Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Atomfritz]

The image I came across may have been right at the margin of the satellite camera resolution. Here's best version of the DigitalGlobe image I could find:

http://upload.wikimedia.org/wikipedia/commons/7/7d/Fukushima_I_by_Digital_Globe.jpg

You are right.
Bandwidth issue. Roof girders apparently too small to be displayed. Resulting in dirty grey. This phenomenon is even aggravated by non-integer scaling.

Look at the vertical diagonal girders of #1 on the same pic:

You see the bandwidth problem. The X looks more like the 5 on a dice.
And. you clearly can recognize the debris on #4 roof that is not aligned with the ceiling bars.

However, look closely at the satellite photo that has been taken several hours before the helicopter film.
The rightmost three steel pillars (NE side) are clearly bent outside, way more than you can recognize in the satellite photo. So it seems reasonable for me to assume that in the aftermath of the explosion the building and the debris settled/moved for some time until getting (temporarily) stable.

 

[Atomfritz]

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example.

This is true. But as nuclear society is closed society, investigators like CNIC need help from inside informers.
So it is often not possible to reveal the source to protect the leakers of nuclear secrets.

I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66. It looks like the image in the CNIC document of the cross-section of piping may have been created by combining 2 or more of the images on that page. Lack of sourcing lowers credibility, IMHO. In this case, though, I may have found the source.

Thank you very much for your effort. This is a very long document with much meaningless "information" for the public. Very interesting, see below.

However, it is probably not the source for the CNIC information.
The picture in the CNIC newsletter seems to be high-resolution, very exact and professionally annotated, probably photographed from an internal (non-public) report.
The scan on the document you found in contrast very coarse-grained and incomplete, to be of limited use of the public.
And, the diagrams on the public document are way less illustrative than the drawing intended only for "nuclear insiders".

However, the really important parts of the document are revealing. See Chapter 4:

4. Investigation of pipe wall thickness control
[...]
(2) Validity of PWR Management Guidelines
For the PWR Management Guidelines, more than 10 years have passed since the
establishment, and a lot of thinning data has been obtained. Nevertheless, no review has
been done based on the latest data.
[...]
This time, actual values of the thinning rate based on
the data obtained by the inspections so far, described later, at nuclear power plants
throughout the country were analyzed, and it was found that these values are less than the
initially set value of thinning rate prescribed in the PWR Management Guidelines except
for only a few of them. Therefore, the initially set value of thinning rate prescribed in
the Guidelines can be assessed to be valid in principle.

Selection of sampling points
For the portions showing no tendency of thinning, the PWR Management Guidelines
stipulate inspection of those portions at a rate of about 25% every 10 years
​

It is very interesting to read this.
Such a long document just to hide the fact that profits go before safety.

We now know that a big part of our NPPs never gets examined.
This regards a big part of the primary circuit.
There just tests of other locations are being interpolated, and if this interpolation is satisfiable, then "tests" are passed without actually testing the tubing in question, or even knowing its state.

The nuclear industry and "regulation" says: Because our method of "testing" is valid in principle, we are correct and no changes are necessary.

We Krauts have a proverb: "Die Ausnahme bestätigt die Regel." (The exception confirms the rule.)
So you basically cannot be sure if you only interpolate instead of actually looking/measuring what's there.

You always have to expect that possibly something unusual/irregular could happen. You cannot conclude that nothing is wrong without actually checking, just because the probability that something is wrong is only 1%.Just another example: Davis-Besse RPV "passed" so-called "tests" over years while actually almost breached, etched through. leaving only the thin stainless steel layer as protection from an uncontrollable accident.
Remember, the problem was discovered only by somebody who was so bright not to regard the massive stains of leaking boric acid as "unimportant", as his colleagues did for years.
(See http://iweb.tms.org/NM/environdegXII/0855.pdf" for many illustrative photos)

And with this "regulation" the nuclear industry does not even need to lie: "We did all checks necessary by regulations" when in fact checking almost nothing of real safety relevancy.

Pipelines are specifically designed to be pigged. I am not sure that Nuclear Power Plants, however, are so designed (I don't think smart pigs were in existence when some of these plants were built).

In principle, pigging using smart pigs permits 100% inspection of the full length of piping, especially critical piping that may not be easily accessible. Obviously, implementing a pigging program in a plant that was not designed for it would present a number of challenges. Among them would be I would think radiation hardening (smart pigs are electronic devices), launching/retrieval issues, fittings that might prevent passage of the pigs and so forth. Does anyone know if this has been tried in practice?

Nuclear plants are not designed for pigging.
In fact, pigging is used there only as the very last resort, if there is nothing to be lost anyway.

Several reasons:
Pigs are difficult to use around corners because you have to open the tubing if the pig gets stuck.
However, tubing in NPPs has many turns, making pigging extremely risky.
One stuck pig = massive, expensive repair work creating lot of outage time.

And, tubing diameters are not continuous. You have ups, downs, turns, orifices, varying diameters, etc. Many opportunities for problems with pigs.

