Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[GJBRKS]

something else is very hard to explain:
if the hydrogen was produced by a zircaloy reaction, this means the assemblies must have been exposed to the air. right?
but there was no water added to the pool until 4 days after the explosion.
actually, they put big efforts to spray water on the #3 SFP, before they started with #4.

questions to be answered (find my answers in {}):
- was fuel in #4 exposed? {no}
- if not: could enough hydrogen have been produced (radiation decomposition, steam)? {no}
- if yes: why was the fuel covered after the explosion (why did TEPCO obviously did not worry about exposed fuel, + #4 was [only] INES 3 rated after the explosion [weak evidence though]) {i have posted a thesis on this before, but it is too weird to be true}

if the reason for the destruction of #4 was *not* hydrogen:
- could #4 has been damaged by an explosion in #3? {no}
- as no damage to #4 has been observed: was there a second explosion in #3? {no}
- if yes, what kind of explosion in #3 could have an impact on #4 as observed (must have been very directed, no damage to #2...)? {no}
- what else could have exploded in #4? {nothing}

if all my answers are correct, unit 4 has not exploded at all...

Cryptome.org has an assesment from the NRC where they say the fuel in the #4 SFP might have been partially uncovered , producing hydrogen :

http://cryptome.org/0003/daiichi-assess.pdf

 

[|Fred]

OK, but I meant what do you think about something having fallen into the northeast corner of the roof of Building 4?

I know I hadn't formulated answers to your question yet.
I like to speculate when I have some form of intimate conviction, and right now I do not and I'm not sure I clearly grasp the things that I'm seeing.

There is a second green crane or some type of machine inside the service floor of the north end of Bldg 4 clearly seen through the second open panel from the right.

I though I made this point 18 days ago and a fact two days ago :p

Once the south end of the roof was lifted sufficiently high, the north end slid into the top of the building like a giant knife.

Could you please clarify this , I don't picture it right

Odd lighting, for sure, and really poor resolution, but I believe the damage was already done. ...

agreed

simply from being superheated

how do you suggest this happens?, why wouldn't the watter just boil

 

[MiceAndMen]

Here are two more Oyster Creek drawings. One PDF shows a schematic depiction of drywall penetrations and the other shows the PCV. The second one is not too clear, but it's informative nevertheless.

View attachment Oyster Creek Dwg DW Pen.pdf
View attachment Oyster Creek Dwg PCV.pdf

I also attached a PNG that shows the general layout of the refueling level of the Susquehanna I reactor in Pennsylvania USA. There are 2 reactors at Susquehanna and they are located in the same building, mirror images of each other. They share a common cask storage pit that lies between their individual SFPs. They are BWR Mark II designs.

The interesting thing about the Susquehanna reactors is their refueling openings above the drywells are octagonal in shape instead of round. There are pictures around that show openings like this, such as this one at the nuclear tourist website:

http://www.nucleartourist.com/images/rflg-fl1.jpg

Have we seen definite information that says whether the refueling cavity openings at the Fukushima Dai-ichi reactors are round or octagonal (or some other shape)?

 

[MadderDoc]

The vertical position of the fuel handling machine of unit 4 appears to me to be about right, judged from the apparent spatial relationship between the hockey stick, the overhead crane, its rails, and the concrete pillars (taking into account that the hockey stick has been distally somewhat bent, see attachment)

 

[Jorge Stolfi]

The vertical position of the fuel handling machine of unit 4 appears to me to be about right, judged from the apparent spatial relationship between the hockey stick, the overhead crane, its rails, and the concrete pillars (taking into account that the hockey stick has been distally somewhat bent, see attachment)

Indeed. By the way, the "hockey stick" is not bent. Look closer.

However this seems to be the other end of the machine, which has a taller structure rising above the hockey sticks.

 

[bytepirate]

I've already explained how something could have exploded in #4. The water in the spent fuel pool could have had up to 1/10 kiloton of explosive force, simply from being superheated under 2 atm of pressure - the pressure under 40 feet of water. 1E10 grams in the pool, 4 J/g/C, 25 C over 1-atm boiling point... once you do the math, it's clear that if even a small fraction of the pool's volume were unable to cool by convection, the resulting burp of steam could easily take out the building.

