Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[NUCENG]

Paper warning of Fukushima nuke plant risks draws attention on Net

http://english.kyodonews.jp/news/2011/05/89638.html

This is one of the issues I have been researching as discussed in the Fukushima Management and Government Performance thread. Professor Takagi wrote his paper in 1995 and it was certainly true at that time. However it appears that NISA initiated reevaluations ofseismic design basis in 2006 (better late tjan never). In 2008 TEPCO apparently performed that evaluation and, according to WNA, upgraded the seismic qualification at Fukushima to 600 Gal which is greater than the peak ground acceleration during the March 11, 2011, quake.

 

[elektrownik]

Not the RPV. I was referring to flooding the containment (drywell) around the RPV. The theory is that by flooding the containment it may fill the RPV through any pipe breaks or holes that may exist and are preventing filling the RPV directly.

Yes, I know, I was asking about RPV in general, why it is not filled wit water yet, if there are leaks from RPV to drywell it also should be filled now, I think that water is leaking from RPV and drywell in some way, because if they are injecting 8m3/h and there is no steam from unit 1 then this mean that water must leak...

 

[NUCENG]

Story accessible at the link below (unfortunately the link shown above requires the viewer to be a client of Kyoudou News Agency):

http://mdn.mainichi.jp/mdnnews/national/archive/news/2011/05/07/20110507p2g00m0dm054000c.html

The paper itself is here:

http://ci.nii.ac.jp/els/110002066513.pdf?id=ART0002195281&type=pdf&lang=en&host=cinii&order_no=&ppv_type=0&lang_sw=&no=1304756220&cp=

Unable to open the Takagi paper. Can you check that link?

 

[PietKuip]

In 2008 TEPCO apparently performed that evaluation and, according to WNA, upgraded the seismic qualification at Fukushima to 600 Gal which is greater than the peak ground acceleration during the March 11, 2011, quake.

How could Tepco have upgraded the seismic stability of their plant?

I would regard it as impossible the modify the concrete and steel construction physically. Maybe they just accepted that design criteria should be 600 gal. Without being able to do much about it, other than shutting down the reactors.

"The design basis acceleration for both Fukushima plants had been upgraded in 2008, and is now quoted at horizontal 441-489 Gal for Daiichi and 415-434 Gal for Daini. The interim recorded data for both plants shows that 550 Gal was the maximum for Daiichi, in the foundation of unit 2 (other figures 281-548 Gal), and 254 Gal was maximum for Daini. Units 2, 3 and 5 exceeded their maximum response acceleration design basis in E-W direction by about 20%. Recording was over 130-150 seconds. (Ground acceleration was around 2000 Gal a few kilometres north, on sediments.)"
http://www.world-nuclear.org/info/inf18.html

 

[ernal_student]

Unable to open the Takagi paper. Can you check that link?

I just opened it again from the link I posted and did not encounter any problem. Please try again.
You can also get to that same link by way of this link:
http://ci.nii.ac.jp/lognavi?name=nels&lang=en&type=pdf&id=ART0002195281

 

[Borek]

Think of an explosion as air moving away in every direction radiating from the explosion centre. Once the expansion caused by heating phase is over, the air keeps on moving due to kinetic energy, this results in a under pressure at the explosion centre

But it has nothing to do with the condensation. That's all I wrote. You even quoted me on it.

 

[Borek]

If H2 and O2 gas and H2O gas were at the same temperature and pressure after the reaction as before then the volume should be reduced to 2/3

At STP it is wrong, for reasons so obvious I feel ashamed pointing that out.

Call it nitpicking if you like

 

[~kujala~]

I guess you all noticed this: Miroslav Lipar who is in charge of IAEA reactor status summary has made these more thorough explanations of the reactor status after the general summary page:

http://www.slideshare.net/iaea/technical-briefing-11-0505

The more thorough summary begins on page 4.

For every unit they now have some guesses about the leakings:

Unit 1:
Reactor Pressure Vessel is assumed to be leaking most probably through connected recirculation system (Pump seal LOCA).
Exiting gap in PCV is assumed (On-going injection of nitrogen gas has not led to increase of pressure in PCV)

Unit 2:
Reactor Pressure Vessel is assumed to be leaking most probably through connected recirculation system (Pump seal LOCA).
Containtment is believed to be damaged.

