Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[clancy688]

I will try to find a picture illustrating what I'm talking about and will edit this post if I can find what I'm looking for. If I'm wrong, let me know, because then I've got the building layout all wrong in my head.

The horizontal portion of the "L-shape" you're talking about is integrated into the long turbine building which's between the reactors and the sea. It is at the bottom of the picture. That can be easily verified since the reactor's wall has a giant "dent" on the right side. The dent is facing Unit 3, so the turbine building and the horizontal portion of the L-shape is below.

 

[SteveElbows]

Actually, this has already been reported by SteveElbows on post #9406. With a more interesting fact that the previous video which holds an "action scene" showing some workers wandering in front of the camera.

What I did not realize at the time was that less-sped up versions of these videos existed, so its possible to get a bit more detail once you use the faster version to spot hours where something visible happens.

I also did not realize that in the video after the one showing reactor 1 wall spraying, a similar activity being carried out at reactor 3 is just about visible, if memory serves me correctly this operation is in full flow by 11:30 of that day.

I had also missed another spraying event at reactor 1, they sprayed the 'roof' of the building in the video below, which makes for an interesting visual compared to the usually dull webcam.

http://www.youtube.com/user/fuku1long#p/u/62/ntjOm7x-KaY

 

[clancy688]

It could easily be broken into ten or more different threads. There are some topics that we can only speculate on. Since that is going to happen anyway, it is better that it be allowed for with the understanding that it is physics being applied to possible scenarios. We use physics for that purpose every day anyway.

Single threads for every Unit (such as the explosion thread for Unit 3) would be a very effective measure to organize this information monster.
But we somehow have to make sure that users won't use this thread for Unit specific discussions which could be outsourced into those threads... it's a pain in the *** to find informations or discussions in this megathread.

 

[Quim]

Thank you. MY observation was that the top of the fuel modules were visible at the depth in the water where they should have been located, regardless of the debris. If there had been an explosion as Artie Gunderson claimed, those modules should have been blown out of the pool like a shotgun blast. Since they were still visable, I believe Artie's conjecture is wrong.

I haven't kept up with Gunderson's analysis(s) although I have held a similar view that the added boost apparent in the #3 explosion footage came from a steam explosion created when a momentary criticality injected a burst of joules of heat into the pond.

Originally, I assumed that most of the contents of the FP were disgorged into the rising cloud, but after becoming more familiar with the quantity of material around the site (despite Tepco's unwillingness to actually disclose with any clarity what is there) I can see that there probably isn't enough hot material around the site to account for the entire contents of the FP.

But it isn't necessary for a criticality to have happened at the bottom of the pool, it could have occurred at any level of the rods. That something provided an added boost to the #3 explosion is seen beyond a doubt in the video, to my eyes.

That "the boost" came from the fuel pond is obvious from the video of the later wreckage. The pattern of wreckage of the roof joists makes that clear. And with the equipment crane lying directly over the containment vessel we know the blast could not have come from the reactor containment.

When I view the few seconds of the video you indicated which shows the round objects that could possibly be the tops of fuel rods in the pond, I do have to pause and look again to what happened to provide the source of energy for that boost - while the video doesn't actually confirm that there are fuel rods remaining in the position they were originally stored, it does suggest that possibility.

The salient event in the #3 explosion is the very directional blast seen rising up from the #3 building which I can have no doubt was a vectored blast.

In fact, there seems little doubt that it was a vectored steam explosion, as opposed to a more violent detonation. A steam explosion would be expected to cause the "slower" release of energy than what a chemical explosion or a fast criticality would provide and that is what we see in the video.

Thus, the basic premise remains unchanged.

The source of energy for that vertical blast originated in or just above the fuel pond, to say otherwise is akin to saying that there was no 500 meter vertical blast and that the chunks of heavy material seen coming off the column at about the 300 meter level were just some kind of illusion.

But that's not so.

So, how can I justify the criticality theory with the (possible) evidence of intact fuel rods (2) in the pond becomes the question of the day.

Obviously, the first theory would be that those round shapes are not what they appear to be, and that is quite possible.

Another way to approach the problem is to look closer at what a criticality event might have looked like. Would it be possible that a localized criticality created a steam pocket which ejected only some material?

The reason I struggle with these theories is simply because something beyond an explosion of hydrogen/oxygen gasses in open air sent that column of steam and debris skyward.

The original hydrogen blast can be seen to have been vectored southward (and upward) in the first few milliseconds of the event. This was followed by a less visible excursion to the north which was obscurred by smoke. Thus, the original blast was vectored in a south/north direction by the "cattle chute", it also sent some of its energy upward, that is visible in the stop action videos of the explosion.

But I can see no possible way that original blast could have been vectored straight up.

There was a second application of energy which was vectored skyward, that could only have come from the pond.

I am also in a discussion with Jorge Stolfi. Let's see how that develops.

