Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[clancy688]

The readings from the only sensors that are still working say that water level in the cores of reactors #1--#3 are 1.6 meters, 2.1 meters, and 2.2 meters below the top of the fuel, respectively. The most optimistic interpretation is that the fuel rods are still there, but uncovered by that amount.

Hm, that could be true for the Unit 1 reactor. But in Unit 2 and 3 the core pressure is very low, close to atmosphere level. I have no clue of thermodynamics, but I have heard that high pressurized steam is able to channel heat very well (=cool the fuel rods even if they are out of the water).
But that doesn't apply to steam at normal pressures... so how can they still be cooled?

 

[Samy24]

Please note: per forum rules all posts should be in English and those in other languages should be deleted.

I did the answer in German and also in English. That was the way a senior member of this forum did it before. But no problem, I do not want to brake the rules. The post is deleted now.

 

[Joe Neubarth]

Do you have a source for the "about four meters" ?

Looking at the "predicted maximum level caused by tsunami O.P. 5.7 meter" caption leading via the blue arrow to the red dots just above the sea wall at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf , I am wondering how tall that sea wall is. If the sea wall is 5.7 m high and the tsunami only "about four meter" high, should not the nuclear plant have been safe then ?

I would be glad to read more basic science on this topic : how tsunami height and tsunami "run up" are related with each other and possibly modelized, and how sea walls are designed to ensure some predicted level of protection.

What is the meaning of the "O.P." acronym ?

OP stands for Original Poster. The answer to your other questions is contained in the data on this chart. There are historical accounts in Japan of runups well in excess of 40 feet on the Japanese east coast. Why Fukushima was not built to protect against those reports is beyond me. We know that unbelievable errors have been commited by highly intelligent people in life. The Hubbell space telescope problem when it was originally put in orbit comes to mind. The Mars probe that impacted the planet because somebody did not make a conversion from feet to meters. The crash of the KLM 747 into another 747 on the ground in the Azores killing hundreds. The pilot of the KLM 747 was their company safety officer, yet, he violated all of the rules of safety that day.

On the chart note the tidal heights (tsunami height up and down the east coast of 3.3 to 4.2 meters) and the run up heights which were considerably higher in most cases.

 

[HowlerMonkey]

It's possible the "leaks" that are allowing water to be pumped in without level changes are both from damage and purposeful draining of the water to create flow.

If you simply fill containment with water, it will heat up and boil off so flow is needed to slough off the heat.

Just a theory.

I wonder if they can use pumps to recirculate the water from the basements back into the containment in a sort of cooling loop but I'm not sure how much heat that would slough off.

 

[TCups]

One last comment to that idea:

I checked the T-Hawk Video for the two impact spots you mentioned. There's a guard rail or something like this going along the turbine building. But the debris is sticking between the guard rail and the building, indicating it's come from above.

If it has come from the east side of Unit 4, it should have smashed the guard rail. But that's not the case. The impact damage on the west side of the turbine building origins in the blast at Unit 3. The smoke is probably an optical illusion, it's most likely smoke from Unit 3 as well.

Yes, the dark spots are draped debris, probably roofing insulation, and presumably from the explosion at Unit 3, not from an explosion at Unit 4. But, regarding the report of a fire at Unit 4, check this on-line (copyrighted) document:

https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Fukushima%20Earthquake%20and%20Tsunami%20Station%20Blackout%20Accident.pdf

On page 6, seems to conclude that a fire has started "in the side of the Building 4" and has a different photograph of the smoke, less from Bldg 3 and more from Bldg 4. I still can't separate what smoke is definitely coming from the exhaust tower vs what might be coming from the east side of Bldg 4.

Photo excerpt attached. It would be useful to have the original photo. Resolution is poor and the light is tricky.

 

[clancy688]

The answer to your other questions is contained in the data on this chart.

Not-so-fun-fact:

http://english.kyodonews.jp/news/2011/04/82888.html

Maximum run-up height was 37.9 metres in Taro. The village was featured in an 2005 Discovery Channel documentary about Tsunamis. They talked about their 10 metre tsunami wall and how this wall is offering them only partial protection.
Watching that documentary now is like watching a prophecy... Taro's been totally shattered by the March 11th monster wave.