Usually tube checking is done with ultrasonic or X-raying at a few points, at least in Germany.
And, please don't forget the tendency in the nuclear industry to just protocol some random "acceptable" values if the real measurement results do not satisfy!

(I have this information from a newspaper interview with a nuclear engineer; the reporter asked the engineer why there were not used pigs to examine tubing. It was after some aging German reactor had to be shut down because deep cracks were accidentally detected in primary circuit feedwater lines. This was before the Internet age, so it may be difficult to find the source. Maybe Astronuc or Nuceng can confirm the information.)Edit:
P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

 

[jmelson]

P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

They had to build a massive facility to offload the liquid sodium into drums under a nitrogen atmosphere, then they were finally, about a decade later, able to lower cameras into the reactor to observe what the problem was. The part that broke loose and wedged into the core was not even on the drawings, but was added days before the design was locked in, to spread a melt-down and prevent pooling of melted fuel.

There was a book called "we almost lost Detroit" about this and other accidents. It is extremely breathless "journalism" but if you read through that stuff, it has a lot of good info that wasn't easily available anywhere else at the time I read it.

Jon

 

[tsutsuji]

- At 2:45 PM on July 26, TEPCO's employee who moved from Fukushima Daini
Nuclear Power Station to Fukushima Daiichi Nuclear Power Station and had
driven a vehicle in the site with wearing full face mask, noticed that
the charcoal filter was not installed on the full face mask when the
worker came back to the Main Anti-Earthquake Building. As the result of
dose evaluation of internal exposure, we confirmed that no affect on the
body.
http://www.tepco.co.jp/en/press/corp-com/release/11072703-e.html

http://www.fnn-news.com/news/headlines/articles/CONN00204177.html 11 people have been sent to unit 3's reactor building. Their mission is to inspect the piping on the second and third floors as part of a plan to create an alternative water injection route which might be more efficient than the present one which requires a 9 m³/hour flow and is a major source of accumulating contaminated water. It is a difficult work because in some places in this reactor building radiations up to 75 mSv/hour are observed. A pump in the megafloat low contaminated water filling system has been found leaking, and the system had to be shut down, but there is no radiation released outside or into the sea.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110727/index.html Today's manned mission is the result of yesterday's robot mission that showed that unit 3's piping and valves were little damaged. 6 people are going to the second and third floors.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110727_01-e.pdf robot Quince's yesterday mission.

 

[tsutsuji]

I am not impressed with CNIC's sourcing practices. Reading some of the linked reports, there are multiple unsourced references. The http://cnic.jp/english/newsletter/pdffiles/nit103.pdf publication which reports on the Mihama pipe rupture as mentioned above is one example. I have tried to source the diagram of the pipe thinning and I believe that I have found what may be the original source document from which this image was created. Please see http://www.atomdb.jnes.go.jp/content/000025568.pdf , page 66.

I tried to see if could find something, but I didn't find anything much interesting apart from a few photographs that were released to the press :

[PLAIN]http://www.atomdb.jnes.go.jp/content/000018631.jpg
From http://www.atomdb.jnes.go.jp/events-data/events-001585.html

[URL]http://www.fukuishimbun.co.jp/jp/mihamaziko/0811b.jpg[/URL]
From http://www.fukuishimbun.co.jp/jp/mihamaziko/kiji1.htm (11 August 2004)

[URL]http://www.fukuishimbun.co.jp/jp/mihamaziko/0811bb.gif[/URL]
From http://www.fukuishimbun.co.jp/jp/mihamaziko/kiji1.htm (11 August 2004)

Kepco inspected other facilities and replaced the pipes at the Takahama Nuclear Power Plant's No. 3 reactor and Oi Nuclear Power Plant's No. 1 reactor, both in Fukui Prefecture, with stainless steel ones between 1998 and 2003 because they had worn so thin that they would not last another two years, the sources said.
http://search.japantimes.co.jp/cgi-bin/nn20040811a1.html

 

[gmax137]

...
P.S.: After I wrote this, I remembered that I really never understood by what means people at http://en.wikipedia.org/wiki/Enrico_Fermi_Nuclear_Generating_Station" found out that there was a piece of Zirconium cladding at the bottom of the reactor, blocking coolant circulating and causing partial meltdown.
Sodium is opaque and the "part" officially being the cause of the accident was at the bottom of the reactor vessel, below the molten core.
So, I ask myself, how did they find this out?

...
There was a book called "we almost lost Detroit" about this and other accidents. It is extremely breathless "journalism" but if you read through that stuff, it has a lot of good info that wasn't easily available anywhere else at the time I read it.