 

[SteveElbows]

Very clever!
While the closed circuit shot says "Live", there is no way to prove that it is not put through an edit loop, to censor undesirable images before they get broadcast. An earthquake is hard to plan for, however, so it should show whether the video is real time or not.
Unfortunately, I could not reconcile the time lines in your videos, so the status is till up in the air, whether it is real time or not. Have you come to a conclusion on this issue?

I don't spend much time pondering sophisticated censorship by TEPCO in terms of editing, rather I expect that if any circumstances arise that they do not want to show, they will just switch the feed off completely. The time delay of some 30 seconds is freely acknowledged by TEPCO, and apart from possible technical reasons for this, that would give them a buffer to pull the feed before we saw the start of the unexpected event taking place, but I'll cross that bridge if we ever come to it.

I haven't tried too hard to line the TEPCO timestamp up with reality, there are differences between the time my devices tell me is now, the TEPCO timestamp, and the time that earthquakes are reported to happen, but they seem to be well within a minute of each other so I don't fret it. Plus I have no idea how long it can take earthquakes to be felt in locations a bit away from the epicentre, (any takers on this?), nor whether the webcam is only visibly affected by certain kinds of earthquake motion and not others.

 

[Bioengineer01]

http://www3.nhk.or.jp/daily/english/10_26.html

 

[elektrownik]

This doesn't look like steam/fog ?
[PLAIN]http://img9.imageshack.us/img9/5008/40726091.jpg

 

[StrangeBeauty]

http://www3.nhk.or.jp/daily/english/10_26.html

I'm going to ask publicly that people please not post uncommented links. Even a *very* short sentence fragment about what is of interest there is much better than nothing. Or just copy and paste a bit. Thanks :)

Unless I missed something, this is old news on this thread and already covered in much more detail (maps of readings):
"The workers withdrew after measuring radiation of 100 millisieverts per hour near the reactor's containment vessel."
"TEPCO says it intended to limit the workers' exposure to below 5 millisieverts per hour. But as all 9 received higher doses, it has suspended work while considering a course of action."

 

[clancy688]

This doesn't look like steam/fog ?
[PLAIN]http://img9.imageshack.us/img9/5008/40726091.jpg[/QUOTE]


Maybe that's an optical illusion. Right behind the plume is the third exhaust stack. It's possible that because of that the plume appears darker.

 

[Bioengineer01]

TEPCO 10th, early 40s, male workers of the subcontractors working at Fukushima Daiichi Nuclear Power Station, became unconscious in the dormitory, announced that the city was taken to hospital by helicopters Iwaki
http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fwww.yomiuri.co.jp%2Ffeature%2F20110316-866921%2Fnews%2F20110610-OYT1T00597.htm

 

[jim hardy]

"""So, how can I justify the criticality theory with the (possible) evidence of intact fuel rods (2) in the pond becomes the question of the day."""

you might read up on criticality,

http://www.if.uidaho.edu/~gunner/ME443-543/LectureNotes/ReactorPhysics.pdf

i did and abandoned the idea for a pool with so little fuel in it.

did anyone ever hear what was location of the worker fatalities in that explosion?

i have looked but to no avail.

 

[Bioengineer01]

100,000,000 becquerels per cubic centimeter of radioactivity estimated for Fukushima sludge
http://mdn.mainichi.jp/mdnnews/news/20110610p2a00m0na010000c.html

this is 100 Terabecquerels per cubic meter~!

 

[NUCENG]

I don't spend much time pondering sophisticated censorship by TEPCO in terms of editing, rather I expect that if any circumstances arise that they do not want to show, they will just switch the feed off completely. The time delay of some 30 seconds is freely acknowledged by TEPCO, and apart from possible technical reasons for this, that would give them a buffer to pull the feed before we saw the start of the unexpected event taking place, but I'll cross that bridge if we ever come to it.

I haven't tried too hard to line the TEPCO timestamp up with reality, there are differences between the time my devices tell me is now, the TEPCO timestamp, and the time that earthquakes are reported to happen, but they seem to be well within a minute of each other so I don't fret it. Plus I have no idea how long it can take earthquakes to be felt in locations a bit away from the epicentre, (any takers on this?), nor whether the webcam is only visibly affected by certain kinds of earthquake motion and not others.

The horse is out of the barn and we're watching pictures of the empty stall and arguing if it live or memorex. If anything happens I will wait for the inevitable release of the recorded clips. If people are really watching this live cam hours every day, I hope they can get back to their lives in a few years.

 

[clancy688]

100,000,000 becquerels per cubic centimeter of radioactivity estimated for Fukushima sludge
http://mdn.mainichi.jp/mdnnews/news/20110610p2a00m0na010000c.html

this is 100 Terabecquerels per cubic meter~!

Well, it's to be expected. The radioactive materials won't disappear if you send all that water in the basement through AREVAs reprocessing facility.
That's the waste which'll be produced.

 

[NUCENG]

"""So, how can I justify the criticality theory with the (possible) evidence of intact fuel rods (2) in the pond becomes the question of the day."""

you might read up on criticality,

http://www.if.uidaho.edu/~gunner/ME443-543/LectureNotes/ReactorPhysics.pdf

i did and abandoned the idea for a pool with so little fuel in it.

did anyone ever hear what was location of the worker fatalities in that explosion?

i have looked but to no avail.