BTW, my alias is looking more cryptic to me all the time, and that wasn't my intention. I'm Chris Phoenix, and my email is my alias at gmail.com. Nice to meet you all.

might be an explanation.
but:
- just a gut feeling: i wonder if convection is neglectible (2 bar pressure, 120°C at the bottom - geysers usually have much higher values.)
-would there be water left in the pool after the explosion?
-could a geyser-like event be responsible for the observerd damage (especially the massive damage *below* the top of the pool, actually quite far away from the pool)

anyway, i will put this in my list of possible reasons. a very small list...

 

[|Fred]

the lower part of the crane is (should be) about 2.5 m above the floor , it is not at present. The lower part or the crane is may be 70 cm above the floor.
I suspect the hockey stick to be slightly bent


edit: no I was using the crane from reactor 3 for reference and not the one on unit 4, I believe you are about right, the fhm crane is probably about where it should and no more than 1 m bellow where it should be

 

[bytepirate]

Cryptome.org has an assesment from the NRC where they say the fuel in the #4 SFP might have been partially uncovered , producing hydrogen :

http://cryptome.org/0003/daiichi-assess.pdf

it looks, as if they do basically the same as we do: speculation based on sparse information...

 

[TCups]

@Fred

I thought I made this point (about a third crane) 18 days ago and a fact two days ago :p

You did indeed, verbally as I recall. If you referenced the picture showing the third crane, I missed it. But 18 days ago, I hadn't seen the FHM or part of it still in the SFP3, and 2 days ago, I did see the FHM, or part of it still in the SFP3. Today, I finally did see inside Bldg 4 and visibly verified the presence third crane. I am a visual sort of person. But no matter. That issue is settled in my mind for now.

Could you please clarify this , I don't picture it right

I will try to draw you a picture or maybe even an animation, but it will have to be later. The roof was likely a big slab of asphalt or asphalt like material - a thick, somewhat flexible slab. Imagine it lifting up first over the southeast corner of SFP4, then, still attached at the north end, peeling back from south to north and billowing upward like a sail catching the wind, then, the weight of the large slab collapsing the north wall inward, and finally the south end collapsing vertically on top of the north end of the slab.

 

[|Fred]

I had made a nice picture for you

Considering the states of the unit 3, I 'm just suggesting it as I can not really prove it, apart from an analogy to unit 4 who feature 3 cranes [PLAIN]http://k.min.us/ikzpLE.jpg.
I'm not nulling out that the FHM from the SFP was partialy moved to the north either.

 

[jmelson]

Um, there's something I just spotted about Unit 4...

Sat-Image of March 16th, Unit 4 is already destroyed but the roof is still covered:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi2_march16_2011_dg.jpg

Sat-Image of March 17th, the cover on Unit 4s roof is gone:

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichirec_march17_2011_dg.jpg

Very different view and different sun angle. I'm not sure you can conclusively state there is a difference. Yes, I agree, it APPEARS different, but it could be a trick of the illumination and view.

Jon

 

[jmelson]

I've already explained how something could have exploded in #4. The water in the spent fuel pool could have had up to 1/10 kiloton of explosive force, simply from being superheated under 2 atm of pressure - the pressure under 40 feet of water. 1E10 grams in the pool, 4 J/g/C, 25 C over 1-atm boiling point... once you do the math, it's clear that if even a small fraction of the pool's volume were unable to cool by convection, the resulting burp of steam could easily take out the building.

BTW, my alias is looking more cryptic to me all the time, and that wasn't my intention. I'm Chris Phoenix, and my email is my alias at gmail.com. Nice to meet you all.

40 feet of water has a static head of 17.3 PSI, just over 1 ATM. And, of course, that is only the bottom of the pool, the mid-level would be half that. So, the amount of energy that could be stored there is a lot less than you give numbers for.

Without some mechanism to force the water to remain still and not convect, I just don't see how this can happen. A very messy boiling mess is quite possible when the active cooling fails, but great superheating and then explosive vaporisation just defies logic. But, maybe with superpure water, it is possible. Not sure how pure the water was after the earthquake.