 

[tsutsuji]

Wow. The tsunami-chart is interesting. They plotted wave heigths along the coast for three major tsunamis (1611, 1896, 1933).
But at the Onagawa location, all of these three tsunamis were around 5 metres. The really big wave heights of 20 metres and more were reached on the shore starting at 100 km north of the plant location.

Yet they don't seem to have paid any attention to the 869 tsunami : http://www.sciencemag.org/content/332/6025/22.summary

I also wonder why they ruled out those 20 m height tsunamis. I know that the shape of the coast can increase the tsunami's height, so that one possibility might be that Onagawa has a good coast shape. Otherwise, to my layman's eyes, it seems intuitively difficult to rule out that future similar earthquakes might have an epicenter located 100 km to the South, even if their probablility is smaller.

Warning, highly speculative:
So that's probably one of the reasons, they only build Daiichi 10 metres above sea level and not really water proof - because historic tsunamis didn't reach 15 metres at Fukushima which's between 100 and 200 km south of Onagawa...?

Or did they rely on those "hazard maps" :

The Japanese authorities publish annual "hazard maps" to highlight parts of the country deemed at risk from major earthquakes, but there is no reliable scientific basis for the technique, the researcher [Robert Geller at the University of Tokyo] said.
http://www.guardian.co.uk/science/2011/apr/13/flawed-earthquake-predictions-fukushima

Note also, per http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf that 10m is for units 1, 2, 3 & 4, while units 5 & 6 are 13m high.

By the way, a http://blogs-images.forbes.com/oshadavidson/files/2011/04/Tsunami.jpg"

 

[clancy688]

Photo excerpt attached. It would be useful to have the original photo. Resolution is poor and the light is tricky.

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichiov_march14_2011_dg.jpg

That's the original. The version in the pdf has been zoomed and angled. But it's a photo from March 14th, not 15th as stated in the pdf. It's been taken three minutes after the explosion in Unit 3, at least that's what I've been told by other forum users... ^^ (and I remember too DigitalGlobe stating that they took the pictures immediatly after the explosions)

 

[MadderDoc]

At the TEPCO (lowres) webcam I can not see any steam since the last two days
http://www.gyldengrisgaard.dk/tepcowebcam/tepweb20110420.html"

So does that mean that reactor 1-3 and all the SFP's are run dry?

Actually the webcam photos for today show quite a lot of steam coming from SFP4 in the early morning. (According to Tepco, spraying to SFP4 started at 5:08, so the steam seen on the webcam must have been from water already in the pool)

The webcam is sited at the knoll south of the plant and has direct view to the top of the upper floor of the south side of unit 4, and we currently see the outlet of the concrete pump hovering over it.

Unfortunately we have view to little else:

- Unit 1 is blocked completely out of view

- Of unit 3 is so little left in the height that it 's presence cannot be discerned (except for the occasional smoke/steam from it, then originating from a point about center of unit 4.)

The upper profile of unit 2 can be seen in the webcam as a horizontal line, above the unit 4 building. Also a bit of the top of the vertical vent pipe hanging on its western face (to the left) can be discerned. The 'window' to the east however, from which unit 2 has done most of its steaming is out of view, including an eventual steam fan from it. The window is at the bottom top floor, and that's lost behind the trees, so we would not see even a steam fan from it, if there is one.

 

[etudiant]

Has there been any further evaluation of the impact of accumulated salt on the cooling inside the reactors?
It seems entirely possible that dried salt is blocking the water flow to the core, so the reactor might show as much cooler than the actual core conditions really are.
In that case, would it not take considerably longer for the core to cool down?

 

[clancy688]

Hm, another observation on Unit 3:

Image of March 14th, 3 minutes after the explosion:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichiov_march14_2011_dg.jpg

Image of March 16th:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi3_march16_2011_dg.jpg

Note that on both pictures, which are two days apart, there are two different steam plumes originating in Unit 3.

Plume 1 = SFP, Plume 2 = RPV maybe?