Jon

Here's a book with more detail than you probably want (and it's not 'breathless' by any means):

https://www.amazon.com/dp/0894480170/?tag=pfamazon01-20

 

[tsutsuji]

http://www.yomiuri.co.jp/science/news/20110728-OYT1T00524.htm The water treatment utilization rate for last week is hardly better than before with 58%, far from the 70% (originally 90%) target. The over-all average since the beginning is 63%. 29,000 tons have been processed so far.

http://www.at-s.com/news/detail/100048546.html (Shizuoka Shimbun) It was revealed today that the only one remaining fuel assembly in Hamaoka unit 1 (under decommissioning) 's spent fuel pool is the very fuel assembly that caused a radiation leak incident in 1994. According to a nuclear power administration related source, this is not the only plant in Japan because transporting damaged fuel is an unsolved problem. As no rule has been decided concerning the processing of damaged fuel, the country's regulatory complacency is also emerging. In December 1994 that fuel had pinholes, causing an exhaust gasses radiation alarm and a manual shut-down of the plant. While being myriads of times lower than the yearly allowed limit, this exhaust radiation level was abnormal. In October 1990 five damaged assemblies were found. One was sent to Nippon Nuclear Fuel Development Co. in Oarai, Ibaraki prefecture, and the other 4 were sent to British Nuclear Fuels. In 1994 NNFD said "pinhole damaged fuel is difficult to research" and BNF said "contract has reached its term". Chuden plans to move the damaged fuel assemblies from units 1 and 2 into the unit 4 and unit 5 spent fuel pools by the end of 2013 fiscal year, and is now studying what sort of consequences such a transportation might bring and if countermeasures are needed. (http://www.atomdb.jnes.go.jp/events-data/events-000581.html Hamaoka 1 1994 pinhole incident - INES level 0) (http://www.atomdb.jnes.go.jp/events-data/events-000198.html 1990: 5 assemblies found leaking, 78 assemblies found with abrasion. INES Level 1. Found during inspection. No radiation consequence on the environment).

 

[NUCENG]

This is true. But as nuclear society is closed society, investigators like CNIC need help from inside informers.
So it is often not possible to reveal the source to protect the leakers of nuclear secrets.
...
And, the diagrams on the public document are way less illustrative than the drawing intended only for "nuclear insiders".
And with this "regulation" the nuclear industry does not even need to lie: "We did all checks necessary by regulations" when in fact checking almost nothing of real safety relevancy.

Pipe Rupture occurred on Aug 9, 2004.

NISA Interim Report Sep 27, 2004

http://www.atomdb.jnes.go.jp/content/000025567.pdf

NISA Final Report March 30, 2005

http://www.atomdb.jnes.go.jp/content/000025568.pdf

CNIC Report Nov Dec 2004

http://cnic.jp/english/newsletter/pdffiles/nit103.pdf

Where is the evidence of secrecy in that timeline? The lack of adequate inspections was identified shortly after the event and resulted in plant shutdowns across Japan. I am not defending the utilities that weren’t performing required inspections, nor am I defending Japanese regulators for their failure to look further than shroud cracks at TEPCO a couple of years earlier. But your conspiracy theory of secrecy on this issue seems to be blown. CNIC did not discover this problem. It was discovered by the workers who were injured and killed. That is definitely not the approved method.

Mihama pipe rupture was not unique to nuclear plants. Do a little research on pipe ruptures due to flow accelerated corrosion and you will find other fatalities. You ignore the increased inspections and reviews from plants across the world as a result of Mihamas accident.

You also raise the specter of Davis Besse. First, there was no whistle blower. The problem was found when a worker found he could "wiggle" the CRDM. The lessons learned from the shutdown order and fines were severe and resulted in replacement of reactor vessel heads at many PWR plants. Even NRC came in for a lot of corrective action as a result of that event.

In short , you should probably be a little more sure of your facts on this forum, because there are people here that won’t let you get away with unfounded claims.

 

[LabratSR]

TEPCO to sample the air in the containments of units 1 and 2

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110728_02-e.pdf

 

[Joe Neubarth]

TEPCO to sample the air in the containments of units 1 and 2

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110728_02-e.pdf

That should be very interesting. Very interesting indeed.

 

[tsutsuji]

Reactor injection rate instability again :

At 5:30 pm on July 28, flow rate of injecting water to Unit 2 reactor through feed water system was adjusted to approx. 3.6m3/h after reduction of flow rate was observed.
http://www.tepco.co.jp/en/press/corp-com/release/11072902-e.html

Kurion system pump suddenly stopping again :

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110729/1335_kadouritsu.html At 5 AM 29 July it was found that one of the four pumps in the cesium removal system was stopped. This is having no consequence on the quantity of water treated. Tepco is investigating the cause [They don't say if the pump was restarted or not]. This article is also saying that the water level in the waste treatment building basements having reached 20 cm below maximum, transfer of water from units 2 and 3 turbine buildings was interrupted. This is a consequence of the poor utilization rate at the water treatment facility.

http://www.fnn-news.com/news/headlines/articles/CONN00204209.html The number of employees between 50 and 100 mSv is 1680. The number of employees above 100 mSv is 480.

