Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[mscharisma]

...
The original source is an NRC document about the Fukushima crisis

http://www.nytimes.com/2011/04/06/world/asia/06nuclear.html?_r=1

"[A] confidential assessment prepared by the Nuclear Regulatory Commission... The document, which was obtained by The New York Times, provides a more detailed technical assessment than Japanese officials have provided ... The document also suggests that fragments or particles of nuclear fuel from spent fuel pools above the reactors were blown “up to one mile from the units,” and that pieces of highly radioactive material fell between two units and had to be “bulldozed over,” presumably to protect workers at the site. The ejection of nuclear material, which may have occurred during one of the earlier hydrogen explosions, may indicate more extensive damage to the extremely radioactive pools than previously disclosed. "

So, NY Times says they have this NRC document and quote it verbatim as "up to one mile from the units". Is this "confidential assessment" NRC document now publicly available somewhere? It was either voluntarily provided, or leaked, to NY Times 5 weeks ago, according to the article.
...

As previously pointed out, the word "may" is a key word throughout here as well as in the original NRC document, indicating possibility, but not certainty. The document is available here:

http://www.fairewinds.com/content/nrc-report-official-use-only-fukushima-assessment-march-26th-2011

 

[SteveElbows]

The republished data certainly contains a lot more data points, though I have not had time to notice whether there are any really significant new bits of data yet.

OK first stuff of significant I notice is for reactor 2. New version of data contains tons more information about water levels and reactor pressure during a very crucial period of time between 13:00 and 23:11 on the 14th. Given what was happening during that time period (fuel uncovered) its tempting to say that they had a reason to hide this data before.

 

[Astronuc]

Thanks for the source!
http://ziphilia.net/bbs.cgi/economy/1304793715/detailview#A_DEFAULT

Even though mudstone may be "relatively firm" it is still a different thing than bedrock.

First there is (or was) a 25 meter layer of clay and sandstone.
Below that is mudstone.
And below that is bedrock (-46 meters from the current ground level).
http://mdn.mainichi.jp/mdnnews/news/20110427p2g00m0dm091000c.html

As jlduh https://www.physicsforums.com/showpost.php?p=3304601&postcount=7428" TEPCO is lying again when they state in their web-page that "the plants are built on solid bedrock".
http://www.tepco.co.jp/en/challenge/energy/nuclear/plants-e.html

BTW: Does anybody want to translate the texts in this picture from Japanese to English?
http://gbleez.myhome.cx/uploader/src/up7713.jpg
I could make a bigger version of it, with English texts.

I'm guessing that 'mud-stone' rock is a reference to sedimentary or metamorphic rock as opposed to clay or sandstone. Generally, large structures like containment buildings and dams are built on or into 'bedrock' which hopefully is geologically stable, and doesn't creep. Soft soils amplify the effects of seismic waves.

For general interest - http://www.world-nuclear-news.org/RS-Fukushima_fuel_melt_confirmed-1605115.html

I disagree with the term 'confirmed'. They have not confirmed, but rather strongly expect that the core of unit 1 melted. That is not necessarily the case, unless they had no cooling water or steam whatsoever in the core, i.e., within the core barrel. Outside the core barrel is the annular region around between the core barrel and RPV shell. That is where coolant normally goes from the feedwater system, and that is then pumped into the bottom plenun and up into/through the core. In the jet pump design, the pump risers would preclude water from the base of the annulus from getting to the core. If they were able to pump water into the bottom plenum, it's not clear why they couldn't get it into the core - unless some of the control rod drive housings had broken or the seals had given way. Then it would be possible that they pumped water into the RPV, but it leaked out the bottom without entering the core.

We really won't know what happened until they get a camera inside.

Bear in mind that the core did have water at some point. Without cooling, stagnant water would have boiled, and that water/steam should have been 'saturated'. When the water was gone, then the steam can become superheated. That steam would have reacted/corroded the cladding, and possible the channels and control rods, which would have produced hydrogen, which ostensibly escaped through breaks or leaks into containment. From the primary containment, the hydrogen is expected to have leaked into the secondary containment structure where it ignited/detonated. It's a similar scenario to Unit 3 and 2, but ostensibly there was more success in getting cooling water into the reactors of those units.

Melting of the core is not necessary for significant release of fission products, particuarly the gases (Xe, Kr) and volatiles (I, Cs, perhaps Te). The corrosion and breaching of the Zircaloy cladding is all that is necessary, and there was probably a lot of oxidation of the Zircaloy.

