Fukushima Japan earthquake - contamination & consequences outside Fukushima NPP

[zapperzero]

I don't think residents are supposed to commute and work regularly in those areas, at least on paper. You can read a definition of the three zones in this document from December 2011: http://www.meti.go.jp/english/earthquake/nuclear/roadmap/pdf/20111226_01.pdf

In relation to areas between 20 and 50 mSv/year ("Areas in which the residents are not permitted to live"):

"In this case, residents are ordered to remain evacuated in the areas, but people concerned can temporarily return home in the areas (but staying overnight is prohibited), pass through the areas along main roads, and enter the areas for purposes beneficial to the public interest, such as repairing the infrastructure and conducting disaster prevention-related work." [p. 10]​

Based on more recent Japanese documents, it does not seem like the definition has changed, though I guess residents would be able to commute daily as long as they can justify that their work is related to repairing basic infrastructure. Even in that case, they would only be exposed to part of the annual dose, since they are not allowed to stay overnight.

However, I've read of at least one farmer, Naoko Matsumura, who went back to the exclusion zone very early on after the accident and lives there taking care of his animals, so it seems the police is not forcing people to evacuate if they decide to stay: http://www.dailymail.co.uk/news/art...led-Fukushima-nuclear-plant-care-animals.html

Thank you very much for your explanation.

 

[gmax137]

I wonder if someone here could confirm or infirm this? http://ex-skf.blogspot.ro/2013/03/radioactive-japan-50-millisieverts.html
There's crazy talk in there about commuting to work being allowed in 50 mSv/y areas.

I wouldn't let 50 mSv/year keep me from moving back into my home. But that's just me I guess.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130328/index.html Google started on 28 March to display "Google street view" on the internet for the streets of Namie town, as requested by the municipality. Buildings knocked down by the earthquake have not been removed, more than 2 years after the earthquake. Hardly any person or car can be seen. Google said it plans to cover more areas affected by the nuclear accident.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130315/index.html [15 March 2013] Among the fish samples taken in Fukushima Daiichi harbour between February 19 and 21, whose analysis results were released on March 15, the most highly contaminated fish until now has been found, with 740,000 Bq/kg of radioactive cesium (134 + 137 added together). As countermeasures, Tepco plans to exterminate the fish in the harbour and to install a net between the harbour and the open sea.

http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/fish_130315-e.pdf page 9/13: "Greenling (Muscle) No.5 In the Port of Fukushima Daiichi NPS (Around the Water Intake Open Conduit at Unit 1-4) February 21, 2013 260000 480000 740000" ; page 12/13: "<Reference> Outline Process (Draft) of the Countermeasures for Fish in the Port at Fukushima Daiichi NPS
① Preventing fish from moving out
② Sampling (extermination) of fish
②-1: Basket fishing ②-2: Gill net in the port entrance
③ Improving environment of the marine soil in the port (dredging)

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130315/0600_osensui.html [15 March 2013] As the cesium concentration in Fukushima Daiichi harbour is almost not declining, a Tokyo university research group calculated an estimate suggesting that it is possible that a quantity of radioactive cesium up to 73 times the yearly regulatory limit has been poured into the Fukushima Daiichi harbour even after the main leak was stopped in June 2011. Since last spring, the Cs 137 concentration has stopped declining, and remains stable around 100 Bq/litre. Based on the assumption that 44% of the harbour water is changed everyday by currents and tides, it was found that a Cs-137 source from 8 to 93 billion Bq/day is necessary. This has almost no consequence on the fish in the open sea, but it is feared that the fish in the harbour might accumulate the radioactive substances in their body. According to Tokyo University professor Jota Kanda, "it is difficult to imagine that contaminated Earth is washed out by rain and poured into the harbour, but it is possible that contaminated water pours into the harbour from ground water or broken pipes. A detailed investigation and a research of the cause is necessary". In response to this, Tepco said "we don't think that radioactive substances are pouring into the sea from the plant premises. However, as we don't know the reason why the harbour concentrations are not declining, we shall continue to investigate".

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130305/0910_80km.html [5 March 2013] A ministry of Education and Science survey performed in November 2012 in the 80 km range around the plant collected radiation data in 140000 locations onland and by helicopter. The average radiation at 1 m above ground is 40% lower than the value found one year earlier. Nuclear decay accounts for a 21% decline. The remainder of the decline is presumably due to the radioactive substances being washed by rain and poured into rivers and sea.

http://radioactivity.nsr.go.jp/ja/contents/7000/6749/24/191_258_0301_18.pdf The 6th aerial monitoring campaign (helicopter maps)

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130301/index.html [1 March 2013] The Joban expressway decontamination work has been started on a 17 km stretch between Hirono and Tomioka which is planned to reopen in fiscal 2013. The decontamination is done with high pressure washers and hoses that suck up the spent water. The radiation is reduced by more than one half. Cut branches and leaves are compressed to one fourth of their original volume before storage.