Unit 3:
Reactor Pressure Vessel is assumed to be leaking most probably through connected recirculation system (Pump seal LOCA).
The leak elevation is about -1500 from the top of the active fuel (level of ejectors of RCPs).
Containtment is believed to be damaged.

 

[PietKuip]

I guess you all noticed this: Miroslav Lipar who is in charge of IAEA reactor status summary has made these more thorough explanations of the reactor status after the general summary page:

http://www.slideshare.net/iaea/technical-briefing-11-0505

The more thorough summary begins on page 4.

That is a tremendous improvement in the IAEA reporting!

There are no power spikes, no significant neutron flux, and no short-lived isotopes at any of the units (no La-140). At the moment. And there is a caution to keep an eye on this.

 

[NUCENG]

How could Tepco have upgraded the seismic stability of their plant?

I would regard it as impossible the modify the concrete and steel construction physically. Maybe they just accepted that design criteria should be 600 gal. Without being able to do much about it, other than shutting down the reactors.

"The design basis acceleration for both Fukushima plants had been upgraded in 2008, and is now quoted at horizontal 441-489 Gal for Daiichi and 415-434 Gal for Daini. The interim recorded data for both plants shows that 550 Gal was the maximum for Daiichi, in the foundation of unit 2 (other figures 281-548 Gal), and 254 Gal was maximum for Daini. Units 2, 3 and 5 exceeded their maximum response acceleration design basis in E-W direction by about 20%. Recording was over 130-150 seconds. (Ground acceleration was around 2000 Gal a few kilometres north, on sediments.)"
http://www.world-nuclear.org/info/inf18.html

You may be right. We may have here another example of conflicting information. I provided a link to the WNA statement that TEPCO had upgraded the seismic qualification to 600 Gal in 2008. I would assume that this was done by reanalysis, not physical modifications or there would have been some discussion of the mods. There is usually added margin in any design and it is not unusual to "sharpen the pencil" to show that a small increase in the PGA was acceptable. I had also seen reports of the lower number of 449 Gal. Either way, they were doing something between 2006 and 2008 to reevaluate the seismic risk. Absolutely, they should have been doing that periodically over the last 30+ years.

There have been cases where a building, once erected showed unexpected sesitivity to winds or other loading or was later found to be more vulnerable to seismic forces. I think that either the Sears Tower or Hancock building in Chicago was featured in a documentary about this kind of post-construction engineering. Active dampening can sometimes be added after construction. My guess is that the reanalysis was paper only, but that doesn't mean it was wrong. If it was still short of the actual event, it doesn't sound like it was much of a problem since the diesels started and ran until the tsunami hit.

 

[jim hardy]

[q]There are no power spikes, no significant neutron flux, and no short-lived isotopes at any of the units (no La-140).[/q]

i think they got control of criticality early on.

i think i'd use CO2 rather than nitrogen to inert atmosphere. it's heavy so will stay in the vessel up to level of leak and not mix so much with air..

 

[yakiniku]

I don't recall seeing mention of the data published on April 23rd by the Center for the Promotion of Disarmament Non-Proliferation Japan. It contains data for a number of radioactive isotopes that might be interesting from the CBTO Takasaki station in Gunma:

http://www.cpdnp.jp/pdf/110427Takasaki_report_Apr23.pdf

http://www.ctbto.org/verification-regime/featured-stations/types/radionuclide/rn38-takasaki-japan/page-1-rn38/

 

[StrangeBeauty]

I guess you all noticed this: Miroslav Lipar who is in charge of IAEA reactor status summary has made these more thorough explanations of the reactor status after the general summary page:

http://www.slideshare.net/iaea/technical-briefing-11-0505

The more thorough summary begins on page 4.

For every unit they now have some guesses about the leakings:

thx for the resource. Is this the first time that 'those in charge' have officially admitted they have pictures of a crack in #3 primary containment (pg 6 "Images of Unit 3 show crack in the primary containment")? I believe others (e.g. NRC) have referenced this, but I haven't seen this picture as of yet.