 

[triumph61]

I found a Video at Stern.de 15. März 2011, 14:09 Uh.
B3 is dameged, B4 still ok.
http://www.stern.de/panorama/atomunfall-fukushima-explosion-reisst-loecher-in-reaktor-4-1663871.html

 

[Jorge Stolfi]

I've updated my plots of Fukushima Daiichi reactor variables, units #1--#3, up to NISA release 104 (20/apr 15:30) :

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/Main.html

The sudden factor-of-ten drop in the CAMS reading (A) of reactor #1 suppression chamber, which happened betwen NISA releases 97 and 98, is persisting. Perhaps all previous readings were wrong?

I am surprised at the large difference between readings for the CAMS od suppression chamber in reactor #2: the (A) reading is 0.55 Sv/h, the (B) reading is 103 Sv/h. (Yep, sievert, not millisievert.) How could that be?

 

[clancy688]

I found a Video at Stern.de 15. März 2011, 14:09 Uh.
B3 is dameged, B4 still ok.

Um... your video has been taken from the north west side, so you can't see the east side. Furthermore, the titel of the video is "Explosion reißt Löcher in Reaktor 4", translated "Explosion tears holes in reactor 4".
So it's NOT okay. ;)

 

[triumph61]

i don´t know when the video was taken. The original is NHK. There is no smoke at B3 seen.
B4 seems intakt at this side. Perhaps more than one explosion

 

[MadderDoc]

<..>regarding the report of a fire at Unit 4, check this on-line (copyrighted) document:

https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Fukushima%20Earthquake%20and%20Tsunami%20Station%20Blackout%20Accident.pdf

On page 6, seems to conclude that a fire has started "in the side of the Building 4" and has a different photograph of the smoke, less from Bldg 3 and more from Bldg 4.

It's the same photo, still from 11:04 JST. You can use the center smoke from unit 3 for 'fingerprinting'. It's all in how you cut and expose it. What your eye interprets as 'more smoke' from unit 4, is just the light of the sun reflected by the roof of the unit 4 turbine building.

Reflected why? Because the roof is still _wet_ from the fallout of the grand expulsion of steam and water from unit 3 that happened a few minutes earlier.

I still can't separate what smoke is definitely coming from the exhaust tower vs what might be coming from the east side of Bldg 4.
Photo excerpt attached. It would be useful to have the original photo. Resolution is poor and the light is tricky.

Indeed it is :-)

 

[jmelson]

clancy 688: that may be A difference (I have to confirm your elevation data) but still, the picture i posted shows that there has also been a heavy flooding of the platform at the Daini plant (which i didn't really know about to tell you the truth). At the Daichi plant, if i remember well, the diesel generators were at ground level (or even below ground level maybe, in the basement of the turbine building? Don't remember...). So my point is: ok the tsunami has been worse at Daichi than at daini because some difference of height of the platform but still, did the EDG at Daini went under water, or close to go under water too?

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf

Daini maintained grid power, so the Diesel generators were not critical to maintaining cooling.
I think THAT may have been the main difference. The extra elevation sure didn't hurt, though.

Jon

 

[triumph61]

one more Video
http://www.stern.de/panorama/atomkatastrophe-in-japan-erneute-explosion-setzt-radioaktivitaet-frei-1663662.html

 

[clancy688]

http://www.stern.de/panorama/atomkat...i-1663662.html

If you're referring to the helicopter flight video around the plant - that was probably taken before the accident. All Units are fine and there's no tsunami damage whatsoever at the other buildings.

-------------------------------------------------------------------------------

Robot videos online: http://www.tepco.co.jp/en/news/110311/index-e.html

 

[jmelson]

Not-so-fun-fact:

http://english.kyodonews.jp/news/2011/04/82888.html

Maximum run-up height was 37.9 metres in Taro. The village was featured in an 2005 Discovery Channel documentary about Tsunamis. They talked about their 10 metre tsunami wall and how this wall is offering them only partial protection.
Watching that documentary now is like watching a prophecy... Taro's been totally shattered by the March 11th monster wave.

Holy cow, that's 124 FEET!

Jon

 

[AntonL]

...

What is the meaning of the "O.P." acronym ?

Observation Post a fixed reference level set in concrete before work begins.