Jon

 

[jmelson]

might be an explanation.
but:
- just a gut feeling: i wonder if convection is neglectible (2 bar pressure, 120°C at the bottom - geysers usually have much higher values.)
-would there be water left in the pool after the explosion?
-could a geyser-like event be responsible for the observerd damage (especially the massive damage *below* the top of the pool, actually quite far away from the pool)

anyway, i will put this in my list of possible reasons. a very small list...

If the SFP did flash to steam, it would likely have been an unmistakable event, with a HUGE steam cloud, and water splashed over the entire facility. Anyone outside would have had horrible scalding, and probably anyone in the building at the time, also. The water everywhere would have taken a couple hours to evaporate. So, I think a massive flashing of tons of water to steam would have been clearly different from what we did see, and therefore that isn't what happened.

Also, this would have removed a bunch of the water in the pool, although maybe not completely emptied it, if this stratification theory is possible (I don't believe it is). So, then there WOULD have been major damage to the fuel in the pool, which they say is not so.

Jon

 

[Jorge Stolfi]

Without some mechanism to force the water to remain still and not convect, I just don't see how this can happen.

After re-racking, the fuel assemblies are packed tight against each other into crates (each containing perhaps 7x7 assembles), and these are packed tight too. That is essentially a 4m thick fairly solid slab of metal, weighting several thousand tons. Water circulation is still possible through the fuel assemblies, in the space between the rods. There is some space below the layer of assemblies and along the walls of the pools.

I do not know whether convection through such long and narrow channels would be effective without external circulation pumps; http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf" seems to address this question but its estimates seem rather crude,

Does someone know the disposition of cooling water pipes in the SPF? I recall a SFP model shown on NHK which showed two round pipes. One entered near the top of the wall, horizontally, made a 90 turn and continued down for a short distance. The other pipe entered vertically through the bottom, near the wall; went all the way up, then made an U-turn and went back almost to the bottom, siphon-like. I couldn't figure out which was in and which was out.

if that SPF model was correct, then perhaps the earthquake (which included strong and lasting horizontal shaking) shook loose the entire pack of fuel assemblies, which snapped the second pipe and perhaps created a leak through the pool's bottom. It may also have bent the supports that kept the fuel away from the bottom, causing it to settle and thus cutting off convection.

 

[MadderDoc]

Indeed. By the way, the "hockey stick" is not bent. Look closer.

However this seems to be the other end of the machine, which has a taller structure rising above the hockey sticks.

It is actually the same hockey stick, just seen from the opposite (reactor) side, see attachments. I've looked and looked, it still looks bent to me. But perhaps it's the perspectives fooling me.

 

[gmax137]

...

I do not know whether convection through such long and narrow channels would be effective without external circulation pumps; http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf" seems to address this question but its estimates seem rather crude,...

Yes, natural circulation through the assemblies is sufficient to remove the decay heat. I have seen such calculations for PWR fuel and I'm pretty certain that it is true for BWR fuel as well. In fact, in the typical design, the SFP cooling system removes heat from the bulk fluid while the assemblies are cooled by natural circulation (in other words, the cooling loop flow is not 'pumped' through the assemblies at all).

 

[MadderDoc]

<..> 2 days ago, I did see the FHM, or part of it still in the SFP3.

Did you? Perhaps I have been missing something. I am not saying they are not there, just haven't seen any photos of FHM parts in the SFP3. In fact I haven't seen any photos looking into the SFP3.