 

[zapperzero]

Another excellent article from ex-skf - the decontamination of detector sites continues apace, and the new lower numbers are being presented as improvements in the overall situation, which of course they are not. Disgusting.

http://www.ex-skf.blogspot.ro/2013/04/fukushima-prefecture-installs-fixed.html

FNN Local News reported on April 2, 2013 that radiation levels as measured in Koriyama City got significantly lower in one day. Its reporter spoke with the government official, and found out that, in addition to installing the fixed monitoring posts in locations that just got decontaminated, they also changed the unit of measurement from microsievert/hour to microgray/hour, shaving off 20% in numbers

EDIT: looking at the video now... the location of the old monitoring post is ridiculous.

 

[nikkkom]

The Joban expressway decontamination work has been started on a 17 km stretch between Hirono and Tomioka which is planned to reopen in fiscal 2013. The decontamination is done with high pressure washers and hoses that suck up the spent water. The radiation is reduced by more than one half. Cut branches and leaves are compressed to one fourth of their original volume before storage.

Got to love government at work. It took only two years to start washing down the roads.

 

[tsutsuji]

Got to love government at work. It took only two years to start washing down the roads.

If there is no prospect that many cars are going to use that motorway, it could be meaningless, or not a useful way of spending public money and not worth risking the decontaminating workers' health. I guess very few cars are going to use that stretch as long as the next stretch which runs just behind Fukushima Daiichi is sufficiently decontaminated and car drivers are confident enough to risk driving that close from Fukushima Daiichi.

 

[nikkkom]

If there is no prospect that many cars are going to use that motorway, it could be meaningless, or not a useful way of spending public money and not worth risking the decontaminating workers' health.

Letting Cs-137 contamination sit on the roads for years allowed it to soak into the road surface.

Considering how little washdowns cost and how little exposure workers get, it should have been done a few months after the disaster, not years.

I mean, come on. Bring standard spraying cars already owned by nearby cities, and make them drive around washing roads, when they aren't needed elsewhere and would alternatively sit in their garages doing nothing. The most expensive part of such effort may be not the usage of these cars per se, but the chemicals added to the water which promote washing out of caesium salts.

 

[zapperzero]

I mean, come on. Bring standard spraying cars already owned by nearby cities, and make them drive around washing roads, when they aren't needed elsewhere

Please, please for the love of Freya, start thinking before you write. The washing trucks themselves would become contaminated for sure, from wind and back-spray if nothing else. You would want them used somewhere else, after? Really?

 

[nikkkom]

Please, please for the love of Freya, start thinking before you write. The washing trucks themselves would become contaminated for sure, from wind and back-spray if nothing else. You would want them used somewhere else, after? Really?

"Oh no, we are all going to die!1111eleven!"

Contaminated to what level?

 

[tsutsuji]

http://josen.env.go.jp/material/pdf/jissyou_jikkenn.pdf Leaflet (released in February 2013) explaining decontamination tests. (26 pages, Japanese)

http://josen-plaza.env.go.jp/materials_links/pdf/kamishibai_omote.pdf Radiations explained to children (nuclear accident depiction on page 14/46) (the yellow dots figure the radiations) (released on 26 March 2013)

http://josen-plaza.env.go.jp/materials_links/pdf/kamishibai_ura.pdf Dialogues providing explanations to the pictures (nuclear accident dialogue on page 13-14/46)

http://josen-plaza.env.go.jp/materials_links/pdf/kamishibai_fukudokuhon.pdf?20130405 Supplementary reader (for children, 26 pages)

http://josen-plaza.env.go.jp/materi...130a.html?TB_iframe=true&width=600&height=400 Video on temporary storage design

http://josen-plaza.env.go.jp/materi...130b.html?TB_iframe=true&width=600&height=400 Slideshow on temporary storage (real photographs)

http://josen-plaza.env.go.jp/materi...405a.html?TB_iframe=true&width=600&height=400 Temporary storage safety video (distances)

http://josen-plaza.env.go.jp/materi...405c.html?TB_iframe=true&width=600&height=400 Temporary storage safety video (shielding)

http://josen-plaza.env.go.jp/materi...405e.html?TB_iframe=true&width=600&height=400 Decontamination basic principles video (removal)

http://josen-plaza.env.go.jp/materi...405b.html?TB_iframe=true&width=600&height=400 Decontamination basic principles video (farming fields, deep plowing)

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130423/0415_josen.html A ministry of environment specialist committee meeting was started on 22 April, examining a revision of the decontamination guidelines. The proposed revision includes new technologies such as real time recovery of the waste water, solutions for the disposal of waste water, etc. Diagrams and photographs provide easy to understand explanations.

http://www.yomiuri.co.jp/science/news/20130422-OYT1T01248.htm The new guidelines are expected to be released before or after the Golden Week (late April - early May).