 

[MadderDoc]

Hm, another observation on Unit 3:

Image of March 14th, 3 minutes after the explosion:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichiov_march14_2011_dg.jpg

Image of March 16th:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi3_march16_2011_dg.jpg

Note that on both pictures, which are two days apart, there are two different steam plumes originating in Unit 3.

Plume 1 = SFP, Plume 2 = RPV maybe?

In most photos there appears to be two distinct sources of steam/smoke from unit3. The northern of those plumes seems to originate from the area of the chute between the reactor and the utility pool. The southern plume from the opposite side of the reactor area, close to the chute to the SFP. I don't remember any photos in which steam unambiguously was seen coming from the SFP itself, rather than the chute. Between the two apparent sources lies the booms of the heavy overhead crane and the crane itself, sunk into the concrete reactor lid and the service deck

 

[triumph61]

If you're referring to the helicopter flight video around the plant - that was probably taken before the accident. All Units are fine and there's no tsunami damage whatsoever at the other buildings.

-------------------------------------------------------------------------------

Robot videos online: http://www.tepco.co.jp/en/news/110311/index-e.html

No! Look at 1.36 at the Video. Left B1 (damaged) B2, B3 damaged, B4 still seems ok.

 

[Rive]

Yes, the dark spots are draped debris, probably roofing insulation, and presumably from the explosion at Unit 3, not from an explosion at Unit 4.

It's possible that one of the dark spots are predate the explosion of U3 - check the video in #4433 at 01:19.

Do we have any earlier high resolution picture about this area?

 

[clancy688]

No! Look at 1.36 at the Video. Left B1 (damaged) B2, B3 damaged, B4 still seems ok.

Nope. You can't say that for certain. We can only see the north and west walls of the building, not the south and east ones.
Destruction at Unit 4 startet with two panels which were blown out. But I don't know on which side of the building.

 

[tsutsuji]

Observation Post a fixed reference level set in concrete before work begins.

I have tried to google it again and found the following, seemingly meaning some sort of altitude reference used in Japan :

O.P. (Osaka Peil) means the lowest low-water level observed in Osaka Port in 1885 and this level is used as the standard datum in Osaka area

page 185 of http://wwwrcamnl.wr.usgs.gov/rgws/Unesco/PDF-Chapters/Chapter9-5.pdf

See http://en.wikipedia.org/wiki/Datum_(geodesy)

Other datums used in Japan are the "Tokyo Peil" (T.P.), "Arakawa Peil" (A.P.), "Yodogawa Peil" (Y.P.) : http://www.dobokunet.com/modules/xwords/search.php?term=peil

► At Fukushima Daiichi, countermeasures for tsunamis had been established with a design basis height of 5.7 m above the lowest Osaka Bay water level.

page 16 of http://www.vgb.org/vgbmultimedia/News/Fukushimav15VGB.pdf

Peil is borrowed from Dutch :

2.peil noun
♦level
♦plane
♦standard
http://www.systranet.com/dictionary/dutch-english/peil

 

[triumph61]

Nope. You can't say that for certain. We can only see the north and west walls of the building, not the south and east ones.
Destruction at Unit 4 startet with two panels which were blown out. But I don't know on which side of the building.



And that's, as mentioned before, archive material from BEFORE the tsunami.

When the south and east Side is blown away, you think so, then there was more as one Explosion.

 

[MadderDoc]

Also remember that the SkyGlobe pic is taken from orbit, so it will include any clouds that happened to be between the plant and the satellite, even in the statosphere. Not so for wbcam and airplane pics.

That is generally true, however at the time of this particular photo, shortly after the unit 3 explosion, no clouds got into the picture. On the zoomout you see that clearly:

 

[clancy688]

When the south and east Side is blown away, you think so, then there was more as one Explosion.

Hm... I was confused by the report of two holes in the side of the reactor:

Japan's nuclear safety agency NISA reported two holes, each 8 meters square, or 64 square metres (690 sq ft), in a wall of the outer building of unit 4 after the explosion.

http://www.reuters.com/article/2011/03/15/japan-nuclear-holes-idUSTFD00668920110315But I have taken a look at the webcam pictures from the NPP-Webcam. There you can clearly see, that ALL of the damage occurred on March 15th between 6:00 and 7:00 am JST (because the roof is blown off then).
So every video shot at March 15th or later should show a destroyed Unit 4 building. If not, it's from March 14th or earlier.