 

[MiceAndMen]

Oyster Creek Blueprints

Upon further review there are direct-download links for the Oyster Creek blueprint drawings. These 4 PDFs are part of a document titled, "Revision 12 to Updated FSAR for Oyster Creek Nuclear Generating Station". These are publicly available documents hosted on an NRC website. Below each document link I listed a few pages that I found particularly interesting, but there is a lot more information than that contained in these files.

http://adamswebsearch2.nrc.gov/IDMWS/ViewDocByAccession.asp?AccessionNumber=ML011270077" (70 pp)

• 42 Main Stack
• 49 Drywell Cooling

http://adamswebsearch2.nrc.gov/IDMWS/ViewDocByAccession.asp?AccessionNumber=ML011270243" (82 pp)

• 06 Site Plan Showing Intake and Discharge Tunnels
• 31 Containment Spray System
• 35-38 Refueling Floor Plan and Details
• 59 Drywell Penetrations
• 72-74 Drywell Diagrams

http://adamswebsearch2.nrc.gov/IDMWS/ViewDocByAccession.asp?AccessionNumber=ML011270300" (58 pp)

• 04 Symbols and Legend
• 05 Spent Fuel Cask Safe Load Path
• 08-09 Reactor Bldg Floor & Equipment Drains
• 20-28 Reactor Bldg General Arrangement Plan & Elevation

http://adamswebsearch2.nrc.gov/IDMWS/ViewDocByAccession.asp?AccessionNumber=ML011270286" (31 pp)

• 02 Drywell and Torus Vacuum Relief System
• 19-20 Radwaste Cask Safe Load Path

One can access these PDFs and the other parts of the FSAR at the NRC's Web-based ADAMS search page as follows:

1. Go to the main ADAMS site at http://wba.nrc.gov:8080/ves/
2. Select the Advanced Search tab
3. In the search box put "Accession_Number:ML011270* $titleyster" without the quotes
4. Press the Search button and wait

You should get 8 results including the 4 PDF files above.

I've done a lot of searching there over the past few weeks and have been unable to find any other reactor building drawings or blueprints (except for 2 minor PDFs regarding the Susquehanna NPP). If anyone finds any please share them here. Drawings help to visualize the insides of these reactor buildings, even if they are not 100% exactly the same as the Fukushima Daiichi designs.

 

[MadderDoc]

Have we seen definite information that says whether the refueling cavity openings at the Fukushima Dai-ichi reactors are round or octagonal (or some other shape)?

Attached is a photo of Daiichi unit 1 in operation, it is definitely octagonal. I have seen no similar photos from the other units, however, for unit 4, I've seen pictures with the cavity open, and apparent kinks in the railing circle, suggesting a 'not round' shape

 

[MiceAndMen]

Attached is a photo of Daiichi unit 1 in operation, it is definitely octagonal. I have seen no similar photos from the other units, however, for unit 4, I've seen pictures with the cavity open, and apparent kinks in the railing circle, suggesting a 'not round' shape

That photo is part of the "Inside the BWR Power Plant" page at the Nuclear Tourist website http://www.nucleartourist.com/areas/bwr-in1.htm

Under the section "Refueling activities" the last picture link "Refueling floor during operation (120K)" is that same exact photograph. At the top of the page it says,

The following photos and graphics illustrate the equipment representative of the BWR plant. Contributors include CP&L, TVA, General Electric, KKN, Niagara Mohawk, and Detroit Edison.

I'm not sure that photograph really is from the Fukushima Daiichi plant.

 

[Jorge Stolfi]

I've looked and looked, it still looks bent to me. But perhaps it's the perspectives fooling me.

As I see it, there are two hockey sticks on each side of the machine, each makes two 45 degree angles and ends horizontally. There is a transverse bar connecting the ends of those two sticks. Then there is a single stick that comes out horizontally from near the middle of transverse bar, bends another 45 degrees down, and ends with the square box.

The joysticks and attached structure apparently is a set of hollow metal conduits for electrical cables. You can see the cables coming out of the square box and hanging in festoons from a light rail attached to the wall, a couple feet below the crane's much heavier rail. In the right picture cables and their rails are gone.

But you are right, in the "after" picture the whole set seems indeed slightly bent. The tops of the hockey sticks are tilted some 20 degrees, the sides of the square box are not vertical, and the transverse bar is bent, with both ends lower thant the middle. And the vertical part of the hockey sticks seems to be detached from the body of the FHM.

The tops of the hockey sticks seem to be at the correct height relative to the crane and the concrete pillars.

Your right picture shows a green "castle" on top of the FHM, with two floors with railings, which does not exist in the left picture. Presumably the castle was positioned near the opposite wall when the left picture was taken.