 

[biffvernon]

Looks like it's been raining.

http://crofsblogs.typepad.com/h5n1/2011/07/fukushima-hit-by-torrential-rains.html

Since Wednesday, more than 650 millimeters of rain has been recorded in some parts of Fukushima. Niigata has gotten more than 600 millimeters.
The flooding will also, presumably, move radioactive soil into new locations.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110730/index.html the number of employees

above 250 mSv = 6
200 to 250 mSv = 2
100 to 200 mSv = 100

Among the 3410 people who had worked for one month or longer at Fukushima Daiichi as of the end of May and who must undergo a medical exam every month like checking their white blood cells or their skin, 1339 or 39% have not undergone the exam.

http://mainichi.jp/select/science/news/20110728k0000m040076000c.html A company in Ibaraki has developed a new method to adsorb contaminants. It uses silica, where 2~20 nanometer diameter holes are arranged in a regular fashion and a set of chemical compounds, which are chosen according to the substance you want to adsorb. Every gram of this new material can adsorb 20 mg of iodine or 13 mg of strontium, which converts into 65,000,000,000 Bq in the case of Sr-90. The adsorbing materials used so far adsorb Ca and Mg together with Sr and chlorine together with iodine. It is not the case with the newly developed material which selectively adsorbs iodine or strontium. They say it is cheap and several tons can be produced every day.

http://www.nikkei.com/news/category...39F9FE2E2E2E2;at=DGXZZO0195579008122009000000 Tepco released the result of the unit 1 containment vessel gas analysis. The cesium concentration is 1000 times lower than expected (20 Bq/cm³ instead of the several 10000 Bq/cm³ that were expected as a result of the RPV crack(s)). It is feared that it was dissolved into the contaminated water and flowed into the reactor building or anywhere else. Tepco says this measurement alone is not sufficient to determine the status of the reactor (like the RPV cracks). Meltdown being suspected, it is thought that fuel leaked from the RPV to the containment vessel. A similar gas analysis will be undertaken at unit 2 in the first decade of August.

http://sankei.jp.msn.com/affairs/news/110730/dst11073013040013-n1.htm When they first tried to analyse the 25 cm³ sample, they used a measurement tool with a 40,000 Bq minimum and could not detect anything. Then they performed the analysis again with a lower minimum and finally found 37 Bq/cm³ . Tepco said the following possibilities can be thought : 1) the radiation substances leaking from the RPV are diminishing 2) cesium is dissolved in water 3) it is pushed outside by the nitrogen injected as a hydrogen explosion prevention measure. The same measurement will be performed again in the future at regular intervals.

http://www.tokyo-np.co.jp/article/politics/news/CK2011072802000029.html?ref=rank Minister Goshi Hosono said he will announce next week concrete plans for the ground water shielding underground walls construction. (the other part of this article goes to the "more political thread")

 

[LabratSR]

Unit 1 Contaiment Air Sampling Results

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110730_01-e.pdf

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110731/4_reikyaku.html The new unit 4 SFP cooling system is being started today for a test. The temperature is expected to reach 30~40 °C in one month's time or less. The test run of unit 1 SFP cooling system is planned for the first decade of August.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110731/2000_4gouki.html They increased the flow little by little and achieved the full flow rate of the unit 4 SFP cooling system at 12:40 PM. They plan to lower the SFP temperature from 86°C this morning to 55°C in one month's time.

http://www.nikkei.com/news/headline...19595E0EBE2E38B8DE1E3E2E5E0E2E3E386989FE2E2E2 A 50 l leak occurred at the desalination facility today. It has already been repaired and the facility has been restarted. This is decontaminated water so there is, so to speak, no radiation. At the Fukushima Daini unit 4 turbine building, an air exhaust pipe was found leaking by the team inspecting the consequences of the 31 July early morning earthquake. There is no radiation. It has been repaired with fibre reinforced plastic sheet.

 

[Jim Lagerfeld]

Unit 1 Contaiment Air Sampling Results

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110730_01-e.pdf

I am absolutely intrigued by this result. If air inside containment is exactly as radioactive as air outside containment, then containment is not containing much, is it?

I'd like to read some informed interpretations of this result.

 

[rmattila]

I am absolutely intrigued by this result. If air inside containment is exactly as radioactive as air outside containment, then containment is not containing much, is it?

I'd like to read some informed interpretations of this result.

Not being an expert in this field, I've been wondering how it would be even possible for large amounts of Cs to exist in the containment air: the rate of release of new Cs is very low, once the fuel has been cooled down to below 500 deg C or so, and what was released earlier, has had plenty of time to get deposited on surfaces and dissolved in water.

Is there something I'm missing here?

 

[hellbet]

... containment is not containing much, is it? ...

There is many more ambiguous terms to say the least within Tepco reports like "reactor" or "cold shutdown". We can't hope for any cold shutdown with a broken reactor (RPV), and we can't hope for any containment with a broken Dry Well and a "leaking" concrete shell. I'm well afraid everything in this mess is more or less leaking since the intatial earthquake, the consequent tsunami and the following explosions.

 

[NUCENG]

Not being an expert in this field, I've been wondering how it would be even possible for large amounts of Cs to exist in the containment air: the rate of release of new Cs is very low, once the fuel has been cooled down to below 500 deg C or so, and what was released earlier, has had plenty of time to get deposited on surfaces and dissolved in water.