Fatalities that I am aware of included a crane operator at Daini, a heart attack, and the two workers drowned or smashed in the trubine building during the tsunami. I may have missed a report, but don't think any of the reports 11 (unit 3) + 4 (unit 1) explosion injuries were fatal.

 

[clancy688]

I may have missed a report, but don't think any of the reports 11 (unit 3) + 4 (unit 1) explosion injuries were fatal.

There were rumours of six fatalities in the Unit 3 explosion event. But I never saw an official confirmation.

Still it's a miracle that nobody died in the Unit 1 explosion. They must've been in the middle of setting up the portable power generators and wiring the Units when number one went airborne and wrecked those generators and wires.

 

[SteveElbows]

If people are really watching this live cam hours every day, I hope they can get back to their lives in a few years.

I would not be surprised if some people are. Personally I think I would go nutty if I spent hours watching it per day, minutes is hard enough going. I tune in live once in a while but get bored after a minute or two, and I skim those sped up videos someone is putting on youtube to see if anything interesting has happened. If it were not for those youtube videos then the only thing Id have spotted to date, apart from the usual steam and camera wobbles due to earthquakes, would be a couple of animals, a few instances of vehicle lights at night, a few unidentified animals and a person who I caught out of the corner of my eye while not even watching the stream properly one day, which gave me quite a fright for half a second.

 

[jim hardy]

""I may have missed a report, but don't think any of the reports 11 (unit 3) + 4 (unit 1) explosion injuries were fatal.""

thanks Nuceng

and i shouldn't have made that claim from memory. I could easily be wrong.

i thought i recalled four fatalities in the unit 3 blast

but my memory is not infallible, will research it again for myself.

sorta like in this video >>Note not nuclear related, older folks will appreciate it most<<

 

[robinson]

If only there was some way to put a camera on each part of the plant. A good one.

 

[jim hardy]

my mistake,,,
the four fatalities were at a coal plant...

http://www.ocala.com/article/20110404/ZNYT03/104043000

"Four other workers died at Tokyo Electric’s Hitachinaka thermal power plant when they fell from the chimneys they were working on."

sorry

--- forgot to engage brain before typing -
slip of the fingers
old jim

 

[MiceAndMen]

Tepco doesn't tell us also about unit 5 pressure stress test during earthquake until last gov report... so who know... maybe there was fuel in unit 4.

Highly doubtful since they were doing a core shroud replacement. They've done them before and the entire job takes about 10 months. In early March they were about 5 months into it. My guess for the thermal signature is there was water being heated by residual radiation of the irradiated core components inside.

 

[Bioengineer01]

""I may have missed a report, but don't think any of the reports 11 (unit 3) + 4 (unit 1) explosion injuries were fatal.""

thanks Nuceng

and i shouldn't have made that claim from memory. I could easily be wrong.

i thought i recalled four fatalities in the unit 3 blast

but my memory is not infallible, will research it again for myself.

sorta like in this video >>Note not nuclear related, older folks will appreciate it most<<

"Six soldiers from the Japanese Central Nuclear Biological Chemical Weapon Defence Unit are reported to have been killed in the explosion.[166]"
http://en.wikipedia.org/wiki/Fukushima_I_nuclear_accidents#Explosion_of_reactor_4_building

On the reference 166 provided by Wikipedia, you have a witness account of one of the workers:

"Workers told how the earthquake ripped through the plant, immediately knocking out the main power. A ghastly boom was heard in the suppression chamber of reactor 4, said Kenji Tada, who was there at the time. Cracks started ripping in the asphalt and the sides of the building. They fled before the tsunami arrived and did its worst. As the situation deteriorated, the first explosion, at reactor 3 on March 14, happened at the precise moment that six soldiers from the Japanese Central Nuclear Biological Chemical Weapon Defence Unit arrived at the reactor in two vehicles. The six of them are now dead, buried under flying concrete."

Now the question arises again, was this suppressed?
I knew that I had read it on the first hours or heard it in TV, but had a hell of a time finding a report on it. The original article quoted in Wikipedia is gone, but you can still find "exact" text references in Google search of the report, like here:
http://ninme.com/archives/2011/03/fukushima_fifty.html

 

[MiceAndMen]

English Appendices Up for Japanese Govt Report to IAEA

All the appendices (appendixes?) are also available in English now.

http://www.kantei.go.jp/foreign/kan/topics/201106/iaea_houkokusho_e.html

I spent a couple of hours trying to merge them all into one big PDF but ran into a few technical problems. Adobe Acrobat 8 doesn't like some of them (font issues, I think). This is the first time I've ever had major problems with Acrobat and, I must say, the error messages it displays are virtually useless when it comes to saying exactly what the problems are.

If I have time I'll try to do some more with them over the weekend.

