-death-tolls-junk-science/

Jacobson has collected supplementary info, comments, and replies here:
http://www.stanford.edu/group/efmh/jacobson/fukushima.html

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120801/1230_tako.html Octopus fished in the Fukushima waters was sold in Tokyo and Nagoya for the first time since the accident
http://mainichi.jp/english/english/newsselect/news/20120802p2a00m0na009000c.html "First seafood shipment from Fukushima Pref. made to Tsukiji market since nuke disaster"

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120727/1645_kuni.html decontamination work performed under the direct management of the national government was started for the first time in the evacuation zone, in Tamura city, on 27 July. On that day they did such things as removing fallen leaves at the cemetery, in preparation for the traditional visit at the Obon festival on 15 August. The goal for Tamura is to ultimately decontaminate 400 houses and 420 hectares of forests by March 2013. The decontamination efforts in the 11 cities and villages of the evacuation zone is planned to be completed by the end of March 2014. The Ministry of environment was supposed to prepare the plans by March of this year but in 6 cities and villages such as Futaba, Namie and Tomioka, the plan has not been prepared yet. Among the cities and villages where the plan was prepared, only in two of them, Tamura and Naraha have the contractor companies been decided.

 

[clancy688]

Nature: "The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly"

The collapse of the Fukushima Dai-ichi Nuclear Power Plant caused a massive release of radioactive materials to the environment. A prompt and reliable system for evaluating the biological impacts of this accident on animals has not been available. Here we show that the accident caused physiological and genetic damage to the pale grass blue Zizeeria maha, a common lycaenid butterfly in Japan. We collected the first-voltine adults in the Fukushima area in May 2011, some of which showed relatively mild abnormalities. The F1 offspring from the first-voltine females showed more severe abnormalities, which were inherited by the F2 generation. Adult butterflies collected in September 2011 showed more severe abnormalities than those collected in May. Similar abnormalities were experimentally reproduced in individuals from a non-contaminated area by external and internal low-dose exposures. We conclude that artificial radionuclides from the Fukushima Nuclear Power Plant caused physiological and genetic damage to this species.

http://www.nature.com/srep/2012/120809/srep00570/full/srep00570.html

 

[cockpitvisit]

According to the EX-SKF blog, this research is flawed and it is normal for these butterflies to have genetic defects in colder climates (the natural habitat is Okinawa):

http://ex-skf.blogspot.com/2012/08/butterfly-mutations-caused-by-fukushima.html

 

[tsutsuji]

http://radioactivity.mext.go.jp/ja/contents/6000/5847/24/203_0727.pdf Hokkaido helicopter map

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120821/1930_plutonium.html The ministry of education and science released a study performed last June and July, taking Earth samples in Fukushima prefecture and looking for plutonium concentrations. Plutonium was found in 10 locations. 0.69 Bq/m² of Pu238 and 2 Bq/m² of Pu239 and Pu240 put together were found in Iitate. It is thought to be a release from the nuclear accident. Plutonium had been found in 6 locations in a previous survey performed in September 2011.

http://radioactivity.mext.go.jp/ja/contents/7000/6030/24/5600_0821.pdf The ministry of education and science's plutonium survey

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120824/index.html The testing of each bag of rice grown in Fukushima prefecture started with 14 bags (420 kg) of early rice in Nihonmatsu on 25 August. 188 testing equipments have been installed in farming cooperatives, etc. for a cost of 5 billion yen. Each bag (30 kg) is tested in 15 seconds. The equipment displays an OK symbol meaning the rice is below the 100 Bq/kg limit. The main harvest is expected in the last 10 days of September, producing a quantity of around 360,000 tons.

 

[mheslep]

Cal Berkeley physics professor Richard Muller's Fukushima radiation impact article in the WSJ here, taking issue with Richard Garwin's figure of 1500 cancer deaths over 70 years.

...Dr. Garwin uses the same numbers that I use, but he extrapolates forward in time 70 years to the continuing damage that residual radiation could cause, assuming that the radiation cannot be covered, cleaned or washed away, and that the population of Fukushima doesn't change. Moreover, he ignores the sort of argument that I have made about the Denver dose and includes in the calculation the numbers of deaths expected from tiny doses, assuming that even small exposures are proportionately dangerous. (This is an assumption that has also been adopted by the U.S. National Academy of Sciences.)