Is there something I'm missing here?

That is a good possibility. Measuring airborne radiation at such low levels does not mean there isn't a lot of cesium inside the containment. It is very likely to have settled and deposited on every horizontal surface inside the containment. This is just as it is still measured at higher concentrations in dust and debris than in the air outside the containments and offsite. It also does not mean it will be possible to send people into the containment any time soon. Direct radiation, or "shine" from deposited fission products or unshielded corium will not show up in air samples.

 

[rmattila]

Since the containment is presumably at saturation conditions around 100 deg C, one would assume there's constant condensation of steam taking place on the outer walls of the containment. It would be very easy to assume that this constant flow of steam from the containment atmosphere to the walls would drive the Cs to the walls as well, thus reducing the atmospheric content over a period of time.

 

[Gary7]

Water temperature in the SFP of #4 is now down to 63 degrees celsius (from 83) after one night of operation. They eventually hope to stabilize it at around 30 degrees.

http://news.google.com/nwshp?edchanged=1&ned=jp&ar=1312185466

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110801/index.html The SARRY water treatment system (a set of 14 diameter 1.4 m, height 3.5 m cylindrical tanks with filtering minerals inside) installation has been completed. The system will be launched in the first decade of August. From today on they will connect the pipes and perform test runs.

http://news.tv-asahi.co.jp/ann/news/web/html/210801021.html The SARRY cylinders are shielded. The test run of SARRY starts today. The unit 4 SFP temperature has already dropped to 63° C as of 08 AM this morning. It is planned to bring it to around 30°C.

http://news24.jp/articles/2011/08/01/07187671.html Tepco found 700 tons of highly contaminated water in the Waste treatment facility's Site Bunker Building basement. It is thought that the water flowed in a pipe that connects this building with another building where contaminated water is stored. Works had been performed to enable the Site Bunker Building to receive contaminated water but the permission to do so from the NISA has not been received yet.

http://www.jiji.com/jc/c?g=soc_30&k=2011080100330 Water has started flowing in the SARRY system. It will be used as a backup of the Kurion system. If the tests are OK, it is planned to start it running with contaminated water on 5 August. The hose connecting the two Waste treatment facility buildings had been prepared in June in case more storage volume would be needed as a consequence of rainfalls. Water was not supposed to flow without the pump running, but it seems that the water flowed naturally in the hose as a result of the difference of levels.

 

[Gary7]

Radiation level of 10 Sv/hr recorded outside in between reactors #1 and #2. Tepco has placed the area off limits and is checking on the source.

http://www.47news.jp/CN/201108/CN2011080101000992.html

 

[Jim Lagerfeld]

Radiation level of 10 Sv/hr recorded outside in between reactors #1 and #2. Tepco has placed the area off limits and is checking on the source.

https://www.physicsforums.com/newreply.php?do=newreply&noquote=1&p=3430531

Here is a link to http://www.nikkei.com/news/headline/article/g=96958A9C93819595E2E3E2E0E58DE2E3E2EAE0E2E3E3E2E2E2E2E2E2"

- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out, so the true figure is possibly higher. They speculate that radioactive materials released / leaked during the initial venting (pre-explosion) may have adhered to the pipe.

 

[zapperzero]

- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out

Goes to show how much trust we can put in TEPCO's cutely-colored site contamination maps.
I hope that worker got out of there in time

 

[Rive]

For me, the google translates those linked webpages up there with 10mSv/h value.

Please, can somebody confirm the 10Sv/h value?

 

[turi]

http://www.47news.jp/CN/201108/CN2011080101000992.html says 10 Sievert in the title and again 10 Sievert in the article with 10000 Millisievert in parentheses (１万ミリシーベルト). (I can't read most of the rest of the article without a dictionary.)

 

[Bandit127]

An article in English, presumably syndicated from Bloomberg.
http://www.sfgate.com/cgi-bin/article.cgi?f=/g/a/2011/07/31/bloomberg1376-LP8WWK6JTSEJ01-5PIJEFGJ36KM50OK194CMKAJ22.DTL"

It also states 10 Sv/h

 

[sp2]

So there's (let's say) 20 Sv an hour coming off some junk, outside, in the middle of everything... and nobody noticed it till now?!

Can someone help me out here?

 

[clancy688]

Well, it's inside the main ventilation stack. So it's probably leftovers from the venting process.

But I think the real question is what the hell they vented there when there's still 10+ Sv/hr five months after the accident. How big must the levels have been in early march? With all that radioactive iodine which's nearly gone by now? Several hundreds?

 

[sp2]

Inside the stack? Okay. (The first piece I read said 'debris near the stack.')

I'll look for follow-up.

(As you said, I'm not sure that's terribly comforting anyway.)

Thanks.

 

[etudiant]

Here is a link to http://www.nikkei.com/news/headline/article/g=96958A9C93819595E2E3E2E0E58DE2E3E2EAE0E2E3E3E2E2E2E2E2E2"

- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out, so the true figure is possibly higher. They speculate that radioactive materials released / leaked during the initial venting (pre-explosion) may have adhered to the pipe.