So here is another proposal: the FHM was originally parked above the SFP, with that square box just below the concrete "capitel" that supports the crane's rail. When the SFP exploded, it lifted the whole FHM. The square box hit the concrete capitel. The impact bent the jockey sticks and ripped them from the FHM. The FHM then crashed back over the pool. Whether it returned at its original height or sank further, I cannot tell.

 

[HowlerMonkey]

What about this strange idea ?
[PLAIN]http://img864.imageshack.us/img864/770/7d39a2e665024e3f8856f31.jpg[/QUOTE]

It does look like it didn't quite clear the edge of the roof of that other building after taking the path you suggested, bounced off the edge, and fell to where it sits.

The two gouges on the same roof further up make me wonder if something didn't glance off the roof there and end up in the water.

 

[biggerten]

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

Picture 5 speaks of a circular plug for reactor 3.

 

[MiceAndMen]

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

Picture 5 speaks of a circular plug for reactor 3.

Very interesting photos, thank you for that link. Trivially, perhaps, note that picture 4 has the Kanji symbol for "North" on the column. http://hararie-japan-tokyo-tokyo.co...ws-direction-of-japanese-element-symbols.html

 

[razzz]

Remembering these building were built back in the 70s and 80s... the superstructure is framed out with its major components of 'I' beams and girders (either poured in placed or prefabbed) with ceilings/floors created by filling in with joists between the superstructure components then corrugated structural metal sheets (pieces might remind someone of the corrugated roof seen on a mountain cabin) laid on top of the joists for concrete pump mix to be poured on top and finished as a smooth floor. Also, plywood can be used and concrete poured on top of it, either way metal or wood is left in place. Another way would built temporary wood or metal support to the pour concrete on or in then remove the 'false' work, leaving just the concrete in-place especially done this way when pouring walls.

I the read the exterior wall panels are meant to blow out while withstanding the occasional passing typhoon with earthquakes thrown in on a regular basis and you can see in the pictures that the concrete squares forming the exterior wall between the major upright and horizontal members are not seriously attached, almost floating. Steel reinforcement bar would have been larger and tied in-to the major members in a more direct fashion instead it was meant for the squares to peal away.

Concrete breathes, expands and contracts therefore not waterproof so if used on the roof section has to be covered over with a impermeable material.

These housing structures would be child's play for an engineer/architect as they stand alone, separately built around the reactor. The major function in design would be load bearing for the winch to move the caps and support for the SF ponds.

 

[etudiant]

Has anyone developed a plausible/possible mechanism for the damage to the supports of SFP 4?
A hydrogen blast should impact the upper part of the structure.

 

[rowmag]

Fred's picture gives me an idea about what that thing is that landed on #4's roof:
[PLAIN]http://k.min.us/ikzpLE.jpg

From the coloring and shape, I am beginning to suspect that it is concrete wall panel from #4's own wall, that somehow got blown upwards to land on its own roof. Imagine, for example, a 2-3 "cells" high by one or two "cells" wide section of exterior concrete panelling being blown off the east wall, but still attached at the top for a while, allowing it to hinge up and over to land on the roof. (In fact, is that the pivot point below the capital "C" in Fred's "2: SFP Crane" label?)

The section could also perhaps have come from the west wall.

If true, might be supporting evidence for a below-decks (below the refueling floor level) explosion in building 4?...

 

[MadderDoc]

That photo is part of the "Inside the BWR Power Plant" page at the Nuclear Tourist website http://www.nucleartourist.com/areas/bwr-in1.htm

Under the section "Refueling activities" the last picture link "Refueling floor during operation (120K)" is that same exact photograph. At the top of the page it says,
I'm not sure that photograph really is from the Fukushima Daiichi plant.