 

[etudiant]

Fourth and final section of the Asahi Shimbun report on the Japanese nuclear experience is here:
http://www.asahi.com/english/TKY201106100215.html

This part of the report deals with the earthquake and tsunami provisions, which were apparently mostly retrofitted after the plants were already built.
There is no editorial wrapup, which might have added some local perspective.
Overall, a very good series.

 

[rowmag]

Fourth and final section of the Asahi Shimbun report on the Japanese nuclear experience is here:
http://www.asahi.com/english/TKY201106100215.html

This part of the report deals with the earthquake and tsunami provisions, which were apparently mostly retrofitted after the plants were already built.
There is no editorial wrapup, which might have added some local perspective.
Overall, a very good series.

From the article (bolding mine):
"The earthquake-resistance guidelines were revised in 2006. They required nuclear power plants to withstand a 20 to 30 percent stronger earthquake.

They also included provisions for tsunami protection for the first time. "

Before the notion starts to spread that nobody even thought about tsunamis before 2006, it should be noted that in the civil engineering article from 1967 (see https://www.physicsforums.com/showpost.php?p=3346821&postcount=9367) it is specifically mentioned that setting the ground elevation at +10 m was considered sufficient to protect against typhoon storm surges and tsunamis.

Obviously TEPCO underestimated the elevation needed to protect against tsunamis, but they did at least consider the issue in advance.

 

[robinson]

"Six soldiers from the Japanese Central Nuclear Biological Chemical Weapon Defence Unit are reported to have been killed in the explosion.

I saw a recent interview with the head of a six man team who talked about the explosion in Unit 1, his men were injured and they had to flee, but never found any other mention of that 6 dead account.

 

[Jorge Stolfi]

... There were broken pipe(s) venting hot steam and gases directly off the "pile" into the drywell. The water being poured into the RPV was coming in the well as steam - that was the intent. Along with the steam came a steady stream of hydrogen. The Drywell became an immensely hot cauldron of hydrogen and steam under a steadily increasing pressure and temperature. Just before the number three blast, the atmosphere in the well was at least 60 psi.

I would agree so far, except that the consensus now seems to be that the RPV had been breached several hours earlier, and part of the fuel had already dropped to the bottom of the drywell. Published radiation figures start just before the explosion, on the morning of 3/14, and already show 200 Sv/h in the drywell atmosphere.

The Japanese are good craftsmen and they made their own octagonal pattern for the lid so it may that those lids held up to 125 psi.

There may be some confusion here. AFAIK the concrete shield plugs are meant to block radiation only, not pressure. They may be octagonal in other reactors, but in #2--#4 all drawings indicate that the opening of the refueling pit is round and the plugs are three disks, 1--2 feet thick, each cut into two halves (presumably so that they can be more easily moved and stacked on the cramped service floor). AFAIK those plugs are held in place only by their weight.

It doesn't much matter what the actual pressure was the first time the lid was lifted enough to send a jet of this chamber gas to the realms above. The sequence came as a result of trace amounts of oxygen which began developing inside the leaky containment - we know there were sources for at least a small amount of oxygen production in there.

This seems unikely. At those temperatures and pressures, any oxygen that remained in the drywell from before the breach or that was generated by radiolysis/thermolysys should have been promptly consumed by the excess hydrogen, before it could buid up to an explosive concentration.

But maybe not.

So, in the reciprocal of what we in our normal world see, a gaseous mixture "flashed over": this may have been triggered by a sharp reduction in pressure as when the steam pressure forced the lids to float a little bit.

I did not do the math, but pesumably a massive leak of steam at 60 psi (400 kPa) into the refueling pit could have lifted the shield plugs, enough to let that steam escape into the service storey --- unless it found some easier way out.

However, I do not see how a sudden reduction in pressure (which would have cooled the steam) could have caused it to explode. Everything I see in the wreck suggests that the explosion happened some time after the H2 began to escape -- enough time for it to flow down to the 4th and 3rd storeys and mix with the air. I would rather believe that the steam leaked ignited the colder H2+O2 mixture that was already there, just with for being hot.

At the time just before the blast, the lid(s) had been seeping hydrogen into the region of the cattle trough, where it was beginning to rise up in a column of an explosive hydrogen/oxygen mixture.

According to the floorplans, he "cattle trough" that leads to the SFP (through which steam may be still leaking) is very narrow and short. The gate on the opposite side, to the dryer storage pool (through which steam is definitely still leaking) is as wide as the storage pool. I do not see either as being able to vector the steam significantly upwards.

I don't see any likelyhood that the head bolts stretched nor would they be needed to stretch under either of our specific views.

The head bolts *of the RPV* probably held fine, since the bottom had already been breached so the RPV was at ~400 kPa instead of its normal ~6500 kPa.

But for this scenario we need a path for the steam to get from the drywell to the refueling pit. One possibility is by breaching the diaphragm that connects the drywell wall to the RPV flange, and then leaking between the flanges of the yellow *drywell* cap. This may require stretching the bolts *of the yellow cap*. But there are other possible paths.

I don't see any reason to think the steam-dryer storage pool was involved in any significant way other than as a passageway for water or steam.

