|Sep18-12, 07:06 AM||#579|
Japan earthquake - contamination & consequences outside Fukushima NPP
I'm quite reassured by these numbers.
|Sep19-12, 08:22 PM||#580|
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 :)
|Sep19-12, 09:45 PM||#581|
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.
|Sep19-12, 10:22 PM||#582|
Many thanks for the details Sorai.
|Sep20-12, 02:34 AM||#583|
More info in English about food test results can be found on the Ministry of Health, Labor, and Welfare's (MHLW) site:
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:
Levels of radioactive contaminants in foods tested in respective prefectures.
Latest is 18 September, 2012:
Some people in Italy have made a useful front end to the MHLW database:
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:
None of this appears to be available in English.
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
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.
|Sep21-12, 12:49 PM||#584|
http://www3.nhk.or.jp/news/genpatsu-...921/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.
|Sep23-12, 02:12 AM||#585|
http://ajw.asahi.com/article/0311dis...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".
|Sep24-12, 05:52 AM||#586|
"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?
|Sep29-12, 04:24 AM||#587|
http://www3.nhk.or.jp/news/genpatsu-...929/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/c...4/203_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/c...2_203_0928.pdf It says that the data will be available at http://radb.jaea.go.jp/mapdb/ starting on 1 October 2012.
|Oct1-12, 10:50 AM||#588|
http://wwwcms.pref.fukushima.jp/pcp_...TENTS_ID=31331 This is the web page providing rice test results for the 2012 crop.
For example on http://wwwcms.pref.fukushima.jp/down...kei_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.
|Oct3-12, 07:13 AM||#589|
http://www3.nhk.or.jp/news/genpatsu-.../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.
|Oct8-12, 12:06 PM||#590|
|Oct30-12, 01:29 AM||#591|
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 :
|Nov9-12, 03:27 AM||#592|
http://www3.nhk.or.jp/news/genpatsu-...108/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/c...4/203_1107.pdf Press release with drawings showing how they plan to move the battery further away from the detector.
|Nov18-12, 04:14 PM||#593|
http://www.agu.org/pubs/crossref/201...GL052928.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
|Nov19-12, 07:36 AM||#594|
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?
|Nov20-12, 01:14 PM||#595|
Last year the following reports were completed
http://www.env.go.jp/jishin/monitori...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).
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