 

[tsutsuji]

An Asahi article mentions the following :

The collapse of a transmission tower at Fukushima Daiichi NPP is seen by Tepco as being a consequence of a mudslide caused by the March 11th earthquake.

Some readings are missing in the seismometer data of Fukushima Daiichi and Daini. NISA is instructing Electric Power companies to review their seismometers.

The earthquake design basis which had been set in 2006 was overridden at Fukushima Daiichi units 2,3 and 5. Slightly so too at unit 1 during some phases of the quake.

A seismometer located 200 m underground recorded quake intensities below the design basis.

http://www.asahi.com/national/update/0516/TKY201105160568.html

Reuters deems newsworthy to say:

The magnitude 9 earthquake that struck a Japanese nuclear plant in March hit with almost 30 percent more intensity than it had been designed to withstand, raising the possibility that key systems were compromised even before a massive tsunami hit.

http://uk.reuters.com/article/2011/05/16/uk-japan-nuclear-idUKTRE74F17K20110516

 

[jlduh]

You can arrive at a stronger conclusion by looking at another and later photo which shows where the part of the pipe that came off the wall ended up on the ground. In that way you will have two corroborating pieces of information from this photo you are looking at:

a) the pipe does appear to broken (although some would not like to say so conclusively)
b) the part of the pipe that came off does appear to be lying under it, in the same spot, and angled similarly to how we find that part on later photos.

Added together, this would seem to me sufficient evidence to force us to reject the hypothesis that the pipe remained intact after the unit 3 explosion.

Edit: By 'later photo' I mean any photo showing this area and _taken in the period March 14 through March 20._
We know from the photos that Tepco in order to make access for spraying to the pool had moved the part of the pipe that fell to the ground by March 24th, but had not done so on March 20th.

I post below one of these pictures that show the broken venting pipe from N°3: we can very well see in the alignment at the right of the building:

- the remaining part going to the stack (which is towards the right, outside of the picture), - - the fallen part laying on the ground,
- and remaining pipe coming from the building at the bach (east side)

http://www.netimago.com/image_200730.html

To me, looking at several pictures, this pipe has been broken by the n°3 explosion (probably falling wall).

 

[razzz]

Once the foundations are in place the site would be backfilled around the foundations to reach current levels, In the US there are extensive provisions for controlled runoff and draining to ensure potential released of ground water are not contaminated or if contamination exists, that it is monitored and reported. Would that help stabilize the mudstone so it wouldn't erode?

Keep it dry via de-watering. It's not the their term for bedrock that is the problem or even if construction techniques can overcome the shortcomings of poor soil conditions, it's the area between sea level and to the bottom of the evacuation where underground water can travel. To control the flow of underground water from traveling inland, you pump water out of a well to keep underground water traveling to that point of the well(s) intake level and not allowing water to pool underground and/or flow inland. The situation is twofold now. Keep the ground from saturating and keep the contaminated (underground) water from migrating inland from the plant site.

 

[tsutsuji]

BTW: Does anybody want to translate the texts in this picture from Japanese to English?
http://gbleez.myhome.cx/uploader/src/up7713.jpg
I could make a bigger version of it, with English texts.

Here you are :

 

[SteveElbows]

OK first stuff of significant I notice is for reactor 2. New version of data contains tons more information about water levels and reactor pressure during a very crucial period of time between 13:00 and 23:11 on the 14th. Given what was happening during that time period (fuel uncovered) its tempting to say that they had a reason to hide this data before.

OK I didnt find any further differences between previously available data and this new release that struck me as really significant.

However, as many people may never have seen the data before, there are probably some noteworthy things in there that may have room left for further discussion.

I do wonder if there has been a large release of data officially at this time because of the leak to the newspaper, and this is TEPCO responding by publishing the material themselves.

For example the following Japanese page appears to have some very large pdfs which contain the raw data from the period, collected in a bewildering array of forms and those little measurement graphs that get plotted in realtime by clunky old equipment at the plant:

http://www.tepco.co.jp/nu/fukushima-np/index10-j.html

 

[Uagrepus]

To me, looking at several pictures, this pipe has been broken by the n°3 explosion (probably falling wall).

... and the mysterious green-scaffold-builder were there ...