Should this be a surprise?
When there are three cores worth of material getting leached for months, one would expect every surface in the facility to be dripping with redeposited cesium, especially the venting paths.
What it says to me is that there is no rational way forward other than to drain the water and then bury the facility.
It surely would be irresponsible to have people risk their lives to dismantle a massive site just to rebury the debris elsewhere. Plus the burial need only last for a thousand years or so. By then, the cesium will have decayed.

 

[NUCENG]

Using the Freedom of Information Act, UCS obtained the Draft State of the Art Reactor Consequences Analysis (SOARCA) Report which analyzes the response of the Beach Bottom plant in Pennsylvania for a seismic event resulting in Station Blackout. The analysis includes unmitigated short and long-term SBO responses with and without mitigation steps by operators. Thisw is the first quantification I have seen of the use of B.5.b systems added to US plants after the 9/11 attacks. The unmitigated long-term SBO scenario may be useful in comparing the BWR4 response at Fukushima (RCIC plants).

Go to the ADAMS search page at www.NRC.gov[/URL] and search for the following ML numbers:

Report

ML11168A034

Appendix A Peach Bottom (3 parts)

ML11192A300
ML11192A301
ML11192A302

Edit: Rod Adams at Atomic Insights has some interesting observations about UCS and the SOARCA report here:

[PLAIN]http://atomicinsights.com/2011/08/spreading-calm-certainty-and-reassurance-about-nuclear-energy-counteracting-focused-fud.html

 

[Gary7]

My translation of Mainichi's article on the 10 Sv/hr reading:

On August 1st Tepco announced the observation of very high radiation of more than 10 sieverts (10000 millisieverts), high enough to exceed the limit of the measurement devices and the highest value seen since the beginning of the meltdown accidents, coming from the area near the surface of a pipe from the lower part of the exhaust tower on the west side of the #1 and #2 reactor buildings. 10 sieverts is extremely high, and would result in death for virtually everyone exposed to this amount. The workers at Fukushima Daiichi who have had their maximum exposure limit set at 250 millisieverts/hr would reach their maximum allowed limits at about a minute and a half of exposure to 10 sieverts.

Tepco says they have forbidden entrance to the area to a radius of a few meters, and that they will use metal plates to shield off the area so that work in that area will not be affected. They noted that if they find places with similarly high radiation it could affect work to bring the plant under control. Thorough and complete management of radioactive areas, including detailed surveys to ensure there are no other areas of high radiation, will be necessary to avoid exposing the workers to unnecessary exposure.

According to Tepco, at around 2pm on the 1st a worker noticed a change in the dosimeter reading after clearing away rubble. The pipe that had the high radiation is used in emergencies for carrying exhaust away from the inside of the reactor building. Tepco believes the high radiation may have come from either highly radioactive gasses that were stuck in the pipe after reactor #1 was vented to reduce pressure in the reactor containment on March 12th, or that radioactive particles from outside had settled on the outside of the pipe. The pipe is not currently in use. The highest recorded radiation up until now had been 4000 millisieverts, discovered inside the reactor building of #1.

The 3 Tepco employees who measured the radiation had a maximum estimated exposure of 4 millisieverts. There were few employees who worked near this area, and there has been no confirmation of any workers receiveing a large amount of radiation.

http://mainichi.jp/select/jiken/news/20110802k0000m040063000c.html

Also attaching the latest (July 31st) radiation survey map. As of this point the 10 Sv/hr spot had not been identified.

http://www.tepco.co.jp/nu/fukushima-np/f1/images/f1-sv-20110801-j.pdf

 

[Gary7]

Updated survey map showing the 10 Sv/hr region.

http://www.tepco.co.jp/nu/fukushima-np/f1/images/f1-sv-20110802-j.pdf

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110802/0625_shiunten.html Tepco plans to own by next October 8 evaporative concentration equipments in addition to the present reverse osmosis equipments, 2 of which have already been put on location as of 1 August. They are now tested and will be launched in one week's time. Together with 3 more that are to be brought this month, they will have a desalination capacity of 160 tons/day.

[URL]http://www.tepco.co.jp/en/news/110311/images/110801_3t.jpg[/URL]
Evaporative concentration equipment manufactured by Toshiba (http://www.tepco.co.jp/en/news/110311/images/110801_3.jpg)

 

[rowmag]

You are tireless, tsutsuji.

I admire and applaud your effort.

 

[SteveElbows]

Yes, thanks very much for these translations & news updates, its really helpful.

I've not had much to say for some weeks now, the sorts of things I'd like to know are unlikely to be known for a long time. This > 10 Sieverts stuff interests me, I'd like to know whether it came from reactor 1 or 2. Reactor 2 is thought to have contributed around 90% of total emissions from the early days of the disaster, but I don't think we have any visual evidence that venting via the stack happened for reactor 2.

There is the following webcam image from 3pm on March 12th, where something may be happening at the top of the stack in question, and which I assume is due to reactor 1?