Neither do I. I suppose that both gates (to the SFP and to DSP) were closed, and that there was no water in the SDP or in the refueling pit at the time of the explosion.

 

[Joe Neubarth]

OK, let's say we dismiss Gunderson's Prompt Criticality theory because we can see a few square feet of what looks like the top of the spent fuel modules. If the fuel modules are in place then there must have been NO EXPLOSION from the pool.
The Hydrogen explosion only seems to carry us so far. We saw the horizontal explosion and almost all of us agree that THAT was the hydrogen explosion clearing out the rafters at the top of the building.
Assuming that we did see a second and more powerful explosion that was directed UPWARDS, what was that?

 

[jim hardy]

Bioengineer

Thank you - that's a real interesting article.

It links to this Telegraph article
http://www.telegraph.co.uk/news/wor...nami-Fukushima-Fifty-the-first-interview.html

which repeats the tale as related by an unnamed worker
"As the situation deteriorated, the first explosion, at reactor 3 on March 14, happened at the precise moment that six soldiers from the Japanese Central Nuclear Biological Chemical Weapon Defence Unit arrived at the reactor in two vehicles. The six of them are now dead, buried under flying concrete."

The Wikipedia at
http://en.wikipedia.org/wiki/Fukushima_I_nuclear_accidents#Explosion_of_reactor_4_building

has several references related to the incident, two in Japanese i couldn't read.
Ref #208, dated June 7th says four of the soldiers were injured none killed
http://search.japantimes.co.jp/cgi-bin/nn20110607a5.html

It relates a conversation with Col. Shinji Iwakuma the CO of the outfit.

While the team is experienced in dealing with nuclear, biological and chemical weapons, Iwakuma, 49, said that a mission requiring the cooling of an out of control reactor was an "unforeseen" scenario.

Iwakuma, who headed out to the No. 3 reactor with five men in three vehicles, was about to open the door of his car when the hydrogen explosion occurred at 11:01 a.m.

The thundering explosion and accompanying blast wave sent concrete and radioactive debris soaring about 70 meters into the air, obscuring his view in a cloud of gray dust, the colonel said.

"I think the debris fell for several dozen seconds, but it felt like it was for a very long time," Iwakuma said.

After managing to get out of his car, he noticed that his men were injured, dragging their legs or holding their arms tightly.

"Are you all right? We will get out of here right now," Iwakuma told them. One man had to be carried over his shoulder.

The dosimeter they had with them was giving off readings of about 20 millisieverts at the time.

Thanks - at least i have something to go on.
I was checking whether somebody mihgt have been spraying down the pool and it sounds like they hadn't yet got started.

I have a zillion of these loose ends floating around my alleged mind and am tracking them down one at a time.

thanks for the help. i wasnt so far off on that memory it seems, and new info has come in since i made the mental note.

old jim

 

[swl]

)
There was a second application of energy which was vectored skyward, that could only have come from the pond.

Why could energy only have come from the pond?

 

[NUCENG]

""I may have missed a report, but don't think any of the reports 11 (unit 3) + 4 (unit 1) explosion injuries were fatal.""

thanks Nuceng

and i shouldn't have made that claim from memory. I could easily be wrong.

i thought i recalled four fatalities in the unit 3 blast

but my memory is not infallible, will research it again for myself.

sorta like in this video >>Note not nuclear related, older folks will appreciate it most<<

Thanks, that clip made my day,n now, what day is it again?

 

[swl]

There were rumours of six fatalities in the Unit 3 explosion event. But I never saw an official confirmation.

I heard that rumor broadcast by NHK on the day of the explosion at unit 3. The broadcast was in Japanese, so I asked my 'translator' to verify my understanding of the six fatalities and she told me that it sounded like 6 soldiers had died, but that the wording used could also have indicated missing or injured.

I recently read an interview from NHK where the reporter spoke with a lieutenant responsible for 5 other men (for a total of six) who were preparing to start water spraying at unit 3 on the day of the explosion. He described how he was just opening the door of his vehicle when the unit exploded and injured many of his men. I believe he described the injuries as being serious, but that the men had survived. I don't know if his experience is related to the the NHK report of six dead, missing or injured men.

It also should be pointed out that many of the people working at the plant are contractors or soldiers, so if TEPCO say none of their employees have died, that does not indicate that nobody has died. And of course, with history as our guide, TEPCO could also be telling the truth or lying.

 

[joewein]

This ? If (as we seen on underwater sfp 4 video) gate is undamaged, there is no other explanation...
[PLAIN]http://img535.imageshack.us/img535/3165/gggss.png[/QUOTE]

According to this analysis of the hydrogen explosions:
http://tec-sim.de/images/stories/fusfpfail.pdf

the gate is only watertight while some rubber seals around it are inflated by a compressor.

According to this report by Daily Yomiuri Online:
http://www.yomiuri.co.jp/dy/national/T110428006723.htm

the reactor pit was flooded at the time and TEPCO thinks the explosion triggered a leak from the reactor pit to the SFP.