 

[zapperzero]

"Oh no, we are all going to die!1111eleven!"

Contaminated to what level?

Contaminated enough to become radwaste themselves perhaps. Generally speaking, I'm tired of your constant drone of "oh this is too costly" "oh sure there needs to be some corner-cutting over there" "oh poor TEPCO is going to go into receivership if they are to pay for the cleanup". I don't really care. There are well known and universally accepted standards for cleanup and you are advocating that everyone should just ignore them... for the love of money.

 

[nikkkom]

Contaminated enough to become radwaste themselves perhaps. Generally speaking, I'm tired of your constant drone of "oh this is too costly" "oh sure there needs to be some corner-cutting over there" "oh poor TEPCO is going to go into receivership if they are to pay for the cleanup". I don't really care. There are well known and universally accepted standards for cleanup and you are advocating that everyone should just ignore them... for the love of money.

You are distorting my position.

In particular, in this thread I am expressing my dismay at the fact that road cleanup WAS NOT DONE. If I would be caring only about saving money, would I be unhappy about that? Doing nothing is the cheapest "solution".

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130423/0415_josen.html A ministry of environment specialist committee meeting was started on 22 April, examining a revision of the decontamination guidelines. The proposed revision includes new technologies such as real time recovery of the waste water, solutions for the disposal of waste water, etc. Diagrams and photographs provide easy to understand explanations.

http://www.yomiuri.co.jp/science/news/20130422-OYT1T01248.htm The new guidelines are expected to be released before or after the Golden Week (late April - early May).

The new guidelines are available now :
http://www.env.go.jp/jishin/rmp/attach/josen-gl-full_ver2.pdf (256 pages, Japanese)

http://josen-plaza.env.go.jp/info/rebirth/pdf/rebirth_43.pdf Rebirth magazine, vol. 43, 30 May 2013. The lower right picture shows the JA (Central Union of Agricultural Cooperatives) direct sale shop with rice and vegetables grown in Tamura, Fukushima prefecture (Evacuation Directive Lift Prepared Area). Farming tests with rice and 10 vegetables performed in that town produced products well below the legal radiation limits. The decontamination work necessary to lift the evacuation order has been almost completed.

http://josen-plaza.env.go.jp/info/weekly/pdf/week_process_kawauchi.pdf?20130528 "Week process Kawauchi" map showing with red circles the decontamination work areas in Kawauchi city from 27 May to 1 June 2013.

http://josen-plaza.env.go.jp/info/weekly/pdf/week_process.pdf?20130528 "Week process Naraha" map showing with red circles the decontamination work areas in Naraha city from 27 May to 1 June 2013.

http://josen-plaza.env.go.jp/info/weekly/pdf/weekly_130531b.pdf Countermeasure area waste treatment weekly report, 31 May 2013

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130627/1015_bunpuzu.html A US-Japanese team (JAEA - US department of Energy) produced a new map of Iodine 131 releases during the accident. Contrary to the cesium releases, an area south of the plant was contaminated by iodine.

http://journals.lww.com/health-phys...nalysis_Methods_to_Derive_the_Spatial.10.aspx Health Physics: August 2013 - Volume 105 - Issue 2 - p 192-200

Abstract: This paper applies both new and well tested analysis methods to aerial radiological surveys to extract the 131I ground concentrations present after the March 2011 Fukushima Daiichi nuclear power plant (NPP) accident. The analysis provides a complete map of 131I deposition, an important quantity incalculable at the time of the accident due to the short half-life of 131I and the complexity of the analysis. A map of 131I deposition is the first step in conducting internal exposure assessments, population dose reconstruction, and follow-up epidemiological studies. The short half-life of 131I necessitates the use of aerial radiological surveys to cover the large area quickly, thoroughly, and safely. Teams from the U.S. Department of Energy National Nuclear Security Administration (DOE/NNSA) performed aerial radiological surveys to provide initial maps of the dispersal of radioactive material in Japan. This work reports on analyses performed on a subset of the initial survey data by a joint Japan-U.S. collaboration to determine 131I ground concentrations. The analytical results show a high concentration of 131I northwest of the NPP, consistent with the previously reported radioactive cesium deposition, but also shows a significant 131I concentration south of the plant, which was not observed in the original cesium analysis. The difference in the radioactive iodine and cesium patterns is possibly the result of differences in the ways these materials settle out of the air.

http://www.jaea.go.jp/02/press2013/p13062701/index.html JAEA press release with attachments :

http://www.jaea.go.jp/02/press2013/p13062701/02.html Iodine release map (as of 3 April 2011)

http://www.jaea.go.jp/02/press2013/p13062701/press_annex.pdf Explanations about the making of the map

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130627/1015_bunpuzu.html A US-Japanese team (JAEA - US department of Energy) produced a new map of Iodine 131 releases during the accident. Contrary to the cesium releases, an area south of the plant was contaminated by iodine.