 

[elektrownik]

Here are 60 pages of data plots: http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_8_Parameter_graph.pdf

 

[MadderDoc]

Here are 60 pages of data plots: http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_8_Parameter_graph.pdf

This, elektrownik, is a most interesting document. It includes far more datapoints than I have seen before, including during the most interesting moments. I've previously estimated the pressure drop within the containment during the explosion of unit 3 to be >=0.1 MPa. Based on this document, the estimate of DW pressure drop must be revised to >=0.4MPa.

It is also news to me from this document, that the RPV during the period of the 'black smoke event' on March 21st briefly peaked out at >12MPa, before it dropped back abruptly and went down to to atmospheric. My,my.

 

[jlduh]

... and the mysterious green-scaffold-builder were there ...

Where did you get this picture? When was it taken? Are you sure it was there (the scaffold builder) when the explosion occurred? I don't see it on the pictures...

Probably a stupid remark, and I don't know if this has been discussed already but i find something strange in the way this vent has been destroyed: the remaining part of the tubing at the west side is in perfect shape, including the very end of it, where the part that fell was supposed to be connected... That's quite bizarre, because if the part that fell was crushed by the falling wall, one could imagine that the remaining end would have so damages at the jonction. Here it's perfect! The comparision with the other side is very self explanatory of what I mean...

Something else is strange: from the top view, we have the impression that the fallen part is in fact TOO SHORT to cover the whole initial distance, like if one part of the tubing was missing?

http://www.netimago.com/image_200771.html

I mention this because it looks strange and also because of the scaffold builder you mention, with an idea in mind: could it be possible that they were doing some maintenance on the vent at this place, so the pipe was disconnected at this point when explosion happened?

Of interest, on later pictures, we can see that the curved tubing that was intact after the explosion in now... bent towards the ground!

See it:
http://www.netimago.com/image_200769.html

Do you think they bent it purposely in between? Why? For the crane to go maybe?

 

[StrangeBeauty]

...To me, looking at several pictures, this pipe has been broken by the n°3 explosion (probably falling wall).

Agreed. That pipe was definitely broken after the #3 explosion. Also it can be seen on this page (about half way down):
http://www.houseoffoust.com/fukushima/april15.html

However, I thought Tepco was claiming that the hydrogen went from #3 to #4 via a different piping system? Here's the quote:

According to Tepco, hyrogen produced in the overheating of the reactor core at unit 3 flowed through a gas-treatment line and entered unit No. 4 because of a breakdown of valves.

Where is this gas-treatment line?

 

[I_P]

This, elektrownik, is a most interesting document. It includes far more datapoints than I have seen before, including during the most interesting moments. I've previously estimated the pressure drop within the containment during the explosion of unit 3 to be >=0.1 MPa. Based on this document, the estimate of DW pressure drop must be revised to >=0.4MPa.

It is also news to me from this document, that the RPV during the period of the 'black smoke event' on March 21st briefly peaked out at >12MPa, before it dropped back abruptly and went down to to atmospheric. My,my.

The 21st is when the radiation monitors in Ibaraki showed a large abrupt spike in radiation - similar in character and magnitude to the one on the 15th. Measured levels have been steadily declining since the 21st with no other major peaks - just very minor increases during periods of rain showers or disturbed weather.

 

[SteveElbows]

Do you think they bent it purposely in between? Why? For the crane to go maybe?

Either that or perhaps it was damaged when the control room concrete from the south west corner of the building fell (we don't know when this fell, or even if it was deliberately removed, but at some point it goes from being still attached to the building to being on the ground.)

 

[SteveElbows]

It is also news to me from this document, that the RPV during the period of the 'black smoke event' on March 21st briefly peaked out at >12MPa, before it dropped back abruptly and went down to to atmospheric. My,my.

Yes I think that's the main event that stands out when looking at data from later than the initial days of the crisis.

You are probably better off looking at the version of the documents that contains the data in tabular form, which for reactor 3 is this one:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/level_pr_data_3u-j.pdf

So it didnt quite get above 12Mpa.

I think it would also be most useful to look at the temperature data for the same time period:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/temp_data_3u-j.pdf

So yes, there is a match, with some very high temperatures at the same time, 01:25 on the 21st.

I had previously keep a somewhat open mind about the black smoke events that happened that week at reactor 3, simply because it was also a week where they were switching various things back on after restoring power. So I thought maybe some piece of equipment caught fire. But the temperature & pressure data does make it seem more likely that something more dramatic was happening at that time.