If there's water circulation between the SFP and the reactor pit then the hot spot on the thermal image could well be the location of the RPV, without there having to be any fuel in it.

 

[elektrownik]

According to this analysis of the hydrogen explosions:
http://tec-sim.de/images/stories/fusfpfail.pdf

the gate is only watertight while some rubber seals around it are inflated by a compressor.

According to this report by Daily Yomiuri Online:
http://www.yomiuri.co.jp/dy/national/T110428006723.htm

the reactor pit was flooded at the time and TEPCO thinks the explosion triggered a leak from the reactor pit to the SFP.

If there's water circulation between the SFP and the reactor pit then the hot spot on the thermal image could well be the location of the RPV, without there having to be any fuel in it.

Yes, but for example, unit 4 sfp is 80-90C from sensor data, from thermography sfp was for example 31C, this is not great computation but we can see that 10C from thermography = 30C from sensor, in some photos difference (Core location temp bigger) was 10C, so it would mean that when sfp was 80-90C, core location ~120C, this is big difference between core and sfp...

 

[joewein]

it would mean that when sfp was 80-90C, core location ~120C, this is big difference between core and sfp...

I'm not sure I understand what temperature data you're referring to, but an empty core can't be hotter than 100 deg C, especially when filled with liquid water at atmospheric pressure.

There is no way they could have left the core in there while they were cutting up the old shroud to replace it.

It was scheduled for refueling once the shroud replacement was done, but the fresh fuel for that was still in the fuel pool - the only fuel in the pool not giving off decay heat. That's why the fuel count was revised upward from an initial value of 1331 to over 1500, they remembered that was also there.

 

[tsutsuji]

Fourth and final section of the Asahi Shimbun report on the Japanese nuclear experience is here:
http://www.asahi.com/english/TKY201106100215.html

This part of the report deals with the earthquake and tsunami provisions, which were apparently mostly retrofitted after the plants were already built.
There is no editorial wrapup, which might have added some local perspective.
Overall, a very good series.

I am not sure if the following statement by the Asahi writer fits very well with the contents of the Japanese Government's report to the IAEA :

Both the earthquake and tsunami exceeded levels anticipated by the revised guidelines.
http://www.asahi.com/english/TKY201106100215.html

Compare with :

Incidentally, the Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor Facilities finalized in 2006 specifies in "8. Consideration for the event accompanied by an earthquake" that "During the service period of the facilities, safety features in the facilities [must not] be significantly affected even by such a tsunami that could likely to occur on very rare occasions," and the guideline asks for proper design for such a assumed tsunami.

IV-139 of http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/chapter_iv_all.pdf
([] is my own translation from page IV-111 http://www.kantei.go.jp/jp/topics/2011/pdf/04-accident.pdf , changing "might not" into "must not")

Compare also

In February, the subcommittee held discussions on the Jogan Earthquake of 869
http://www.asahi.com/english/TKY201106100215.html

with :

Regarding this, NISA requested TEPCO at the 33rd Joint Working Group (July 13, 2009) to take into account the Jogan earthquake for evaluating design tsunami height when new knowledge on the tsunami of the Jogan earthquake is obtained.

III-31 http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/chapter_iii-2.pdf

The Jogan earthquake is presented to the Asahi readership as a problem emerging in February 2011, while the Japanese government tells us that it was raised as early as July 2009.

Asahi's "Behind the myth" series was published in 8 instalments in the Japanese language paper version of Asahi Shinbun. http://www.asahi.com/english/TKY201106100215.html is an English translation of the 8th one published on June 1st. Perhaps it is already becoming a bit outdated as the Japanese report to the IAEA was published on June 8th.

Obviously TEPCO underestimated the elevation needed to protect against tsunamis, but they did at least consider the issue in advance.

I agree. See also :

...in the application document for establishment permit, subject tsunami source is Chile Earthquake (M9.5 in 1960) and the design basis tsunami water level is 3.1 m. In 2002, TEPCO evaluated (...) assessing Fukushima-oki Earthquake (M7.9 in 1938) (...) and the highest water level of each Unit was set as 5.4 to 5.7 m. According to the evaluation, elevation of Unit 6 sea water pump motor for emergency diesel generator was raised up 20 cm and also that of sea water pump motor for High Pressure Core Spray was raised up 22 cm.

III-31 and III-32 http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/chapter_iii-2.pdf

 

[htf]

If there's water circulation between the SFP and the reactor pit then the hot spot on the thermal image could well be the location of the RPV, without there having to be any fuel in it.

The whole story is puzzling! I don't see any reason why they should have fuel in the RPV. But we see these hot spots. If it is water circulating between the RPV and the SFP why do we these delimited hot spots within the circle. Shouldn't the whole circle be an equally warm area? If it is from irradiated parts of the reactor then I can't believe that there is water in the RPV. How could parts get so hot when covered with water?

 

[etudiant]

Thank you, Tsutsuji, for the incremental perspectives.

A more complete story of the decisions made and the warnings not heeded gradually emerges.
It will be interesting to see the Japanese community's eventual response.