So the dose rate calculations for those in the evacuation area go out the window, right?

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130801/index.html Whole body counter testing of children aged below 4 years old has started on 1 August 2013. The target is the below 4 years old in 5 towns and villages around the plant, but Fukushima prefecture plans to expand the target area. The whole body counter was adapted to children by the use of a 90 cm high chair where children can sit whereas adults are standing. A father of a 3-year-old said, "while it is honest to test children, I think this is too late". A Fukushima prefecture health administration official said "we plan to expand such testing to the whole Fukushima prefecture".

 

[Azby]

I haven't posted in a while, but have been following along regularly. Two articles I wrote about food monitoring in Japan have been published by the FCCJ (Foreign Correspondents' Club of Japan). I hope they'll help fill a gap.

One is a detailed list of major food testing programs, govt and independent, with commentary about policies and results, and many links to sources. My main purpose was to provide a resource for journalists, who often don't know where to find this data:

Food testing in Fukushima, and observations about the results
http://no1.fccj.ne.jp/index.php?option=com_content&view=article&id=958The other is based on spending time talking to farmers in Fukushima, Tochigi, and elsewhere about the challenges they face and what they'e doing about it:

Do Fukushima’s farmers have a future?
http://no1.fccj.ne.jp/index.php?option=com_content&view=article&id=953

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130809/2010_chudan.html Because of the contaminated ground water problem, all test fishing in Fukushima prefecture waters has been suspended.

 

[zapperzero]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130809/2010_chudan.html Because of the contaminated ground water problem, all test fishing in Fukushima prefecture waters has been suspended.

Wait, what? Talk about ostrich policies...

 

[Hiyodori]

Wait, what? Talk about ostrich policies...

Why? They have been "test fishing" since June of last year, and the fish they have caught have had cesium levels far below the safety levels 100 Bq/kg. With the current news about leaking contaminated water, they foresee no market acceptance for any fish caught in waters offshore Fukushima Prefecture, so they have stopped fishing. Their heads are anywhere but in the sand.

Reading the entire article, even if you have to use some sort of machine translator, might help keep your incredulity in check. "Test fishing" was to eventually lead to full on "normal fishing", but now that seems out of the question, and the fishing consortiums are not at all happy about the situation.

 

[zapperzero]

With the current news about leaking contaminated water, they foresee no market acceptance for any fish caught in waters offshore Fukushima Prefecture, so they have stopped fishing. Their heads are anywhere but in the sand.
[...]the fishing consortiums are not at all happy about the situation.

So, "testing" is only OK if it produces happy results. If it might show actual contamination, it is promptly discontinued. How is this testing? How can this be science? How does it show a concern for the truth and for the well-being of customers?

It may be normal for Japan, but in other parts of the world covering your ears so as not to hear bad news is not seen as sane, productive behaviour.

 

[Hiyodori]

So, "testing" is only OK if it produces happy results. If it might show actual contamination, it is promptly discontinued. How is this testing? How can this be science? How does it show a concern for the truth and for the well-being of customers?

It may be normal for Japan, but in other parts of the world covering your ears so as not to hear bad news is not seen as sane, productive behaviour.

Testing was NOT scientific testing done by the Japanese government, or by NGO groups. It was done for purely business reasons by fishing groups. Now that there is little chance for public acceptance of fish caught anywhere off of the entirety of Fukushima Prefecture, the fishing groups decided to not waste their time and money any more. A decision that any normal business would make.

Japan the country, nationally and locally, as well as NGOs continue their scientific testing.

You might want to avoid insulting an entire nation based on the unfortunate one line translation posted earlier, which certainly may lead one to believe as you do, instead of the entire linked article which makes it quite clear who is stopping testing, and why.

 

[zapperzero]

Testing was NOT scientific testing done by the Japanese government, or by NGO groups. It was done for purely business reasons by fishing groups. Now that there is little chance for public acceptance of fish caught anywhere off of the entirety of Fukushima Prefecture, the fishing groups decided to not waste their time and money any more. A decision that any normal business would make.

So it was advertising (for potentially harmful products, natch), disguised as testing. Excuse me for having believed that said fisheries might have had their customers' interests at heart...

Japan the country, nationally and locally, as well as NGOs continue their scientific testing.
You might want to avoid insulting an entire nation based on the unfortunate one line translation posted earlier, which certainly may lead one to believe as you do, instead of the entire linked article which makes it quite clear who is stopping testing, and why.

I don't think Japan the country needs you to defend its honor from me.
Please, feel free to point to studies done by Japan the country which detail the cesium content of fish in Fukushima and its environs.

 

[Azby]

Please, feel free to point to studies done by Japan the country which detail the cesium content of fish in Fukushima and its environs.