 

[MadderDoc]

<..>To me, looking at several pictures, this pipe has been broken by the n°3 explosion (probably falling wall).

I agree, we can leave the theory that the exhaust stack pipes between unit 3 and 4 after the explosion in unit 3 would have been able to lead hydrogen from unit 3 to unit 4.

If I remember correctly Tepco's original idea was that the leak of hydrogen to unit 4 went through the 'gas treatment lines'. I suggest what could be meant there is the large pipe system running along the turbine buildings, leading to a minor building at the Centralized Radiation Waste Treatment Facility, and from there to the big south exhaust stack SW of unit 4.

 

[jlduh]

Yes I think that's the main event that stands out when looking at data from later than the initial days of the crisis.

You are probably better off looking at the version of the documents that contains the data in tabular form, which for reactor 3 is this one:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/level_pr_data_3u-j.pdf

So it didnt quite get above 12Mpa.

I think it would also be most useful to look at the temperature data for the same time period:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/temp_data_3u-j.pdf

So yes, there is a match, with some very high temperatures at the same time, 01:25 on the 21st.

I had previously keep a somewhat open mind about the black smoke events that happened that week at reactor 3, simply because it was also a week where they were switching various things back on after restoring power. So I thought maybe some piece of equipment caught fire. But the temperature & pressure data does make it seem more likely that something more dramatic was happening at that time.

One possibility IHMO being that the RPV got eaten by the corium, maybe helped with some local criticality... Your opinion?

By the way, the BLACK SMOKE was reported on March 23, not 21 if I'm not wrong...

But of course, black smoke can be the visual effect seen from outside of an event started earlier inside the RPV.

 

[MadderDoc]

Yes I think that's the main event that stands out when looking at data from later than the initial days of the crisis.

You are probably better off looking at the version of the documents that contains the data in tabular form, which for reactor 3 is this one:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/level_pr_data_3u-j.pdfSo it didnt quite get above 12Mpa.

When I say pressure, you can assume that I am talking absolute pressure, Tepcos data are gauge. Thank you so much for pointing me to the tabular data, that is most convenient (drool).

I had previously keep a somewhat open mind about the black smoke events that happened that week at reactor 3, simply because it was also a week where they were switching various things back on after restoring power. So I thought maybe some piece of equipment caught fire. But the temperature & pressure data does make it seem more likely that something more dramatic was happening at that time.

Indeed, I had it also parked there, that since data appeared to say nothing particular happened -- reactor-wise -- then probably nothing of that sort happened. It could have been some plastic caught fire, lubricant, whatever giving off yucky smoke, but nothing really to see as a main development. Oh well.

 

[tsutsuji]

As Reuters puts it :

In another instance of an apparent error in judgement, Tepco said that a worker may have shut down a cooling system known as the isolation condenser shortly after the earthquake when he saw that the No. 1 reactor was losing temperature quicker than the utility's guidelines allowed.
http://uk.reuters.com/article/2011/05/16/uk-japan-nuclear-idUKTRE74F17K20110516

But http://www.chunichi.co.jp/s/article/2011051790014812.html says that while Tepco is emphasizing that the shutdown of the isolation condenser by a worker, in accordance with the manual which instructs to do so when reactor temperature falls by more than 55°C per hour, is one possibility, the other possibility is that the isolation condenser was damaged by the earthquake before the tsunami struck. Tepco says that the second possibility can't be ruled out.

 

[SteveElbows]

When I say pressure, you can assume that I am talking absolute pressure, Tepcos data are gauge. Thank you so much for pointing me to the tabular data, that is most convenient (drool).


Indeed, I had it also parked there, that since data appeared to say nothing particular happened -- reactor-wise -- then probably nothing of that sort happened. It could have been some plastic caught fire, lubricant, whatever giving off yucky smoke, but nothing really to see as a main development. Oh well.

The data is also in csv format if you want to manipulate it in some way. You should be able to spot the links on this page, as they are preceded by the word csv:

http://www.tepco.co.jp/nu/fukushima-np/

None of the CAMS readings seem to do anything different at that point on the 21st at reactor 3, so I am still not really sure what to think. When reading the wikipedia entry it sounds like they blamed the fuel pool for the smoke on the 21st, and it was the darker smoke of the 23rd that caused more reactor suspicion at the time?

 

[Bandit127]

This, elektrownik, is a most interesting document. It includes far more datapoints than I have seen before, including during the most interesting moments. I've previously estimated the pressure drop within the containment during the explosion of unit 3 to be >=0.1 MPa. Based on this document, the estimate of DW pressure drop must be revised to >=0.4MPa.