 

[Bioengineer01]

Thank you, Tsutsuji, for the incremental perspectives.

A more complete story of the decisions made and the warnings not heeded gradually emerges.
It will be interesting to see the Japanese community's eventual response.

More than warming not heeded, the explanation is different, it is a common regulatory practice, even in the USA of not defining in hard numbers the limits when those are known to be too high due to cost considerations and leaving the decision making to Industry, fully knowing that they will be forced to compromise. The problem with NP is that the final liability is taken by taxpayers, differently from other industries.

 

[Bioengineer01]

"TEPCO did the test run of the contaminated water processing facility by Areva at Fukushima I Nuclear Power Plant, and found leaks in more than 10 places."
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-system.html

 

[Bioengineer01]

Reactor 3 Bldg RadiationSource: TEPCO press conference June 10.

5 TEPCO employees, 4 from affiliate companies entered the reactor building to prepare for nitrogen injection into Containment Vessel. In 30 minutes, surveying ~half the floor, got exposed to 5.88 to 7.98 millisieverts

96 millisieverts/hour radiation at the staircase going down to the basement, at the southwest corner blue print at llink.
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-reactor-3-bldg_10.html

 

[etudiant]

More than warming not heeded, the explanation is different, it is a common regulatory practice, even in the USA of not defining in hard numbers the limits when those are known to be too high due to cost considerations and leaving the decision making to Industry, fully knowing that they will be forced to compromise. The problem with NP is that the final liability is taken by taxpayers, differently from other industries.

Interesting insight into the regulatory system. Illustrates the process of regulatory capture to perfection.
If imposing the proper standard would kill the project, (as well as the need for the regulators), just fuzz the requirement to what is commercially viable.
Also interesting that the final liability is with the taxpayer no matter what the regulatory structure. Japan has no Price-Anderson Act, but the government is paying compensation for the TEPCO accident anyways.

 

[thehammer2]

"TEPCO did the test run of the contaminated water processing facility by Areva at Fukushima I Nuclear Power Plant, and found leaks in more than 10 places."
http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-arevas-system.html

This story is of precisely zero importance.

In the process and related industries, when a unit is new/repaired/modified/etc., one of the things you do is to run a hydrostatic test with just plain water (or a compatible fluid if water is not compatible with the process going on inside the unit). This test is SUPPOSED to find the leaks and all the little gremlins in the system. You run the test, you fix what you find, and you repeat until you run the test and the system holds. Then, you introduce the process to the system. It's how you ensure that what's supposed to be on the inside stays on the inside and what's supposed to be on the outside stays on the outside.

Nuclear is just a process industry with WAY more rules. This is completely normal in a new unit or process.

 

[Quim]

I would agree so far, except ...the RPV had been breached several hours earlier......

No matter Jorge, as long as we are in agreement that there was a path between the RPV and the drywell we have no differences here.

There may be some confusion here. AFAIK the concrete shield plugs are meant to block radiation only, not pressure. They may be octagonal in other reactors, but in #2--#4 all drawings indicate that the opening of the refueling pit is round and the plugs are three disks, 1--2 feet thick, each cut into two halves (presumably so that they can be more easily moved and stacked on the cramped service floor). AFAIK those plugs are held in place only by their weight.

This is another trivial divergence, but I was under the impression that the original GE design had a round hole at the top and at Fukushima they had used an octagonal design - I probably got this from T-Cups' post #649 on page 41.

There were a number of design considerations for the secondary containment structure; it was meant to shield radiation, but it was also meant to be able to ward off at least medium sized aircraft or debris from tornadoes etc.

Another of it's qualities obviously was to seal the drywell from the rest of the building (which was at a negative pressure.)

In an earlier post it was disclosed that a GE mark I had been subjected to a real life pressure test and it had leaked at something like 60 psi. The report or the post about that implied that it had "failed" at 60 psi.

When I said that the Fukushima design may have held to 125 psi I was trying to avoid that apparently controversial subject, but it appears that I found another aspect to be controversial about.

Sorry for the lack of detail.

At those temperatures and pressures, any oxygen that remained in the drywell from before the breach or that was generated by radiolysis/thermolysys should have been promptly consumed by the excess hydrogen, before it could buid up to an explosive concentration. But maybe not.

This point lies at the heart of the matter IMO and I would love for one of our forum chemists (or physicists) to chime in with an opinion.

When I describe "flashovers" I believe I am describing the exact process described by "(oxygen)should have been promptly consumed by the excess hydrogen"

I did not do the math, but pesumably a massive leak of steam at 60 psi (400 kPa) into the refueling pit could have lifted the shield plugs, enough to let that steam escape into the service storey --- unless it found some easier way out.

What I was attempting to describe is a process whereby hydrogen had been seeping out of containment and was building up in the building above before any "massive leak of (hydrogen laden) steam" occurred.

However, I do not see how a sudden reduction in pressure (which would have cooled the steam) could have caused it to explode. Everything I see in the wreck suggests that the explosion happened some time after the H2 began to escape -- enough time for it to flow down to the 4th and 3rd storeys and mix with the air. I would rather believe that the steam leaked ignited the colder H2+O2 mixture that was already there, just with for being hot.