I'm not sure what the misunderstanding is. Fish and other seafood products caught off Fukushima and surrounding prefectures have been being monitored regularly by the government for contamination since 2011, and just like farmers in Fukushima and elsewhere do, many fishing cooperatives often supplement the official testing with independent testing they pay for out of their own pockets. Below is the relevant section from the guide to finding and interpreting food test data I wrote for the Foreign Correspondents' Club of Japan. Pardon the length; even so, this excerpt doesn't include the info about independent (non-government) testing. By all means take a look at the entire report to get up to speed on what is being tested, how often, by whom, and what the results have been.

+++++++++++++++++++++++++++++++++++++++++++
Food testing in Fukushima, and observations about the results
http://no1.fccj.ne.jp/index.php?option=com_content&view=article&id=958

4. FISH:
A lot of testing focusses on fish, or more specifically, on "fisheries products," which includes shellfish, octopus and squid, as well as seaweed and a few other items. These items are included in the MHLW testing, but the MAFF conducts its own tests and maintains a separate database as well, through its Japan Fisheries Agency (JFA) branch. Reports can be downloaded here (Japanese only):

http://www.jfa.maff.go.jp/j/housyanou/kekka.html

Page with links to reports in English:
http://www.jfa.maff.go.jp/e/inspection/index.html

Report for July 1-10, 2013 (English)
http://www.jfa.maff.go.jp/e/inspection/pdf/eigo250710.pdf

Fairly informative Q&A about seafood monitoring (English):
http://www.jfa.maff.go.jp/e/q_a/index.html

Map and description of restrictions in place, for oceans off which prefectures, and on which species, as of July 4, 2013 (Japanese):
http://www.jfa.maff.go.jp/j/housyanou/pdf/130704kaimen-zu.pdf
http://www.jfa.maff.go.jp/j/housyanou/pdf/130704kaimen.pdf

A typical individual report, in this case covering from July 1-18, 2013:
http://www.jfa.maff.go.jp/j/housyanou/pdf/130719_result.pdf
http://www.jfa.maff.go.jp/j/housyanou/other/130719_result.xls

Summary of the results for July 1-18, 2013:
Of 1096 items caught between Kanagawa and Aomori for testing, 10 (about 1%) were over 100Bq/kg; highest was a suzuki caught off of Ibaragi, at 1000 Bq/kg. About 300 samples, however, had measurable cesium; about half of these were below 10Bq/kg, and many were close to the detection limit.

It's very detailed report, with over a thousand individual test entires, giving results, testing parameters, dates, the location the fish were caught, etc.. The data can be downloaded in both pdf and excel formats, and all the older data is available. These reports are nevertheless unwieldy, and it is difficult to extract trends regarding specific locations, or kinds of fish. But in October 2012, a US-based researcher named Ken Buesseler at the Woods Hole Oceanographic Institute released a study that used the same MAFF database, and sliced and diced it to show what kinds of fish were decreasing in contamination and where, and what kinds were not:

"Fishing for Answers off Fukushima"
http://www.whoi.edu/page.do?pid=7545&tid=3622&cid=153749
http://www.sciencemag.org/content/338/6106/480.summary

Related article:
Seafood Safety and Policy
http://www.whoi.edu/oceanus/viewArticle.do?id=167889&sectionid=1000

The MAFF should be preparing and providing these kinds of analyses and visualizations itself, to help citizens evaluate the risks.

+++++++++++++++++++++++++++++++++++++++++++

 

[tonio]

What surprises me is that the contaminated area has not been geohydrlogically isolated. That could have been reached by:
- digging an interception trench along the foot of the steep slope at the land site of the contaminated area
- constructing an impermeable barrier along the seafront of the contaminated area
- installing a number of extraction wells inbetween the reactors
- lowering the water table in the trench to slightly above the average sea level
- lowering the water table in the extraction wells to somewhat below the average seawater level

In principle, the water from the trench (if maintained slightly above the average seawater level), will only intercept (slightly contaminated) surface runoff and groundwater from the slope above the contaminated zone and may be discharged into the sea. The water from the extraction wells of course will be highly contaminated. If possible, it could be somewhat (or largely) decontaminated before being re-used for corium cooling. And part of it will have to be decontaminated to a save level previous to discharge into the sea or (if sufficient decontamination is not possible) stored on site.

But in any case, the net production conaminated water will be much less than in the present situation and the inflow into the sea will be greatly reduced. See the attached sketches (second sketch: purple: interception trench, green: barrier, orange: interception wells, red: reactor buildings)

 

[tonio]

Sketch of likely present situation

 

[tonio]

To be clear: the previous is a regularly used method to contain contamination spreading from contamination sources (landfills, contaminated factories, etc.).