You can also see that there are very bad weather conditions on that day. Since there's been a no fly zone 20 or 30 km around the plant, every video was shot from 20 or 30 km away. With such weather conditions, that would be impossible. That's why we don't have videos or sat images from March 15th.

 

[Jorge Stolfi]

I am truing to build a computer graphics model of the Fukushima reactors #1--#4. Does anyone know where I can get dimensional data? Even the basic data would help:

* outside width,length,height of the top part building
* ditto for the lower part
* diameter of RPV and drywell
* depth of basement below road level

Those would be enough to get started, as I can deduce other rough measurements from other cutaway drawings, photos, and models.

Thanks...

 

[clancy688]

Those would be enough to get started, as I can deduce other rough measurements from other cutaway drawings, photos, and models.

Don't know if that helps you, but here are Blueprints of Unit 1:

http://www.houseoffoust.com/fukushima/blueprint.html

 

[|Fred]

some nice 3d modeling has already been done ;) but they are not entirely accurate


Outside (fukushima)

http://sketchup.google.com/3dwarehouse/details?mid=f04823398eed697d3fdfd6bc6322f73b&hl=fr&ct=lc

http://sketchup.google.com/3dwarehouse/details?mid=11b70c1651c0b152f0725315050aa28f&prevstart=12


Inside (not fukushima)
http://sketchup.google.com/3dwarehouse/details?mid=9d08f6a2a38642b0ef378390a82b2ba&prevstart=24

 

[MadderDoc]

<..>
But I have taken a look at the webcam pictures from the NPP-Webcam. There you can clearly see, that ALL of the damage occurred on March 15th between 6:00 and 7:00 am JST (because the roof is blown off then).
So every video shot at March 15th or later should show a destroyed Unit 4 building. If not, it's from March 14th or earlier.



You can also see that there are very bad weather conditions on that day. Since there's been a no fly zone 20 or 30 km around the plant, every video was shot from 20 or 30 km away. With such weather conditions, that would be impossible. That's why we don't have videos or sat images from March 15th.

Indeed there is a dearth of images from that day. This is the only photo I think likely was taken on March 15th. (I think that because inland smoke plus overcast appears to have ben a rare combination on the 16th)
[URL]http://www.tepco.co.jp/en/news/110311/images/110316_1f_chijou_2.jpg[/URL]

However I am sure there must be other photos, clearly there were choppers in the air, see the webcam 7 am on March 15th:

[PLAIN]http://pointscope01.jp/data/f1np/f1np1/pic/20110315070000.jpg

 

[triumph61]

Unit 3(Shut down)
-Explosive sound and white smoke were confirmed at approximately 11:01am
on March 14th. It was assumed to be hydrogen explosion.
-From 6:02 pm on March 25th, we started injecting fresh water to the
reactor and are now injecting fresh water by a motor driven pump powered
by the off-site transmission line.

Unit 4(outage due to regular inspection)
-At approximately 6:00 am on March 15th, we confirmed the explosive sound
and the sustained damage around the 5th floor rooftop area of the Nuclear
Reactor Building.

Therefore the Video was taken between 14.3. 11.01am till end of day ~7.00pm.

 

[clancy688]

Don't know if that's been recognized before - Seawater contamination levels are clearly falling. TEPCO's advances to stop water leakage into the ocean are apparently successfull:

http://fukushima.grs.de/sites/default/files/Daten_Seewasser_I131_20110420-0800.pdf
http://fukushima.grs.de/sites/default/files/Daten%20Seewasser_Cs137_20110420-0800.pdf

And I didn't realize it until now, but since three weeks, there has been no new airborne contamination!

http://fukushima.grs.de/sites/default/files/Messwerte%20ODL%20Fukushima%20Daiichi_110420-1230_Gesamt.pdf

So I guess the reactors are somehow stable / not open to the environment...?

 

[htf]

@default.user There are German forums

Das ist fraglich.
...
Wie lange war die Kühlung in Daiichi unterbrochen?