It is also news to me from this document, that the RPV during the period of the 'black smoke event' on March 21st briefly peaked out at >12MPa, before it dropped back abruptly and went down to to atmospheric. My,my.

Perhaps I am missing a physical connection between pressure in the drywell and the pressure in the building, but if there was one, a 0.4 MPa pressure drop would turn a SFP full of water at near 100°C into a SFP full of steam expanding at a rapid rate - possibly 340 m/s.

At 0.5 MPa, water will boil at 81.33°C.
http://www.simetric.co.uk/si_steam.htm"

 

[jlduh]

I agree, we can leave the theory that the exhaust stack pipes between unit 3 and 4 after the explosion in unit 3 would have been able to lead hydrogen from unit 3 to unit 4.

If I remember correctly Tepco's original idea was that the leak of hydrogen to unit 4 went through the 'gas treatment lines'. I suggest what could be meant there is the large pipe system running along the turbine buildings, leading to a minor building at the Centralized Radiation Waste Treatment Facility, and from there to the big south exhaust stack SW of unit 4.

I don't know if these lines have something to do with the reactor buildings. Visual analysis on the pictures seem to show that they are coming from the turbine buildings, but who knows how it's laid out inside. I don't see very well how this could lead to reactor hydrogen from N°3 going to reactor 4.

Did you remark by the way (i'm sure some did already ) that a huge chunk of concrete from probably N°3 reactor landed right on the two long parallel tubings just at the level of N°4 reactor? This is a huge piece and i wonder from where it could come fron N°2 reactor (see the thickness of this!):

http://www.netimago.com/image_200794.html
On this view, based on some known distance (the distance between the pillars of N04 reactor for example), this chunk is around 7-8 meters wide and 4 meters thick...

http://www.netimago.com/image_200796.html
On this view, based on some known distance (the distance between the pillars of N04 reactor for example), this chunk is around 7-8 by 6-7 meters big...

The shape is very intiguing also...

Too thick to come from a regular wall, so maybe a piece of a floor or... a piece of containment?

I'm wondering if this is not one of the big chunk that we see falling down on the right side of plume during N°3 reactor explosion.

EDIT I correct immediately what i just said about this huge piece of concrete. It's not coming from N°3 explosion, as this piece doesn't appear at this place on satellite view after this explosion:

http://www.netimago.com/image_200872.html

This huge piece comes probably from N°4 "1st floor visible" (actually it is i think second floor) broken wall.

Look at this picture:

http://www.netimago.com/image_200874.html

The hole just behind the big chunk on the rightmost side of the wall is IMHO where it comes from.

Looking at how thick this piece of concrete is, we can imagine the force of the explosion at this place to break such a piece in a place which seems a little far from the attic SFPs where H2 "could" have originated (the only place in fact where there was fuel). Did the explosion at N°4 originated in the lowest floors in this area? The only place where the roof has disappeared is above this place and the north wall is heavily dislocated.

 

[GJBRKS]

I agree, we can leave the theory that the exhaust stack pipes between unit 3 and 4 after the explosion in unit 3 would have been able to lead hydrogen from unit 3 to unit 4.

If I remember correctly Tepco's original idea was that the leak of hydrogen to unit 4 went through the 'gas treatment lines'. I suggest what could be meant there is the large pipe system running along the turbine buildings, leading to a minor building at the Centralized Radiation Waste Treatment Facility, and from there to the big south exhaust stack SW of unit 4.

(off topic)



This helicopterfootage shows (at 5:30) some piping next to reactor 4 that has been ruptured and seems to be coming from the exhaust stack between units 3 and 4
There's some strange yellowish material that is laying on the pipe.

Looking at the posted high resolution arial photo of this area I notice a ' streak ' of yellow material that seems to point towards the big hole on top of the turbine building next to unit 3
http://img716.imageshack.us/img716/8693/reactor4piping2.jpg

And then I notice the shape of the hole compared to the yellow cap visible in unit 4 :

(Highly speculative ...)

Could this hole in the roof have been formed by the yellow reactorcap from unit3 ?

And the yellow streak be scattered debris from the impact ?