Also the marine monitoring portion of the presentation from the same date is here:
http://www.slideshare.net/iaea/marine-briefing-11-0505-hn-rev

 

[elektrownik]

I don't recall seeing mention of the data published on April 23rd by the Center for the Promotion of Disarmament Non-Proliferation Japan. It contains data for a number of radioactive isotopes that might be interesting from the CBTO Takasaki station in Gunma:

http://www.cpdnp.jp/pdf/110427Takasaki_report_Apr23.pdf

http://www.ctbto.org/verification-regime/featured-stations/types/radionuclide/rn38-takasaki-japan/page-1-rn38/

Interesting, there are Xe data also on page 7

 

[NancyNancy]

It was suggested that I share this here. A couple of people had mentioned #4 looked like it was falling over or it is an optical illusion of the wide angle lens on the TBS camera. I am not totally convinced it is the camera since there is no oddity on the opposite side of the camera. I also have a screen shot that shows even further right of #4, everything is totally vertical. #3 isn't leaning, as if there was a distortion, it would gradually get worse rather than being sudden in one spot only. I marked up a couple of images to explain what I was seeing. TEPCO also moved the watering crane that has been on the south side of #4 to the corner of #4 on the land side about 4 hours ago. I don't have a screen shot yet but the person who saw it is reliable. I am hoping to get a screen shot of that once it is daylight again. Another concern to add to this is that TEPCO employees were telling a couple of different Japanese reporters I have spoken to that the stability of #4 was a big concern. This was about 2 weeks ago. The concern was the building framework instability and the impact it is having on the SFP. There were plans to pour concrete columns underneath and also a plan to put a steel framework underneath. There is already damage to the frame work on both the north and south sides.
Image of all reactors and towers http://www.houseoffoust.com/fukushima/sinking.jpg
Close up of 4 http://www.houseoffoust.com/fukushima/sinking5_6a.jpg
4 with lines tracing the building framework http://www.houseoffoust.com/fukushima/sinking5_6b.jpg
large image of reactors with vertical lines http://www.houseoffoust.com/fukushima/sinking2.jpg
web page of all of this http://www.houseoffoust.com/fukushima/r4sinking.html

 

[elektrownik]

I look into data and I see Tc99m for example, half-life 6h it was detected in big concentration (100 000 - 600 000 uBq/m^3) on 3.16, 3.21, 3.22, 3.29, 3.30 and last time when it was detected it was only ~3000 on 4.9,
For Xe133: 3.16 - 400 Bq/m^3, 3.17 - 50 Bq/m^3, 3.21 - 62 Bq/m^3, 3.22 - 30 Bq/m^3,
What this mean ?

 

[StrangeBeauty]

I too think that #4 looks like it's leaning in these images, but I am not convinced that's it not an optical distortion of some form. The low resolution also hinders analysis. Does anyone have recent images from a different angle to compare? A satellite image would be good.

Welcome Nancy... Thanks for the images you have posted on your site.

...TEPCO also moved the watering crane that has been on the south side of #4 to the corner of #4 on the land side about 4 hours ago. I don't have a screen shot yet but the person who saw it is reliable.

evidence please? A picture would be good :)

...TEPCO employees were telling a couple of different Japanese reporters I have spoken to that the stability of #4 was a big concern...

link please? The collapse of the building would be a very bad development...

 

[Jorge Stolfi]

It was suggested that I share this here. A couple of people had mentioned #4 looked like it was falling over or it is an optical illusion of the wide angle lens on the TBS camera. I am not totally convinced it is the camera since there is no oddity on the opposite side of the camera

Nancy, there are a few things in those images you must take into account:

(1) The camera is a bit tilted. Your 'vertical' lines are a bit off; check carefully the tower, you should tilt them clockwise by a couple of pixels at each end.

(2) There is, definitely, radial distortion of the barrel type, stronger in the high-zoom images. Check that the vertical edges of #2 seem to be leaning counterclockwise, as much as #4 seems to be leaning clockwise. Because of that, the 'vertical' in the corner where #4 is should be tilted even more clockwise.

(3) The upper edge of the South wall of building 4 is damaged and has been displaced down by 1-2 meters, and there is a large foreign object sticking out of the roof at the NE corner (on the far side of the building, near the center of its outline on the photo). Thus the pink lines you drew to show the outline of the building are incorrect. The top of the building is actually almost level with the camera, so the outline at the top is very nearly a single straight line from the upper left corner to the upper right corner (like that of #2).

(4) There is some dark obstacle (a tree?) near the base of the right edge of #4 in tht photo. That obstacle gives the impression that the right edge is more tilted than it really is.

(5) The pillar at the NW corner, that defines the left edge of the building in the photo, was damaged too. Its middle part bulges out by a meter or two. What you see in the webcam is only the upper half of that pillar, which therefore seems to be tilted.