 

[etudiant]

Tonio is clearly on the money with his perception.
To solve the water problem, the site must be isolated as much as possible. It is surprising that this has not been a focus of the efforts to date.
That said, there are challenges, the site is really big, the ground is quite permeable and the plant is both way below the nearby ground level and not built on bedrock, so there is water coming in from below as well as from the sides.
Given the massive cost of this cleanup, I cannot understand why the contaminated water is not simply pumped into some large tankers instead of being stored on site in hastily constructed tank farms. It makes no sense to have the cleanup facilities right by the disaster site, especially if more things can go wrong. The contaminated material should be moved to a separate processing site, so the cleanup can be implemented without interference from the waste processing.

 

[nikkkom]

It makes no sense to have the cleanup facilities right by the disaster site

In fact it does make a lot of sense to have water purification equipment on site. There will be a stream of water in need of decontamination for years to come.

 

[tonio]

... there are challenges, the site is really big, the ground is quite permeable and the plant is both way below the nearby ground level and not built on bedrock, so there is water coming in from below as well as from the sides.

In fact the site is not that big, the length of the area to be isolated is about 700 m, there are landfills that are comparable in size of even bigger.

Regarding the interception trench, it is not so problematic when the subsuface is very permeable. The main issue is to intercept the groundwater flowing in from above to avoid that it continues through the site, picks up the contamination, and discharges this contamination into the sea. That could be done with a trench or, if digging a trench is problematic, with the installation of a large number of extraction wells.

I expect that the water thus intercepted is clean or almost clean (as it comes from above and flows towards the site). It can therefore be discharged into the sea. The amount of intercepted water is thus not critical. It is however very important to maintain a water level in this trench or in these wells that is just above the ground water level in the contaminated area, to avoid inflow of contaminated groundwater into the trench/wells. But that is technically simple to achieve.

The main issue, after the interception has been installed, is to keep the water level in the contaminated area somewhat below the seawater level. Thus, the groundwater flow from the contaminated area to the sea will be reversed and the inflow of contaminated ground water into the sea will be greatly reduced.

In order to minimize the amount of water that has to be extracted to keep the water level in the contaminated area somewhat below the seawater level, the barrier is needed. If the soil is very permeable to a great depth, its effectivity will be limited, but it will still have some effect, expecially to avoid the inflow of contaminated shallow groud water that has almost reached the sea.

The barrier could be constructed by digging a trench and filling it with bentonite clay, or by hammering steel sheets or, if that is not possible, by installing a large number of injection wells in order to freeze the soil, which will also create a barrier.

In summary, I have the impression that it would not be that difficult to create an effective geohydrological isolation, which could significantly reduce the ongoing seawater contamination and which could significantly reduce the present need for withdrawal, storage and decontamination of water from the contaminated area. And it could well be profitable!

 

[Rive]

Sketch of likely present situation

The situation is not exactly like on your drawing.
The groundwater level around the reactors and turbine buildings is higher than the water level in the units. At those points no outflow is possible, it is exactly that kind of separation you want.

The problem is that there are some cable trenches in direction of the ocean, connected to the buildings. The outflow occurs in areas where the water level in the trenches is higher than the local groundwater level.

At this point of events it would not be a good idea to lower the groundwater level below the reactor/TB basements. This would generate outflow there, at the very worst point.
They have to separate those trenches from the buildings ASAP and empty them.

Ps.: I've uploaded a second drawing. The mountain side wells are ready as I know, you can check them f you search their 'groundwater bypass' plans. They are doing the seaside wells and the impermeable wall right now. But: as I know they have no idea how can they separate and when can they empty the trenches.

 

[tonio]

OK that’s new information for me. That poses an interesting question: is the water table in the buildings kept relatively high in order to avoid excessive inflow of ground water into them? Do you know if that is the case?

If that is the case, a geohydrological isolation using the interception wells (mountain side wells) for a general lowering of the ground water level around the buildings, in combination with a lowering of the water table in the buildings, could help to reduce or even stop the outflow of contaminated water via the trenches. In any case, it will reduce the inflow of ground water into the buildings. See the sketches.

Also, such an isolation would make it easier to remediate the ground water contamination near the sea caused by the outflow from the trenches, as such a general lowering would reduce the ground water pressure on the barrier (impermeable wall) to be installed, which eventually will lead to leakages of contaminated water underneath the barrier or through weaknesses in this barrier. See the sketches.

As for the management of the geohydrological system, this will require a number of monitoring wells in order to continuously monitor the ground water level and the level of ground water radioactivity, the ground water flow patterns that can be derived from them and manage the ground water levels in the interception wells on the basis of these measurements. But that is more or less standard work.

 

[Rive]

OK that’s new information for me. That poses an interesting question: is the water table in the buildings kept relatively high in order to avoid excessive inflow of ground water into them? Do you know if that is the case?

As far as I know: yes.