What else here is yellow ( not yellowcake I presume ?)Not that I expect a confirmation of course , I don't know if TEPCO has even been able to investigate that part.

http://img96.imageshack.us/img96/561/aerial201133002011yello.jpg

 

[Uagrepus]

Where did you get this picture? When was it taken? Are you sure it was there (the scaffold builder) when the explosion occurred? I don't see it on the pictures...

I found that old picture from Reuters here:
http://hken.ibtimes.com/articles/124108/20110318/fukushima-daiichi-nuclear-power-plant-risks-at-each-reactor-japan-stricken-plant.htm

It is from 2008, so their work should be done.

Very good observations from you, but my english ist too limited to discuss in this professional circle. Let me say just thanks to all contributors of this excellent thread!

 

[SteveElbows]

One possibility IHMO being that the RPV got eaten by the corium, maybe helped with some local criticality... Your opinion?

By the way, the BLACK SMOKE was reported on March 23, not 21 if I'm not wrong...

But of course, black smoke can be the visual effect seen from outside of an event started earlier inside the RPV.

I haven't been able to form an opinion on things like criticality or corium traveeling past the rpv, I don't feel like I have enough information yet and there seem to be sensible arguments both for and against these things.

There were several smoke events during that week, and you are correct that the latter one is the one that seems to be described as black. I think I just talked a little bit about this in my last post, I will say more once I have looked at more data.

 

[SteveElbows]

I do wonder if there has been a large release of data officially at this time because of the leak to the newspaper, and this is TEPCO responding by publishing the material themselves.

For example the following Japanese page appears to have some very large pdfs which contain the raw data from the period, collected in a bewildering array of forms and those little measurement graphs that get plotted in realtime by clunky old equipment at the plant:

http://www.tepco.co.jp/nu/fukushima-np/index10-j.html

OK I've had a bit more time to look at documents on this page, wow its a treasure trove. And it does seem quite likely that its the same material a newspaper got hold of, so TEPCO have released it themselves to stop further speculation I guess.

Many of the documents are going to be hard for us to understand due to language issues, or extremely technical nature of the documents, or just poor legibility. However I believe that documents in sections 5 and 6 of that page contain a wealth of reactor data from the hours immediately following the arthquake. Some of it we have seen in far more readable form elsewhere, such as the other documents that we have been talking about today which show some additional reactor pressure, temperature, water level & CAMS readings. But there is far more, it seems to show us when certain pieces of equipment are switched on and off, stuff to do with RCIC and other systems including what look like flow rates upon first inspection. I have no doubt it will take a while to figure all this out, and there may not be a huge amount of interest, but for someone who undersatnds this stuff there may be some stories of some of the things that went wrong in the first hours, buried in this data.

Documents in section 4 looks like notes and is going to be tough to comprehend but should be skimmed through anyway because there are some photographs of some hideous whiteboards from hell that likely show the frantic scribblings of those first responding to the disaster.

 

[clancy688]

Another translation by EX-SKF:

PM Assistant Hosono said that there was no water being poured into the Reactor 1 for 14 hours and 9 minutes, Reactor 2 for 6 hours and 29 minutes, and Reactor 3 for 6 hours and 43 minutes. He said "We should be prepared for the possibility of the complete meltdown of the reactor core."

http://ex-skf.blogspot.com/2011/05/asahi-shinbun-core-meltdown-in-reactors.html

 

[triumph61]

The same source:

According to TEPCO, based on the records, the Reactors 1, 2 and 3 stopped automatically after the quake, and there was no sign of any physical damage to the reactor. Emergency diesel power generators were working. TEPCO concluded that all the equipments were working normally after the quake and there was no major damage to the plant until the tsunami hit.Well, this last bit is highly questionable. Other reports say that the emergency core cooling system stopped working even before the tsunami hit, and that a very high level of radiation was detected at the reactor building of Reactor 1 on the night of March 11, too high unless the RPV and the Containment Vessel were breached by the earthquake, not by tsunami.

http://ex-skf.blogspot.com/2011/05/asahi-shinbun-core-meltdown-in-reactors.html

 

[jlduh]

I found that old picture from Reuters here:
http://hken.ibtimes.com/articles/124108/20110318/fukushima-daiichi-nuclear-power-plant-risks-at-each-reactor-japan-stricken-plant.htm

It is from 2008, so their work should be done.

Very good observations from you, but my english ist too limited to discuss in this professional circle. Let me say just thanks to all contributors of this excellent thread!

Ok, thanks, if it's 2008 the work should be finished, yes I was thinking of a recent picture just before the accident...