I don't dispute Dr. Garwin's number, but I believe it has to be understood in context. If you apply the same approach to Denver , you have to take into account the fact that the Denver dose is delivered every year. Over 70 years, it sums to 0.3 rem times 70, or 21 rem per person. If you multiply that by 600,000 people (the current population of Denver) and divide by the cancer dose of 2,500 rem, you get the expected cancer excess in Denver. That figure is 5,000, over three times higher than Dr. Garwin's number for Fukushima.

I am uncomfortable with these large numbers of predicted deaths. They are based on a theory that assumes proportionality in the way that radiation increases the likelihood of cancer—a theory that has never been tested, will not be tested in the foreseeable future, and which is known to fail for leukemia.

I can't be sure that the theory is wrong, but I consider these relatively large numbers for Denver and Fukushima to be misleading. Remember that Denver has a lower cancer rate than the rest of the U.S., not a higher one. There is a strong argument for ignoring radiation dangers below the level of the Denver dose. In doing so, we would be ignoring risks that are unobservable and which we routinely ignore (and properly so) in other circumstances.

 

[zapperzero]

The DoD has published estimated dose rates for locations where US personnel have lived and worked during operation Tomodachi.

https://registry.csd.disa.mil/regis...a311ef50a0d94a45c2.e3yLbh8Nch0Ke3iPc3ePbh8Le0

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120910/0640_ryou.html　& http://www3.nhk.or.jp/news/genpatsu-fukushima/20120910/index.html The number of seafood species fished off the Fukushima prefecture coasts as part of "test catches" has been brought to 10 species. The "test catches" began in June 2012 with only 3 species of octopus and whelk. The species added in September include horsehair crab and Japanese flying squid. Radioactive substances were not detected in these species in tests performed by Fukushima prefecture government. On 10 September 2012 at around 03:00 PM, 11 fishing boats came back to Matsukawaura fishing port in Soma City, carrying a 4300 kg catch. Some samples will be tested for radiations, and if the test result is OK, it will be sold for example on the local market from 11 September. It will be the first time that seafood suitable for eating raw coming from Fukushima waters is sold on the market.

http://www3.nhk.or.jp/daily/english/20120911_13.html "High levels of radiation have recently been detected in some fish types. A cod landed at a port in Aomori Prefecture in early August was found to be exposed to 132.7 becquerels of radioactive cesium per kilogram. That was 1.3 times the government safety limit. Radiation 380 times the limit was detected in a rock-trout caught off Fukushima in early August. A black sea bream caught off Miyagi Prefecture, in July was 33 times over the limit".

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120910/0640_ryou.html　& http://www3.nhk.or.jp/news/genpatsu-fukushima/20120910/index.html The number of seafood species fished off the Fukushima prefecture coasts as part of "test catches" has been brought to 10 species. The "test catches" began in June 2012 with only 3 species of octopus and whelk. The species added in September include horsehair crab and Japanese flying squid. Radioactive substances were not detected in these species in tests performed by Fukushima prefecture government. On 10 September 2012 at around 03:00 PM, 11 fishing boats came back to Matsukawaura fishing port in Soma City, carrying a 4300 kg catch. Some samples will be tested for radiations, and if the test result is OK, it will be sold for example on the local market from 11 September. It will be the first time that seafood suitable for eating raw coming from Fukushima waters is sold on the market.

http://www3.nhk.or.jp/daily/english/20120911_13.html "High levels of radiation have recently been detected in some fish types. A cod landed at a port in Aomori Prefecture in early August was found to be exposed to 132.7 becquerels of radioactive cesium per kilogram. That was 1.3 times the government safety limit. Radiation 380 times the limit was detected in a rock-trout caught off Fukushima in early August. A black sea bream caught off Miyagi Prefecture, in July was 33 times over the limit".

So, which is it? No contamination? Some contamination?

 

[Rive]

So, which is it? No contamination? Some contamination?

By the numbers and the news it's the worst kind - sporadic contamination.
So practically every 'dose' of fish should be tested independently.

 

[zapperzero]

http://www.city.koriyama.fukushima.jp/upload/1/4731_24_8syokuhinnitirann.pdf

everything in Koriyama is a bit dirty...