If that is the case, a geohydrological isolation using the interception wells (mountain side wells) for a general lowering of the ground water level around the buildings, in combination with a lowering of the water table in the buildings, could help to reduce or even stop the outflow of contaminated water via the trenches. In any case, it will reduce the inflow of ground water into the buildings.

That's the plan behind their whole 'groundwater bypass' business.

As for the rest: the impermeable wall (with chemical soil solidification) is almost ready. They have installed some wells between the wall and the buildings (and started with the pumping), so the water level inside the wall is closing to the seawater level.

It'll prevent the further contamination of the ocean but with the trenches still full with that stuff up to the old level the amount of soil to be cleaned up later will increase rapidly - the contamination of soil inside the barrier will speed up.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130801_04-e.pdf
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130815_03-e.pdf
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130820_04-e.pdf

 

[tonio]

Interesting information!

In the first pdf, a photograph of the core of boring 1-5 is added. When looking at the phoptograph and the added text, I see:
- +1,3 – +3,5 m OP: apparently sand-like material
- -1,9 – +1,3 m OP: apparently clay-like material which according to te author is “soil solidified like a concrete due to the ground improvement”
- -12 – -1,9 m OP: apparently clay-like material

Furthermore, radiation is only detected above + 1, 2 m OP (i.e. in the sand layer) and not in the “solidified” layer and the claylike layer underneath. Thus it seems that, at least at location 1-5, radioactive water did not penetrate the (probably quite impermeable) soil below + 1 m OP. I would like to know what they have found at the other boreholes.

Furthermore, I see a rapid rise during 8 july – 1 august of the ground water table in holes 1 and 3 (from appr. + 2 to + 3 m OP), and a smaller rise in hole 2 (from appr. +2 to +2,3 m OP). Is that the result of the installation of the impermeable barrier? I assume so.

But what surpirses me very much is the daily fluctuation of the water level in the wells, synchronous with the seawater tide, which however is about 1-2 meters lower. How is that possible?

All in all, if the core of boring 1-5 is more or less representative for the whole site, i.e. that the soil below + 1 OP is quite impermeable, the situation looks quite favourable to me!

 

[zapperzero]

All in all, if the core of boring 1-5 is more or less representative for the whole site, i.e. that the soil below + 1 OP is quite impermeable, the situation looks quite favourable to me!

http://fukushima.over-blog.fr/article-the-geology-of-fukushima-88575278.html
EDIT: it's a beautiful report and it references even a post from Azby on here...

 

[Azby]

http://fukushima.over-blog.fr/article-the-geology-of-fukushima-88575278.html
EDIT: it's a beautiful report and it references even a post from Azby on here...

Yes, that is a good report. And it's hard to believe that post is from June 2011. I think it's time to get in touch with that geologist again.

 

[tonio]

This is indeed an interesting report. It shows that:
- the original land surface was appr. 30 m above sea level;
- the whole site was excavated to a level of appr 10 m above sea level;
- the central part was even further excavated to appr. 5 m below sea level, to enable the construction of the reactors, and then re-filled (to 10 m above sea level?);
- the site is constructed on a 50 m thick layer of muddy and sandy rocks (T3 layer: page 6);
- above appr. sea level, this T3 layer consists of sand (profile: page 2);
- there is an ancient fault in the deep subsurface( > 200 m depth), but it is not present in layers T1-T3, suggesting that it has not been active for several million years.

I assume that the muddy and sandy layer (T3) consists of an alternation of sandy(river) and clayey (river, sea) sediments. Such layers tend to show a great horizontal and vertical variation in composition (sand-silt-clay alternation) as they are formed due to deposition from river beds - which are constantly changing their position (sand sedimentation in bed and clay sedimentation away from bed) - and due to sea water intrusion (marine clay deposits).

Based on these data:
- the composition of the T3 layer may well be very heterogenous (alternation of sand and clay in horizontal and vertical direction;
- the soil of the central part of the site (around the reactor buildings) consists of an appr. 15 m thick layer of backfill, probably consisting of previously excavated T3 material;

Thus, in order to assess the composition and permeability of the soil and the ground water flow patterns and contamination situation, it may well be necessary to execute a significant number of drillings and install a large number of wells.

 

[Rive]

But what surpirses me very much is the daily fluctuation of the water level in the wells, synchronous with the seawater tide, which however is about 1-2 meters lower. How is that possible?

I don't know, but some water levels are ... interesting. Disturbing. What's happening there??

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130823_04-e.pdf

 

[a.ua.]

I don't know, but some water levels are ... interesting. Disturbing. What's happening there??

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130823_04-e.pdf

Perhaps this is due to the full moon.
The strongest tides.?