Hydrogen is lighter than air, it would not flow "down."

According to the floorplans, he "cattle trough" that leads to the SFP (through which steam may be still leaking) is very narrow and short. The gate on the opposite side, to the dryer storage pool (through which steam is definitely still leaking) is as wide as the storage pool. I do not see either as being able to vector the steam significantly upwards.

But steam had been accumulating above the trough also. And I had hoped to be painting a picture of hydrogen accumulating in the trough before the explosion.

The head bolts *of the RPV* probably held fine, since the bottom had already been breached so the RPV was at ~400 kPa instead of its normal ~6500 kPa.

Again, I was just trying to head off what I see as an extraneous argument.
I probably should not have mentioned the headbolts.

But for this scenario we need a path for the steam to get from the drywell to the refueling pit.

I left off before the explosion had progressed that far.

Neither do I. I suppose that both gates (to the SFP and to DSP) were closed, and that there was no water in the SDP or in the refueling pit at the time of the explosion.

Well, we agreed on something!

 

[Atomfritz]

Neither do I. I suppose that both gates (to the SFP and to DSP) were closed, and that there was no water in the SDP or in the refueling pit at the time of the explosion.

Well, we agreed on something!

Maybe you are both wrong?

These seals are not watertight, as Christian Mueller explained in the document Joe linked at in his https://www.physicsforums.com/showpost.php?p=3350807&postcount=9598"?
Unclear yet is, how much water could leak when the inflated rubber seals lost their pressure when the compressor's electric supply failed?

The whole story is puzzling! I don't see any reason why they should have fuel in the RPV. But we see these hot spots. If it is water circulating between the RPV and the SFP why do we these delimited hot spots within the circle. Shouldn't the whole circle be an equally warm area? If it is from irradiated parts of the reactor then I can't believe that there is water in the RPV. How could parts get so hot when covered with water?

Maybe because water cools down in the RPV, compressing/getting more dense, and so the RPV as a heat sink sucks up the hot water circulating over from the SFP?
Sort like the gulf stream going north, being sucked to there by the cooling-down and falling water masses there?

Maybe there are some "interesting water dynamics" in the other reactors' pools also?

(Just the 2 cents of an annoying layman...)

 

[htf]

Well, but why are these spots in the RPV the hottest points on the whole image? If the RPV is full of water this would mean that there are powerful heat sources located at this place that can maintain a temperature gradient. Can irradiated reactor parts generate so much heat? I am not an expert but I hardly can imagine thas.

Or is the explanation quite simple: was the picture taken before the gates started leaking?

 

[jim hardy]

So are we looking down into the vessel with that IR photo, or are we seeing hot water & steam at surface of pool?

 

[triumph61]

http://ex-skf.blogspot.com/


"In the first photo, you can see the pipe that's bent. That was the pipe that TEPCO was counting on to connect the cooling system for the Spent Fuel Pool, according to Jiji News (6/11/2011). The cooling system for the Reactor 4 Spent Fuel Pool won't be operational at least until July, as TEPCO will have to either fix the pipe or come up with alternative connection.

The second photo shows a mess of broken pipes, concrete bits and equipments. Any mechanics, engineers, who want to dissect the photo?

The Reactor 4 was in a scheduled maintenance when the earthquake hit on March 11. All the fuel rods had been moved to the Spent Fuel Pool. The workers were in the process of replacing the stainless-steel shroud of the Reactor Pressure Vessel at the time of the earthquake."

That means: The RPV was empty, no Water in the RPV at the time of the Earthquake

 

[Quim]

Well, but why are these spots in the RPV the hottest points on the whole image? If the RPV is full of water this would mean that there are powerful heat sources located at this place that can maintain a temperature gradient. Can irradiated reactor parts generate so much heat? I am not an expert but I hardly can imagine thas.

Or is the explanation quite simple: was the picture taken before the gates started leaking?

As I understand it, unless you have calibrated the infrared camera to some standard of sensitivity and heat spectrum a photograph like that one is meaningless.

 

[Joe Neubarth]

http://ex-skf.blogspot.com/


"In the first photo, you can see the pipe that's bent. That was the pipe that TEPCO was counting on to connect the cooling system for the Spent Fuel Pool, according to Jiji News (6/11/2011). The cooling system for the Reactor 4 Spent Fuel Pool won't be operational at least until July, as TEPCO will have to either fix the pipe or come up with alternative connection.

The second photo shows a mess of broken pipes, concrete bits and equipments. Any mechanics, engineers, who want to dissect the photo?

The Reactor 4 was in a scheduled maintenance when the earthquake hit on March 11. All the fuel rods had been moved to the Spent Fuel Pool. The workers were in the process of replacing the stainless-steel shroud of the Reactor Pressure Vessel at the time of the earthquake."

That means: The RPV was empty, no Water in the RPV at the time of the Earthquake

But there could be debris in the reactor.