 

[Sorai]

http://www.city.koriyama.fukushima.jp/upload/1/4731_24_8syokuhinnitirann.pdf

everything in Koriyama is a bit dirty...

After scrolling through the document I see an overwhelming majority of non detections, with detection limits between 20 and 30 Bq/Kg for the most part, that is.

 

[Shinjukusam]

After scrolling through the document I see an overwhelming majority of non detections, with detection limits between 20 and 30 Bq/Kg for the most part, that is.

Yeah, I only counted 8 items with a combined count over 100, and two of those were wild bear and monkey (not on the menu) meat, one was sesame (who eats a kg of sesame?) one was blueberry (grown wild?) one was pumpkin, and two were a type of shallot usually used as a garnish.

I'm quite reassured by these numbers.

 

[jarvik]

http://www.city.koriyama.fukushima.jp/upload/1/4731_24_8syokuhinnitirann.pdf

everything in Koriyama is a bit dirty...

While I'm pretty sure I can pick out the columns for 137Cs and 134Cs activity, is there an English translation so I have a better idea of what all the measurements are from exactly?

Assuming the values are Bq/kg these values don't seem that scary.

For a personal frame of reference I pulled up some lake sediment core data of mine from a remote region of N. America:

From a slow sedimentation rate lake (less dilution of atmospheric fallout by sediment) I have values generally ranging between 100-200 Bq 137Cs /kg sediment in the top 15 cm (post ~1960 period) of sediment.

Looking at a high sedimentation rate lake from a river flood plain lake (much more dilution of atmospheric fallout by sediment) but otherwise same region I see values range 4-15 Bq 137Cs /kg sediment in the top 20cm (post ~1950 period).

And yes if your are curious I mean slow and fast sedimentation rate with respect to dry mass accumulation rate. Depth accumulation rate on a cm basis is often misleading due to large differences in sediment porosity etc.

Oh and 40K activity is in the range of 150-600 Bq /kg sediment.

So yes, I certainly think this Cs contamination should never have happened, but at least the values don't seem to be particularily scary overall.

Mental note; I should measure my backyard one day :)

 

[Sorai]

While I'm pretty sure I can pick out the columns for 137Cs and 134Cs activity, is there an English translation so I have a better idea of what all the measurements are from exactly?

This is a list of food samples tested during August in Koriyama City, which is around 30-40 miles west of the Fukushima NPP. The samples themselves are mostly from Koriyama City, but there are others from other areas within Fukushima Prefecture, some from other Japanese Prefectures and a few for which the origin is unknown.

The values we can see on that PDF are, for the most part, the detection limits for both isotopes, since most tests come back as ND (不検出）.

The columns from left to right would be: sample number, category (vegetable, fruit, etc.), product, origin, measurement date, Cs-134 concentration detected, Cs-134 detection limit, CS-137 concentration detected, Cs-137 detection limit. The unit used is Bq/Kg.

 

[jarvik]

Many thanks for the details Sorai.

Cheers,
Jarvik

 

[Azby]

More info in English about food test results can be found on the Ministry of Health, Labor, and Welfare's (MHLW) site:

http://www.mhlw.go.jp/english/topics/2011eq/index.html#corrected15Aug2012

Data for the entire period March 2011 to now is available; in most cases it's in both .html and .pdf form, with several reports in searchable/sortable .xls files

Corrected Test results of radionuclide in foods sampled since 19 March 2011 to 31 March 2012:
http://www.mhlw.go.jp/english/topics/2011eq/index.html#corrected15Aug2012

Levels of radioactive contaminants in foods tested in respective prefectures.
Latest is 18 September, 2012:
http://www.mhlw.go.jp/english/topics/2011eq/dl/18Sep2012.pdf


Some people in Italy have made a useful front end to the MHLW database:
http://www.contaminazione-alimentare.tk/dom-en.html

It's not necessarily up to date, but very good nonetheless.

==========
The Japan Fisheries Agency (JFA) keeps its own testing stats for fish and seafood:
http://www.jfa.maff.go.jp/j/sigen/housyaseibussitutyousakekka/

None of this appears to be available in English.