 

[tonio]

I just looked at the data. I didn’t realize that the remediation efforts are focused at a very small area inbetween the reactor 1 and 2 inlets, possibly related to a ground water contamination caused by a spill in 2011? Three images:
- 01: general ground water quality data;
- 02: detail of area inbetween 1 and 2 inlet, with newly constructed barrier
- 03: ground water levels on 23 august 2013

Thus the ground water cleaunup works seem to be limited to the small area inbetween reactor 1 and 2 inlets. Due to the installation of the barrier in this area, the ground water level in this area significantly increased in the weeks before august 8. The ground water level in other areas (holes 2 and 3) didn't change much.

On august 8, the water level in hole 1 and the surrounding holes starts to decline. I assume that this is due to a ground water withdrawal somewhere near holes 1 /1-2. On august 17, the lowering started to accellerate, probably due to an increased withdrawal speed.

The level in hole 1-4 seems to be erratic, possibly due to a malfunction of the measurement device (electronic device).

The typical daily fluctuation of the water levels, expecially in hole 2, puzzles me. Ground water levels can show tidal variations comparable to the sea water tide, but with much smaller amplitudes, in the order of centimeters, as far as I know. Very strange!

 

[zapperzero]

Fukushima Voice version 2e: Twelfth Prefectural Oversight Committee Meeting: Thyroid Ultrasound Examination Results

 

[a.ua.]

tonio

Ground water levels can show tidal variations comparable to the sea water tide, but with much smaller amplitudes, in the order of centimeters, as far as I know.

But on Monday, Tepco said that data it collected showed the levels of the water in its test wells was rising and falling along with sea-water levels, according to the tides. That led the company to conclude that there could indeed be a link between the groundwater at the coastal side of the plant where the wells are, and sea wate

July 23, 2013,

Fukushima Watch: What's Different About the Latest Radioactive Leak Into the Sea - Japan Real Time - WSJ

 

[Rive]

I just looked at the data. I didn’t realize that the remediation efforts are focused at a very small area inbetween the reactor 1 and 2 inlets, possibly related to a ground water contamination caused by a spill in 2011?

They've just started the ground improvement work between Unit 3-4 some days ago.

The level in hole 1-4 seems to be erratic, possibly due to a malfunction of the measurement device (electronic device).

IMHO it's not likely. That data requires immediate checks. It would be really stupid from (somebody) to let it unchecked for so long.

Otherwise, it has a kind of fluctuation related to the tidal wave, but much greater scale than anything else there. Really strange. Maybe the hole was (Fortunately? Unfortunately?) drilled directly into a flow path between the trenches and the ocean?

 

[tonio]

Some observations about the ground water fluctuations:

- a.ua quotes Tepco concluding that "there could indeed be a link between the groundwater at the coastal side of the plant where the wells are, and sea water". It is difficult to believe that Tepco has made such a silly statement. Unless the site has been constructed in some sort of "bath tub" totally isolated from the surrounding ground water and sea water (which clearly is not the case), there will always be such a link.

- the ground water lever wil fluctuate together with the sea water tide with an amplitude that is equal to the tide at the contact between the seawater and the ground water (i.e. at the sea bed) and which will decrease with increasing (hydraulic) distance from the sea bed.

- the exact ground water fluctuation at any point of the site (x, y and z coordinates) could be predicted if you have a three dimensional geohydrological model of the site with the hydraulic permeability of the soil (including the backfilled materials), the just installed barrier and other possible barriers such als underground walls, quay walls, etc. I am quite certain that Tepco must have made such a model, which is absolutely required for the effective planning of ground water remediation measures.

- With respect to the fluctuation of the ground water level in hole 1-4, I would believe that a direct flow path between this hole and the sea as suggested by Rive could exist, but only if the water level in the hole would be (almost) equal to the sea level. But that is clearly not the case. Thus, it seems to me that there must be another explanation for it.

 

[zapperzero]

https://www.physicsforums.com/showpost.php?p=4486102&postcount=14130

 

[tonio]

translation...

 

[tonio]

Interesting report! Also available in English? I can't read it, but the figures more or less speak for themselves, I copied two of them.

P43 cross section geology shows the geology of the site, as far as I can see. I assume that the dark green layer is a relatively impermeable layer.

P53 cross section withdrawal shows the withdrawal wells and a map with the positions of these wells. I assume the dotted blue line gives the normal ground water table and the continuous blue lines the lowering of the ground water table as a result of the withdrawal. But what are these shallow holes left and right of the buildings?

What surprises me is that the withdrawal wells are relatively shallow, probably because of the presence of the (brown coloured) impermeable layer which prevents deeper emplacement of these wells. But it means that there will remain quite a significant ground water slope (and thus groundwater flow) towards the sea.

I don't known why Tepco emplaced these wells at the plateau and not at the foot of the steep slope, because that would have enabled a further reduction of the ground water slope and thus a further lowering of the ground water flow through the site.

 

[zapperzero]

err

the shallow holes should be piping trenches and such