However, that is not my source to that photo at all. I'll post a link to that source, if I can backtrack to it. It was a huge pdf, I remember very well, with a blasted copy-protection and I had to grab the photos in small sections which was a pain, took only what I had not seen elsewhere, otherwise mainly known photos from the unit 3 refueling in 2010. The photos I grabbed were clearly attributed to the Daiichi reactors, I am sure. I grabbed a juicy photo of the reactor vessel head of unit 3 from the same document, btw. :-)

My complete collection of photos from Daiichi as originally grabbed is at:
http://www.gyldengrisgaard.dk/daiichigrab/

Do say if you have good reason to believe misattributions have crept in there. It is _meant_ to hold only reasonably well sourced images from Daiichi.

Edit: I've found that the metal structure on those photos, although similar to those of unit 1, is not identical, that's a good enough reason for me assume misattribution. Thanks for provoking me to reassess.

 

[TCups]

Fred's picture gives me an idea about what that thing is that landed on #4's roof:
[PLAIN]http://k.min.us/ikzpLE.jpg

From the coloring and shape, I am beginning to suspect that it is concrete wall panel from #4's own wall, that somehow got blown upwards to land on its own roof. Imagine, for example, a 2-3 "cells" high by one or two "cells" wide section of exterior concrete panelling being blown off the east wall, but still attached at the top for a while, allowing it to hinge up and over to land on the roof. (In fact, is that the pivot point below the capital "C" in Fred's "2: SFP Crane" label?)

The section could also perhaps have come from the west wall.

If true, might be supporting evidence for a below-decks (below the refueling floor level) explosion in building 4?...

No, the simplest explanation is the correct one. It is a piece of the roof, right down to the little square holes than can still be seen in the roof. The roof has been blown upward on its south end, billowed outward, and crashed down into the top of Bldg 4.

Pre-explosions of the top of Bldg 4 confirm a pattern of the small squares -- whatever they are. Bldg 1 had a few as well. The curve of the slab exactly matches the damage to the underlying girders. The underside (to the south) is irregular from being blasted and torn from the underlying girders. The topside (to the north) still has its pattern of smaller square sections, as do all of the flat roofs at Fukushima.

https://www.physicsforums.com/attachment.php?attachmentid=34557&d=1303159967

https://www.physicsforums.com/attachment.php?attachmentid=34558&d=1303159967

No big green machines to confuse here -- that is a big slab of asphalt (or something like asphalt) roof lifted up and dropped on end, on the north side of Bldg 4, and it brought the north side face of the building inward with it when it cut in and downward.

See, for example:

http://www.gaf.com/Roofing/Commercial/Products/Modified-Bitumen-Roofing/Ruberoid-Modified-Bitumen-SBS-Membranes/Documents/Commercial_Full_Line_Brochure-13-719-v5.pdf

Oh, yeah, the drawing of what happened . . . well, think of it this way. Have you ever had a convertible with a folding top? Goodnight.

 

[MiceAndMen]

However, that is not my source to that photo at all. I'll post a link to that source, if I can backtrack to it. It was a huge pdf, I remember very well, with a blasted copy-protection and I had to grab the photos in small sections which was a pain, took only what I had not seen elsewhere, otherwise mainly known photos from the unit 3 refueling in 2010. The photos I grabbed were clearly attributed to the Daiichi reactors, I am sure. I grabbed a juicy photo of the reactor vessel head of unit 3 from the same document, btw. :-)

My complete collection of photos from Daiichi as originally grabbed is at:
http://www.gyldengrisgaard.dk/daiichigrab/

Do say if you have good reason to believe misattributions have crept in there. It is _meant_ to hold only reasonably well sourced images from Daiichi.

Edit: I've found that the metal structure on those photos, although similar to those of unit 1, is not identical, that's a good enough reason for me assume misattribution. Thanks for provoking me to reassess.

That picture of the reactor vessel cap is scary looking, if I do say so. It looks like it might be part of an electric chair for a giant (no ambiguous meaning intended there).

Keeping track of everything I've downloaded is getting to be a chore. It's one thing to store a document or a photograph, and it's quite another to remember where it came from in case a source cite is needed. I've got my hard drive folders organized pretty well now. I think I have enough to fill a DVD already between the PDFs, photos, videos and saved web pages. All the bookmarks I've made in the last few weeks are a different story, though. I think I have a dozen bookmarks just for posts in this thread so I can refer back to them.