@default.user Jag es durch den google-Übersetzer - der haut ganz gut hin.

But now in English.

There are German forums where you can ask your questions in your mother tongue. This forum is quite nice (but it is a much smaller community than physicsforum.com):
http://fukushima.physikblog.eu/discussions
They have a summary of the current status of Fukushima plant and the course of the events of the accident.

And there is the dedicated page of the GRS (Gesellschaft für Anlagen- und Reaktorsicherheit). They are payed by our taxes to collect, summarize and evaluate information regarding Fukushima accident:
http://fukushima.grs.de/
They may not have thrilling news like Arnie Gunnarson but what they say is reliable information.

BTW - google translator does a good job. So my English seems to be not too bad ...

 

[jlduh]

Jon

Daini maintained grid power, so the Diesel generators were not critical to maintaining cooling.
I think THAT may have been the main difference

well, your are right, that may be the main difference in fact. In this case, that would be more a big LUCK, considering the flooding of the plant...

 

[jlduh]

When i consider the layout of the Daichi plant, and especially the transversal cut of the buildings, it is clear that the reactor building and the turbine building go deep in the ground of the platform, so the basement of these buildings (for example where the torus sits) is i think something like almost 10 meters below the ground (more data on this would be needed though). Considering that the platform is around 10 meters abose sea level, it is clear that there is not much margin between the basements of the buildings and the sea level.

This leads me to consider that one of the reason (and maybe the main reason at the time of the design??) for the plaform was also to put the basement of these rooms a little bit above what we can imagine being the phreatic level, so the concrete doesn't lay in undergroud water.

It is reasonable to consider that the phreatic level of underground water is more or less the sea level, based upon the proximity of the ocean. This leads me to the subject of the contamination of the the phreatic water by contaminated water: it is said (but with very few data until now, if you have some please post!) that phreatic water is now heavily contaminated, but i didn't sea any map of the underground phreatic water in this area (deepness, size and direction of flows, and of course possible impacts on various uses of this resource).

Did somebody found some useful data on this subject?

 

[Joe Neubarth]

Don't know if that's been recognized before - Seawater contamination levels are clearly falling. TEPCO's advances to stop water leakage into the ocean are apparently successfull:

http://fukushima.grs.de/sites/default/files/Daten_Seewasser_I131_20110420-0800.pdf
http://fukushima.grs.de/sites/default/files/Daten%20Seewasser_Cs137_20110420-0800.pdf

And I didn't realize it until now, but since three weeks, there has been no new airborne contamination!

http://fukushima.grs.de/sites/default/files/Messwerte%20ODL%20Fukushima%20Daiichi_110420-1230_Gesamt.pdf

So I guess the reactors are somehow stable / not open to the environment...?

What we know from the data as presented.
After the explosions the contamination on the ground is decaying and not spreading.
The flow into the sea is greatly decreased.
Radiation released to the atmosphere is not known with any accuracy.

 

[Dmytry]

Jon



well, your are right, that may be the main difference in fact. In this case, that would be more a big LUCK, considering the flooding of the plant...

dont forget electrical equipment was also in basement in daiichi, not only the generators.

 

[MiceAndMen]

Don't know if that helps you, but here are Blueprints of Unit 1:

http://www.houseoffoust.com/fukushima/blueprint.html

You will notice a lot of references to "OP" on that drawing. I interpret OP as roughly "above sea level". There are also elevation numbers abbreviated with "EL". They seem consistent. Notice the level of the ground is listed as "OP. 10000", i.e. 10 meters above sea level.

 

[MiceAndMen]

That's probably not the case. The recently announced TEPCO-6-month-plan stated, that they'll fill the containments of Units 1 and 3 with water in the near future, indicating that they're currently dry and unfilled.

It also assumes the containments are able to hold water without leaking. Are they even in a position to determine that yet with any certainty?

To me, it seems as though their announced plans/roadmap are all a bit premature and designed to give the appearance that they know what they're doing lest anyone challenge their competence further.