Thus I think that the "leaning over" is an illusion due to the unlucky combination of effects, all conspiring to tilt the outline of #4 clockwise.

 

[elektrownik]

You can see red concrede pump on live cam now...

 

[dh87]

i think i'd use CO2 rather than nitrogen to inert atmosphere. it's heavy so will stay in the vessel up to level of leak and not mix so much with air..

CO₂ is toxic, even at pretty low levels (2%), not that anyone should be breathing the atmosphere, and CO₂ will acidify the water.

 

[turbo]

CO₂ is toxic, even at pretty low levels (2%), not that anyone should be breathing the atmosphere, and CO₂ will acidify the water.

Another reason to use nitrogen is that is generally readily available in liquid form. You can get a large volume of nitrogen gas from an amount of liquid nitrogen that is easily transported by truck.

 

[DSamsom]

You can see red concrede pump on live cam now...

And it seems the smoke from reactor 3 is black (and thick). Look at this short excerpt from the live feed.

http://goo.gl/JBdwI

 

[ascot317]

And it seems the smoke from reactor 3 is black (and thick). Look at this short excerpt from the live feed.

http://goo.gl/JBdwI

I don't see much there. It's dark. Looks "normal" to me.

 

[DSamsom]

I don't see much there. It's dark. Looks "normal" to me.

Hm, this array of screenshots from apparently (can't verify) a few hours ago doesn't look very 'normal' or am I mistaken

http://twitpic.com/4unrpd

 

[unlurk]

Hm, this array of screenshots from apparently (can't verify) a few hours ago doesn't look very 'normal' or am I mistaken

http://twitpic.com/4unrpd

No. 3 blew up again.

The live cam seems to verify it.Edited

 

[ascot317]

Hm, this array of screenshots from apparently (can't verify) a few hours ago doesn't look very 'normal' or am I mistaken

http://twitpic.com/4unrpd

That black smoke (if it is black smoke) could be coming from #4.

I'm sceptical about interpreting low resolution pictures at night.

 

[elektrownik]

Interesting unit 3 have big temperature and cooling problems, they are injecting 9m^3/h but last data show that after litle drop temperature was increasing again

 

[biffvernon]

In this video:
http://www.youtube.com/watch?v=9BN0teWjt3Y&feature=player_embedded#at=44

the smoke seems to be coming from both #3 and #4

 

[MadderDoc]

Here is an annotated version of the Air Photo Service snapshot of reactor #3, from nearly above:

[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/out/reactor3-Z-3-c-A-i.png

To the best of my knowledge:

(A) Outline of the service floor, out to the outer surface of the building.
(B) Stairwell (?).
(C) Elevator shaft.
(D) Spent-fuel pool. The North edge is guessed, the East edge may be a bit off.
(E) Steam-dryer storage pool (= equipment pool). The South edge is guessed.
(F) Overhead crane (outline of upper surface).
(G) Winch box of the overhead crane.
(H) E-W and N-S cuts through the reactor axis (as in blueprints).
(I) Estimated broken edge of service floor slab.
(J) Grappling attachment for the containment cap?<..>
Higher resolution images:
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un3_foto_exploded_Z_1.png
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un3_foto_exploded_Z_2.png
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/good/un3_foto_exploded_Z_3.png
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/edited/out/reactor3-Z-3-c-A-e.png (annotated version of the latter)

Here is another stab of it (a higher resolution image is attached):
[URL]http://gyldengrisgaard.dk/fuku_docs/20110324_down_3thumb.jpg[/URL]
1) Approximate location of apparent kink in the northern boom of the overhead crane (as if it is bent or broken)
2) Approximate location of fire with grey/black smoke on March 21st-22th. Soot on roof girders and wall concrete structure. At floor below, dark shape or possibly crack in service floor.
3) Signature of heat on the winch, and possibly a burn through of the southern boom in this location
4) Missing rails on the top of this section of the southern boom.
5) Areas in which the booms have sunk into the concrete deck of the service floor, extending the NW broken region of the floor.

 

[Uagrepus]

Thanks MadderDoc,
I came to a similar result based on a thermo pic of No.3. (Drawn 19.04.11).

http://i54.tinypic.com/2iie3pw.jpg

Edit by Borek: image was too large, replaced by the link.