JFA data:
3/30/2012 results, (covers 12/27/2011- 3/30/2012)
3386 items total
41 between 500 and 1000Bq/kg (1.2%) , 28 items over 1000Bq/kg,(0.82%)

8/10/2012 results (7/1-8/10/2012)
2214 items total,
17 between 500 and 1000Bq/kg (0.76%), 2 over 1000Bq/kg(0.09%)


9/18/2012 results (7/14-9/18/2012)
(I made a little more detailed breakdown)
3971 items total
1756 44.2% ND
2215 55.8% detected
241 6.0% over 100Bq/kg
1974 49.7% less than 100Bq/kg limit

211 5.3% 100-500 Bq/kg
27 0.6% 500-1000 Bq/kg
3 0.07% over 1000 Bq/kg
(highest 3300 Bq/kg "kurodai" = black sea bream, caught off Miyagi pref)

=====
Adding info from MHLW on fish:

Jan 1-Feb 1 2012 (several sample dates),
307 samples total:
ND 108 35%
1-100 Bq/kg 118 38%
under 100Bq/kg total 226 74%
100-500 Bq/kg 55 18%
500-1000Bq/kg 15 5%
over 100 total 81 27%
over 500 total 26 8.4%
over 1000 11 3.7%

The highest was rockfish, at 3100Bq/kg; there were 2 other rockfish samples over 1000 Bq/kg.
5 samples of greenlings were over 1000Bq/kg. Sea bass and poacher also had samples over 1000Bq/kg.

========
March 1-April 1 2012 (tested March 7)
451 samples total:
ND 126 28%
1-100 Bq/kg 203 45%
under 100Bq/kg total 329 72.9%
100-500 101 22.4%
500-1000 19 4.2%
over 100 total 125 27.7%
over 500 total 28 6.2%
over 1000 total 9 2%

The highest was land-locked salmon from the Niida river, Iitate at 18,700Bq/kg.
Other items over 1000Bq/kg include poacher and greenling; there were several instances of skate (spelled "skete") over 500Bq/kg. Other high items included flounder, rockfish, greenling, land-locked salmon, char, poacher.

========
June 1-July 1 2012 (tested June 5)
421 samples total:
ND 170 40%
1-100 170 40%
under 100Bq/kg total340 80%
over 100 total 81 20%
100-500 75 17.8%
500-1000 5 1%
over 500 total 6 1.4%
over 1000 total 1 (rockfish, 1600Bq/kg)
over 2000 none

High items include rockfish, greenling, flounder.
========
July 31, 2012 data
ND 38.7%
1-100Bq/kg 44.8%
under 100 total 83.3%
over 100 total 15%
over 500 0.75%
over 1000 (0)
highest level found: 640Bq/kg

=======

Basically, from looking at these and other reports, it appears that the percentage of samples over 100Bq/kg have been declining, as have percentages over 500 and 1000Bq/kg; the percentage ND is fairly steady and probably not really increasing (around 40%), and the percentage detected but less than 100Bq/kg also continues to fluctuate around 40%.
The number/percentage of really "high" items, i.e. over 1000Bq/kg seems to be declining, but the levels found are not. Some species, like rockfish and greenling, exhibit strong bioaccumulation, and we'll probably continue to see occasional high levels in other species like the kurodai as well. This is just the first year, so we'll need to see the results of a few cycles to get a better grasp of what kinds of changes are seasonal, connected to migration, etc.

Azby

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120921/index.html The Ookuma town town council held a meeting on 21 September in Aizu-Wakamatsu city, and they unanimously approved a "recovery plan" which says that the inhabitants won't come back home for 5 years. It is the first time that a plan saying inhabitants won't come back for a prolonged time is officially approved. During that time, they will have an "outside of town community" with town hall and school functions performed somewhere else, in some other local area, and will carry out the environmental measures needed for coming back.

 

[tsutsuji]

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201209120067 [September 12, 2012] "The first round of thyroid tests for about 80,000 children in Fukushima Prefecture found no direct effects from last year's accident at the Fukushima No. 1 nuclear power plant" ... "The Fukushima prefectural government also released the estimated external radiation exposure levels for about 97,000 residents in the first four months after the nuclear accident. Excluding individuals whose work involved exposure to radiation, there were 18 individuals with radiation exposure levels of 10 millisieverts or higher".