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110802/index.html The robot found more than 5000 msV/hour in a room on unit 1 reactor building 2nd floor. The 10,000 mSv/hour pipe mentioned yesterday runs across that room.

 

[Bandit127]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110802/index.html The robot found more than 5000 msV/hour in a room on unit 1 reactor building 2nd floor. The 10,000 mSv/hour pipe mentioned yesterday runs across that room.

A Bloomberg report about the same thing here:
http://www.bloomberg.com/news/2011-08-02/tepco-reports-second-deadly-radiation-reading-at-fukushima-plant.html"

 

[SpunkyMonkey]

There is the following webcam image from 3pm on March 12th, where something may be happening at the top of the stack in question, and which I assume is due to reactor 1?

Fyi, that stack receives vents from both Units 1 and 2 http://3.bp.blogspot.com/-tkSlPJ7D6fA/TZXteYtJ7yI/AAAAAAAAh7s/XpV9Ky3YKXU/s1600/9.jpg". But for reasons cited in the replies just above this, the source for these new high readings seems to be Unit 1.

 

[clancy688]

I found an image of the highly dangerous 10 Sv/hr spot on www.tec-sim.de[/URL] !

[PLAIN][URL]http://tec-sim.de/images/stories/10svha.jpg[/URL]

According to the german description it's the brown tube coming out of the big stack.

 

[jim hardy]

i would guess it's a small but extremely hot piece of something
were the whole inside of that pipe filled with the stuff i doubt he'd be able get that close to it.
it's likely something that has been around neutrons(near reactor core) .

i'll keep ears open for more info as to what that pipe does and when it was used since the accident.
If indeed it's an emergency containmnent vent line then a hot particle in it would seem consistent with primary venting that first weekend.

Bloomberg included a "gamma camera image" but I'm not skilled enough to make it appear.
http://www.bloomberg.com/photo/tepco-reports-second-deadly-radiation-reading-at-nuclear-rea-/90617.html

old jim

 

[etudiant]

Does this not mean that the stack emissions were the primary source of the contamination plumes that Japan is now starting to focus on? It seems to indicate that the explosions may have played second fiddle to the stack emissions in propagating the radioactivity beyond the plant boundaries.
An earlier posting had noted that the stack emissions for the Swedish reactors are put through a large absorption bed. Should this not be a requirement generally, along with the hardened stack?

 

[zapperzero]

Does this not mean that the stack emissions were the primary source of the contamination plumes that Japan is now starting to focus on?

No. Other than that, you are correct, of course. Vents _should_ be hardened and provided with scrubbers&/filters. Google Cockcroft's Folly.

 

[tsutsuji]

http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110803_04-j.pdf Water treatment facility bypass line No. 1 and bypass line No. 2 diagram (not yet translated into English)

http://www.nikkei.com/news/headline/related-article/g=96958A9C889DE1E1E1E3E4E4EBE2E2E0E2EAE0E2E3E39797E0E2E2E2;bm=96958A9C93819595E2E3E2E0E58DE2E3E2EAE0E2E3E3E2E2E2E2E2E2　 On 1 August, Tepco announced that the ground water shelding wall construction would start seaside before January. It is an 800 m long, 30 m deep wall made of steel tubes and plates. The construction will take two years. Its cost will be announced together with the April-June financial closing. The decision to build or not to build a wall hillside will be taken by January.

http://www.meti.go.jp/press/2011/08/20110803004/20110803004-2.pdf The water treatment facility treated 6190 m³ during the 27 July-2 August week. Utilization rate 6190/(50*24*7) = 74%.

http://www.mbs.jp/news/jnn_4792306_zen.shtml A new independently acquired JNN video taken last week. The car passes close to the 10000 mSv/hour pipe. Then workers are shown being busy with hoses outside the water treatment facility. Their geiger counter reaches 4 mSv/hour as they are driving seaside close to unit 4 turbine building. This is higher than the 2.2 - 2.5 mSv values written on Tepco survey maps.

http://www.tepco.co.jp/cc/press/betu11_j/images/110803l.pdf This is the Japanese language press release version of Tepco's report to NISA about the stability of securing cooling to units 1,2,3. According to http://mainichi.jp/select/weathernews/news/20110803ddm008040042000c.html it contains details such as the earthquake safety of the system, or how much time it would take to recover from a blackout. I have begun to read some pages. Page 11-1 (pdf page number 33) tells how much time it would take to reach 1200°C if cooling stops : 15,14,13 hours respectively for units 1,2,3.

 

[zapperzero]

Using the Freedom of Information Act, UCS obtained the Draft State of the Art Reactor Consequences Analysis (SOARCA) Report

Any idea where they got their 10E-6/reactor-year probability for an accident?

 

[joewein]

Does this not mean that the stack emissions were the primary source of the contamination plumes that Japan is now starting to focus on?

I think the bulk of the radioactive release that came down over land was from units 2 and 3, not unit 1.