 

[PietKuip]

And I didn't realize it until now, but since three weeks, there has been no new airborne contamination!

http://fukushima.grs.de/sites/default/files/Messwerte%20ODL%20Fukushima%20Daiichi_110420-1230_Gesamt.pdf

That is not quite true. When winds are inland, there is fallout in Ibaraki and as far away as Tokyo; see pages 4 and 5 of http://www.slideshare.net/iaea/radiological-monitoring-and-consequences-19-april-2011

 

[clancy688]

That is not quite true. When winds are inland, there is fallout in Ibaraki and as far away as Tokyo; see pages 4 and 5 of http://www.slideshare.net/iaea/radiological-monitoring-and-consequences-19-april-2011

Okay, let's change it towards "no airborne contamination which's strongly changing the radiation levels". ^^

 

[jlduh]

Does somebody understand this strange statement:

"The company says water levels are also rising in the Number 5 and 6 turbine buildings."

http://www3.nhk.or.jp/daily/english/21_03.html

Why would the water level rise in these buildings?

 

[tsutsuji]

That is not quite true. When winds are inland, there is fallout in Ibaraki and as far away as Tokyo; see pages 4 and 5 of http://www.slideshare.net/iaea/radiological-monitoring-and-consequences-19-april-2011

The increases on April 9th, April 10th, and April 12th as shown on pages 4 and 5 of that document

A) are quite small as you can see on page 2 of that document
B) can you rule out that they are caused by rainfall depositing onto the ground "old particles" that have been flying in the air for weeks, rather than "new particles" extracted from the nuclear plant a few hours before their arrival at that measurement location in Ibaraki prefecture ?

For example, I attach the measurements at the Ishikawa district of Mito city, Ibaraki prefecture (Source : http://www.bousai.ne.jp/vis/tgraph.php?area_id=108&post_id=1080000014 - you need to adjust the maximum level by clicking on the 最小・大値の入力　button to a suitable value like 2000 nGy/h and to click on the 90 days button : ９０日). I think the 600 nGy/h peak shown on March 21st was caused only by rain, without being related to any specific incident at the plant.

 

[mscharisma]

Does somebody understand this strange statement:

"The company says water levels are also rising in the Number 5 and 6 turbine buildings."

http://www3.nhk.or.jp/daily/english/21_03.html

Why would the water level rise in these buildings?

Just happen to have read a reason for that a few minutes ago for the first time. This is what the WSJ wrote in a somewhat unrelated article:

"Meanwhile, at Reactor No. 6, one of the two units that have survived the March 11 earthquake and tsunami, workers Tuesday pumped 100 tons of water from the basement of the turbine building into the reactor's condenser unit. NISA said underground streams are a possible source. Before the crisis, streams beneath reactors No. 5 and 6 were pumped to divert water, a process that hasn't been conducted since the quake."

http://online.wsj.com/article/SB100...622.html?KEYWORDS=fukushimaKEYWORDS=fukushima

 

[jmelson]

Jon



well, your are right, that may be the main difference in fact. In this case, that would be more a big LUCK, considering the flooding of the plant...

Oh YES! Totally luck that none of their high tension towers fell down. And, you shouldn't be leaving reactors to just luck! Also, some design changes and elevation helped at Dai ni.

Jon

 

[jlduh]

Just happen to have read a reason for that a few minutes ago for the first time. This is what the WSJ wrote in a somewhat unrelated article:

"Meanwhile, at Reactor No. 6, one of the two units that have survived the March 11 earthquake and tsunami, workers Tuesday pumped 100 tons of water from the basement of the turbine building into the reactor's condenser unit. NISA said underground streams are a possible source. Before the crisis, streams beneath reactors No. 5 and 6 were pumped to divert water, a process that hasn't been conducted since the quake."

http://online.wsj.com/article/SB100...622.html?KEYWORDS=fukushimaKEYWORDS=fukushima

Well, this would then relate to the post i just added concerning the level of the phreatic water relative to basement of the buildings: it seems the basement is in fact surrounded by underground water , so below phreatic surface? This is a very surprising info...

If water can enter the buildings, one can imagine how contaminated water can go inside underground water...

This nuclear plant turns to an interesting mess to deal with, to say the least.

 

[tsutsuji]

Because restoring sea water cooling might be too difficult, they are studying the possibility to use air cooling instead : http://www.asahi.com/special/10005/TKY201104200745.html