 

[LanceV]

"The first round of thyroid tests for about 80,000 children in Fukushima Prefecture found no direct effects from last year's accident at the Fukushima No. 1 nuclear power plant"

How does that fit together with the data published in July?
https://docs.google.com/open?id=0B68f83tqq7QuZUdCZXhTLVl2dEE
http://fukushimavoice-eng.blogspot.com/2012/07/position-statement-what-is-currently.html
"Thyroid cysts found in 35% of Fukushima children examined with an average age of 10. "
There is no contradiction in the numbers, since the quoted article only refers to "lumps" over 5mm and "cysts" over 2cm, but is it appropriate to say that no direct effects are found when 35% of the children have lumps and cysts of all sizes?

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120929/index.html A ministry of education and science study based on on-land and helicopter data measured during the last 10 days of June 2012, found that the average radiation at 1 m above ground of 140,000 measurement points in the 80 km range around the plant declined by 23% compared with the previous study based on measurements in the first 10 days of November 2011. The natural radioactive decay over that period accounts for a 14% decline. The remaining decline of about 10% could be due to the rain, or to discrepancies between helicopter trajectories, etc.

http://radioactivity.mext.go.jp/ja/contents/7000/6289/24/203_0928.pdf The above mentioned study. It includes 2012 measurement maps outside the 80 km range in Miyagi, Ibaraki, Tochigi and Gunma prefectures.

http://radioactivity.mext.go.jp/ja/contents/7000/6291/24/192_203_0928.pdf It says that the data will be available at http://radb.jaea.go.jp/mapdb/ starting on 1 October 2012.

 

[tsutsuji]

http://wwwcms.pref.fukushima.jp/pcp...ECT&NEXT_DISPLAY_ID=U000004&CONTENTS_ID=31331 This is the web page providing rice test results for the 2012 crop.

For example on http://wwwcms.pref.fukushima.jp/download/1/suiden_jizen_syuukei_120927.pdf page 2/5 we can see that the highest value among 231 tests (that means 231 bags) measured between 17 September and 23 September 2012 in Former Hirata village, Fukushima city, was 47 Bq/kg, and all 231 tests are below the 100 Bq/kg safety limit. The detection threshold is 25 Bq/kg. Expected harvest in that village: 28,253 bags.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121002/1805_3km.html On 2 October, JAEA started mapping the 3 km range around the plant using an unmanned helicopter. Until then, the 3 km range had been left out of surveys because it is a no-fly zone. As the unmanned helicopter flies at altitudes between 30 m and 100 m, it can find hotspots [with a better precision than manned helicopters, which fly at higher altitudes]. The unmanned helicopter can map a 1 km x 1 km square in 2 hours, and it can go over areas otherwise difficult to access. On 2 October, they slowly surveyed a strip of grass land along the coast, and the radiation data were collected in real time, and converted into colors on a map on a personal computer. The survey results are planned to be compiled within this month.

 

[zapperzero]

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395030/

We conducted I-131 activity measurements in the thyroid of residents and evacuees during the period from April 12th to 16th, placing a 3-inch × 3-inch NaI(Tl) scintillation spectrometer at the neck of examinees. The study was approved by the Committee of Medical Ethics of Hirosaki University Graduate School of Medicine (Hirosaki, Japan). In total, 62 people aged from 0 to 83 years old (of which accurate information on age was unavailable for eight people) underwent the measurement with informed consent. Net thyroid and background count rates were determined from the detected gamma spectra measured for the most conservative dose assessment, we used thyroid equivalent dose coefficients for iodine in elemental form, as given by ICRP Publication 7116, and the thyroid uptake factor equal to 0.3. We found detectable I-131 activity in 39 of the 45 people evacuated from coastal areas, and in 7 of the 17 residents in Tsushima District. Figure 2 illustrates the distribution of thyroid equivalent dose in children and adults assessed using the equivalent dose coefficient by inhalation and by ingestion for their comparison16,17. Table 1 summarizes the range of I-131 activities and thyroid doses according to age. Thyroid equivalent doses by inhalation ranged from none detected (N.D.) to 33 mSv. The median thyroid equivalent dose for children (under 20 years of age) and adults was 4.2 and 3.5 mSv, respectively.

 

[tsutsuji]

http://www.sciencemag.org/content/338/6106/480.summary Science 26 October 2012: Vol. 338 no. 6106 pp. 480-482 DOI: 10.1126/science.1228250 "Fishing for Answers off Fukushima" by Ken O. Buesseler :

The statement in the summary saying that "the nuclear power plants continue to leak radioactive contaminants into the ocean" is kind of misleading, if all the scientist has been able to demonstrate actually is :

"There's no doubt there's a continued source of contamination," Buesseler says.