An earlier posting had noted that the stack emissions for the Swedish reactors are put through a large absorption bed. Should this not be a requirement generally, along with the hardened stack?

What I have read before, but can't provide the source of right now, is that the normal venting path uses filters / charcoal scrubbers, but the hardened venting system added in the 1990s (based on modifications installed in US reactors after TMI-2) uses an unfiltered vent path. From what was explained, the back-pressure from filters would have been too high for a quick release of large amounts of gases threatening the integrity of the containment vessel.

When the JP government first announced that some venting would take place at unit 1 they also said the vented gases would go through filters. The http://www.iaea.org/newscenter/news/2011/fukushima110311.html" :

Japanese officials have also reported that pressure is increasing inside the Unit 1 reactor's containment, and the officials have decided to vent the containment to lower the pressure. The controlled release will be filtered to retain radiation within the containment.

Christoph Mueller of http://www.tec-sim.de/" writes (translated from the German original by me):

1) Clarification about the high radiation figures in the pipe elbow. It is a typical phenomenon that tiny particles in a gas flow deposit at an elbow, as they have difficulties, flowing "around the corner". They fly straight on and hit the wall and remain stuck there. Therefore highly radioactive deposits form at elbows. This has nothing to do with rain or other effects, as some "experts" theorize in the press today. In all elbows, through which radioactively polluted gases gases flowed in a controlled venting such deposits can be found. It is only a matter of time when they are detected.
2) Clarification about the contaminated rooms in unit 1. Since at the point of controlled venting of the containments the containment atmosphere was highly contaminated because of the melt-down, a large portion of the radioactivity will have condensed in the filters, which because of that will radiate strongly. That's exactly what TEPCO has now found while inspecting the filter room in unit 1.

(See his original post: "Aktuell 3.8.: Klarstellung zu den heißen Stellen in der Abluftleitung und I am Filterraum" for the German text)

EDIT: I found my source for the statement that the new venting system was unfiltered. It was http://www.nytimes.com/2011/05/18/world/asia/18japan.html?pagewanted=2&_r=1":

The improved venting system at the Fukushima plant was first mandated for use in the United States in the late 1980s as part of a “safety enhancement program” for boiling-water reactors that used the Mark I containment system, which had been designed by General Electric in the 1960s. Between 1998 and 2001, Tokyo Electric followed suit at Fukushima Daiichi, where five of six reactors use the Mark I design.
(...)
The fortified venting system addressed concerns that the existing systems were not strong enough to channel pent-up pressure inside the reactors in an emergency. Pressure would be expected to rise along with temperature, damaging the zirconium cladding on the fuel rods at the reactor core and allowing them to react chemically with water to produce zirconium oxide and hydrogen gas.

The new vents were designed to send steam and gas directly from the reactor’s primary containment, which houses the reactor vessel, racing past the usual filters and gas treatment systems that would normally slow releases of gas and eliminate most radioactive materials.

 

[zapperzero]

The normal venting path uses filters / charcoal scrubbers, but the hardened venting system added in the 1990s (based on modifications installed in US reactors after TMI-2) uses an unfiltered vent path.

IOW, the operators got permission to release contaminants directly to the environment during emergencies instead of having to spend money on replacing their existing, severely undersized filters and scrubbers.

Neat.

 

[rmattila]

What I have read before, but can't provide the source of right now, is that the normal venting path uses filters / charcoal scrubbers, but the hardened venting system added in the 1990s (based on modifications installed in US reactors after TMI-2) uses an unfiltered vent path. From what was explained, the back-pressure from filters would have been too high for a quick release of large amounts of gases threatening the integrity of the containment vessel.

Regarding the Finnish/Swedish BWR:s referred to previously:

With the exception of the already-closed Barsebäck units, the Swedish BWR:s (and their two sister plants here in Finland) were backfitted with two separate severe-accident systems: the containment overpressure protection system (system 361 in ASEA coding) and the filtered venting system (system 362). 362 is filtered with so called SAM scrubbers, whereas 361 is unfiltered.

See page 12/51 on this document for the solution by TVO.

Both systems are equipped with frangible plates such that the filtered line (system 362) will open in lower pressure (typically around 4 bar) and the unfiltered system 361 at a couple of bars higher. The sole purpose of the unfiltered system 361 is to provide a pressure release path in a rapid overpressurization of the containment, caused by a large-break LOCA coincident with loss of the pressure suppression function of the containment. Depending on the plant, the manual valves of the unfiltered system 361 will close automatically or manually 10-20 minutes after the LOCA is detected, and will remain closed thereafter.

So the venting after fuel damages are to be expected is always done through the filtered-venting line (system 362). Since it has frangible plates, human decision will not be needed to initiate the first venting, but after the venting begins and the manual valves are closed for the first time, re-opening them will require manual action. Both lines are "hardened" in the sense that they are dimensioned for the severe accident conditions, and are separated from the normal containment venting lines used for atmosphere change etc. And as said earlier, they were installed in the late 80's following the TMI accident (which initiated the SAM system projects) and ultimately Chernobyl (which gave it more urgency).