Mitsuo Uematsu, of the University of Tokyo, says this makes sense. Rivers wash contaminated sediments into the ocean

(...)

Aoyama says there is no evidence contaminated groundwater is leaking into the ocean

http://www.newscientist.com/article/dn22426-radiation-still-high-in-fukushima-fish.html

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20121108/index.html It was found that about 700 dosimeters installed on the ministry of education and science's monitoring posts have been displaying wrong values that were up to 10% lower than the real radiation. The cause is an "assembly mistake". The total of 675 is made of 545 dosimeters in Fukushima prefecture and from 10 to 30 dosimeters in each surrounding prefecture that started operation in April 2012. The dosimeters' values are displayed in real time on the internet. Inhabitants had noticed that the values on their own handy dosimeter were significantly higher. The ministry launched an investigation, which found that a battery containing lead was shielding the radiation. The ministry will spend 150 million yen in repair works that are starting next week.

http://radioactivity.mext.go.jp/ja/contents/7000/6437/24/203_1107.pdf Press release with drawings showing how they plan to move the battery further away from the detector.

 

[tsutsuji]

http://www.agu.org/pubs/crossref/2012/2012GL052928.shtml Kato, Onda & Gomi, "Interception of the Fukushima reactor accident-derived 137Cs, 134Cs and 131I by coniferous forest canopies", Geophysical Research Letters, VOL. 39, L20403, 6 PP., 2012

They found that as the study went on, the concentration of cesium found in stemflow and throughfall started to surpass that arriving through precipitation, suggesting that the radionuclides were being stored in the tree canopy and later seeping out. The authors determined that cesium-137 concentrations in the forest canopy would have a half-life of 620 or 890 days, depending on whether the trees were cypress or cedar.

 

[etudiant]

http://www.agu.org/pubs/crossref/2012/2012GL052928.shtml Kato, Onda & Gomi, "Interception of the Fukushima reactor accident-derived 137Cs, 134Cs and 131I by coniferous forest canopies", Geophysical Research Letters, VOL. 39, L20403, 6 PP., 2012

This sounds very much as if the ecosystem is storing the Cs 137 in the forest canopy. As the canopy components (needles and leaves) fall and decompose, their Cs content leaches out and is recycled. The trees pull up fresh Cs from the groundwater. via water transpiration.
Still, a three year half life is only a tenth of the actual Cs 137 half life, so the recycling is only about 10%. Presumably the other 90% are swept away to the sea in the water flows.
Are there any efforts to monitor the contamination burden carried by the rivers that drain this forest?

 

[tsutsuji]

Last year the following reports were completed

Miyagi:
http://mainichi.jp/area/miyagi/news/20111217ddlk04040073000c.html A study of Miyagi prefecture rivers and lake has been released by the ministry of environment. Cesium was found in water only in one out of 138 tested locations, with 3Bq/kg. 11,000 Bq/kg was found in the mud at the bottom of Nanakita river in Sendai. As a whole, 21 locations were found with river mud above 1000 Bq/kg. The radiation is comparatively higher close to river mouths.

http://www.env.go.jp/jishin/monitoring/result_pw111216-1.pdf Miyagi prefecture river monitoring results

Tochigi:
http://sankei.jp.msn.com/region/news/111217/tcg11121702120004-n1.htm The ministry of environment released a Tochigi prefecture river and lake survey. In one location 1 Bq/l was found in water. 4900 Bq/kg was found in river bottom mud in Nikko. They also checked the Earth in areas surrounding rivers, and found 9400 Bq/kg of Cs137 in Nasu.

http://www.env.go.jp/jishin/monitoring/result_pw111216-2.pdf Tochigi prefecture river monitoring results

Updates are done periodically : http://www.env.go.jp/jishin/monitoring/results_r-pw.html

http://www.env.go.jp/jishin/monitoring/result_pw121011-1.pdf This is the last one, for Fukushima prefecture rivers (11 October 2012). Radiation doses in river water : All Cs-137 values were between undetected and 3 Bq/l ; Cs-134 between undetected and 2 Bq/l. In river mud, Cs-137 goes up to 37,000 Bq/kg (dry mud).